Lifan 138cc FMI vs. FMJ

[goldenboy81]

Hello and thanks in advance,

New to the boards and I am restoring/customizing a 1976 ct70. Have the orginal honda 72cc engine, which works, but I am looking for more power. Looking at the Lifan 138cc engines on ebay right now. From what I have read, I want the engine with the gears N1234 vs. 1N234 because the latter tends to slip into neutral when shifting. I also read that one is not a true 138cc but a 125cc??? From what I see on ebay, people are selling two types of 138cc Lifan engine. One is the 1P54FMI (which I believe is the 1N234) and the other is the 1P54FMJ (which I believe is the N1234)? Please correct me if I am wrong.

Also, do you know any other differences between the two models? Is there any other reasons I should not run this engine? Right now, looks like the best price I found is around $410, however, this includes a 24mm Mikuni carb, oil cooler, intake manifold, shifter, kick starter, wiring harness, CDI, spark plug and ignition coil. This price includes $60 shipping, so the price of the actual engine/parts is $350.

To summerize:
1. Difference between the 1P54FMI vs. 1P54FMJ.
2. Reasons I should/shouldn't go with the 138cc Lifan.
3. $410 all in = good price?

Thanks again.

[Gerotor]

I am looking for the same info like where to find the best deal and what really needs replacing on the bike to make the new system work.

[racerx]

Can't speak to every issue. However, I'd favor dealing with an outfit that maintains a business presence outside of ebay, in other words, someone who's into more than just moving tonnage & might simply split once the batch of motors is sold or problems surface. After-the-sale support is a good indicator.

As for what changes may be necessary:

• Gearing - sprockets & chain (may need #428 and should run HD chain with a motor lager than 90cc)
• Carburetor - may also need to run an angled intake + open element air filter
• Throttle, the stock internal twist grip runs out of room at 22mm
• Clutch cable & mounting bracket
• External petcock if you want to retain "reserve" function with an aftermarket carb.
• 12v battery
• Battery carrier
• Bulbs
• CDI wiring
• Voltage regulator
• Turn signal relay
• Footrest asm, including kickstand length/placement
• Exhaust & rear mount
• Engine guard fitment
• Chain guard