how do u feel about stroker cranks!!!

[Grande Huevos]

i was just wondering what ur guys opinions on stroker cranks are??? whats the pros and cons , if the pros out weigh the cons whats the best mm stroke to have?????

[wilkin250r]

Stroker cranks are one of those difficult and specialized modifications. Hotrods sells a stroker crank, but just because somebody sells one doesn't mean it's a drop-in upgrade. There are a LOT of modifications that need to be done to get it to run right.

In general, a stroker crank will give you more torque and low-end power, but won't rev out quite as well. This is obviously a over simplification, because it's also highly dependent upon your particular porting and pipe specs. But done properly, stroking is a great upgrade. In fact, back in the day when 250s dominated the ATV racing scene, 265cc was the max limit (to allow for overbores on the stock sleeve). However, many of the factory racing teams actually kept the stock bore, and stroked their motors to 265cc, rather than boring them to 265cc.

[Grande Huevos]

so if a guy were to tell a builder exactly what his motor is from pipe to carb to timing and so on and wanted to add a stroker crank and wanted them to port the cylinder then they could make it work "perfect" and it would turn out good and prob be a pretty sick mod ?????

[machwon]

The porting and the head work play an important role in any motor, but especially in the stroker build up.

[C-LEIGH RACING]

The most important part, have you ever seen a 250R crankshaft that the tins have been removed from ??.

The thinner you get a piece of formed metal, the less strength it retains.
Neil

[atv fan 28]

Originally posted by C-LEIGH RACING
The most important part, have you ever seen a 250R crankshaft that the tins have been removed from ??.

The thinner you get a piece of formed metal, the less strength it retains.
Neil

I love my 6mil! But it took some getting use to, far as shifting. It seems you have to short shift it more. At first i was revving it to the moon. But im getting use to it.

[C-LEIGH RACING]

Originally posted by atv fan 28
I love my 6mil! But it took some getting use to, far as shifting. It seems you have to short shift it more. At first i was revving it to the moon. But im getting use to it.

I think I'm just before doing another one like that, except with a 330PV.
Neil

[86 Quad R]

Originally posted by atv fan 28
I love my 6mil! But it took some getting use to, far as shifting. It seems you have to short shift it more. At first i was revving it to the moon. But im getting use to it.

she does run saaa-weet!!! i was very impressed with the amount of low end grunt it has to be drag ported. i liked it so much that i too am considering this setup on my current build..... only not with a drag port. :cool:

[C-LEIGH RACING]

Hummm, drag ported but it had some bottom end, ol port man must got hold on something & aint telling nobody.
:p Neil

[brandonw]

that motor was a blast on alki and race gas :D glad you are loving it. pulls from the bottom and will rev to the moon. stop smiling neil lol

[C-LEIGH RACING]

:D :D :D :p You know just what to say, dont you.

Hey, Pro guy I been talking bout running 2 stroke, engine will be here shortly & WE GONA RUFFLE SOME FEATHERS in 2011

Oh, first race, season opener probably be at Kinston.
Neil

[Langbolt]

I've been setting up my stroker for years!....yes Years!

I ordered a 3mm (75mm Stroke) and they accidentally offset the PIN 3mm ....which in turn creates a 6mm....So I was trying to get a 78mm stroke to work with my 310-Pro-X ......then I had a stock cylinder sleeved with a custom sleeve that was designed around the 310 displacement....it ran like a Diesel

Tons of torque but not much HP on the top end

Then I tried a 3mm...75mm Stroke and my stock 66mm bore Cylinder....once I got it jetted right it was AWESOME!!!

I've been running this setup for the past 3 years!

It's a 272cc Screamer now! 68mmm bore & 75mm Stroke.

I wonder why nobody has taken the time to create the perfect Port Layout for a 75mm Stroke and sold the SLEEVE as a KIT for guys that purchase Stroker Cranks ???

Theres another perfect business opportunity for someone to make a few buck$

:devil:

[1promodfan]

Originally posted by C-LEIGH RACING
Hummm, drag ported but it had some bottom end, ol port man must got hold on something & aint telling nobody.
:p Neil

Yeah, I think it was one of those Nash Co. country boys!!:blah:

[atv fan 28]

Originally posted by 86 Quad R
she does run saaa-weet!!! i was very impressed with the amount of low end grunt it has to be drag ported. i liked it so much that i too am considering this setup on my current build..... only not with a drag port. :cool:

Yeah she was running pretty good that day, wasnt she? And that was the first trip out with it. Im sure with some more tuning i could get more out of it.

