300ex Power??

[Tweeked]

hey i've got a few questions about the 300ex's power--

First off, whats the stock HP rating--and after adding a Pro Meg Slip on, K&N filter, aibox lid removed and rejetted--About how much HP and top speed will it be making?

one more thing--what does the 300ex redline at?

[300exazzkikr]

it comes stock with 17hp. After all those mods you might have 20-22hp, just taking a guess there. I believe it redlines at around 7-8 grand.

[Tweeked]

What all would I have to do in order to get around 28hp, would it cost a whole lot and would I be giving up on reliability?

Thanks

[swamprider7]

It definitely would cost alot. The reliability depends on who builds it and how it is built. You are better off putting a 350x motor in it. You will have close to those numbers and it will be cheaper and more reliable.

[Tweeked]

Where can I go about finding a used 350x motor, about how much would it cost, will it bolt right up--even the pipe without customizing it and are there mods availible for it such as pipes and stuff?


Thanks

[01TRX300EX]

I would check eBay first for 350X motors, I believe I saw a couple on there, but that was a few weeks ago. I just rode a 350X for the first time a week ago, it would make a huge improvement in the 300EX chassis. I hear it bolts right in with an exhaust mod, but I could be wrong.

[300exazzkikr]

A 300ex with a 350x motor rips period. It basically bolts up, you need to cut one motor mount by an inch and a half. Ebay would be the place to check, you need to get the cdi box also. You can get 400ex headers and "bend" them slightly to make it fit and just get a silencer. 350x motors are 6 speeds, just food for thought and full of torque.

[Tweeked]

Thanks for the help guys,
Heres my delima. I'm going to pick up a '95 300ex this weekend from a guy whos selling it to me for 800. The reason its so cheap is the guy said some of the parts were in rough shape--He also mentioned the enigne had a clicking noise. I'm trying to decided wheather to keep that engine and mildly modify it or--save the money i'd use to modify and get the valves and stuff fixed from tapping and buy a 350x Motor. This will be my first big project quad so I'm wondering if it would be over my head to change the engine. I'm pretty mechanicly inclined so i'm sure I could do it--I just don't want something always breaking on me and end up having to swap back, mod the original enigne and fix the clicking valves.

So, I come to you guys for some advice, I am very interested in doing this swap because it sounds like a VERY easy swap and in turn will give gobs of power. When you say "bend" the head pipe some, about how much--Is it something I could do by bolting it on, then with my hands or a rubber mallet bend it some? I also have a plummers torch, would it work better if I heated the pipe, then bent it? Now with a 400ex header on there, will the silencer just slip on and bolt up? One more thing, where exactly do you have to shave off an inch or so on the mount and is it easy to do?

A really apriciate all the help guys. Thanks

[stroked300ex]

heres a great idea. Strip the 300ex down, powdercoat the frame grey/black,
buy lonestay a-arms +2, buy a durablue axle +2, buy razrs all the way around, keep the motor a ex.. dont move to a 350x.. if you are gonna go into the engine @ all.. u just need to go ahead and make it a powerhouse... do some porting and polishing.. bore it, adjust the valves, and bigger compression piston. If ur gonna buy a whole new head for it.. start the shaving :p.. trust me.. i have done everything there is to do to a 300ex and mine will top out faster than a 500 predator.. they are bad. FUll bore plastic of maier. other various things.. XC or MX the dang thing! lol.. good luck man.. later

[300exazzkikr]

So, I come to you guys for some advice, I am very interested in doing this swap because it sounds like a VERY easy swap and in turn will give gobs of power. When you say "bend" the head pipe some, about how much--Is it something I could do by bolting it on, then with my hands or a rubber mallet bend it some? I also have a plummers torch, would it work better if I heated the pipe, then bent it? Now with a 400ex header on there, will the silencer just slip on and bolt up? One more thing, where exactly do you have to shave off an inch or so on the mount and is it easy to do?

A really apriciate all the help guys. Thanks [/B][/QUOTE]


you could "bend" it with a hammer or whatever, you can probably even do it with your hands. The rear mount on the motor that has to be cut about an inch an a half so that the chain lines up, i did it with a hack saw. :macho

[Tweeked]

Thanks for the help,
I think the 350x conversion would be allot less exspencive. Plus i'm on about a $900 budget, that means I gotta replace the seat cover, plastics (i'll probly go with 400ex plastics cause they're way cheaper), possibly sprockets and stuff. Leaving me with about 600 bucks max to do the convertion, is that possible? I'll get the motor then buy the mounting kit and instructions from Powroll and go from there. How much did it cost you to do you convertion?


