1972 ct90 Lifan swap

Tuuubbs

New Member
Been working on swapping a 125cc into my ‘72 ct90. It’s been one problem after another. I ordered the rear engine mount adaptor from dr atv and then took the bike over to a guys house who builds flat track bikes and drag cars to have the top mount looked at. He took one look at the adaptor mount I bought and said he wouldn’t trust it (has anyone used these? Any negative reviews?). He cut me some basic brackets that reach forward about 1.5” from the rear frame mount and mounted the top into the top frame mount with a smaller bolt. Then the intake manifold for the carb wouldn’t fit under the frame, so I found some brackets that work enough to get the intake under the frame, but the chain drive on the engine will pull the chain onto the the support for the arm that goes back tot he wheel. I was able to adjust the new rear brackets enough to fit but it just feels like so much more has been done than has to. I’m almost 2 month in and I haven’t even tried firing the new motor. I’m going to get a chain this week that will fit the stretch then HOPEFULLY I can connect the throttle cable and see if it’s a dud motor or not. (Images may be out of order)
 

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Old Guy Too Many Bikes

Well-Known Member
NO NO NO, that doesn't look good at all! Using the DrATV adapter will work fine. You need to use the top hole on the frame to go through the top hole on the engine. This supports most of the weight of the engine. The rear bottom mount uses the adapter and supports the engine from moving, not so much the weight. Besides looking ugly, and messing up your chain geometry, that set up will not support the engine solidly.
 

Tuuubbs

New Member
Put the Dr atv brackets back on and I remember now that it doesn’t line up, that’s why I originally took the bike to get looked at and had those other brackets made. I’m the first picture you can barely see the top of the adaptor through the frame mount, so it need to come up close to an inch. Can I bend them enough to fit it? Also this makes my carb jam in to the frame..
 

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Tuuubbs

New Member
Okay I figured out how to get it mounted with the purchased brackets, it comes with 2 spacers, a small one and a long one, and they don’t go together, the small one goes on the outside of one of the brackets with the long one in between them. Now my only problem is the carb is touching the frame, which I’m positive will lead to the intake manifold cracking while trail riding.
 

Tuuubbs

New Member
Thanks for the tip. I ended up boring them out from ~1/4 to 5/16. That allowed the carb to clear just left of the frame. I’ll need to find a longer boot to fit to the air filter box, any tips on that?
 

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Old Guy Too Many Bikes

Well-Known Member
You could switch to a uni type screen mesh filter, or else find a piece of tubing with an outside dia about the same as the inside dia of your boot. Cut the boot and use the tubing as an extension with hose clamps if needed. Paint'em black and be done.
 

Tuuubbs

New Member
It was one of the few damaged pieces. Small crack around one of the holes where it mounts. I bored out the holes on the Lifan intake to allow a little wiggle room and it clears now.
 

Tuuubbs

New Member
Can I cap off one of the gas lines and just run from the reserve? Or will I need a petcock anyways and should just run both into the petcock?
 

kirrbby

Well-Known Member
You CAN, but you'll probably miss having the reserve eventually. Might be further ahead to just run the dual petcock from the get.
 

joel1234567

Active Member
Might be a little more likely to pick up some sediment in the reserve line.
Also, I can't 100% remember for sure... but I think you need to cap both ends of the line if you're not using it- ie the line out of the tank and the fitting at the carb. Like, if you just run the res tank to the res carb nipple, and leave the non-res carb nipple without a line on it, when you open up the petcock gas will run full speed out of the non-res nipple. Been a while, may want to double check that. Or I guess you could tee both ends.
 

Tuuubbs

New Member
Might be a little more likely to pick up some sediment in the reserve line.
Also, I can't 100% remember for sure... but I think you need to cap both ends of the line if you're not using it- ie the line out of the tank and the fitting at the carb. Like, if you just run the res tank to the res carb nipple, and leave the non-res carb nipple without a line on it, when you open up the petcock gas will run full speed out of the non-res nipple. Been a while, may want to double check that. Or I guess you could tee both ends.
Carb only has one gas nipple. That’s why I was wondering if need to get a petcock and put it online before the carb.
 

Old Guy Too Many Bikes

Well-Known Member
Yes, you always want to have a petcock between the tank and the carb. A bad float or a needle and seat issue could result in a garage floor full of fuel. Also, a good habit is to shut off the fuel supply when done riding for the day and let the engine die before shutting off the key. It prevents crap from building up in your bowl, especially if you only ride occasionally.
 

Tuuubbs

New Member
Found a rubber plumbing connector that fits over the carb(once cut) and will enough over the carb boot to get good a good seal. I got a can of Toyota metallic gray and it was a pretty close match to the original filter box color, much better than the bright red though. I connected the wires and she fired right up. Any ideas where to mount the petcock or is it okay just suspended like this?
 

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Old Guy Too Many Bikes

Well-Known Member
Absolutely, that's what you're supposed to do. Left lever clutch, right lever front brake. Also, you need to mount that petcock. Make a bracket coming off the frame or the carb mount. Use longer hoses is necessary.
 

Tuuubbs

New Member
Just found out this engine isn’t clutchless. Can I re-rout the brake lines and make the left cable go to the clutch?
First gear works at least. Too loud without an exhaust on it to test all the gears.
Did you get a clutch cable with the engine package? I thought they were usually included.
I don’t believe I did I’ll check the box though
 

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