never have ia ever: broke a magneto key???

[mrameswmartin]

well daddy-o's ive got a ringer for ya'. i have a 81 gs 450 (http://www.thegsresources.com/_forum...d.php?t=174320 )which back fires out the carbs and wont hit. this initially tells me timing is off but compression is good ( which im told a valve would bent if it jumped a tooth). so is it possible to have broken the key and the magneto spun? causing the timing to be off ?

ohh and the only reason i posted this in a new thread is because i wasnt sure of the rules here yet.

[chuck hahn]

whats the previous history? A rebuild? anyone take the coils off and have them plugged into the wrong plugs in the wiring harness? That will produce that symptom. I did it myself reinstalling a wiring harness. Switched the coil leads around and she fired right up. That doesnt mean this is your problem, but its possible.

[mrameswmartin]

negative because one harness has 3 prongs and the other only 2.. also no rebuild as far as i know.

[chuck hahn]

just a thought..i dont know how i got mine switched ..but i did it. Mine was on my 78 100 C ..two wires on each coil..

[Steve]

It might encourage you a bit to learn that your bike does not have a magneto that would affect ignition timing.

Compression can still be good, even if the cam timing is off by one tooth.

With the cam timing off by (just) one tooth, you will likely not have bent a valve.
I think you have to go more than three teeth for damage to happen.

When is the last time the valves were adjusted?
If you can't remember, it's past time to adjust them.
Tight valves (which is typical) will cause backfiring while trying to start the engine.

One final thought, ... a new thread is the perfect place to put this. It addresses YOUR problem with YOUR bike,
not tagging along on someone else's thread that we might have gotten tired of reading.

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[OldVet66]

I'm not familiar with the 450, but if it is spitting out of the carbs and you have the air box off, it's because you have the air box off, making it super lean. It won't run without air box and filter unless it is jetted for it. Typically these bikes sit around and the fuel system gets rusted and full of particles that make it into the carbs, the carbs get varnished and plugged up and require a complete strip down, soaking in carb cleaner, new O-rings adjustment and syncing to run right. They don't normally get run long enough to have a cam chain jump a tooth.

[mrameswmartin]

It might encourage you a bit to learn that your bike does not have a magneto that would affect ignition timing. .

well thats one problem not to worry about. as far as adjusting the valves i just got it last week. i will try that next.

-OldVet66- i dont believe the carbs are causing this issue ( but lord knows it wouldnt be the first time ive been wrong) and heres why. i took the tank off and carbs are wide open ,but even with starting fluid it wont fire. i did take the carbs apart and they are in a carb dip now.( also need new diaphragms. can you believe they want $75 a pop!)

so how possible would it be to jump a tooth?

[Steve]

...so how possible would it be to jump a tooth?

It's very possible if the cam chain tensioner is not working properly.

How likely is it? Very likely, if the cam chain tensioner is not working properly.

Since you are getting ready to do your valve adjustment, take a look at my sig.

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