Thanks

[300exazzkikr]

I did the conversion for my friend, He paid about 800 for everything..motor, exhaust, cdi..etc..You could probably do it for 600, just gotta look around. It's not a hard conversion to do. good luck, you'll like it.

[Tweeked]

Thanks,
I hope everything works out, it would be a Kick ***** convertion. I just checked ebay but there was only one 350x engine on there and its like brand new so its going for 9-- something.

two more things, Can I used the 300ex Wiring harness and/or the CDI unit for the 350x, or are they totaly different? And will the 300ex Carb work fine as well?

Thanks again

[300exazzkikr]

you need a 350x carb and cdi

[300exazzkikr]

I think you could put a 400ex carb on their also, if you can't find a 350x.

[Tweeked]

Why wouldn't the 300ex carb work? Its a 32mm whereas the 350x is a 31mm, or is that not the problem? So all the things I need are the Carb, CDI unit, Engine(does the oil pump and oil cooler usualy come with the engine?), and then the mounts and instructions from Powroll, will I also need the wiring harness?


Thanks

[300exazzkikr]

good question about the 300 carb, not really sure. i guess you could try it. The oil pump is within the motor, the cooler should come with the motor that you buy, if not i just bought one off of ebay for 10bucks, so no biggie there. As far as the wireing harness, i don't remember if it will work or not, you could do a search on the web. Definitely need the CDI.

[Tweeked]

Ok, Thanks that pretty much answered most of my questions. I've got everything strait except the pipe, thats one thing thats hendering me from saying I am 100% sure I want to do this. If I found a cheapo' stock 400ex pipe off ebay--Then bolted it onto the motor, would it be clear to me as to where to bends need to go? I also hear you need to "dent" the pipe for the kickstarter. Will the pipe require any welding at all whatsoever (I don't have a welder:( ), or does it just need to be bent to fit?

Also---It would be awsome if you could try the 300ex carb and let me know if it worked, that would save allot of money if it did.


Again thanks a bunch for the help

[300exazzkikr]

no welding necessary, you could probably find a cheap stock 400ex exhaust off of ebay and adapt it to fit. I don't have the bike anymore so i can't try out the carb for you..sorry.

[Tweeked]

Oh ok,
well i just checked ebay last night and the head pipes are very inexspencive--that would be the way to go. If I end up doing the swap i'll use the EX head pipe and adapt it.

Thanks for the help

[madmike300ex]

i have a 1993 300ex that has biggun ehaust bored 40.00 over curtis sparks cam,and a new wiesco piston and it still has the stock cdi which only lets it rev to 5500 rpms and it will run about 85 with cdi with out 93mph:devious:

[Tweeked]

:rolleyes: :rolleyes: Run without the CDI? It'll either not run, or you'll blow your motor dude. :huh :huh

Besides--5500 is pretty low, i've never heard of a CDI set to cut off that low, the stock is about 8500 I believe...

[bradley300]

Originally posted by Tweeked
Thanks for the help,
I think the 350x conversion would be allot less exspencive. Plus i'm on about a $900 budget, that means I gotta replace the seat cover, plastics (i'll probly go with 400ex plastics cause they're way cheaper), possibly sprockets and stuff. Leaving me with about 600 bucks max to do the convertion, is that possible? I'll get the motor then buy the mounting kit and instructions from Powroll and go from there. How much did it cost you to do you convertion?


Thanks
i did a 309 kit with a cam for less than 450, (just as fast as a 350x fourwheeler) that gives you another 150 to find the tick in the valvetrain, which should be easy.
i have heard the 350x was a slightly inferior design to a 300 motor and the 300 would last longer modded than the same mods on a 350. just what i know/think:)

[bradley300]

Originally posted by madmike300ex
i have a 1993 300ex that has biggun ehaust bored 40.00 over curtis sparks cam,and a new wiesco piston and it still has the stock cdi which only lets it rev to 5500 rpms and it will run about 85 with cdi with out 93mph:devious:

man, thats the funniest thing ive heard all day:rolleyes:

[Tweeked]

Do you know anything about the Powroll piston kits?

I've concidered buying the "297cc BORE KIT--76mm Forged Piston, 13:1 - 10.5:1 Compression." kit along with a racing cam and maybe some heavier springs. Does this sound like a good setup? I can do all that for around $400-425. How much power would I gain, and where would I feel it the most, bottom-mid or top end? Also, with the 13:1 - 10.5:1 piston will I have to run race gas or would 92octane pump gas be fine?


