Planet Minis

fachman

I have a 1984 z50r that has spark and cleaned the carb...but it wont start or run ...the only wat to get it started is to jump start it ........HELP

AHPminis

Put your engine on top dead center and adjust your valves to .002"

__________________
Website - www.ahpminis.com
Email - mark@ahpminis.com

AHP - TB -Sano - RB - Kitaco - iShock - Fox - Marzocchi - F50s - Utopia - Takegawa - Crower

mexicanyella

How does it run once you've got it started? Exhaust smoke? Throttle response? Power? Backfires, hesitations, surges, interesting smells, fire?

You said it had spark...I've seen bikes be hard to kickstart with weak spark, but you could bump start them. They ran sort of okay once started. More info would be helpful, but I'm going to suggest cleaning and setting your points. Like valve clearance, your points setting can't be too correct.

popcorc

um i've been looking at most of your threads and im guessing you know alot about 84 z50r's. i have one that does the similar thing. I can sit there and try to kick start it all day and it won't even fire up, but i can shift it into second and roll it down my big hill and it will start to fire about halfway down and then i have to warm it up. after the engine is warm it starts up ever kick but im just wondering what might be wrong with it when i try to start it cold, i have a new ngk spark plug, good oil, i don't know what to check. the muffler doesnt have any smoke because it has a gapping hold in the side, its very loud, maybe this has something to do with it, its like the side facing the frame is just missing a metal chunk. how can i check if i have a weak spark or how to make it stronger? what you're describing is helpful because that is what my motor is doing

also, it doesn't idle and i have to give it gas to keep it running maybe you could help with that too. thanks!

dave65721

If it doesn't idle and won't start you're probably going to find that your carb is dirty. If your pilot jet is plugged the spark plug won't have anything to ignite. When you are push starting it do you have to give it a bit of throttle for it to fire? After you take care of your points and valve lash go straight to the carb. Do you have any experience cleaning carburetors?

popcorc

I think my carb is dirty, i really never have cleaned a carb besides a lawnmower, which all i do is poor some gas inside and try to get the gunk out. yes i do have to give it a lot of gas for it to start up. i don't know what the main jet or points or valves are so please help me with that, thanks

chewdipty5

In my experience with a problem like that (I've had it twice), your compression is too low. It is an '84 and sometimes the rings have never been changed or it has been too long since last top end change or etc. If you have a compression tester it should be around 90 - 120psi indicating good compression. Bad readings will be anything from 50ish down to barely reading at all. You can buy one for $30.00 at O'Reillys auto parts store or Advance Auto Parts (10mm thread).

Without tearing the motor down, try first by squirting some oil (regular motor oil) into the cylinder through the spark plug hole. If you can use an old school one with the pump to squirt it in that's best. I have used a straw to blow it in. The oil coats the cylinder and blocks the warn out rings from losing the compression. Kick the bike a couple times and if it fires up relatively easy from being cold, you have worn rings, piston, or cylinder typically.

If that doesn't work you may still be losing compression, but it may be a timing issue too...

Good Luck

mexicanyella

I agree on the compression thing, but if your compression is low enough to cause starting problems I'd think you'd be likely to see at least some bluish oil smoke. Even with a large exhaust hole. I've had to squirt oil in the plug hole and kick it over a few times when an engine's been sitting for a long time, to reestablish an oil film on the cylinder wall (even new rings/bores need a film for the rings to do their job).

Not to be Mr. Contradictory Pants or anything, but it's entirely possible your compression is not bad just because it's a 1984; my bike is a 1971 and is running one of my two engines right now which has never had the top end off in almost 40 years. It isn't "fresh," but it runs fine with little to no visible smoke and doesn't use much oil either. It's got a bunch of hours on it. All I'm saying there is don't assume it's worn out just because it's 25 years old. These things last a long time if they get an occasional oil change and what usually goes wrong with them in my experience is just due to fuel varnish blocking carb passages or ignition systems needing maintenance attention.

Regarding strong vs. weak spark, if you remove the plug and ground it on the head, hooked up to the wire, and you kick it over, you should get a nice bright bluish-white spark. If the spark looks like a weak little purple thread, chances are your points need to be cleaned and have their opening gap adjusted. If you have no spark chances are still good that all you need to do is clean and gap the points. If you don't know how to do this and don't have a manual, say so; I can talk you through it and so can others here. Get a manual one way or the other though. It will be money well spent if you plan on hanging onto the bike. You'll also need to get a flywheel puller for that model, probably available online from numerous PM advertisers, or CHP racing, or Dr. ATV, or your local motorcycle shop's Tucker-Rocky or Parts Unlimited catalog. And a feeler gauge with feeler blades as small as .002" (for setting valve clearance) and at least as large as .016" (points gap has to be between .012" and .016").

Your problems could also be caused by a dirty carb, as said above. If you remove the float bowl you'll see inside that there are two brass jets protruding down into the bowl where fuel would normally sit. The smaller one is the pilot jet, and supplies fuel from idle up to about 1/8 throttle. Fuel is metered by the larger one from there on up, in conjunction with other stuff interacting up above in the venturi. Both the jets have to be free of dirt, grit and fuel varnish deposits. It takes very little of either to obstruct fuel or restrict it enough to cause a lean mixture and crapadelic performance. Carb cleaner spray, compressed air, maybe a thin torch tip cleaner wire or an old high E string from an electric guitar to poke gently through...

As always, if you have not done any of this before say so and more specific instructions will be appear, like a gentle rain of manna from the sky.

crf50187

see if you are getting the right amount of fuel