rdlsz24

I had this situation with 3rd gear on a Honda 200x three wheeler several years ago. It was a constant humming in 3rd gear, not just when first shifting into it. Yours only makes the noise when shifting into 4th but once there it stops? Mine ended up being a chewed up gear, when then took out the corresponding gear on the other shaft. So I had to split the cases and replace two gears. A lot of time, but not hard or very much money.

Rob

If you have the piston at TDC you should install the cam with the lobes facing down. That will put you at TDC on the compression stroke. Install the cam sprocket into the chain with the marks lining up to whatever they should line up with (different by brand), and bolt the sprocket onto the cam. Then spin it over counter-clockwise by hand and the marks should still line up. This is for all 4 strokes.

Rob

Nice, glad it is doing better.

Rob

Did it used to run fine? If so, what was done around that time? Fresh gas?

Rob

Just found this, it may help you

Rob

Get the toe fixed so the wheels are pointing straight ahead, and make sure the air pressure is the same from side to side. If riding on pavement at high speed I always feel a little nervous since those high grip off tires aren’t made for that

Rob

Looks like a 280, which were made 91-98. I agree the VIN is the sure way to tell

Rob