Group Project - New 2 Stroke Engine or Other???

[ARC250R]

Hey All,

So I have read and seen lots of discussion on people’s interest in bringing parts back to production, along with investment in production of new aftermarket and many more ideas along these lines.

Along with this one of the main threads has talk of engine cases getting built again (lots of interest it seems) and talk of people saying they would love a large displacement balanced 2 stroke engines. (I was wondering is this a general consensus?)

Anyways to my point all this stuff seems like a great idea but its so difficult to get it started as one person or to back it up with funds, so my Idea is why don’t we start a group project on it. Kind of like open source programs or similar. Do you think its possible we could all work on literally making our own engine design? (Just one possible idea) I am an aerospace engineer and would love to use my skills to “bring the 2 stroke back to life to speak”. Some people on here know porting like the back of their hand, some have probably seen every performance 2 stoke engine on earth. The list goes on. And the thought is we work on this as a team and everyone basically gets a blue print when were done of how to make the bad boy.

To make it realistic we can combine components readily available, transmission, crank, cylinder ect. And make a few parts custom, most likely cases and some other bits to get it all together, bring it to the modern age with fuel injection (a simple task with things like “megasquirt” ecu these days – its running my Silverado). If nothing else we could design cases for a balanced modern 250

I know there will be much to do and many challenges but I wanted to put the idea out there.... Lots of us on here have skills we build atvs we have the nack, we could take it to the next level, think of the pride when its done. I think we have the capability to make it happen....

So what does everyone think?


And other suggestions or topics alike very welcome!

Cheers,

[jcs003]

i sort of see where you are going with this. whats the best bore/stroke combination to fit most type and style of rideing.

what transmission gear ratios are best suited to the engine's performance type. who prefers 5 or 6 gears.

of course, crankcase design is a large factor in an endevour like this.

i will assume 300cc would be ideal.

trx250r geometry frame/chassis is the only way to go.

[CorvetteZ06]

Originally posted by ARC250R
Hey All,

So I have read and seen lots of discussion on people’s interest in bringing parts back to production, along with investment in production of new aftermarket and many more ideas along these lines.

Along with this one of the main threads has talk of engine cases getting built again (lots of interest it seems) and talk of people saying they would love a large displacement balanced 2 stroke engines. (I was wondering is this a general consensus?)

Anyways to my point all this stuff seems like a great idea but its so difficult to get it started as one person or to back it up with funds, so my Idea is why don’t we start a group project on it. Kind of like open source programs or similar. Do you think its possible we could all work on literally making our own engine design? (Just one possible idea) I am an aerospace engineer and would love to use my skills to “bring the 2 stroke back to life to speak”. Some people on here know porting like the back of their hand, some have probably seen every performance 2 stoke engine on earth. The list goes on. And the thought is we work on this as a team and everyone basically gets a blue print when were done of how to make the bad boy.

To make it realistic we can combine components readily available, transmission, crank, cylinder ect. And make a few parts custom, most likely cases and some other bits to get it all together, bring it to the modern age with fuel injection (a simple task with things like “megasquirt” ecu these days – its running my Silverado). If nothing else we could design cases for a balanced modern 250

I know there will be much to do and many challenges but I wanted to put the idea out there.... Lots of us on here have skills we build atvs we have the nack, we could take it to the next level, think of the pride when its done. I think we have the capability to make it happen....

So what does everyone think?


And other suggestions or topics alike very welcome!

Cheers,

Really cool idea! :cool: As someone stated above, I also think a powervalved 300cc 2-Stroke is ideal for engine size (for all around riding mx, xc, etc..) a counterbalanced 500cc for all those dune/drag guys who still want a CR500 powered quad. Fuel injection would be great!! Something with the most modern/efficient port design, light weight materials, etc..

[YFZ_Racer42]

I would take a counter balanced 05+ YZ250 engine that fits bolt on in a 250r chassis anytime...

