400ex 440 stroker

[FisherRacing94]

I am thinking about making my 400ex into a stroker. I am thinking about a 440 stroker, +4mm stroke crank with a 87mm piston. Has anybody built one and can give me any imput if this is a good or bad idea. I figured a 440 stroker would be more reliable than a 460. I cannot find a 87mm stroker piston tho, were could I find one. Any imput would help. Is there any other reliable strokers?

[HondaRacing83]

i thought 87 was 416 or 426? i think you want like an 88 or 89mm

[FisherRacing94]

yea thats what I want, I want a 416 bore (87mm) with a +4mm stroke (74mm) to make a 440 stroker. I cant find a 87mm bore piston that will work with a stroker though, I thought I have seen somebody talk about one maybe they dont make a piston that will work not sure.

[xcracer416]

you just buy any 87mm piston and have your piston machined for the stroke. pretty much taking alittle skirt off for the clearance.

any engine machine shop can do this in a snap.

but if you really ant it to be reliable have it balanced for your piston. example send your crank and piston to crankworks they will machine and balance the crank.

your quad will love you for that.

[FisherRacing94]

Thanks for all the info. I have been looking at powroll.com kits. they machine your crank to be a stroker but you can run any bore piston with them. Has anybody had any problems with them.

[Stickman400]

Here ya go: http://www.powroll.com/P_HONDA_TRX400EX.htm

Just scroll through there. They have the full stoker kit or just the 87mm stroker piston, plus alot of other high performance goodies for the 400.

[FisherRacing94]

yeah they have a lot of good stuff I saw. I can either send them my crank and they can machine it to use any size piston or I can buy any brand stroked crank and put there 87mm stroker piston on it. I think I may go with a hotrod +4mm crank/rod assembly with the powroll 87mm stroker 11.5:1 piston. That would be cheaper than them machining my crank. Have you heard good stuff about powroll.

[Stickman400]

There is a couple members on here who have had their 440 stroker kit in their 400 for a few years and haven't had any problems with it. I plan on going with their kit when I have to rebuild after I get to a 426.

[FisherRacing94]

How can you keep big bores cool. I have a cfm larger oil tank now and titanium header wrap. But what other things can I do? I have heard of a secondary oil cooler by fourstroketech but what is it exactly just another oil cooler? I think I may just go with a small trans cooler and a spal puller fan.

[CJM]

Easiest way to keep it cool is to buy an automatic trans cooler. Then mount it to the front of the quad on the frame sideways and plumb it into your system.

FST kits cool but $$$ and you gotta tap the rocker cover.

[FisherRacing94]

O ok I think thats what I'm going do, buy a trans cooler thats maybe alittle bigger than the stock one and mount a small spal puller fan on it as well.

[FisherRacing94]

Has anybody built a 440 stroker 87mm bore x 74mm stroke 400ex and ran it on a drag strip or another size 400ex so I can know what to expect if I build one. I currently run on average 5.9 seconds on 300ft dirt drags now with a stock bore stock stroke 400ex. I dont want to end up putting a lot of money in this and have to run a different race class and not get results I want. So anybody that has ran there 400ex on a 300ft drag please post some times and what size 400 you have.

[drew416ex]

I dont have any 300ft dirt drag times, but you will not be dissapointed with a 440 stroker. Ive had mine for roughly 5 years and no problems yet. I have the hot rods crank and have had no problems, but if I could do it over again I would go with powroll since you can use any piston. Also go with a stage 3 cam. I tried a stage 2 and it would fall on its face top end. I havent had any cooling problems, but I did add a spal fan to my stock cooler. Also if you can get your hands on some E85 and a 3-4 degree timing key it would make worlds of difference in power and run a little cooler than race fuel.

[JOHNDOE83]

Originally posted by FisherRacing94
How can you keep big bores cool. I have a cfm larger oil tank now and titanium header wrap. But what other things can I do? I have heard of a secondary oil cooler by fourstroketech but what is it exactly just another oil cooler? I think I may just go with a small trans cooler and a spal puller fan.

I havent had any heat issues, it is a good idea to do a bigger oil cooler or a spal fan.

Im not a fan of second oil coolers, I think that you could get the same effect from just switching to the trans cooler with a spal fan.

But I havent tested that yet.

[d90rick]

what type of performance difference would there be if you simply did a 440 big bore or the 416 w/4mm stroker (440 as well)? i race harescrambles and was thinking of having the motor worked this winter. won't a stroker give more torque than a simple big bore? will both run the same temp? i was thinking of a sparks 12.5 piston and powroll 4mm crank and run race fuel. throw in the 3 degree key, 450r carb and sparks x4 cam. what you all think?

[FisherRacing94]

Yea thats why I want to do a 440 stroker I figured it would have more torque and overall power compared to a simple 440 big bore.

[d90rick]

will it run cooler? yeah, i figured it would also rev quicker. only down side is it probably not "lug" like a 440 big bore.

[JOHNDOE83]

440s dont lugg at all, the ones that lugg arent jetted right, my 440 instantly goes from 0-WOT full rpm as fast as you can open the throttle.

And there is no heat issue to worry about.

A 440 stroker will perform better then a simple 440 bore.

[FisherRacing94]

If I make a 440 stroker out of my bike I want to be able to run around a 5.0 on a true 300ft track is this possible. I would be happy with 5.2 or less.

[Wheelie]

I've been running a Powroll stroker w/the tough rod since 06' without any issues. A head gasket recently blew, but I'm running 11.5:1 compression and a 4 degree timing key on stock head studs.

Powroll can also set you up with a 87mm piston. Great outfit to deal with. They make a quality product and stand by it, although at a higher cost than other strokers.

I haven't had any cooling issues with the stock oil tank and cooler--the SPAL fan has been keeping it plenty cool. The E85 also helps.