250r 4mm stroker

[88mxR]

Does anyone else here have a 4mm stroker 250r? If so, what pipe are you running? My sparks mx did not seem to run very well and an SST ran well on top, but it was pretty pipey. I got a hold of a sparks 330mx pipe and now it runs very strong. Did you guys need a big bore pipe, or is a different pipe working well?
Does anyone know where I can find another 330mx or sparks tt pipe for my brothers 310?

[flotek]

is the porting matched for the stroke ,i see Nick ported it in your sig but is it ported for the stroker crank or is that a upgrade you did later ?

[88mxR]

I put the stroker in after. I had to get a new crank any way, so I went with the stroker. I had to put it together in a hurry because my other cylinder blew in the dunes 11 hr away from home. What I was running was an ebay cylinder that was looked at with the stroker kit. Nick's set up actually ran better, so I was assuming it was matched up well enough. I'll check it out any way next rebuild.

The sparks mx didn't seem to run well, but there were a few leaks in it. I put the 330mx midsection on and it ran a lot better even before I fixed the leaks. I was thinking that the volume of the big bore pipe supported the longer exhaust duration, so I was curious as to what everyone was running.

A 4mm stroker in a 250r doesn't seem as popular as other models, so I was also trying to see more opinions, tips, or tricks from those that have 250r stroker experience.

[flotek]

i ran a 4mill honda 88 250r for awhile ,really fun bike was torquey as hell lift the wheels in about any gear easily and really performed for trails wit h portwork on a midrange duncan pipe not muc h of a hig h rpm screamer ,but could hang wit ha piped banshee all day

[ky 2stroker]

so then your ported cylinder is not matched with the 4 mil stroker crank? it would be best to have it matched, but if its running good by your standards then I wouldnt worry about it.

I have my R setup as a fast-revver, that cr250 ignition is unreal in how fast it lets the motor rev, instant and very pepy throttle response. its probably not the ideal setup for a woods/trail bike, but love it.

[88mxR]

Mine is ported for mx, but it sounds similar to yours with the midrange pipe. Right now it has a lot of low end grunt and then carries into the top. Not like a top end bike, but it carries enough to still feel like a two stroke. The normal sparks mx would not do this and the sst didn't feel half as strong. I think I'm going to like it on the track. Thanks for the input. Do you think there is a reason there are so few 4mm 250rs around?

[ky 2stroker]

well I dont know that much about em, but I think most people use the 4 mill cranks with the big bore prox jugs to get the most displacement and power from em. I love how mine is setup and im not gonna change anything when it comes rebuild time. its has awesome power and response through the whole rev range and it is only at 260cc's right now.

[gimmie11s]

who makes 4mil stroker for the r?

[FPMXer]

Originally Posted by gimmie11s

who makes 4mil stroker for the r?

HotRod makes one and I know motosport.com has them in stock. RJATV might also have them or can get them. I've also seen them on fleabay.