Motorcycle Repair: 74 Trail 70 K3, vacuum leaks, compression stroke

Question
Hello
I just rebuilt my carb, bike idles great and runs OK except it seems to starving for fuel. 1st gear is fine but when I shift to 2nd and throttle up it looses power if I don't accellerate slowly. If I move the choke on 1/4 it solves the problem. The bike has 2400 miles on it.Are there any other adjustments I should be doing on this bike. Valve,timing,points ect. Also where can I get wheel paint for the rims.

Thanks for your help!

Answer
Steve, K1-K4 models have 20mm float level settings, a #65 main jet for AT7B carbs and #58 Main jet for 533A models. Slow jet (idle jet is #35 for all). Needle clip is #2 slot from the top, but you can play with it to increase throttle response.  Adding choke as you indicated means that it is running lean, more than likely. Make sure that the gaskets/O-rings on the intake manifold, insulator and carb flanges are in good shape and there are no vacuum leaks between the carb and the head. These bikes tend to strip the threads in the manifold to head bolt holes.


Be sure that the fuel tank is clean, the petcock (fuel valve passages are clear) and that the gas cap vent is OPEN when riding.

Timing is fixed at 25 degrees before TDC at the F mark alignment. Points should just break open at the F mark. Valve clearances are critical on these small motors... .002" COLD for both intake and exhaust valves at TDC compression stroke.

There are tons of mini-trail type websites out there, plus lots of stuff on EBbay all the time.

Duplicolor makes silver wheel paint for steel wheels that is pretty good for that application. Check WALMART or auto parts stores.
Bill Silver