Sprocket change gs1150

[not a biker]

this is my problem. above 60 mph i hit the worst RPM for vibration that travels threw all the plastic in the fairing in my 84 gs 1150 es. above 4,500 rpm it gets better. my cruise speed is usually 70 mph. what size front sprocket [ teeth] can i go to without other changes being made. sorry i do not remeber the number of teeth on the rear sprocket, but one time i spoke to rapid ray and what he said was stock i had when i counted the rear sprocket. can i go 2 teeth larger in the front over stock ?. i would not be suprised if somebody in its life went to a smaller front sprocket to gain acceleration. i do not care if i hurt acceleration putting on a larger front sprocket. i just want to cruise at 65-75 mph at under 4,000 rpm.
if somewon knows what sprockets came stock on a 84 gs 1150es please advise me. will 1 tooth larger on the front sprocket make a large or small RPM change in 5 th gear on the FWY i would like to make a 500 rpm change in 5 th gear. thanks

[Cooler]

this is my problem. above 60 mph i hit the worst RPM for vibration that travels threw all the plastic in the fairing in my 84 gs 1150 es. above 4,500 rpm it gets better.... i just want to cruise at 65-75 mph at under 4,000 rpm.
if somewon knows what sprockets came stock on a 84 gs 1150es please advise me. will 1 tooth larger on the front sprocket make a large or small RPM change in 5 th gear on the FWY i would like to make a 500 rpm change in 5 th gear. thanks

Hello.
I think the "final reduction" of the transmission refers to the chain sprockets... if so you have 42/15 stock so the front sprocket should have 15 teeth. Usually I look on wemoto.com website for chain sprockets but they don't have +1/-1 sprockets for this model; on the figure of front sprocket there are 16 teeth.. so I don't know if it's a general figure or one specifically for our motorcycle (I also have a GSX 1100 - European designation for GS 1150). I also have the same problem as your however I'm content with the cruise speed of 60.. I'm not content that every time I have to overtake a car I enter the "nasty band". It appears that the 84' and some of the '85 models have higher vibrations.
Here' a link to the manual of the GS1150 courtesy of a user from the oldskoolsuzuki forum: http://www.joanneburnett.com/GSX1100EFE.pdf
Hope this helps.
As for the change in speed if you exchange sprockets.. 1 Tooth in + for a 15 teeths sprocket would cause about 6.6 % more speed; I don't think it's enough for what you want; and I don't know if you can find +2 sprockets; you could also search for -1/-2 back sprockets.. but that would have less of an impact on the speed change.
To elaborate on this.. you can make some mathematical computations .. actually quite a few variants (either by speed or rpms). If you have 42/15 sprockets whis is a 2.8 ratio.. in order to increase speed you need a lower ration. So if for 60 miles/h coresponds to 1/2.8 for 65 miles it corresponds 1/x. In this case 1/x is (65 * 1/2.8)/60.. and that is ~ 1/2584. 42/16 is 2.625 so that's not enough, 42/17 is ~ 2,47. The region of the vibes is very bad as it's one most used by most of the riders for most of the time.
Does your motorcycle vibrate also on other rpms? I plan on doing a carb cleaning + synchronizing and hope the vibration would reduce a little.
Good luck!

[not a biker]

sprocket

thank you for the post. i did a search and found Z1 products. very helpful. they are sending me a 16 tooth replacement front sprocket. it should help about 400 rpm in 5 th gear. i just might find out i have a 14 tooth sprocket up front and not a stock 15 tooth.

[rphillips]

It seems there have been several vibration questions about the 1150's. My "85" 1150 was bad, but not nearly as bad as my "86" 1150. I've tried everything short of truing & balancing the crank, but nothing helped. I wish I could have been one of the lucky few who said their mirrors were useable at speed on the 1150's. Also wish I knew "for sure" why there are so many vibrating 1150's and so few vibrating 16 valve 1100's. Suzuki put rubber motor mounts & at least 4 vibration dampeners on the 1150's like they knew beforehand they were going to vibrate. The 1100's don't have them & don't vibrate. Maybe I should remove the rubber mounts & dampeners, maybe they worked backwards from what Suzuki thought. Something is definitely causing the vibes.

[blowerbike]

some 1150 cranks are a little more"true" than others.
just because a crank is factory welded does not mean it is 100% true.
my 85 1150E was a buzzy basturd.
my brothers 85 1150E was wayyyyyy smoother.
i know a secret....
the small suzuki emblem below your grab bar behind the rear seat..
is all the 1150 guys with me????
check and see what yours is made of..
hard plastic or rubber..
hmmmmmm
mine was hard plastic and broke quite often only to have me crazy glue it back.
my brothers was hard plastic also..his never EVER broke or cracked.
suzuki made these in both hard plastic and rubber..
i think maybe all the 86 1150's emblem was rubber for this reason.
i have owned and worked on alot of 1150's...plus ive parted out quite a few over the years..
this is my observation based on my experiance with the suzuki GS1150E/ES models.

[blowerbike]

oh,
16/40 gearing is pretty good gearing unless your a large person and your better half is a 3 cheeseburger kind girl.

[earlfor]

oh,
16/40 gearing is pretty good gearing unless your a large person and your better half is a 3 cheeseburger kind girl.

I ran 16/42 on my 85 1150. If I remember correctly, that gave me
3800 rpm @ 70 mph and 46 mpg.

Earl

[Mysuzyq]

It seems there have been several vibration questions about the 1150's. My "85" 1150 was bad, but not nearly as bad as my "86" 1150. I've tried everything short of truing & balancing the crank, but nothing helped. I wish I could have been one of the lucky few who said their mirrors were useable at speed on the 1150's. Also wish I knew "for sure" why there are so many vibrating 1150's and so few vibrating 16 valve 1100's. Suzuki put rubber motor mounts & at least 4 vibration dampeners on the 1150's like they knew beforehand they were going to vibrate. The 1100's don't have them & don't vibrate. Maybe I should remove the rubber mounts & dampeners, maybe they worked backwards from what Suzuki thought. Something is definitely causing the vibes.

Interesting opinion....actually the second time I've come across that. I was gassing up my 1100 a couple years ago, and a guy got out of his cage and came over to take a look, and chat a bit. Apparently he used to ride, back in the day, and commented on the harsh vibes on his 1150, that he used to constantly combat with tuning. His thought, was that Suzuki knew full well that most owners wouldn't be willing or able to keep the bike in the narrow 'sweet spot' where they would run as smooth as the 1100's, and attempted to address the issue with mounts, and heavy bar ends etc., instead of solving the problem at it's root.

Tony.

[Cooler]

I ran 16/42 on my 85 1150. If I remember correctly, that gave me
3800 rpm @ 70 mph and 46 mpg.

Earl

Are you SURE? That doesn't sound right. My tacho is not working so I don't know the rpms but some folks on oldskool have said that around 4000 rpms the vibrations are worst (actually that corresponds to this thread first post). My bike vibrates badly between 105-125 km/h.
Did you bike not vibrate on 3800 rmps which you said gave you 70 mph?

[Nessism]

I have no personal experience with these models but the 1150 and 650 are the two GS models with the most complaints about vibration, and the 850 is lauded for it's smoothness. I think the amount of vibration is a matter of harmonic frequencies and manufacturing tolerances when building the engine and most of the large displacement motorcycle engines these days have counterbalancers to counteract the vibes from the design side. Carb sync can make a difference as some report but don't expect it to solve the problem entirely. There are also things like bar weights that some people say helps. Do what you can and live with the rest.

[earlfor]

Are you SURE? That doesn't sound right. My tacho is not working so I don't know the rpms but some folks on oldskool have said that around 4000 rpms the vibrations are worst (actually that corresponds to this thread first post). My bike vibrates badly between 105-125 km/h.
Did you bike not vibrate on 3800 rmps which you said gave you 70 mph?

It has been about five years since I had the 1150 and my memory of the sprocket sizes could be incorrect. I am certain of the 3800 rpm to 70 mph part though. I just remembered that I have a old box of sprocket sets in my shop that are left over from the 1150 and they are 15/38. Those may have been the ones I was using. One thing that I found made a difference was after doing a carb synch, hold the rpm at 4000 long enough for the vacuum guage to steady and note any change in balances. Re synch the carbs for 4k rpm and forget about inconsistencies in the low rpm range. In other words, synch the carbs for the rpm you intend to do most of your riding at. Logically, rpm range should not make any difference to the synch, but in practice, I found that it did. My 1150 was as smooth as my 03 Bandit 12 with almost zero vibration at 70 mph.

Earl

[Cooler]

I just remembered that I have a old box of sprocket sets in my shop that are left over from the 1150 and they are 15/38. Those may have been the ones I was using. One thing that I found made a difference was after doing a carb synch, hold the rpm at 4000 long enough for the vacuum guage to steady and note any change in balances. Re synch the carbs for 4k rpm and forget about inconsistencies in the low rpm range. In other words, synch the carbs for the rpm you intend to do most of your riding at. Logically, rpm range should not make any difference to the synch, but in practice, I found that it did. My 1150 was as smooth as my 03 Bandit 12 with almost zero vibration at 70 mph.

Earl

The 15/38 is quite different from the 15/42 which is supposed to be stock (-4 teeth on the back !!).
But wow.. great advice on the carb synchronizing. Thanks for the tip! What you said makes sense. Did your bike vibrate badly when you bought it and wasn't synchronized? Maybe you had a "good one" anyway..
And I want to ask you something else. On the service manual of the EFE (GSX 1100/ GS1150) there is a mention of synchronizing differently the inner carbs compared to the outer carbs; the inner ones should have lower pressure. That seemed weird and the previous owner said he didn't synchronize them like that, but equalized all the pressures. I don't know exactly the scale of the Suzuki carb synchronizer .. maybe someone has it and can shed a light on this pressure difference.
I had a bad experience because of the vibes. Once I was doing an overtake on a long speedy lorry and close to the finish of the overtake - and because I was doing about 120 kms/h - my engine stopped.. all lights went dead and there was silence. I was afraid some valve might disintegrated or something but the engine fired easily and didn't had any problem; it was just like someone would had pushed the kill switch.

[blowerbike]

1150's also have larger main jets on the 2-3 carbs..
ive never seen this on other suzuki models before.
trying to cool the two inner cylinders that dont get the same airflow as the two outers it appears.

[Cooler]

1150's also have larger main jets on the 2-3 carbs..
ive never seen this on other suzuki models before.
trying to cool the two inner cylinders that dont get the same airflow as the two outers it appears.

Yep.. noticed that:

http://www.thegsresources.com/_forum/showpost.php?p=319656&postcount=34

Is it common for big displacement air-cooled bikes ?

[not a biker]

Sweet spot

up to 4,000 the vibration is nill. starting at about 4,100 to 4,400 rpm is the problem. now that others have said they have the same problem i will be happy with the sprocket change. 4,000 prm at 70 mph is ok. this 1150 es is a very good FWY bike. the fairing works great. and the stability at very high speeds is also good. been past 135 on a streight road with no problems.