Where have you been 86? Havent seen you on here in awhile.

[C-LEIGH RACING]

Originally posted by atv fan 28
Yeah she was running pretty good that day, wasnt she? And that was the first trip out with it. Im sure with some more tuning i could get more out of it.

Where have you been 86? Havent seen you on here in awhile.

Hummm, ol 86 has been quite for awhile, :ermm: wonder where hes been.

I bet one thang both of you ARE wondering about,,,,, whats killing them birds & fish over in LA.
Neil

[86 Quad R]

Originally posted by atv fan 28
Yeah she was running pretty good that day, wasnt she? And that was the first trip out with it. Im sure with some more tuning i could get more out of it.

Where have you been 86? Havent seen you on here in awhile.

yessir! she sure was.... none em 4 pokes wanted any of it. :D as for the absense.... i had a bunch of use or lose i had to take and was away for awhile. puters and all. :cool:

neil, theres a buncha theories but nuttin concrete. seems its happening in more places than the deep south. whats your take on it?

randy

[C-LEIGH RACING]

Got no idea, just heard about it this morning on the weather channel, is weard though.

When its said & done, we'll probably find out it was the buildaburg 7 behind it doing test seeing how it would work when they get their D population deal cranked up.

You know, what ol Jessie Ventura been talking about.

Dont never put nothing past our government, if you not here to fill their pockets or got something they can rob us of, you gone son.
Neil

[mx91a]

Langbolt, I am very interested in your setup. My stock '88 cylinder is currently at 67.5mm and due for the next bore so I have been toying around with the idea of getting my old long rod crank with bad big end bearing rebuilt and stroked 2 or 3mm to give it a little more low end torque.

Currently my porting is a low to mid rang port job that came with the quad when I bought it 10 years ago and had worked pretty well for MX. It has about 185.5 degrees of exhaust duration, 126 degrees of transfer duration and 30 degrees of blowdown.

I have been running through the calculations to see how much I would have to drop the cylinder to get the transfer timing back to 126 and with the 74mm crank the piston would need to be 1.5mm above deck and with the 75mm crank 2.4mm above deck. Both setups would need the exhaust port raised from 0.5 to 1.0mm to get the exhaust duration back up to 185-186 and blowdown back to around 30 degrees. I have test fitted my piston in the cylinder at 2.4mm above deck and the top ring is well below deck and the bottom of the exhaust port it not uncovered so there should not be a problem there. I would probably have to run the stock thick TRX head gasket and have the squish band in the head cut deeper to set the squish clearance at a mm or so.

Does anyone know the thickness of the stock head gasket? I have searched for a while but couldn't find a measurement.

Right now I am favoring the 75mm crank with the 68mm piston to make a nice 272cc sleeper with the right pipe. (I am leaning towards the new ESR TRX5 or TRX MX ?)

If you have anymore info on your setup, porting specs, how it runs, etc. that would be greatly appreciated.

Also who would you guys recommend to rebuild and stroke a crank, ESR, crankworks, or other?

Thanks

[jhtrx250r]

I have a stroker motor I accuired but never ran, I am planing on trying it out this summer.

I dont really know what stroke it is but the rod shaved at the bottom for clearence, and the cases are trenched.

It has a resleeved stock jug that comes out the top of the cylinder about 3mm and it runs a 4.6mm spacer plate on the bottom, it is 72.5mm bore, has PSI stamped on the underside of the intake and LRD,s #s on the inside of the intake, runs a pro designs cool head that has the dome recessed up inside it to accomidate the longer sleeve.
It also had 7mm reed spacer with a rad valve and a exhaust choke.

It looked like a pretty wild set up (wild enough to blow appart the trans gears)

I will get the # off the rod tonight, so hopefully some one can tell me what stroke it is.

[jhtrx250r]

Ok I looked at it again, thr rod says CK 109 but the pin placement has been changed.

[jhtrx250r]

heres another one