55k rpm engine vibration

[antbanks]

I had a 1998 gsf1200 bandit last summer and noticed it had a weird engine vibration around 5 or 6k rpm range. I didn't like it but this 82 gs1100 does the same thing, and now I'm paranoid cuz I read a tread that said the cranks r prone to twisting...please tell me its not that!!

 

[Maddog209]

Two entirely different bikes with the same problem? Could just be a loose nut behind the handlebars .:lol: Just kidding.......It could be with your tires and not the engine.

 

[Darkstang]

My 83 GS1100E is "buzzy" in that rpm rang as well. So was my 82.

 

[makenzie71]

55k rpm engine vibration...

My engine gets pretty buzzy at around 55,000rpm, too...in fact it just runs awful anywhere over the 30,000rpm mark.

I wouldn't worry about it. There are certain constants with any machine...what you have to listen for is a change.

Buzzing can be anything from loose nuts and bolts to worn grommets to maladjusted valve clearances to about a wholelotabazillion other things.

 

[tkent02]

Carbs synched?

 

[antbanks]

Two entirely different bikes with the same problem? Could just be a loose nut behind the handlebars .:lol: Just kidding.......It could be with your tires and not the engine.

Yea that nut could be a little lose :-\\\ put brand new tires on the bandit. no change. its an engine vib, the carbs have not been synced to my knowledge and thats not the first time I have been told that, tiny issue, motor does not like to stay at steady speed, it spits a little if trying to run like 40mph and then roll throttle back a tad. But accelerates smooth till 5500 rpm or so but keeps pullin its ass off till 10,000 thats as far as i have gone. Like I said, I read that twisted crank thing and freaked me out some!! anyone have a sync tool?? I will trade bike parts...or money I guess...

 

[blowerbike]

the bandit has an air cooled engine that has a one piece crank shaft.
you can not twist a one piece crank shaft.
just like you can not spin a rod bearing in a large GS engine.

 

[antbanks]

so the 82 gs1100 has a 2 peace crank?? I was reading the gs owner tread about getting his bike back after 25 years,he said he twisted the crank and I got the impression that was a normal problem for these bikes. The vib feels like an engine that was not balanced before assembly, only reason I considered any issue with crank shaft, but only vibs above 5500 rpm and to worried about watching where im going to notice if it stops...you know, i have only noticed it in 5th gear...but that does not mean it only does it then...guess i need to ride it tonight and c

 

[blowerbike]

the large GS engines are multi piece/press pin roller bearing cranks that have rods/mains with no bearing caps ect..
all the pieces are assembled and pressed together.
the oil cooled engines have an automotive type of insert bearings.
the rods/mains have caps that unbolt and you install a bearing shells.
the press pin cranks can twist if they are not welded at the assembled points.

 

[antbanks]

say I wanted to rebuild this 82 gs1100 motor, I have an auto repair and custom shop, would i have to have special tools to put the crank together or take apart? This is way different than I would have thought!!!

 

[blowerbike]

you have to send the crank to a specialized pressed pin crank re-builder.
i use john pearson racing engines here in the states for all my crank/tranny/cyl. head machine work/cyl. boring ect...

 

[davel]

this 82 gs1100 does the same thing

Yes, carb sync and valve adjustment should be verified. after that:

I have an 82 11000E and have made significant improvements in vibration by adjusting thrust clearancing and balancing the clutch basket. Much easier, faster and cheaper than splitting the case to service the crank. I recommend verifying these things before splitting the cases.

 

[antbanks]

I really don't want to split the case, no reason to at the moment. I was just curious about the internals of this thing, I build big V8's so 2pc cranks with roller bearings are new to me. I rode it over the last couple days and tried to pay close attention to the motor and the vib changes as the temp changes so I think starting with carb sync and I guess checking the valves is a good idea. I will have to check that guy billcliffs website again to c if there is any info on the valve stuff. But...this thing is pretty impressive, at one point I had the motor at about 55-6k or so in 5th going down the highway and dropped it in 4th rolling back the throttle and this thing took off, it didn't pull the front wheel off the street but the handle bars got real light. thats the first time I really got into the throttle like that so yea I'm a lil impressed

 

[antbanks]

My engine gets pretty buzzy at around 55,000rpm, too...in fact it just runs awful anywhere over the 30,000rpm mark.

Ha I just got that I can imagine it would run awful...ok my bad

 

[Guest]

Your bike would be vibrating noticeably throughout it's rev range, not just at 5,500 rpm, with any significant twisting of the crank. To deal with what you're describing, do a valve clearance check/adjust, then sync the carbs.....the 1100 engines are pretty smooth, properly tuned. Most bikes vibrate at a certain rpm range....you can mitigate this somewhat with bar end weights, which will dampen the vibes coming through the bars, and move it to a less offensive range, hopefully.