[troybilt]

Originally posted by jcs003
i sort of see where you are going with this. whats the best bore/stroke combination to fit most type and style of rideing.

what transmission gear ratios are best suited to the engine's performance type. who prefers 5 or 6 gears.

of course, crankcase design is a large factor in an endevour like this.

i will assume 300cc would be ideal.

trx250r geometry frame/chassis is the only way to go.

Just a knee jerk reaction, but I think the CR500 is the way to go. You could sleeve one down to 300 or 350 and/or the drag guys can go up with it too. The transmission would not need to be cryo'd or anything, etc..

Basically if I was designing a motor with what I know today here's how I'd do it, I could be talked into any other motor, YZ, etc...:

1. CR500 bottom end, with counter-balancer, or weighted flywheel, but converted to have the trx250r frame mounts so it bolts into all of our frames, Laeger, OEM, etc...
2. Optional trx250r top end - utilize all the after market cylinders/heads with PV out there, Can also use the stock CR500 cylinder setup for cheaper options...
3. E-start option for us older guys with bad knees... :D
4. forward kick (Service Honda has a conversion for CR250's)
5. If you go EFI, it needs to be closed loop direct injection like Orbital, why not prove that 2 strokes can have less emissions too... lets give the 4 strokes the proverbial finger!! (you need access to a dyno to figure that all out)
6. I've always wanted to reverse the cylinder 180 degrees so the exhaust faces the rear of the bike, and to get more efficient pipe configurations

And my simple mind's approach it wouldn't be too difficult to design a set of cases.
1. I'd scan in a set of trx250r cases to get good models to use (~$2500, I've already quoted them...)
2. I'd scan in a set of CR500 cases (~$2500)
3. This where the engineering comes in, you could modify a. the CR cases to insert a counter balancer, or b. the trx250r cases to insert CR500 components. (just engineering time...)
4. Casting patterns - ($8000 ea) already quoted with a supplier
5. Quoted me rough castings at around $150 per unit, still need to be machined (~200 per side)
6. NEXT ENGINE has a slick scanner that can be purchased for 3000, which would do everything we need. I'm thinking of getting one and pushing back my Laeger build... with my tax return money... :)

All it really takes is money. I just have a hard time dropping 20 grand to design a set of custom cases when I don't know if they'd sell or not and make my money back. Not looking to retire, just recoup the original 20 grand and get a couple sets for myself.

[vroomy]

well i for one would definitely buy a counterbalanced CR500 motor, as right now im considering building a Cr500 trx but im hung up on this vibration problem

[wilkin250r]

A reverse-facing exhaust might not work as well as you think. You might be able to adjust the stinger length a little bit, but the rest of the dimensions on the pipe are going to be pretty consistent. That's a LONG dimension to push straight out the back of the quad.

[troybilt]

Originally posted by wilkin250r
A reverse-facing exhaust might not work as well as you think. You might be able to adjust the stinger length a little bit, but the rest of the dimensions on the pipe are going to be pretty consistent. That's a LONG dimension to push straight out the back of the quad.

I've already modeled some mockup pipes, and I corkscrewed it to get the length I needed. Not saying its perfect, but so far seems manageable, it may be more trouble that its worth but an interesting project. ...Similar to the tornado pipe on the 2011 YFZ 450 dirtbike.

[troybilt]

I was also considering other options for manufacturing the pipe. As it turns out there is ways to make exhaust out of Carbon Fiber by applying a high temp coating to absorb the heat at the cylinder outlet. In fact, the nozzles on a space shuttle are made from Carbon fiber. Also Formula one cars use it too. Just an idea worth considering...

[250Renvy]

As a group project the people who are interested would seriously have to be interested and willing to pony up time or money for it.

I think if people added what knowledge they could bring to the table or who they know that could add knowledge - for example engineers are key and access to prototyping/research facilities.

KTM's are more expensive, but I might be able to find a connection to the factory to find out, if we design it, will they build it? They are IMO the best option for bike conversion. The new 2011 KTM300 has electric start and 6 gears, hydraulic clutch, autoclutch as well as powervalve and 250cc option.

