starting issues and backfiring

[prpldude]

Sorry for long post. you can skip to bottom to find out my problem and then read post for details :0)

'80 GS850GLT

I put my bike back together this spring after taking it apart to paint it. (it didn't happen). It ran good small backfires (I think out of the tailpipe) when idling with the choke on or when I let off the throttle at "high" RPM's. I know I have a charging issue I think I have narrowed down to the stator. Been riding since May 24th with minimal issues. (sometimes I have to use a screw driver across the starter relay to start the bike, but not often)

anyways. Yesterday after getting fuel it decided it wanted to give me problems starting. I got it started and let it idle for a bit.. seemed to idle fine 1050ish RPM no choke. I turned the bike off and it wouldn't start. It would crank over but acted like it wasn't getting spark. I could smell a faint hint of gas but not "flooded" smell. I tried choking it and full throttle and nothing. I let it set a "few" minutes. and I finally got it started. I rode it about 40 miles mostly highways. It ran great.. good throttle.. small backfires "as normal". When I stopped the bike it idled fine nothing out of the ordinary. But when I went to start it back up after 15 mins or so. It just turned over and over would try and do something but wouldn't start. I was on a hill so I got some momentum and dropped the clutch in 2nd gear and "BOOM" like a gunfire out of the tailpipe and it started. It ran fine idled a little low. I rode it home, 40 miles and it ran fine the whole time. I got home and it wouldn't start and the battery had finally died.

I charged the battery over night and tried starting it this morning like normal. Full choke no throttle. The battery seemed tired even after a full nights charge so it took it a bit to start but it did. I drove it a mile. After two hours at a coffee shop I went out to start it and full choke.. vrooom.. started right up.

PROBLEM: Hard time starting after running for awhile and then big backfire when finally "push" started it.

Any thoughts on what would make it give me troubles starting and the big backfire?

Thanks in advance and sorry for long post.
Marc

[Colorado85gs550]

try turning off the gas cock after a long ride when its warm then turning it back on right before starting it........

I've heard of issues with the floats in the carbs allowing too much fuel in when its hot, both atmospheric and mechanically hot.

If turning off the gas works, then you have a float problem.

[prpldude]

Thank you for your advice. I'll try that. I should have cleaned and sync'd my carbs when I had them off this winter ;0( I was lazy.

by off do you mean turning it to PRI. my petcock doesn't have a lever only a "dial" that is turned by a screwdriver. there is norm and pri.

[almarconi]

Symptoms sound similar to vapor lock. Does it start easier with the gas cap off?

The valves could also be out of adjustment. When was the last time you adjusted them?

[prpldude]

I've heard of "vapor lock" before, but not sure what it is or what causes it.
I did not try to start it with gas cap off.
Ummm not sure when valves were adjusted last. I'll put that on my list of things to do. I have a new valve cover gasket already and the link to Basscliff's website with the tutorial on how to do it. I should be good to go. Ohhh Shims.. I might need some of those. I know someone on here will have them when I get to that point :0)

[prpldude]

Ok... I've got my bike apart and I am doing valve adjustment. I need to swap shims from one valve to the other. I have heard to never turn the bike over if a bucket is empty. I do not have an extra shim to put in empty bucket while I get switch shims. I noticed that certain exhaust and intakes are open at the same time:

EXH 1 and IN 3 open at same time
EXH 2 and IN 1 open at same time
EXH 3 and IN 4 open at same time
EXH 4 and IN 2 open at same time

Is this always the same or does it change? It seemed to always be the same. And of course none of these correspond with the shims I need to change.

Any suggestions or tips on how to accomplish swapping out shims?
Thanks in advance,
Marc

[ryonker]

Ok... I've got my bike apart and I am doing valve adjustment. I need to swap shims from one valve to the other. I have heard to never turn the bike over if a bucket is empty. I do not have an extra shim to put in empty bucket while I get switch shims. I noticed that certain exhaust and intakes are open at the same time:

EXH 1 and IN 3 open at same time
EXH 2 and IN 1 open at same time
EXH 3 and IN 4 open at same time
EXH 4 and IN 2 open at same time

Is this always the same or does it change? It seemed to always be the same. And of course none of these correspond with the shims I need to change.

Any suggestions or tips on how to accomplish swapping out shims?
Thanks in advance,
Marc

You'll need to get an extra shim. Yes, DEFINTELY don't spin it around without the shim in; you will scrape the cam lobs.

Rick

[prpldude]

Thanks Rick, I appreciate your help.
I might as well buy a few for the next valve adjustment.

[chef1366]

Sounds like a charging problem. The backfires are unburnt fuel from a weak spark.
See the Stator Papers off the homepage.

[prpldude]

Yep stator and r/r are bad. I'm going to do a rewind on the stator. and try and find a inexpensive r/r.

also:

When I took my bike apart last month and cleaned up the electrical I took the ignitor apart and it looked like crap inside. burnt traces, one of the screws had solder all around it and the PCB looked charred.

I want to replace it when I do my stator and r/r. I'll have to find out how much it is, or find a good used one.

[chef1366]

I have a good R/R.

[prpldude]

Can you PM me with a price and if you have PayPal Please?

Thanks,
marc

[prpldude]

Ok Starting issues were due to a bad charging system. I cleaned all the wires made sure they had good connections, clean and brushed ground to frame and replaced stator. She fires up everytime without skipping a beat.

Backfiring was partially fixed by accident today. My airbox "end gaskets" (the rubber things that go between the chrome ends and the airbox to seal it) were all messed up so I posted in the "parts wanted" section of the forum and found out these are very very hard to come by. So with some advice from bwringer (and I guess it's also a suggestion on the "Greetings" page) I weather stripped the heck out of my airbox ends and and sealed my air filter to the top of where it sits. I screwed it all back together, fired her up... and much much less backfiring.

I also saw that new intake boots may also help this issue. So this winter I will dip my carbs and replace the intake seals and boots.

I hope this helps someone else with same issues.

Marc

[spyder2120]

if you can find a fh012 r/r...get it . they are great. read the r/r replacement thread; thats where i found out about it. it was $40.00 on ebay. if you have extra money burning a hole in your pocket it would be good to have on hand for the future.

[prpldude]

Is that the same one that Duaneage sales? I have a spare R/R on hand but I think its another original.