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Backfire on right side, GL1000

1784 Views 17 Replies 7 Participants Last post by  exavid
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I'm having this backfire on the right hand side and I have no idea what is causing it.

The head on that side was done by someone else and it was running fine when I had longer mufflers and then when I replaced the mufflers with some shorter ones it started to backfire at 4000 rpm. I took the head off and lapped the valves and it was ok for about 2 days on few short runs and then the started again. I noticed that whoever did the valve job replaced some valves and one of them was sort of small for the opening, it fell further into the seat but after lapping it it gave me a decent contact surface.

All this time I was thinking that it had to do something with back pressure since the smaller exhaust was installed so today I replaced the head with a one I had on the shelf that has original valves in it and that I lapped before storing it. Now it's backfiring even more trough the muffler. I did check for air leaks on the carbs on that side with propane and there are none. I did leave the old exhaust gaskets on there and added another set of copper washers that I made and I don't know if that is causing the problem or is it something else. The exhaust gasket setup seem to be working fine on the other side.
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You must have done this a few times so you might have already thought of this but are you sure of the cam timing?
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Maybe you have rust or dirt in the right side carbs clogging the curcuits.
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Well, last night it worked fine after I adjusted the points and this morning it was back to the same ol' crap. I even went and removed the timing cover to check on the alignment and it's perfect, also double checked the points and they are just as good. The backfiring starts at around 4500 rpm.

It could be the carbs but the filter looks clean
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You probably have a exhaust leak on one of the headers on that side. I'd go ahead and replace the gaskets with new ones.

BTW, does your bike backfire all the time at speedor just when letting off the throttle?

Regards,

Hobie
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It backfires all the time at speed and not when letting off the throttle.

I just went and pulled out the copper washers that I had on top of the exhaust gaskets and they look like they had a complete seal. I installed the header back on without them and it does the same. Even when idling, the right side is not running smooth like the left. There's a uneven pop but it's not loud like a backfire.
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I can't help thinking the timing belt on the right side may be off a tooth, just seems timing to me.
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Have you checked your timing with a light?
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I would check the carbs for rust in the bowls.
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I doubt an ignition timing problem since the timing would affect both sides, one cyl on each side for each set of points. You have double checked the cam timing. Have you checked the plug caps and plugs and are you sure you don't have the wires switched between #1 & #3? After that it could be a carb issue.
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Your positive brush might be shorting out on the starter case, check the coated wire for a bare spot.
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I don't know much about starters, so I can't help you there!

I rebuilt my carbs and when finished, I had a popping in the right side. I had installed HD mufflers without a crossover pipe. This made it easy as to which side the miss was coming from.

After numerous dis assembly and cleaning of the #1 carb, it was suggested that I switch the #1 and #3 plug wires. I found a bad connection at the plug wire to end connector.

I don't know if that is your problem, but it was mine!

Terry
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Well, I got the old stater fixed up and running so in case someone runs into a similar problem here's how to fix it. Just to mention that all the bearings must be good in it and most of the time they are. It's the brushes and the accumulation of carbon dust from the brushes that can cause a problem and as Cyclewiz said, it could be the positive wire going to the brush that is touching the wall of the starter but most of the time even if the wire is bare there should be some insulation tape on the side of the starter body at that location to prevent it from grounding.

This is what I did: First I blew out all the dust out and got the contact points on the armature (rotor) sanded "lightly" and since my brushes were still about 1/2" long I sanded the tips square. Then I checked the continuity on the stator between the main positive bolt where the cable hooks to and the lead that connects to the positive brush and that was fine. Next I checked every contact point on the armature to see if there are any "dead" contacts by placing one of the test leads on the armature body and just rotating the other lead along the contact drum and that turned out ok. When I connected it to the battery charger with some 12 gauges wires and the gear unit off nothing happened. Took it to my car battery and with the engine running using the same 12 gauge wires it still didn't want to turn. Everything was clean and the brushes looked as if they were making a good contact. I hooked up a cordless drill to the gear on the armature and turned it full speed back and forth for about 2 minutes to seat the brushes and normally, I had to hold down to the cap that goes over the brush side of the starter since the long screws were not in. Hooked it up to the car battery again but this time I used jumper cables instead of the 12 gauge wires and the starter woke up and ran full speed just as a brand new one.:action:

Now it's time to go back to backfiring. I'm hoping it's just the plugs/caps/wires issue.
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We're never to old to learn something new, congrats on getting the starter working..
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Inside the spark plug boots there's a resister, I replace them with a stainless bolt cut to length for better spark.
I still think you need to check your carbs, they may be clogged but it's hard to say without hearing it run.

I'm sure you will conquer that ole girl...lol
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Astor123 wrote:
Hay Wiz,

If I tell you what the problem was you will laugh your ass off. Yes , the spark plugs. My dumb/cheap ass sees a shiny part and thinks that it's perfect, no rust, go with it,
So Astor123, you're saying that your bike runs great now?


Terry
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HAHA, it's seems like it's always something we over look.
I'm going out and get me some new NGK boots this week for my old bike...lol

I got a speeding ticket last week too, my first in over 21yrs.
take care,
Pop's
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I think the reason the starter didn't want to run at first when you had the long bolts out is the brush plate doesn't make decent contact unless it's clamped tightly to the starter body with those bolts.
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