Scooter lacking power and popping. By thevolget (Read 669 times)

[thevolget]

A couple weeks ago I managed to get caught in a downpour on my way to work. The rain came down hard enough to flood the roads in 5 minutes. Anyway I ended up getting stuck having to go down a road that had just started to flood. Was OK until some jackass in a suv flew past on the opposite side and sent a wave up over my scooter. Bam... Hydrolocked engine, bent connecting rod, cracked piston and scored sleeve.

Well after seeing the damage, I rebuilt the engine. New crankshaft, new 50mm sleeve, and gaskets to boot. Put everything back together and fired up no problem. Running is completely different story however.

It runs, but feels like there is no power once it gets past 25mph. If I keep the throttle wide open it will speed up some but pop loudly out the exhaust constantly as well (will not pass 30mph). Even after changing the jet several times starting at #80 through a #90, it does the same. Once a #90+ jet is put in, it acts as if too much fuel is going in and almost dies out.

Mods done to the scooter:
100cc bbk
Performance exhaust
Free flow filter
6g rollers

I've set the valves to 0.04" intake and 0.06" exhaust. Triple checked the timing, checked the compression (~205psi), made sure that filter isn't clogged, regapped the spark plug. Nothing helps.

[jct842]

Why not go thru the carb since it did get wet paying attention to the slide/needle/diaphragm. When water esp dirty water drys there is usually crud on the surface. A tear or even a small leak on the diaphragm is very bad too. Pay attention to your vacuum too, it can not have any leaks.

and you need a decent aircleaner on it too.

[thevolget]

Well, cleaned it out and took for ride today to get fuel for my mower. Managed to record a 15min video of it running (and how it sounds when running). Noticed that when I put my hand on the intake, there was next to nothing as far as suction unless the motor was running at high rpms. I'll post the video as soon as it's uploaded.

Jct842, I was running a k&n style filter on it. But have replaced with a foam one and still happens

[cyborg]

Valves sound like they are tight to me,,, I'd readjust them paying close attention to TDC when setting them

[cyborg]

I'd also give the intake to head and to carb joints a good look and the manifold itself just to make sure there's no cracks

[thevolget]

Best example is at about 5 min mark. That was at WOT the entire time.

[thevolget]

Well I think I figured it out. I had the plastic spacer for the intake rotated and causing a poor seal and restriction.

[jct842]

A vacuum leak......

Get out and do some riding!

[cyborg]

YES!!!i love it when a plan comes together

[thevolget]

Audio of a quick run around the block. (and some poor video, phone was in pocket recording)