bog

[toby4187]

I recently upgraded from a 24mm to 28mm pwc carb on our drr90. We are running stage 6 clutch with silver springs and stock pipe and bore. Bike ran great with 24mm but now has a slight bog on take off with 28mm. It's great as long as its rolling turns etc.. but not from a complete stop. I have tried from a 110 main up to 130 and all in between also changed pilot jet from 40 to 55 and problem doesn't change. Could the problem be in the clutch or weights now? I'm running 3.5 weights on the front.

[mmsoup]

Too much for the setup


Add a Snyder Pipe (Or Trackside, Hetrick, PCS) and do some mild porting and things will change

[toby4187]

I added a hetrick pipe and the bike ran worse than ever. I called G-force and they told me to take that pipe off the stock pipe would be better for my application. I can always go back to the 24mm carb where the bike runs good just doesn't have to power to keep up with others in her class. Last night I played with a few more combinations and it runs better once its warmed up. Does anyone know the best RPM range for my setup?

[fomospede]

what is the clutch stall rpm?
is carb new and what brand

[toby4187]

I almost forgot the bike does have some mild porting already done. The stall right now is 6k and the carb is Keihin 28mm and its used. I also moved the clip from mid position to 2nd from top which did seem to help a little.

[rcms]

the hetrick pipe should work better than stock,we have used a trackside on stock motors for customers building in steps many times with good results. rpms will depend on the generation pipe you tried and how much port timing has been altered. we would start with 6500 stall 132 main 48 pilot and depending on needle 1 down from middle.most bogs come from low speed lean or low stall speed. if to rich it would miss more so than bog. good luck

[selbygirl]

I would try moving the clip to the top and go with a smaller pilot jet... pilot jet is at 1/4 of throttle needle is at 1/2 main is at 3/4 throttle . if it is bogging go with smaller jets . look at the spark plug , if its wet its getting to much fuel , it should be a brown color , if it a white color go fatter with jets . and if you think the roller wghts are to heavy , take one roller wght and do a test run if the bike feels good go to smaller wght size, I would look at that spark plug that should tell you a lot about your jetting

[Logan #34's Dad]

1st you need make sure it's not in the clutching... put the rear of the tires in the air (jack stand). Then stab the gas. The exact same bog can be from clutching......Welcome to CVT's! When there is no load on the tires and clutch the clutching should not cause a bog(unless your way off).
If I had to guess, it's too rich on pilot(dumping too much fuel). Mine was almost always a 42/40.
A wise man (Reimer) once said...change/adjust on thing at a time. Words to live by!

[toby4187]

OK thanks for all the tips 1st the bike does not bog at all with wheels off the ground next the pipe is Herrick Gen 2 I did move needle to the top with42 pilot and it was way off it would not spin rear tires while holding front brake. Now it is OK on takeoff with clip 1 from top. If we ease on gas (instead of all at once) it smokes and feels like it misses.

All this started with changing of Carb but I have noticed with larger Carb we have more mid range and bike hits higher rpm's

[dewutfan]

you said the carb was used .. i would try another 28 m carb .. that carb my be bad .. been there done that.. just my 2 cents.

[Logan #34's Dad]

If it does not bog while the rear wheels are off the ground, That tells me your clutching is off. Set the carb while on the stand. Lower your weight in the variator - Just remove three of them(every other one) or half (depending on which variator you have) and put it on the ground and give it a shot. If the bog goes away, take a permanant marker and mark the face of the variator to see what you have for belt travel after a 150ft run (or your longest straight away at the track). Add roller weight in 1 gram increments until you get the belt to wipe off the marker to about 1/8 of inch not being wiped off. ALL THIS WITH A NEW TORQUE SPRING.
This is your new variator weight....write it down. When things start falling off....replace rollers and spring with exactly what was in it.