I have a 79 gs850 that I've had since February, managed to get about 3k miles on it this year. I'm having a popping when I let off the throttle, especially when upshifting 1-2, and 2-3. The plugs say lean, well 3 of them fo. When I first got it I replaced the orings at the head, ajusted the valves, sealed the air box. So, where should I look? Re check valves? Carb jets? BTW, I recently cleaned the carbs. The issue was present then, that is why I cleaned them.
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Have you checked for exhaust leaks?https://drive.google.com/open?id=0B9zH8w8Civs8ejBJWjdvYi1LNTg&resourcekey=0-hlJp0Yc4K_VN9g7Jyy4KQg&authuser=fussbucket_1%40msn.com&usp=drive_fs
1983 GS750ED-Horsetraded for the Ironhead
1981 HD XLH
Drew's 850 L Restoration
Drew's 83 750E Project -
Yes, replaced all exhaust gaskets, and 6 broken studs.
OTE=jsandidge;2417993]Have you checked for exhaust leaks?[/QUOTE]Comment
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I assume the plug photo is 1-4. left to right? #3 is rich?
If so, you've got a leaky petcock. You're running lean on all 4, just the flood of gas is making #3 rich
When you had your carbs apart, did you check the jet sizes? You have the stock airbox, stock exhaust?1978 GS 1000 (since new)
1979 GS 1000 (The Fridge, superbike replica project)
1978 GS 1000 (parts)
1981 GS 850 (anyone want a project?)
1981 GPZ 550 (backroad screamer)
1970 450 Mk IIID (THUMP!)
2007 DRz 400S
1999 ATK 490ES
1994 DR 350SESComment
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Yes, that is 1-4 L-R. The tank doesn't leak when sat on ground and petcock pointing down. I guess I could block off the vacuum line to carb and run petcock on prime to see if it helps?Comment
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Just test the petcock and know....
Try this... remove both lines from petcock: get some clear vinyl tubing that fits snugly on petcock vacuum fitting. In "on" and "res" fuel,show flow when you suck on this tubing- otherwise it should not. Any signs of fuel in the tubing means the petcock diaphragm is likely leaking.maybe just when bike is running but maybe at alltimes.1981 gs650L
"We are all born ignorant, but you have to work hard to stay stupid" Ben FranklinComment
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Ok, I could also put a mighty vac on & watch?Comment
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https://drive.google.com/open?id=0B9zH8w8Civs8ejBJWjdvYi1LNTg&resourcekey=0-hlJp0Yc4K_VN9g7Jyy4KQg&authuser=fussbucket_1%40msn.com&usp=drive_fs
1983 GS750ED-Horsetraded for the Ironhead
1981 HD XLH
Drew's 850 L Restoration
Drew's 83 750E ProjectComment
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Ok, tested with mighty vac and no gas was passing thru. I now blocked the vac hose with a bolt. I plan to turn it to prime & test ride to see if it makes a difference.Comment
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Test ride with blocked off vacuum was the same. Any other ideas? Sure could use the help. ThanksComment
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A little random popping is somewhat normal but a lot suggests an air leak somewhere.Ed
To measure is to know.
Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182
Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846
Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf
KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-ResurrectionComment
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I should add that it is down on power with this miss/popping. Also the comp test was a bit low at 110 +/- for all cylinders and the leak down was at 5% and same for all cylinders. The leaking was into the crankcase, meaning it's ring time. Has just under 40k miles.Comment
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Before I went ringing, I'd get new points and condensers and hope that my problem is misfiring in ignition circuit.1981 gs650L
"We are all born ignorant, but you have to work hard to stay stupid" Ben FranklinComment
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I replaced those last weekComment
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Do you think a float that is off do you think a float that is off could cause this?Comment
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