z50 idle/power problem

labatt50

New Member
I bought a z50 today just for kicks. I think it is a '76.

The guy who sold it to me told me he replaced the piston and the rings. He may have mentioned something about the points as well.

I cleaned the carb out when i got it home, it runs, but it still has a few problems.

-It hardly runs without the choke on
-It wont go over 10 or 15 mph
-I can feel it backfiring through the air intake :S


Where do you think i should start?

Thanks
 

69ST

Well-Known Member
Typical symptoms of a blocked pilot (idle) jet, incorrect point gap/timing problem/leaking intake valve. I'd verify that the points are properly adjusted & like new and plan on rebuilding the carb. Check the timing marks on the cam sprocket & flywheel. There's nothing that says the previous owner did the job right or knew what he was doing. I'd also inspect the intake port. If it's black, plan on replacing the intake valve. Worn intake valves are very common on these engines. Fortunately, the valve seat will usually have little wear and will clean up with a light resurfacing/valve lapping.
 

labatt50

New Member
Thank you for the timely response.

I soaked the carb last night.

Is the pilot jet the main jet in the carb? If so it seems to be clear...
I could not remove the jet. it spins inside its housing but i did not want to force it out. As well, there was a small rubber cap loosely fitted on the bottom of the jet.. I am unsure of its function.

I have the flywheel cover off and am looking at the points but they seem to be in contact throughout the engines complete cycle. I have never set a point gap before but this doesnt look right.

I will do some more searching around for gapping procedure and i will pull the cap from the head to check timing.

Thanks
 

snooter

Member
check your spark plug..if its black as black can be your problem most likely is plugged pilot jet..i had the same problem on my 75 xl175..had to run with choke on..diagnosis-pluged pilot jet....course..what racer says always applies..that old dude has yet to stear me wrong so follow his advice
 

labatt50

New Member
I did the valve lash

Gapped the points.. will check the plug gap later tonight

And? It runs much better, it is actually fun to drive now. But, it still likes to have the choke at least one third of the way up.

So.. Do i need a new carb? A rebuild kit? A new jet?


Thanks!
 
Thank you for the timely response.

I have the flywheel cover off and am looking at the points but they seem to be in contact throughout the engines complete cycle. I have never set a point gap before but this doesnt look right.

I will do some more searching around for gapping procedure and i will pull the cap from the head to check timing.

Thanks

OK here is a quick point and timing response. To really understand these little bikes. Get a Clymers manual, they are the bible for these little babies.
On the valve timing when the flywheel is at T (top dead center) it is marked on the flywheel.... the cam's sprocket should be close or @ the 9 O'clock position on the cam sprocket. There is a little O on the cam sprocket you should be able to see with the cam cover off. You will also see a notch on the head where the O should be at. On the points, they should just start opening when the flywheel is at the "F" point on the counterclockwise rotation. And when the flywheel reaches the "T" the gap on the points should be between .012 to .016. You can change the gap by loosening the small phillips screw by the points and moving the point assembly towards the ground. This will open up the point gap so you can set it with a feeler gauge. This should cure the hiccups in the timing if the valves are good.
You tube has some "Alexman videos" that show this process in video format and helps explain/show the written bable that I have tried to pass on here in this rant... LOL :21:
Let us know how it comes out.

Brian
 
Top