Honda GL 1000 “Backfire” Mystery Motorcycle Help –

24 Apr 2015 | Author: | Comments Off on Honda GL 1000 “Backfire” Mystery Motorcycle Help –
Suzuki GSX-R 600SE

Honda GL 1000 Backfire Mystery

Anybody got some Cheese that I can have with my Whine?

History –

Bike: 1977 Honda GL 1000 – 43k miles. Engine rebuilt a few thousand miles before I acquired it last Winter. I’ve ridden it about 3000 miles. Runs great, starts instantly, smooth as silk. 36 – 44 mpg.

No smoking or oil use. No problems until.

During a trip through the mountains / Yellowstone last summer, the bike started popping through the right exhaust, especially during decceleration. Occasionally during a constant throttle position it will also pop through the right exhaust.

I made some inquiries on a Gold Wing forum and got lots of advice. So far I’ve:

1) Checked exhaust valve clearances. They were dead on. I opened the exhaust valve clearances an extra .001 from spec. for good measure.

2) Replaced the (still as new) spark plugs, the plugs which were in place were gapped at .035. Stock gap is .026 with points. regapped a little wide @ .032 due to Dyna electronic ignition as recommended by the Gold Wing Experts.

3) Checked tightened all the clamps / bolts / connections / hoses in the intake system. sprayed ether around all the connections prior to removal / after retightening. No RPM change noted. All the rubber intake tubes look to be new.

4) Loosened / retightened all the exhaust manifold nuts, then removed the right side and replaced the right side copper exhaust manifold o-rings. The old ones looked good.

5) Removed the Air Cut – Off Valve (which everyone was telling me was the problem). The valve consists of a diaphragm / small spring and 2 o-rings. Everything there looked as new, and the small vacuum line to it looks good.

Maybe I should replace it even though I can’t find anything wrong with it? It was probably replaced when the bike was rebuilt a few years ago. The bike went through a frame – up restoration.

Suzuki GSX-R 600SE
Suzuki GSX-R 600SE

6) Bought a decent compression gauge and checked cylinder compression. All were from 140 psi – 145 psi.

7) Ran some Sea Foam through with a few tanks of gas. no change. also ran some Marvel Oil for a few tanks, no change.

8) Readjusted the idle mixture screws to 2 turns or highest idle as recommended.

9) Finally after 2 months of fruitless tinkering, bought some better ear plugs to dull the popping sound. Drove 1000 miles in 2 days. The bike starts easily cold, runs fine, normal engine temperature, no smoke, no oil use, no leaks.

What am I missing here.

I’m getting frustrated and pissed off at this Honda.

Maybe I’ll just start over again and re-perform all the things I’ve already done. Can’t think of anything else to do.

The one thing I haven’t done is mess with the timing. Don’t have a special device needed for that.

Suzuki GSX-R 600SE
Suzuki GSX-R 600SE
Suzuki GSX-R 600SE
Suzuki GSX-R 600SE
Suzuki GSX-R 600SE

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