Advice on ESR big bore kits please

[RIDE-RED 250r]

Looking for some advice from those who know from experience.

I am looking to sell one of my sleds and take the money and get into an ESR big bore kit. Im looking at the standard 330, 350 and 370 stroker kit. I see alot of folks running 330's and hear alot of good about them as far as strong running and retaining great reliability. But, I am looking to be able to compete in drags against moderately modded 450s'. As is whats killing me is the holeshot. I do intend to get a good swinger either +4 or +6 to go with the bigbore kit. Has anyone ever had experience with the 350 and/or 370 stroker? My bottom end has had every bearing replaced no more than 20 engine hours ago, including all transmission bearings. Will my stock transmission hold up to the big 370 stroker? Or am I asking for trouble there? I have had some input regarding this and have been warned that going with the bigger stroker kits will be pretty hard on the transmission. If I sell this sled, I will have enough to get any one of the 3 Im looking at. I just want to get the biggest power package without sacrificing too much reliablity. Im sure there is a line in the sand somewhere, Im just not sure where that would be. Thanks!

Oh and on a side note, Im currently running a stock cyl bored .060, ESR 38mm Airstryker, 1Dir racing reedcage and torque spacer, and full FMF Fatty exhaust. Im figuring I will need to upgrade to the ESR ATC5 pipe whichever big bore kit I decide to go with. Any thoughts on this as well?

[KASEY]

I HAD A 370, 5 MM STROKE,, i ended up selling it because it was ported for topend and was a rea;l pain to ride,,,, it had trx11 porting,, it had huge power all topend, so i bought a new 350 power valve,, the 350 has trx 7 porting and i run a type 6 pt pipe, its not quite as fast as the 370 was,,, but man is it a blast to ride,, great all around power,, if i was going to do it over.. i would have got the trx 9 porting and no power valve, its just one more thing to go wrong. the 350 in my opinion doesn't need a power valve

one thing to remember a cylinder ported for a stroker can never be run on a stock stroke,,, thats why i sold my 370.. because it was the same bore as the 350,,

[RIDE-RED 250r]

Thanks Kasey, was hoping you would have some input on this. I did forget to mention I intend on the trx9 porting. As to the powervalve option, I wasnt sure if the powervalve would fit in a trike vs a quad and consequently planned on getting the non-PV cylinder. Thanks for the advice on the stroker. You have just helped me narrow my interests to the 330 or 350.

[pantera1975]

I went with a new long rod crank and had a 330 no stroker for the ease of being able to swap top ends with out waiting for a bore job.

[RIDE-RED 250r]

Gotcha. Another question Im wondering about is how big a motor my 38mm Airstryker carb can adequately feed. I can always ask ESR about that when I place my order....

[250rmanfmf]

Great thing about the 38mm carb is you can always have it bored to a 39.5mm if you need more air. I think 38mm carb is good to about a 330-350.

[pantera1975]

310 will bolt on and the 330 you can get as a bolt on or a full sleeve kit which you have to have your cases machined for that or bigger.

[RIDE-RED 250r]

Would running the 350 be too hard on the stock transmission I am running? Someone whos opinion I respect keeps telling me to go with the 330 because he feels the 350 will be a little to hard on the transmission unless i spend 600 bucks more and get a heavy duty gear set. Personally, I cant see the 5 or so horse gain in the 350 vs the 330 making that big a difference on the transmission.

[gomer202]

i was thinking of putting an esr kit in my 250r engine (330cc) and this has answered all my questions i was looking for other than the tranny strength
and this esr kit is not for the nos engine in my 250r i just have an 86 engine laying around

[RIDE-RED 250r]

Gotcha, Im really interested in the 350 myself. Want to go as big as I can without getting into a stroker crank.

[KASEY]

the transmission will handle the power just fine... IF its in good shape ... check it out completely all the gears and bearings.. i looked mine ove and only changed 3rd gear.. everything else was great.. so far no problems,

[RIDE-RED 250r]

Thanks Kasey. Luckily for me, every bearing in my bottom end including all the transmission bearings have been replaced recently. (roughly 20-25 hrs back). And in doing so, all the transmission gears, forks and shafts were checked over and found to be in good shape. But I will definitely give everything another good once over when I split the case to send it to ESR for boring.


350 it is then! Thanks everyone for the input and advice. :beer



Now.....to get that darned sled sold so I can order my goodies!!! :twisted:

[riverrat]

Hey Kasey, you say you wouldn't do a PV again. I was thinking of getting one, because when I am ice racing, sometimes you need a little more grunt on the bottom end to get around a corner. Does the PV make a noticeable difference in low end power?

[RIDE-RED 250r]

Riverrat: Are you the guy I have seen on youtube schooling a bunch of quads on the ice tracks? 330rman????

[KASEY]

i think if i was going to do it over would stay away from it.. or have it setup with a rotax valve// reading on trx250r.net there are several of the new gen power valves that have already dropped in to visit the piston... some say bad clearances on the setup ,, some so bad it is hard to tell what happened.. so if this happened to me i would be pissed along with out alot of money ,, thats the only reason, i say one less thing to go wrong.. and yes it does really smo th out the power band.. you don't get the big on the pipe feeling its a smoother hit

[RIDE-RED 250r]

I can see where using a Rotax PV might be desireable. I currently have 3 Doo sleds and have owned a few others in the past. They really have the PV down pat! I have never had one single problem with my Rotaxes in that area.

[ceaserthethird]

Yup i have the Rotax Power Valve set up on mine, Smooth power !

[riverrat]

Riverrat: Are you the guy I have seen on youtube schooling a bunch of quads on the ice tracks? 330rman????

No that's not me, that's ChrisD. Between him and JohnR they both taught me everything I know about ice racing and setting up an ice bike, then I just do the riding. I can keep up with him on a good day. Not only does he have a fast trike, but he knows how to ride it. He took second, and me thrid at icefest this year, open class. I run a 310. But I want to go bigger, was thinking 370 PV motor, but not sure if it is in the funds this year.

Where do I find out about this rotax PV setup? What cylinder do run that on? I am pretty convinced that a PV would be ideal for ice racing. Sometimes you get in that turn, and bog down, and it's so hard to hang off the trike and downshift, that having some extra grunt on the bottom would help so much. I was thinking drag porting with a PV. Kind of best of both worlds thing.

[RIDE-RED 250r]

I see. Well, I just love watching ChrisD show the quads what fast is on those vids! His riding ability definitely shows! As to the Rotax PV setup, Im really not sure which you would want to use. I would take a guess that you would want a pv from a rotax that has as close to the same bore diameter as your engine as possible as the PV guillotine rides very close to the piston in the closed position. I see your point about needing a little extra grunt if you come out of the pipe in a turn, but I would probably do the mid-top porting rather than the drag porting. Not that I know from experience, but I have heard that pure drag porting is difficult to manage unless drag racing. Kasey eluded to that very issue in an earlier post in this thread.

I live up here in CNY just a few miles from Oneida Lake. I have said for years I would love to get into some ice racing if it ever got going up here. But sadly, it hasnt. With a wife and 2 kids that like to go snowmobiling, I just dont have the extra time and resources to commit to racing at far away venues.

[riverrat]

Yea those guys on the quads are getting faster these days. Someone who knows how to ride with a mildly modded 450 anything can give us a run, depending on the track. The 2strokes still get em on top end. But we are all looking to go bigger with our motors, so we can once again rule!!

[RIDE-RED 250r]

Well, you can get all the way up to a 430 stroker from ESR. I think it would take a VERY heavily modded 450 to run with one of those! :naughty: