Carb issue?

Daves Nel Lusso

New Member
Oct 19, 2021
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Hi all, new member here. Great forum with lots of useful info! I have some experience with motorcycles but this is my first bike kit and It's been a lot of fun. I recently installed an 80cc kit on my Nel Lusso and I have about 1.5 tanks of gas through the machine.

My problem is that the bike is hard to start and floods as soon as it starts getting warmed up. I'll go into the boring details below to describe the problem and things I've tried after reading some threads here.

The bike build: Minus some loose nuts and bolts along the way and lots of oil spilling from the exhaust after riding, the bike ran great right out of the box. I didn't plan on doing any mods to the bike, at least not before breaking it in. I have been running 17:1 fuel, but switched to 25:1 since I started troubleshooting. At about 30 miles or so, the carb came loose and slipped off the intake while riding. I tightened everything up but it ran rich afterwards. It would start up (not as easy as when new), but flood as soon as things warmed up. I found out the carb tickler/primer was getting stuck in the down position and the choke continually closed itself due to riding vibration.

I couldn't get the primer to stop leaking so I bought a replacement " Speed" carburetor off Amazon and installed it with a new intake gasket, and offset intake. The bike runs exactly the same as before. Starts ok... Floods as soon as it gets warm.

I've adjusted the needle clip and idle screw to various positions without any luck. Replaced the plug with a NGK B-4L with a .025 gap. No difference. At some point the coil came loose and plug wire got a little crispy so I replaced with one from Amazon that is supposed to fit an 80cc kit. Still runs the same. Plug is always wet and fouled after running a couple of minutes. I can't get the bike to idle at all really. I've checked compression and it's 150psi cold. Looked in the cylinder With a snake cam and I see a little bit of wear near the exhaust and intake ports but nothing really. After finding the bike ran slightly better without a muffler on, I cut it, gutted it, and re welded back together.

Could it be that the bike overheated while the carb was loose, causing internal damage, or do I have an unresolved carb issue? Should I keep messing with the new "Speed" carb or send it back to Amazon for a replacement? None of my carb jets seem to have a number on them so I don't know what I'm working with as far as jet sizes. Help please!
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Los Angeles, CA.
Hi... Welcome to the forum!

The first things I recommend are to use a NGK B6HS spark plug... The next is to switch your gas/oil mix to 32:1

After testing those changes, (If needed), you can try running it without the air filter... (if it runs better?, you should try a slightly smaller jet in the carb)
 
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Daves Nel Lusso

New Member
Oct 19, 2021
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I changed the plug and switched to 32:1 gas. It runs a little better at 1/3 throttle but any more or less and it floods. It still doesn't idle well either.
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
6,827
762
113
Los Angeles, CA.
I changed the plug and switched to 32:1 gas. It runs a little better at 1/3 throttle but any more or less and it floods. It still doesn't idle well either.

Did you test it without the air filter like I suggested???
If it runs better without the air filter, that means it's jetted too rich... If it runs worse, that means it's too lean.
 

Daves Nel Lusso

New Member
Oct 19, 2021
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Yes I tried that as well, sorry. I didn't notice much change. Any suggestions for a range of jets to try for the 80CC? I saw some places sell them online in a "kit" with multiple sizes. The stock jet isn't numbered so I'm not sure where to start. Thanks so much!