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View Full Version : Need suggestions on my motor set-up



1stR
11-24-2004, 11:53 AM
Hi all, I recently rebuilt an R that I bought. I had the engine rebuilt from bottom to top, but I don't know if the pipe, poritng, carb etc are the best choices for the bore size, compression etc.

I am running a stock cylinder bored to a 261 cc with mild top end porting and no head work. I am using an 85-86 atc head gasket, FMF SST pipe and silencer, 38mm Mikuni carb, 37 tooth rear sprocket, no lid with moose foam filter.

The bike runs strong, but I have never ridden an R aside from this one so I have nothing to compare it to. Do all my mods look like good choices for the displacement and top end porting? Meaning I don't wanting to being running a top end pipe, top end porting with nearly stock compression if that is hurting power. Please give me some of your expert opinions!

I ride open fire roads and am aiming for mid to top hard hitting powerband. Thanks!

zedicus00
11-24-2004, 12:41 PM
looks like a good combo actually. i dont think it would b a arm jerker powerband but a good strong hit in the top end anyways. maybe check yur compression and grab a cr gasket and run race gas? or get a ricky stator lightened flywheel, and hav sum more extremem porting dun? i hav a esr trx 11 chrome pipe that helped my topend quite a bit. i would sell for the right price?

1stR
11-24-2004, 02:43 PM
So what exactly can I do with my current set up for fairly cheap money to get some more throttle response, snapiness, power etc? Is getting a new reed cage worth it, such as V-force? I don't want to spend money on mods that give minimal seat of the pants performance increases.

Also, how well do Wiseco pistons hold up compared to other pistons. I have been told that I shouldn't have used Wiseco in this motor? Any truth to that?

Zedicus00: I just bought my pipe and silencer about 2 months ago. I like the ESR pipe but do not need a new pipe, Thanks anyway.

zedicus00
11-24-2004, 03:27 PM
light flywheel would b good seet of the pants improvememnt, a reed cage like v-force would a little bit. i run nuthing but wiseco, never had a problem. pull yur head gasket apart and just use one of the thin pieces, that will help noticably and wont necesarily require race gas, jus watch yur compression. 180 give or take is safe on da pump gas

velocityatv
11-24-2004, 05:26 PM
I AGREE W/ ZEDICUS00 A LITTLE

UPING THE COMP WOULD HELP WITH THROTTLE RESPONSE AND WOULDN'T HURT YOUR TOP END OR YOU POWER CURVE. IT WOULD MAKE THE POWER COME ON SOONER AND PULL A LITTLE HARDER. DOING THIS AND CHANGING TO A V-FORCE SET UP WOULD BE WORTH THE MONEY. I'D STAY AWAY FROM LIGHTENING YOUR FLYWHEEL. IT'LL LET YOUR MOTOR REV FASTER (LESS ROTATING MASS) BUT YOU'LL FIND THAT YOUR POWER CURVE WILL CHANGE. IT'LL REV FASTER BUT IN RETURN THE POWER WILL TAPER OFF SOONER IN THE RPM'S (TAKING TOO MUCH WIEGHT OFF WILL REQUIRE EARLIER SHIFTS TO STAY IN THE SWEAT SPOT OF THE POWER BAND) YOU'LL ALSO NOTICE IT WILL BE MORE LIKELY TO STALL AT LOW SPEED DUE TO LESS ROTATING MASS KEEPING THE MOMENTUM GOING. IF YOU WANT TO TRY AND GET SOME MORE TOP END, DON'T BE AFRAID TO TRY A DIFFERENT PIPE. YOU CAN FIND PLENTY ON EBAY TO SATISFY YOUR CURIOUSITY, AND YOU NEVER KNOW YOU COULD FIND A GREAT DEAL ON THE PERFECT PIPE, AND IF NOT YOU CAN USSUALLY SELL THEM BACK FOR WHAT YOU BOUGHT IT FOR.

#1speedbump
11-24-2004, 11:06 PM
dont mess with the vforce. Get a set of G3's from 1dirracing. You can find them on ebay for around 100. their seller name is 1dircorp. Lightening your flywheel will allow the motor to rev faster but wont add hp. Have someone check the squish on your head. Also a diff. port job could really make you happy. For cheap fixes play with the gearing & jetting.

Here is a link to a very good exhaust comparison. This guy is also one of the best motor builders/ tuners I have met. His 250's will run circles around lrd, ct, duncan.

http://www.davemooreracing.com
http://www.davemooreracing.com/Pipes_Page_1.html
http://www.davemooreracing.com/Pipes_Page_2.html

I realize your pipe is new but sometimes there is alot more power to be gained. I have since soken with dave and he tells me he was actually able to get more hp with a broader powercurve out of the Sparks MX.

zedicus00
11-25-2004, 10:21 AM
v-force is the way to go for a topend set up, also dont b afraid of having the flywheel lightend it makes it rev a lot easier and if u raise the compression a lil u wont notice it boggin easier. and they r right u could sell yur pipe and get a different one just to try. u can even keep yur silencer all pipes swap put.

1stR
11-25-2004, 10:35 AM
Is lightening the flywheel an easy mod, or does it require taking the engine out of the bike, and tearing into the engine?

zedicus00
11-25-2004, 07:22 PM
jus pull the stator cover an its right there, u need a special puller but i c them on ebay for 10$ all the time. and ricky stator sells a flywheel so u dont hav to mod yurs then jus sell yur stock one back on ebay or sumthing.

wilkin250r
11-25-2004, 11:57 PM
I would definitely recommend a new set of reeds. Boyesen and V-force seem to be the most popular choices, either would be an improvement if you're still running the stock reeds.

Next, I would recommend some head mods to increase compression. You can either get a complete aftermarket head which will give you interchangeable domes, or for a little less money you can just get your stock head rechambered. It would compliment your mild top-end porting very well.

I wouldn't start screwing around with changing your gasket thicknesses until you check your squish band.

Wiseco pistons aren't bad, they're forged aluminum. The cast pistons like Pro-X are generally a little better for the 2-strokes, but it's not a big deal. I wouldn't worry too much about it.

In any case and whatever you choose, I would spend a few bucks and an afternoon to get it on a dyno with a professional to get it tuned to perfection.