I would love to see a reverse gear added - either mechanical (preferred) or possibly CDI.

I think if you look into GasGas' design for the quad you may have an idea of what you are looking for, for the difference size displacements. In the same motor, they had options for 200cc to 300cc just by changing bore size and stroke.

[rablack21]

I wonder if it would also be worth talking to Can-Am. They are leading the way in 2 stroke technology right now. I don't know if it was true or not, but the rumor was their DS 450 was supposed to be a 300cc 2 stroke instead. They have some amazing technology tied up in their direct injection powervalve 2 stroke sleds. I wonder if we could talk them into helping us put together a 300-350 pv direct injection motor that will fit the 250r frame. I would shell out some money for that! Seeing that Honda has no interest in providing us with parts for any of our 250rs anymore, perhaps we should consider working with a company who is still interested in 2 strokes.

[YFZ_Racer42]

Interesting rumor... I live at 45 minutes of their factory in Valcourt, and someone that work for them is coming to our home tonight for a little friend meeting, I'll ask her if she know something about it...

[rablack21]

Regardless of whether the rumor was true or not, the company still knows alot about 2 strokes. It might be worth investigating to see if they would be interested in helping us out.

[derby]

ESR will produce the cases.
Billet trannys are being made for drag configuration why not a stock configuration?
Instead of ditching everything we currently have why not work with the best cylinder designer in the world cpindustries?

[ARC250R]

Some great ideas coming in here, Keep them coming lets do lots of brain storming, get lots of ideas on the table...

(I never thought of just getting a large group saying this is what we want and going to a large company and saying here we will buy it "Make It!" In laymens terms who knows this could work....)

I'm going to focus on the heart of this sucker for a bit and say everyone post up ideas for cylinders or injection technology (you can post other items too this is a no limits thread), try to keep it as stated before things we can almost "just bolt up" with some machining and quick engineering design (don't suggest we design a entire fuel injection system as this is out of the scope of this project I believe) get my drift? But it can be off of anything just get ideas on the table.

So,

Sleds have been progressing in two stroke technology like crazy for example take a look at this sucker.

Rotax 600 High Output E-TEC two-stroke

It uses a short-throw direct injection design that pushes fuel at 500 psi directly into the chamber with a small plunger, I think this is the direction to go for fuel delivery with a new two stroke and its compact no fuel pump ect.

But I get the feeling that ESR, cpindustries and dirt bikes design are still kicking the crap of sleds in porting design and sleds need a larger life expectancy I,m sure so performance is most likely lower. Can anyone confirm this? Take apart your Sled now and look at the ports! :blah:

My thoughts at the moment are we make a Head to bolt this puppy onto a ESR cyl or whatever cylinder we pick and using this pre built technology means that's one major step completed.. its also in the right range with 300cc cylinders. and we can produce a race gas head and pump gas head for all.



Anyways that's the thoughts of the day

Cheers,

[troybilt]

Where is the spark plug on that bad Larry?

[rsss396]

Originally posted by derby
ESR will produce the cases.
Billet trannys are being made for drag configuration why not a stock configuration?
Instead of ditching everything we currently have why not work with the best cylinder designer in the world cpindustries?

I agree!

[ARC250R]

Originally posted by troybilt
Where is the spark plug on that bad Larry?

I think its compression is over detonation and it lites up when it fires a fuel charge in... its like a diesel engine crazy eh never knew this stuff was already being done

[troybilt]

That's crazy! I didn't know they did that on 2 stroke gas motors... interesting. I'll have to read up on it.

[troybilt]

Originally posted by derby
ESR will produce the cases.
Billet trannys are being made for drag configuration why not a stock configuration?
Instead of ditching everything we currently have why not work with the best cylinder designer in the world cpindustries?

How much does a billet drag tranny cost? How much is a CPI cylinder?

