Engine barely runs then backfires to a stop.

As you all saw in the subject my 99 Hero Magestic Panther is having some problems. I replaced the cdi and the carb, tuned it and every thing, new spark plug. But when I go to start it it just runs for a little bit then it dies. And if it does run when I pull the throttle it dies out. Then backfires I've been trying to figure out what's the problem but it's difficult. What are y'all's opinion on this problem?

Re: Engine barely runs then backfires to a stop.

Also I'm finding some oily seepage coming out from the lower end part of the cylinder where the exhaust connects, what does that mean?

Re: Engine barely runs then backfires to a stop.

The timing is off most likely. Possibly an airleak as well. The black stuff is unburned fuel/oil from the bike not firing properly.

Re: Engine barely runs then backfires to a stop.

Jesse Nordlander /

Keyway is prob sheared

Re: Engine barely runs then backfires to a stop.

Do you have to set timing on a CDI because I thought the CDI took care of that. Plus I don't think you can te my bike because it has a fixed mount holes so no timing is needed.

Re: Engine barely runs then backfires to a stop.

I checked the flywheel key and sure enough was sheared but I don't think that would be enough to make it act like that.

Re: Engine barely runs then backfires to a stop.

It sure can do that if the woodruff key is sheared and the flywheel is in some random position.

Re: Engine barely runs then backfires to a stop.

Time to think about what timing means to an ice. Say, in a busy restaurant there's the swingy kitchen door, if workers didn't "time" it right going thru that door it would be instant diaster.

Now, if the cook doesn't flip the burger, empty the frying basket, or clean the grill at the right "time" it would be disaster.

Or on the other end imagine if the waiter is taking all the orders and slipping them in randomly on the order carousel. The "timing" of what customer's food gets done first would be off.

Sadly, we are all bound by time some more so than others but in life timing is key.

Re: Engine barely runs then backfires to a stop.

Jesse Nordlander /

Timing is everything. In a pinch u can lap the flywheel to shaft with valve grinding compound eye up the keyways, and roll out.

Re: Engine barely runs then backfires to a stop.

The cdi does not time itself. Tou need to do it with a timing light. No other accurate way to do so. If you had points you could use a few other methods.

Re: Engine barely runs then backfires to a stop.

I put everything back together however it still seems to still act like that. Now I am kind of suspicious of the carb I recently put in it. Because I noticed that all the problems started when I put the new carb in it. I mean the old carb worked much better than the new one did. Plus the new carb was a dellorto vespa carb that fit it. But I am REALLY suspicious of the jet in there, because it might be to small i dont think it's producing enough fuel for the engine and that's why the mixture is so lean.

Re: Engine barely runs then backfires to a stop.

When you say: “put everything back together” what did you do to prep the flywheel to mate to yhe crank after slipping the key?

No judgement. I did the same thing because the CDI flywheel just doesn’t fit right without lapping.

It will slip again if you didn’t do that.

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