125cc "Lifanstein"

[criggs]

Hey guys, need a bit of help again.

My Mom and step-dad got excited after seeing the progress I've made with my two china restorations and decided to buy a pit bike of their own. It is a Frankenstein's monster of a bike, seemingly pieced together from a few other different bikes.

It has a Lifan 125cc in it that actually runs very well, but has a few other issues that need to be addressed. First and foremost, it has street tires on it, on 12 inch rims front and back:

As you can see, the tire BARELY clears the shock mount. The wheel is pulled back so far the chain has zero slack. It also appears that this is about as far back as it can go with the adjusters, so I'm thinking this swingarm was originally intended for 10 inch rims possibly? Also, the front rim is a 12 inch as well, which is different from my other two pit bikes (both have 12 inch rear 14 inch front). We ultimately want to put dirt tires on this bike, but I'm not sure the knobbies will clear in the rear, and I haven't seen any dirt tires for a front 12 inch. Anyway my question here is what do you guys think my best bet is with these wheels? Two 12 inch wheels is fine as long as a dirt tire can clear in the back. Is it fairly easy to source a longer swingarm? Or should I just see if I can pull it back further with a longer chain? What would you guys do?

Also, the throttle is really wonky. You have to rotate it back at least a quarter turn before it actually starts to accelerate, and it has no return whatsoever, it has to be manually twisted back. I'm going to pull the slide out of the carb tomorrow and see if the spring is messed up or something, but either way I'd like to replace the whole throttle assembly, which I've never done. I have a brand new throttle cable and bar mount/perch/thingy, just never installed one before. They're pretty universal, I hope?

Last thing: the Kill switch is gone, along with all of its wiring. I'm sure it is taped up in the loom somewhere, so what color wires should I be looking for? Is it a black and red wire like any other pit bike, or does the Lifan have something different? I doubt it, but I wanted to make sure before I start cutting back all the electrical tape to look for the correct wires.

As always, thanks for all your help guys, really appreciate it =].

 

[my67xr]

Kill switch wiring will be a black w/white stripe wire and a green wire
You should be able to check it at the cdi plug, the middle pin it the kill switch pin
You could just run a wire from that pin through a switch, and another wire out the other side of the switch to an decent earth on the frame somewhere

The engine may not be a Lifan,most of the semi auto engine's normally have the fin's on the cylinder running from the head to the gearbox like this, but that isn't alway's the case

[IMGhttp://i00.i.aliimg.com/photo/v0/1974491710_2/Pit_Dirt_Bike_Parts_Lifan_125cc_Air.jpg[/IMG]


It look like it may have come out with a 10" rear wheel when it was made originally, but you can get pit bike's with 12/12 wheels too.
The chain may have 1 less link than normal, so that may be limiting the rear wheel adjustment, and making it sit to close to the front too
Try dropping the chain link and see if the wheel can move back more then

What is the tyre size of the rear ?
I reckon some one has fitted scooter/motard tyre's to it to use it on a Ashphalt track for circuit racing it
You can buy motard specific (road based) bike's these day's too


Throttle's are pretty universal and are easy to set up
You might be able to take up some of the cables' slack by adjusting the cable out a bit at the top on the throttle where the cable screws into the throttle housing.
Some carby's have an adjuster on the carby top too.
But yeah, check there's a spring on top of the slide, someone might have lost the spring and fitted a shorter spring too, or maybe it's been compressed ?

 

[criggs]

Ok, I know it's been a while, but I finally got some things taken care of on this bike.

I checked the throttle slide in the carb, it did have a spring and it was working fine. The throttle tube and housing on the handle bar didn't fit on the bars right for some reason, which was what was causing it to stick. I had a spare housing and cable laying around, so I picked up a new tube, fitted everything, and it now has a fully, normally functioning throttle.

Next, I unwrapped some of the wiring and found... a mess, to put it lightly. Wherever the kill switch went to ground originally was completely gone, and the black/white wire was just cut and taped up into the harness. What's actually kind of funny is that the fuel line on this bike leaks (one of the many other problems it has), so it will keep running even if you turn the fuel off. And, since it's a semi-auto, it can't be stalled out with a clutch... so I have NO IDEA how the PO had been shutting this thing off without a kill switch. Just pulling the spark plug wire off, maybe? Either way, I hooked the kill switch up at the black/white wire and grounded it at the coil frame ground, and everything seems to be working wonderfully.

If I recall correctly, the tire size on this bike, front and back, is 90/100-12. The dirt tires that I have on the other two pit bikes are 80/100-12 in the rear, so I'm hoping that they will clear this swingarm. I also found some 70/100-12 on Ebay, maybe those might fit a bit better?