[wilkin250r]

There have been complete aftermarket two-stroke motors (like the Black Widow Redhead engine), and they never really took off. Price might have been the biggest obstacle, I'm not sure.

Personally, I only see two options that would be widely popular. First, developing the technology for direct-injection and bringing the 2-strokes back to the market.

Second is the only direction I would ever take with any engine design is to get a counter-balanced CR500 motor. I don't know the specs, but I imagine the Black Widow engine was a better design, but it just doesn't have the notoriety that the CR500 motor has.

[woodsracer144]

what about like a ski doo motor, single cyl verson of their sled to get liek a 300CC and then make it a auto? I think that would be kinda cool... be just like riding a sled. clutching i think would have to be made a little smaller.. or somthing but just a idea.

[Derrick Adams]

I'm with the majority here. I would definately like to have a CR500 counter balanced engine. I think the current 300cc range engines are refined pretty well. But I can always detune the 500cc.

[derby]

Originally posted by troybilt
How much does a billet drag tranny cost? How much is a CPI cylinder?

Right now the drag billet tranny's complete are a little over $1000 but there is also a really small market for those (different ratio and override). CPI spinx with powervalve was $875 unplated so add another 190 after you get portwork. Pumas are about $1100 unplated. I bought my saber topend for $899 unplated.

The sled motors are amazing but remember you have a big a manufacture behind them as well. Some of those sleds are getting over 200hp on pump gas. But even power like that comes at a cost, $13,000 for a sled.

A more economical idea would be to have r&d on a cylinder like a sphinx with a powervalve. Especially because those motor on stock stroke would be in the neighborhood of 340-350cc and we could still use the pipes, carbs, ignitions, reed cages that have already been perfected.

While a 500cc motor sounds like a dream...... my 431 is a pain in the ***** to start even with a cr250 ignition. Now you get into 500cc with 15:1 comp and you better have electric start. I had a cr500 and it was mostly pull started because no one could kick it. Not only that a cr500 motor in a 250r would be lucky to pull 45hp stock. Just a few thoughts.

[troybilt]

Originally posted by derby
Right now the drag billet tranny's complete are a little over $1000 but there is also a really small market for those (different ratio and override). CPI spinx with powervalve was $875 unplated so add another 190 after you get portwork. Pumas are about $1100 unplated. I bought my saber topend for $899 unplated.
s.

Thank you!

I guess my pipe dream is:

58-60 hp, reliable, and I mean MX or Desert racing type reliability, I want to build it and forget it.
must be 2 Stroke
Parts readily available off the shelf
Bolts right in to my 250r frame
Must be lightweight

would prefer Honda...

Other than that, I'm not too concerned how I get there. Too me I think the best solution is a "CB'd" CR500 or CR250 type motor, but I'm open to all kinds of options... converting a trx250r motor to run CR gears, clutch, crank... is a possibility too, via new designed cases... Direct Injection and other stuff would marketing features. I always believe start simple and work from there.

[troybilt]

To ease starting the big CR, could you add a compression release?

[derby]

Originally posted by troybilt
To ease starting the big CR, could you add a compression release?

Its an idea.

[sangheraent]

Im not an engineer, but wouldn't the simplest method be to scan a set of Cr500 cases and find a way to add on a counter balancer?

that way all you would have to do is buy a cr500 motor and the special cases with the counter balancer.

My guess would be the kit would include:
-a set of cases
-new clutch gasket or case gasket depending on which one is alterd
- counter balancer with bearings
-gear or chain to sping the counter balancer. (like a cam chain off of the crank gear?) with a chain I am thinking you can put the counterbalancer anywhere like up front under the pipe?

Like I said not an engineer

[ARC250R]

This has cross my mind too,

knowing the weight of the piston, con rod, flywheels and the off balance, and having cad of the cases it would be quick work to make up a design for it.

If most people start saying a counter balanced CR500 is the ultimate 2 stoke, I'm in for making a design for cases for one, and while were at it we can make the engine mounts fit 250r frames, if we got stupid lucky perhaps we can make a design that picks up 450R and 250R engine mounting points that would be a instant hit then.






Originally posted by sangheraent
Im not an engineer, but wouldn't the simplest method be to scan a set of Cr500 cases and find a way to add on a counter balancer?

that way all you would have to do is buy a cr500 motor and the special cases with the counter balancer.

My guess would be the kit would include:
-a set of cases
-new clutch gasket or case gasket depending on which one is alterd
- counter balancer with bearings
-gear or chain to sping the counter balancer. (like a cam chain off of the crank gear?) with a chain I am thinking you can put the counterbalancer anywhere like up front under the pipe?

Like I said not an engineer

[ARC250R]

Sure could,

its quite standard to have a "pop" decompression on RC 2 strokes, as soon as the cylinder pressure increases from a actual firing it pops shut...



Originally posted by troybilt
To ease starting the big CR, could you add a compression release?

[ARC250R]

How available are cr500?s and parts? isn't this a dieing breed too?

[YFZ_Racer42]

The last production year of a CR500 is 2001, so if you want to put some times in design, I would definetly use an engine that is still in production or no longer in production for the last 2-3 years like the CR250, not 10 years because in not much time we'll have the same problem... parts will start to be discontinued.

For the HP, the RM250 of Carmicheal in 2005 was around 58 HP...(I think the cc limit was at 285cc) so you don't need the big 500cc to have alot of power...

In my opinion, a 300cc PV would be the best!

[derby]

Originally posted by YFZ_Racer42
The last production year of a CR500 is 2001, so if you want to put some times in design, I would definetly use an engine that is still in production or no longer in production for the last 2-3 years like the CR250, not 10 years because in not much time we'll have the same problem... parts will start to be discontinued.

For the HP, the RM250 of Carmicheal in 2005 was around 58 HP...(I think the cc limit was at 285cc) so you don't need the big 500cc to have alot of power...

In my opinion, a 300cc PV would be the best!

Pro design has d/c the coolhead on these motors about 5 years ago. So everyone will need to add that to the list so you can have domes cut for specific setups.

[quad janern]

Cool read guys! Let the ideas comming!

Why not contact this guy:) ?

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[C41Xracer]

instead of going a whole new direction make some parts that are really needed and arent going to cost an arm and a leg.............gears and internal parts. ESR is planning on making cases and there are cylinders being made. One option i would like to see is fuel injection. The price is a killer though, i looked at a kit and the 2k pricetag is steep.

a newer replacement engine would be great too, i like the cr250 idea but would need to be a drop in replacement for the R motor

one other thing that would be good is a crank that doesnt have problems like ive been hearing about a few manufactures

[rablack21]

Originally posted by YFZ_Racer42
The last production year of a CR500 is 2001, so if you want to put some times in design, I would definetly use an engine that is still in production or no longer in production for the last 2-3 years like the CR250, not 10 years because in not much time we'll have the same problem... parts will start to be discontinued.

For the HP, the RM250 of Carmicheal in 2005 was around 58 HP...(I think the cc limit was at 285cc) so you don't need the big 500cc to have alot of power...

In my opinion, a 300cc PV would be the best!

I am worried about this also. Don't get me wrong, a cr500 motor be awesome! I just don't want to get into the same situation we are in now a few years down the road.

ESR does have up to a 431cc cylinder though. So you can almost make a cr500 with what we have now.

Right now, with ESR and Pumas and CPI and whatever else, we can make our 2 strokes as big as we want. What we really need now is cases and internals.

I think it would really be worth a shot to either make cases to fit cr250 internals or to make parts based on a current production 2 stroke. We have to base our decisions on readily available parts. Even though cr 250's are readily available, keep in mind that Honda has also stopped making them, and they have no plan to start them again. Sometime, those parts could dry up also. It would probably take a while though. Just throwing these thoughts out there.

