49cc's running way too lean
 

I'm trying to help out a buddy here. He has a Ruckus that is not running properly at all right now. We installed a high speed variator, an intake, exhaust with new gasket (cant remember the name of the exhaust), stock weights in the clutch, stock carb and it has 85 Jets installed.

Well it will get to about 30kms/hr and then it will bounce off the rev limiter. So we stop, pull the plug and its suuuuper lean. The plug is polished white. Compression is good. The carb seems fine, nothing plugged at all. So we put the stock air box back on and it still ran the same way and was running lean.

So we then just let it idol for a while with the rad cap off to see if the fluids would cycle to make sure there was no air locks or anything. The fluid would warm up but it wouldnt cycle. We let it idol for about 15 minutes, turned it off then checked the plug and its still way too lean.

Anyone know what could be wrong here? The air filter and exhaust was installed before the bike rebuild and it ran fine. It could get up to 60-70kms/hr no problem. Now that its back together it runs like crap.

Re: 49cc's running way too lean
 

i think you might have to rejet

Re: 49cc's running way too lean
 

To something larger? From what Ive read anything over 100 is for larger motors. The air intake is a lot less restrictive than the stocker so you could be right. Hes has a buddy that has more jets so he's going to try out some of those and see what happens.

Any other suggestions? Would hooking up something wrong cause anything like this?

Re: 49cc's running way too lean
 

best bet would be to rejet the main and pilot, theres no magic number because it all depends on independent mods and rider weight. prolly just get set of different sizes and get to testing

Re: 49cc's running way too lean
 

Thanks for the input :beer:

He actually took it to some local dude that races/tunes scooters. This dude doesnt install set sized jets. He bores out existing jets to get the scooter to perform at its best with the mods. So now the Ruk runs fine. It just needs some top end now.

Re: 49cc's running way too lean
 

i suggest getting a variator, lightened flywheel, and rolllers. that should pep up the ruckus pretty good to get it going, that's what i plan to do to mine. or you can just get a gy6 swap but that is more in-depth project and money. goodluck