MOPED ARMY

mine does this too. it did this stock, it did it with a bi-turbo and 58 jet, and now it does it with a 70cc kit and a 60 jet. reguardless how i set it up, it still vibrates as you have described. my friends with their streetmates dont have this problem... a little light on this matter would be GREAT!

where does the air box feed out of? maybe the air is warming up with the engine, and running you rich? i dunno, but you should change the rear sprocket asap! that the main resriction over the whole bike.

i have a 2008 streetmate R with no poblems like that.

speed kit(waiting for bigger jets.)

technigas

24? rear sprocket

Air-Sal piston port kit.

I cleaned the carb. It had no signs of crud, but I wanted to be sure. It was a warm afternoon today, and it didn't run as well as yesterday in the cold. I rode into town, a distance of 4 miles, and couldn't run at full throttle because of the vibration. The best speed I could make on the inbound trip was about 32 on the speedo. It was vibrating and making a roaring sound at full throttle; sounded like some kind of resonance maybe in the airbox. Also, I think the exhaust also had a harsh resonance that isn't there when the engine runs well. Yesterday, I blasted for about 10 miles with the engine running great, and holding a steady 39 on the speedo. Tomos MPH : ) Really powered up some long and steep hills, seldom dropping below 34. Yesterday. Today I was dismayed as it bogged down to less than 30 on a smaller hill. But then, on the last leg of the return trip, it slipped back into good running -- I slowed for the last corner, and as I opened up the throttle again, it quieted down and took off -- sounded quiet and smooth and held steady at 39. Wish I could figure this out. It sounds so crappy when it's running bad -- kind of surges with the throttle backed off, and makes that roaring, vibrating ride at near full throttle. It's only got 600 miles on it, and has been meticulously cared for since new. I figure, if a machine runs right some of the time, it can be made to run right all the time, if I could only figure out what the cause is, and how it comes and goes. Could it be a sonic resonance phenomenon somewhere in the intake or exhaust system?

Sounds like it is running rich, try running it without the airbox just to see if it runs better. If it does then get a few smaller main jets and try them with the airbox back in place.

Yes, that seems to be the problem. While messing with the airbox, I amputated the little right-angle inner air tube that was inside the box . . . figured it was either a restrictor or a noise suppressor. I also enlarged the opening where air feeds from the airbox to the carb. This mod seems to have greatly reduced the high speed vibration. And the engine is running faster, but it still might be borderline rich. It surges some at full throttle. Next step will be to try downsizing the jet a step or two.

you are on the right path now

The screw that sticks out, so you can turn it with your fingers, is the idle speed adjustment.

The screw that is set down into a little socket, toward the air intake end of the carb, is the idle mixture screw. If you take it out, you'll see that it has a tapered end. If you don't know where it should be set, turn it all the way in, then back it out 1-1/2 turns; adjust from there for the best idle.

Evan -- what does your Tomos dealer say about the vibration?

While waiting for a carb jets to arrive, I rigged up a low-restriction air filter. It eliminated the surging, but is so noisy! Wow, that air box does contain the intake noise pretty well. Any ideas how to futher de-restrict the airbox without raising the noise level so much? I took out the right-angle rubber snorkel tube and enlarged the hole through the grommet already -- helped some, without adding much noise. I'm concerned that simply drilling holes in the airbox will let too much noise out!