[woodsracer144]

I like your ideas on the Cr internals and stuff but how do you know that those gears are strong enough. they were meant for the bike not a quad. so if you take the stock gears and then put them in a quad chassis then add more Hp to the combo i think you'll be asking for somethings to break. I think the Cr250 motor is the best bet. I would also like to see the reed cage down in the cases and not on the cylinder. If you would play your cards right in my mind you would be able to run on the lean side from the oil getting right to the crank. but i may be wrong to.

honda doesnt make any 2-stroke rockets for racing do they? i know suzuki made a 500 CC 4 cyl that was a race only bike.


what if you had a external c.b. something that would be a bolt on thing that ran with the motor could be by belt off the fly wheel side...

I talked with the guy that build the Kawi motor when they were in the roll chassis and he had the cranks ballanced. and tuned the motor so the max Hp was at a lower rpm. Bill ballance didnt last long on them cause he revved the **** out of it all the time. where william rode more on the bubble. is the way he put it.

Im not sure if you could take metal off the crank or other parts to create less rotating mass or not.

[wilkin250r]

I'm not 100% familiar with the bikes, what options do we have for internals? Yeah, it would be nice to design something using parts currently in production, but I think our options are rather limited, aren't they?

[dlunn]

Is this project looking at it from the wrong direction? Would it be easier to design a frame that could handle the vibrations from a non counter balanced motor? If you could I would throw in KTM's 300 like 250Renvy mentioned. I would think the costs would be cheaper, you could design the frame to use all 250R components other than the engine and the overall investment in R&D would be cheaper. You could have a design that any of the major frame manufacturers could build.

I think Troy has talked about this before. Just something else to look at.

[woodsracer144]

Chassis may be the cheaper route but im not sure how you could build it to so it doesnt vib.

[troybilt]

Originally posted by woodsracer144
Chassis may be the cheaper route but im not sure how you could build it to so it doesnt vib.

Its not as hard as you might think... but I only know just enough to be dangerous with vibration analysis... I'm sure Honda has guys/gals with Ph.D's running modal analysis on their chassis designs. We do here at my job, anyway... All things vibrate, its just a a matter of managing resonant frequencies, which happen in several different "modes"... hence "Modal" analysis

It may not be possible to rid the frame from the vibrations posed from the cr500 motor totally, IDK, it would be worth the effort to check. Keep in mind, the original OEM frames were designed to manage the vibrations excited from the trx250r motor, not the CR500 vibrations, which are considerably greater... hey it may not be viable, but something to consider.

[ARC250R]

Just had a idea,

Wonder if anyone has ever made a electric counter balanced engine,

Pick up the ignition or a crank sensor and turn a stepper or other accurate indexed motor.

any elec engs on here? bet that's a tough one but possible...

[troybilt]

Originally posted by ARC250R
Just had a idea,

Wonder if anyone has ever made a electric counter balanced engine,

Pick up the ignition or a crank sensor and turn a stepper or other accurate indexed motor.

any elec engs on here? bet that's a tough one but possible...

Its certainly an idea. I've read about an exhaust system on one of the high dollar sports cars that used a device for lack of better word that would basically create noise that was used to muffle the exhaust without restriction. Since sounds waves at similar amplitudes but opposite phase cancel each other out. It was a cool idea.

[wilkin250r]

You could do that, IF you had an incredibly accurate crankshaft position sensor.

For a constant RPM, or even something near constant, you could just use a simple signal like the pulse generator. But that won't work for the rapidly fluctuating RPMs that your quad engine is going to undergo. With only one signal per revolution, it's extremely difficult to match the phase. In fact, it's entirely possibly to be dang-near 180 degrees off, actually creating MORE vibration. Instead of cancelling the vibration with the offset mass, you actually add to it.

Not to say it isn't possibly, but you'd have to add the crankshaft position sensor capability onto the crank, you can't use what's already there. And you also have the added weight of the motor, because you'll need a big sucker to be able to spin up that counterbalance as fast as you need it. And the cost is going to be really high, because large, accurate motors aren't cheap.

For cost, simplicity, and reliability, a gear-driven counterbalance is really the only way to go.

[troybilt]

All excellent points Wilkin..

In one of the older Dirt wheels articles, there is a reference to the GasGas 300 Wild prototype motor and mentioned the flywheel balancing they did to reduce the vibrations, cause for the prototype quad they used the GasGas 300 bike motor... Wonder how much you could effect that on a CR500 by adding or subtracing weight to the flyhwheel to reduce the vibrations... certainly not as good of a soluction as a gear driven balancer but might be another cheap and easy solution.

My other thoughts, if you research any of the import cars, esp the ones heavily modified for drag racing. They add torque dampners to those motors to reduce the vibration into the chassis Basically a gas filled shock that attaches to the motor and frame... since the stock motor mounts can't handle the vibrations of the increase torque and rpms... something else to consider.

[Dustin_Drews]

We know it exist... They are a smaller company in another country with out all of are stupid EPA laws! Smaller companys are usally more willing to work with groups of our size.
Plus allready counterballanced, have the reverse option and from what I have read almost bolt into a 250r frame. If we could talk to GASGAS and get them to commit to producing parts for them for a longtime while all the leg work is done and we would have 300cc powervalved 2 stroke with reverse!
Any thing I am not thinking of?
We just need the Aftermarket companys to get us exhaust... But I think 250r pipes will fit... Hmmm
God Bless,
Dustin Drews

[troybilt]

250renvy has one, he can comment on the compatibility. Its worth a try as well. ...except I'm a Honda nut.

[Dustin_Drews]

But if we could get engine kits for sale I think it would be easy to fab them in!
Call them the Buget racers engine!
God Bless,
Dustin Drews

[C-LEIGH RACING]

Why do so many want to go F/I when the ol carb is already perfected.

F/I will only drive cost up & make the unit more complicated to deal with & the whole idea with a 2 stroke to begin with is the simpleness of it.

Price, ease of use & market base.

I'm working on market base, much as I can with 2 strokes back in racing, but it is only in one sector, Extreme Dirt Track.

We are just before releasing the new ATVA EDT classes & the 2 stroke cc limit has been raised to 306cc.
265cc is gone, but again only in one sector of racing.
Neil

[Dustin_Drews]

Guys do not understand that carbs are much less finicky on a 2 stroke then 4 because of the speed of the air moving threw the engine it its basicly supercharged by the crankcase!
I would even say nay to the Estart then all you would need is a small stator to run the lights and cdi box. Plus that saves weight!
KISS
Most guys strip all the electical stuff off the newer quads now! Lets save them the greif...
God Bless,
Dustin Drews

[Dustin_Drews]

What is the cost of the typical 4 stroke? 2 grand?
If we our going to really have a market place we need to think of overal cost!
God Bless,
Dustin Drews

[profab250R]

I think the easiest way to reduce the vibrations of the cr500 engine would be to counter balance the crankshaft at the "fly wheel" Adding weight at the correct point would drastically reduce vibrations. THis would require the use of a dense and heavy metal to get the amount of weight needed. SOmething like lead but less malleable.

[Dustin_Drews]

I would think it would cause more poroblems it would cancel on vibraton but start another.
Tungsten is heavy and could be put inside the flywheel if it would work

[troybilt]

Its been done before and worked to some extent. The original prototype GasGas 300 quads used the dirt bike motors with a counter balanced flywheel. I've got the article to prove it. It doesn't mention what material was used for flywheel weight. Was similar to a harmonic balancer. I thought this would work too, but I don't have a CR500 to test it on. I doubt it would be perfect of course, but would dampen some of the vibrations... usually this method works to dampen the vibrations at a certain rpm range, not the full range... I don't know the full truth of that, that is my understanding from what I've read. i.e. you could drastically improve the vibrations at say 7000 rpm, but there would be no improvement for say 2000-4000 or something, same kind of philosophy as tuning an expansion chamber... again, I'd need to study that in more detail. But usually when you try to balance a rotating mass you try to create a vibration that is same amplitude but with a phase shift to cancel the vibrations... ...sorry for the long story.

