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I've reached the point with this project that I'm ready to call it quits and try to recoup my losses...
Here's the story:
Bought this '81 GS1000E off a friend of a friend for pennies. No history. Had been sitting in a backyard for ages. Engine turned over fine, ran pretty ****ty in the top end. Figured it needed to be tuned.
Stripped bike down to frame/harness. Bunch of cosmetic work. Rebuilt the suspension. Rebuilt the carbs. Thoroughly soaked and cleaned TWICE. New gaskets throughout, including intakes. Adjusted the valve shims. Bought a dynojet kit and K&N pods. Came with a 4 to 1. Started tuning. Couldn't get the dynojet to work. Huge lean bog in the midrange that I couldn't tune around. Was able to move the bog up or down with the jet needle, but wouldn't disappear.
Decided to scrap the DJ kit and started to tune oem. Still couldn't get rid of the bog. Countless hours of jet needle and main combos, no dice. Settled at 127.5 mains for WOT.
Finally, figured that the timing might be effing me up. Found that the advance governor was retarded slightly @<2350 rpms. Adjusted to proper specs and managed to move the lean bog way up to ~6-7k rpms. Progress?
Messed around with the jet needles some more and found that with 2 washers, the lean bog shows up at ~6k rpms. With 1 washer, there's not so much of a lean bog, but LOUD crackles and pops in the exhaust ~6.5-7.5K rpms (3/4 throttle). And, at 0 washers, the engine goes flat >6.5k rpms, crackles and pops ~7-8k rpms, until she opens back up at WOT.
The tuning attempts go from too lean, to too rich, without any sweet spot in between...
As a hail mary I decided to make sure my cam chain tensioner was operating properly. Pulled it off the bike, all functions were proper, popped it back on, no change in performance.
I'm at a total loss at this point and not really willing to put in many more hours into this project... She runs great, pulls HARD at low rpms. It's just this mid-high range gremlin that just won't go away...
I'm throwing this out into the universe in hopes that maybe one of you are familiar with this strange symptom and know what might be the cause. Thanks for any insight you can provide. I've learned a lot playing around with this one, but **** am I frustrated that I can't get her to be happy...
Cheers
Here's the story:
Bought this '81 GS1000E off a friend of a friend for pennies. No history. Had been sitting in a backyard for ages. Engine turned over fine, ran pretty ****ty in the top end. Figured it needed to be tuned.
Stripped bike down to frame/harness. Bunch of cosmetic work. Rebuilt the suspension. Rebuilt the carbs. Thoroughly soaked and cleaned TWICE. New gaskets throughout, including intakes. Adjusted the valve shims. Bought a dynojet kit and K&N pods. Came with a 4 to 1. Started tuning. Couldn't get the dynojet to work. Huge lean bog in the midrange that I couldn't tune around. Was able to move the bog up or down with the jet needle, but wouldn't disappear.
Decided to scrap the DJ kit and started to tune oem. Still couldn't get rid of the bog. Countless hours of jet needle and main combos, no dice. Settled at 127.5 mains for WOT.
Finally, figured that the timing might be effing me up. Found that the advance governor was retarded slightly @<2350 rpms. Adjusted to proper specs and managed to move the lean bog way up to ~6-7k rpms. Progress?
Messed around with the jet needles some more and found that with 2 washers, the lean bog shows up at ~6k rpms. With 1 washer, there's not so much of a lean bog, but LOUD crackles and pops in the exhaust ~6.5-7.5K rpms (3/4 throttle). And, at 0 washers, the engine goes flat >6.5k rpms, crackles and pops ~7-8k rpms, until she opens back up at WOT.
The tuning attempts go from too lean, to too rich, without any sweet spot in between...
As a hail mary I decided to make sure my cam chain tensioner was operating properly. Pulled it off the bike, all functions were proper, popped it back on, no change in performance.
I'm at a total loss at this point and not really willing to put in many more hours into this project... She runs great, pulls HARD at low rpms. It's just this mid-high range gremlin that just won't go away...
I'm throwing this out into the universe in hopes that maybe one of you are familiar with this strange symptom and know what might be the cause. Thanks for any insight you can provide. I've learned a lot playing around with this one, but **** am I frustrated that I can't get her to be happy...
Cheers
, drilled out vacuum slides but no jet kit, messed up headlight fairing, geared up 530 chain/sprockets, etc.) When I dug into the crabs, I found that he had put in very high-tapered jet needles and I couldn't for the life of me figure out why. Turns out he was likely trying to tune around this lean bog that is apparently engine-related, not a fuel mixture issue.
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