1974 tl125 tune-up

[MOTOPHILE]

I have a 1974 TL125. Anyone know what the gap on the points should be set at? And where to line up for setting? Also I would like to know a good place for starting on the carb settings too. Bike has been sitting awhile and trying to tune it up. Bought carb new a couple years back and just cleaned it out (2 times it is CLEAN). Bike idles good but only runs smoothe up top when the choke is on (ran fine before storage). Maybe the float level? Also the coil burned a hole through the side and was sparking a few years back. I patched it and it ran fine. I put a different coil on and still same effect. Now it will not run wide open without backfiring and sputtering. Tried adjusting carb with engine wide open to smooth it out but made NO difference. But so far the points are just adjusted by ear. Think the ignition turned or timing chain jumped a tooth while in storage? Ran fine before I stored it. Lots of clues. Any ideas?

Thanks, Ron

 

[GMX]

To me it sounds like it may be a little rich on the jet needle clip position or the main jet. Try the needle clip position first; Lean=up Rich=down. Remember each time you change the needle clip position you must play around with the air screw but only effective 1/2-2 turns out(tighten=rich,loosen=lean)
Good luck!

 

[jmics19067]

points are generally set at the thickness of a match book cover, .015" to .018", .015 for used. make sure there is no corrosion/crud keeping the points from springing shut,if the points are floating it will affect high rpm power. Also make sure that the rubbing block of the points is cleaned and has fresh grease on it too keep it from wearing closing the gap up ,just a small dab will do. Keep in mind that as points wear not only does change the coils ability to saturate< abiltiy to make high voltage spark> but it will change your timing slightly. check all wiring for cracks in the insulation and corrosion in the conections including grounds

You might want to also check the screen on your fuel petcock. although I doubt it has much to do with your problem. If you are starving for fuel at high rpm from the tank I doubt turning on the choke is going to help when the float bowl is empty but it is worth a shot . Make sure the air filter didnt dry rot

corrosion,dust ,grime, dry rot and small animals making a nest are the only things that can go wrong to a machine if it is just setting,

 

[TheJunkMan]

Well the TL uses essentially the same motor as the CL,SL,XL..ect honda 125s of that vintage so first pick up a Clymers mannual for those bikes (It is a comprehensive mannual for displacements 80cc-350cc singles) start there for your ignition timing and point gap (roughly 3mm-5mm with the mark on the flywheel "T" if memory serves me well) As for the carb sounds like main or a combination of pilot and main jets are to lean/or plugged from varnish, Like I said the mannual will give stock jetting numbers to get you in the ballpark. Hope this helps in some way!

 

[MOTOPHILE]

Thanks for the help so far. I moved the clip down 2 notches on the needle and backfiring has stopped considerable. I tinkered with the points gap again after carb change and even better. Engine runs wide open pretty smoothly now but only when out of gear. When the engine is under a load, it still backfires when throttle is open. Sound like a main? I have 1 more notch to go down on the needle. It is at least ridable now. But still embarassing! Before it was stored it was running fine in Austin, TX. Now I am in Fort Worth, TX. Elevation is not much different here. Could that make a difference?

 

[TheJunkMan]

No not really I still think you may have some dirt/varnish in the carb get the mannual and set the carburator at the stock jets and clip position. also che the intake manifold for vaccum leaks eaisest way is when the bike is idleing to spray ether around the intake gaskets and if the idle speed increases momentarly you have a leak. also check the timming chain tentioner make sure it is set corectly or if it is out of adjustment, sloppy chain=erratic valve/iginiton timing since they are run off of the cam. also www.bjracing.com has alot of stuff for your TL if you are interested in fixzing it up or modifiying.

 

[MOTOPHILE]

Cool. I was thinking about the intake manifold leaking, that is a good idea for testing it. Last carb I had on there sucked air when it was on too tight. Made sure new one does not. I will do that test and I am going to get the CLYMER manual. Sure would be sweet to get this thing purring.
Thanks!