WTB: Tillotson ML5B carburetor
- Thread starter pedal4416
- Start date
Bikes been running now for a couple days, sometimes starts right up other times peddle your butt off. Seems to run better when cold, after it warms up, hesitates when taking off from stop signs and sometimes dies. When its at open throttle it runs fine, but still getting blowback through the crankcase breather. Two oil changes with Rislone in about 20 miles, oil pretty black for short mileage. Been using Gumout for the last 20 miles or so. Maybe I should stop messing with it till I get the new carb gasket, getting air through the old one. Im getting the best idle with slow idle screw at about 1 1/2 turns out, main jet is 3/4 turns out. Also after I come back from a ride its almost impossible to start back up.
Hi Chopperjoe,
Gaskets are on the way! The oil should be mostly clear after only 20 miles. Sounds like there is still a lot of carbon build up on the piston [ring glands] and I would leave Rislone in and change after 50 miles.
Several items can cause it to start hard after it is warm. Valves, worn rings [or massive carbon build up on the piston], carburetor and lastly ignition. The magneto, when hot, may not fire as well. Points can and should be replaced with the ignition module, and if using the module the condenser must be unhooked. If the points are burned on the contact surface replace the condenser. Make sure the magneto is .010" from the flywheel magnets [use a feeler guage to set]. If the valves are leaking it makes it harder to start when hot. Also check the lifter clearance because valves grow when hot. Set the clearance at .012" on both to make sure the problem isn't valve clearance.
Which spark plug are you using? The "H" with the stock head is a short reach plug [3/8"], and the Hi fin head uses a 1/2" reach plug. If the wrong plug is used it can cause it to start hard when hot if the longer reach version is used. I use Autolite #303 or NGK B6S in the "H" & "J" motors, and NGK B5HS or Champion L90C in the "300" or later motors.
Jetting on the carburetor sounds close to correct.
Have fun,
Gaskets are on the way! The oil should be mostly clear after only 20 miles. Sounds like there is still a lot of carbon build up on the piston [ring glands] and I would leave Rislone in and change after 50 miles.
Several items can cause it to start hard after it is warm. Valves, worn rings [or massive carbon build up on the piston], carburetor and lastly ignition. The magneto, when hot, may not fire as well. Points can and should be replaced with the ignition module, and if using the module the condenser must be unhooked. If the points are burned on the contact surface replace the condenser. Make sure the magneto is .010" from the flywheel magnets [use a feeler guage to set]. If the valves are leaking it makes it harder to start when hot. Also check the lifter clearance because valves grow when hot. Set the clearance at .012" on both to make sure the problem isn't valve clearance.
Which spark plug are you using? The "H" with the stock head is a short reach plug [3/8"], and the Hi fin head uses a 1/2" reach plug. If the wrong plug is used it can cause it to start hard when hot if the longer reach version is used. I use Autolite #303 or NGK B6S in the "H" & "J" motors, and NGK B5HS or Champion L90C in the "300" or later motors.
Jetting on the carburetor sounds close to correct.
Have fun,
Thanks again Quenton, picked up the Autolite today, still waiting for the modual to come in to replace the points. Could you please tell me the correct gap for that plug. After I get it all together with new gaskets and modual im going to have to learn how to check valve clearance. Know anything about that? HA HA Take care for now Joe
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Hi Quenton, when you ship the carb back could you please include 2 new gaskets for the manifold, I will keep 1 for a spare. Thanks Joe
