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Was wondering if anyone else has noticed their carb intake boots "pulsating" when motor is idling? What i mean by pulsating is kind of like there "expanding & contracting" just slightly when bike is idling & was just wondering if this is "normal" or does it suggest something is wrong? The bike does run pretty well, & the only problem i do have with it, is when the bike first starts up for the day, it will sometimes backfire out the exhaust one or two very little "pops", then it's fine & doesn't do it anymore after that. But i have noticed that the idle does go up to about 1500-1600rpm's after it gets warm. The bike is basically a stock 81 gs1100e with CV carbs & K&N filters & a Kerker exhaust system. The carbs have also been jetted for the filters & exhaust. Thanks in advance for any info you may have.
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1981 GS1100E Stock motor except for Kerker Exhaust w/K&N pods -
Welcome to the site, JT.
I have never seen carb boots pulsating. Have you ever synched the carbs?
A potential cause of the backfire is an improper mixture caused by an air leak. An air leak could also be the source of the idle rpm climb.
Your pulsating carb boots might need replacing. Manifold o-rings might need changing as well.
General rule of thumb on back-firing from intake...too lean a mixture.
General rule of thumb on back-firing from exhaust....too rich a mixture.2@ \'78 GS1000 -
My 1150 did that when I bought new inlet rubbers (the pulsating thing). I thought it was a little odd but it never affected the bikes' performance in any way.
1100's and 1150's dont have manifold o-rings:
Current:
Z1300A5 Locomotive (swapped my Intruder for it), GS450 Cafe Project (might never finish it....), XT500 Commuter (I know - it's a Yamaha :eek:)
Past:
VL1500 Intruder (swapped for Z1300), ZX9R Streetfighter (lets face it - too fast....), 1984 GSX750EF, 1984 GSX1100EF (AKA GS1150)
And a bunch of other crap Yamahas....Comment
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Yeah, you can see them pulsing. Perfectly normal, and I suppose it's a good sign that your intake boots haven't gotten glass-hard.1983 GS850G, Cosmos Blue.
2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
2015 Yamaha FJ-09, Magma Red Power Corrupts...
Eat more venison.
Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.
Celeriter equita, converteque saepe.
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+1 for pulsing being a good sign.#1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread New here? ☛ Read the Top 10 Newbie mistakes thread
#2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread Manuals (and much more): See Cliff's homepage here
#3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
#4: 1980 Moto Guzzi V65C – Something to chillComment
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Thanks for all the reply's. Because I was thinking it might be the valves were out of adjustment or something, so that's a relief.
To answer your question Steve, no I haven't synced the carbs. on it, I need to get that tool soon (vacuum gauge set). I do know that at least one of the carb's has a bad needle seat (I'm assuming anyway) because sometimes the gas in the fuel line is gone after sitting for any lenght of time (couple of days), & there's no sign of any leakage anywhere. Thanks again for the quick reply's, I appreciate it.
1981 GS1100E Stock motor except for Kerker Exhaust w/K&N podsComment
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