Carb Jet Size for 110cc


New Member
Sanity question for my new-to me 1971 CT70. It appears the engine has been (somewhat disappointingly) replaced with a 152FMH 110cc. Carb jet sizes are idle 32 and main 78. Seem kind of small? Anyone know if those sizes are correct? I want to make sure I'm not running too lean.


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New Member
Seems to run fine, but the engine does feel pretty hot. But I've never owned an air cooled bike before, so maybe it's normal?


Active Member
So no bogging in any gear? You said you bought this bike from, correct? Did they not tell you that you were getting a bigger motor? Any warranty? Unless you were hoping for an original stock bike, a bigger motor isn’t a bad thing with you and your 10yo riding together. On a side note, there were no white CT70’s sold in the USA.
I assume you live in the San Jose area? It should still be fairly cool there, difficult for an even a lean motor to build up excessive heat unless you’re riding around at continuous WOT. That looks like stock exhaust and a close to stock carb, with a stock airbox, but I have an untrained eye. My opinion is you’re not tapping that motor’s full potential, yet.
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New Member
No bogging of the engine. I'm in California. I bought the bike from a lady who said she had it redone by (paint + engine). She wasn't very knowledgable about what had been done.

I'm not worried about tapping potential, I'm more worried about engine reliability down the road.


Well-Known Member
Never heard of a FUHUA carb, LOL! I would buy a oil temp dipstick. They are a little pricey for a budget China lump but Dratv has one for 50 bucks, and is a good way to know if the bike is running hot or not in real time. Makes it easy to pull over and let the bike cool down if needed.