cr85 to 105 advice

[scottiedawg66]

hello, I am considering building a race motor for my cr85. I can go up to 105ccs. Does anyone have experience with 105cc big bore and or stroker kits that can lend advice. I am hearing different things from every motor builder I talk with...I need mid range top end power, and just enough grunt to get me through the dirt.



Power goals: 25 rwhp / 12 ftlbs AT THE WHEEL



Current power: 17 hp / 8 ft lbs at the wheel (on a tired top end with 9 hours of race time on it, stock motor, FMF fatty pipe) *****WITH A CRACKED PISTON*****

[PlanetMinis.com]

[Paxracing]

Go with the wisco super mini piston you will get more top power. If you need a stroker motor call me i will get you someones number for that. 818 968 2261

[chasetheface123]

Strokers are the way to go with 85's. Thats the best way to make good power with them.

[fiddy4ever]

you cant get the 112cc stroker? reeds, full exhaust, and high octane gas with quality mix is a key to power too.

[chasetheface123]

you cant get the 112cc stroker? reeds, full exhaust, and high octane gas with quality mix is a key to power too.

112's or even 107's for that matter are ALOT more work then the 105's as far as install goes..... You gotta weld the plug up, and do all sorts of other work.

[fiddy4ever]

112's or even 107's for that matter are ALOT more work then the 105's as far as install goes..... You gotta weld the plug up, and do all sorts of other work.

true but 112cc might make a good difference over a 105cc.



105cc will be nice too though. Were are you planning on getting it from?

[BORN2RIDE#56]

yeh but how many hours & how reliable is that gonna be at 112? lol

[klxrider245]

lil homie needs to go with the 117cc!

[fiddy4ever]

its not gonna be very relable at all with the 105 either, its best too just keep them stock

[scottiedawg66]

its not gonna be very relable at all with the 105 either, its best too just keep them stock

care to shed any more light...i dont mind doing a top end every 6 hours, and plan on runing race gas. i was just thinking about what to do with the cooling system?

[chasetheface123]

If you plan on doing top ends every 6 hours, then you will be fine. Around every 15-20 your going to want to pull the whole thing apart and check tolerences though.

[scottiedawg66]

you are referring to the bottom end?

[Luckystar64]

PAX can probably help you out, OR talk to a guy named Gene at High Tech Horsepower. He's very knowledgeable about two stroke performance. I talked to him about doing something to get more mid range torque out of my KX65 pit bike.



I'm not sure what you're application will be for the CR motor, but I came to the conclusion that I'd leave the 65 stock and just enjoy it the way it is, as it would be easier and cheaper to just buy a really nice used 150R and call it a day. --L*64

[scottiedawg66]

i ended up having eric gorr build me a big bore $525 and I get to keep my stock cylinder. i'll post up dyno results in a few weeks.

[Chrome-CRF]

i ended up having eric gorr build me a big bore $525 and I get to keep my stock cylinder. i'll post up dyno results in a few weeks.

Cool man, let us know what kind of power it makes? I just bought a CR105 to swap into my NSR50 and I'm hoping it hauls ass.

[scottiedawg66]

that sounds completely INSANE...



mine is only 100cc. i can still stroke it if i need to but i want the revs..i think...

[Chrome-CRF]

that sounds completely INSANE...



mine is only 100cc. i can still stroke it if i need to but i want the revs..i think...

Yeah man I'd be very interested to hear what your motor dynoes at. As soon as mine is in the bike I will have it on the dyno. Here is the link with some pics of my motor. It has some serious port work. http://planetminis.com/f67/nsr105-co...on-152433.html

[taz69]

The rules for most road race clubs have a 105cc 2 stroke max. I would say that why he is going with a 105 max ccs. And I raced a guy last year that had a NSF100 with a CRF150R engine in it. It was a way cool bike.. I liked it very much.. The NSR should be cool to..

[scottiedawg66]

wow!!!



I was doing my last top end on the stock bore last nite, and my stock piston was cracked almost all the way across, and all over the sides. It was ready to cause huge damage to my cylinder. I have no idea how much time was on the piston as I bought this bike used and it looked great last ring I did....glad i didn't trash the cylinder!

[50race]

well. my $.02 is go check into dean dickinson. when i was in the mini class thats where I went for mod class parts and help with setup, but that was a long time ago. I read a 31 rwhp claim on there site but i have no exp. with the honda stuff. heres a link if you wanna check it out

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