Thanks

[bradley300]

i would not go over 11:1 for reliabilty reasons. i have heard some good things about powrolls work though. just talk to more than one shop before you make a decision, just because one shop is cheaper dosent mean they are the best

with the 297 kit you would notice a decent power increas all over the rev range. would probably come close to mimicking the stock power curve, just more everywhere. my 309 piston (not high compression) and and all around cam was dead even with a stock 400ex, so a 297 should not be far behind.

[bradley300]

oh yeah, 11:1 should require premium gas, but race gas should not be needed

[F-16Guy]

Is it possible that the one of the valves is just out of adjustment? I would definitely take a look at what you've got before you decide to just scrap it. If it turns out to be minor, you could end up with a fresh, strong 330, as opposed to a who-knows ebay 350x motor with about the same investment of time and money. I would rather run a motor that I KNOW won't leave me walking.

[Tweeked]

Thanks for the help guys.

f16,
When I get it i'll fix the valves and ride it for a few weeks just to get used to it. Then i'll go back in and add at the hop-up stuff.

I've got a few more questions for you guys.
I'm debating on wheather or not to buy the WB cams and springs or the powroll cams and springs. Which would you all reccomend?

The other thing is,
With the 297 kit and with the high preformance cams, springs, Pro Meg exaust, K&N filter and jet kit. Will I get just as much power and torque with all that as I would with a stock 350x engine?

And with all those mods. will I be hurting my reliability at all? And will I need to get stronger clutch springs?

Thanks again for the help!!


PS>Are there any big power differences between a 10.8:1 piston than a 11.0:1?

[brownie330ex]

I would go with the WB fast all around cam. I have the fast all around cam and it made a big improvement. Im glad I dont have to mess with the CDI cause of my model year. A lot of reliability has to deal with the builder.

[Tweeked]

Thanks,
I'll go with the WB camshaft and valves then, plus their price is lower than powroll.

Anyone have anymore info on about how much power I'd have with the setup I listed in my previous post, and wheather or not it'd be as poweful as a stock 350x engine?

And also, will I have to run stronger clutch springs?

Thanks again!

[bradley300]

i dont know if its needed, but w/ a 330, i would look into a clutch, maybe not right away, but soon. you could also try an lrd 309 piston like i had, it should be close to the same price as a 297 b/c you still wouldnt need a sleeve, it would also give you even more power. call jeff at the quadshop and tell him you want the 309 piston like i had, he will know what your talkin about.

a 309 with all the work your talking about should be real close to a 350x, probably just a little faster. i cant say about a 297, ive never had a motor modded that small.

even if it is a hair slower, i would still choose the 300ex motor b/c you know where its been, and reverse and electric start are worth a mile per hour. the only place i think a 350x would be faster is top speed b/c it has six gears.

think, it will also be easier to sell a 300ex than it would a hybrid machine.

[bigbadbrad]

bradley did you get your motor built, the 309 not the 330, and what kind of cam do you have?
i need to rebuild my topend this coming up winter and i wanted to go up in size so i can get more power. so it realy costed under 500 for you to build your motor? I was wondering because i will probaly only have $500 to put in to my motor. and what was the compersion you had in your 309?
thanks
bradley

[WildCatRacer]

you might be better off modding your 300, you'll have to look into whats wrong with the motor. for 350X convertion...its pretty simple. you 300 carb will work fine just rejet it. you need a cdi box witch is probly about $100 new or you could get a unlimited rev from www.profabatv.com for about $150 new. you do need to do somthing about a pipe, I dont know if a 400 pipe will work or not, I bought a powroll header and weld the rest of the pipe with parts I had. if you get the powroll kit it will give you good detailed instructions on the swap and also tell you how you can use your old wiring harness. I have a extra 350x motor, but I dont think I want to part with it at this time. if you get a "all around cam" then you dont need heavy duty valve springs...that will save you about $40. and I sure where ever you buy your cam it will most likely be a web cam so just buy is where ever its cheapest. for $900 you could build a pretty nice 330, witch would be a nice equivalent toa 350x with a little diffrent power feel to it. so if you decide to do a the swap you'll need a cdi, motor, mounting kit unless you make your own witch is worth it rather than spending $70 on 3 spacers and instructions, and also a pipe of some sort...I send people just modify the stock 350x pipe. if you buy a 350 you might as well sell your 300 to make up some of the differance. its a good conversion, but completly up to you. just punch some numbers you may be better of keeping your 300. heres some pics of mine..maybe they can help you out a little:
www.geocities.com/quadrcr4/350x