Again all things vibrate, its just the low hz resonant frequencies that we have to worry about. One can live with a high hz frequency, its the low hz frequency resonance that causes stuff to fail or seat of the pants feel... stuff above 200hz ( I don't remember exactly the what it is), the human body cannot "feel" it. ...if that makes sense.

I'm not trying to be a douche or anything, but to do this correctly, there would actually need to be some studing of the vibrations actually measure them with an accelerometer and consequently conduct a complete analysis of the chassis. The "shade-tree" mechanic stuff can work but takes alot of expirementation, i.e. alot of failures => cost...

I know just enough of this stuff to be dangerous, I'm sure some of the other engineers on here have a better understanding of this, or are fresh out of "class" sort of speak. Its been over 5 years ago and previous job, since I was balls deep in vibration analysis....

[wilkin250r]

The problem with adding mass to the crank/flywheel assembly for counterbalance is that the piston moves up and down (one dimension) while the crank and flywheel moves in a circle (two dimensions). You reduce the up and down vibration, but you create a front to back vibration.

That's the beauty of a counterbalance. Because it spins opposite the crank, you offset half the piston weight with the crank, and the other half with the counterbalance. They add together up and down to offset the piston, but they're opposite each other back and forth, so they cancel each other's back and forth vibration.

If you try to do it all on one rotating assembly, you have nothing to offset the back and forth vibration.

[profab250R]

I know that it will not act like a counter balancer but like i said the "easiest" way of "Reducing" the vibrations would be to add weight to the fly wheel. The hardest part woud be to figure out the amount of weight needed and where the weight needs to be placed. probably just off of 180* from lower rod bearing center. dont know which side, but im betting the biggest vibration is not from the weight of the rod and piston however it is more a factor of resistance and friction from compresion and the friction of the piston in the cylinder.

[jcs003]

Originally posted by troybilt
Its been done before and worked to some extent. The original prototype GasGas 300 quads used the dirt bike motors with a counter balanced flywheel. I've got the article to prove it. It doesn't mention what material was used for flywheel weight. Was similar to a harmonic balancer. I thought this would work too, but I don't have a CR500 to test it on. I doubt it would be perfect of course, but would dampen some of the vibrations... usually this method works to dampen the vibrations at a certain rpm range, not the full range... I don't know the full truth of that, that is my understanding from what I've read. i.e. you could drastically improve the vibrations at say 7000 rpm, but there would be no improvement for say 2000-4000 or something, same kind of philosophy as tuning an expansion chamber... again, I'd need to study that in more detail. But usually when you try to balance a rotating mass you try to create a vibration that is same amplitude but with a phase shift to cancel the vibrations... ...sorry for the long story.

Again all things vibrate, its just the low hz resonant frequencies that we have to worry about. One can live with a high hz frequency, its the low hz frequency resonance that causes stuff to fail or seat of the pants feel... stuff above 200hz ( I don't remember exactly the what it is), the human body cannot "feel" it. ...if that makes sense.

I'm not trying to be a douche or anything, but to do this correctly, there would actually need to be some studing of the vibrations actually measure them with an accelerometer and consequently conduct a complete analysis of the chassis. The "shade-tree" mechanic stuff can work but takes alot of expirementation, i.e. alot of failures => cost...

I know just enough of this stuff to be dangerous, I'm sure some of the other engineers on here have a better understanding of this, or are fresh out of "class" sort of speak. Its been over 5 years ago and previous job, since I was balls deep in vibration analysis....

i see where you are going with this.

a dual mass flywheel is what comes to mind. the only problem is that a dual mass flywheel has to be "tuned" to match the engines power characteristics. i.e. torque curve and such.

say for example. you change pipes or porting you would have to make changes to the flywheel.