83GS550E Sprocket Size For Increased Speed/Lower RPM?

[GQROD]

I think 112 is probably incorrect. Stock is around 48 for these bikes. :-k

A little reference:
http://www.bikebandit.com/suzuki-motorcycle-gs550esf-1985/o/m6075

Best of luck!

PS: Of course, if you do actually somehow have a 112 on the rear, that sure would explain the gas mileage and the low speed.

YES i counted the sprocket teeth TWICE! i knew something was up because i thought it should have been no higher than 50t if that.

Now just so i'm not crazy you do have to count EACH tooth correct? The sprocket measures 10 inches wide.

Why would anyone want to put a 112 tooth sprocket on a bike??? ok i think the PO used this bike as a STUNT bike, which explains the sprocket being so big and all the road rash on both sides of the bike, and cracked plastic.

The PO must have been racing against mini bikes and thought he needed an edge.

WOW this is getting weirder and weirder!

 

[MelodicMetalGod]

112? Really? Holy Toledo!!!

I'm by no means a major gear head compared to many folks here, but I've read a LOT over the last few years about sprocket sizes and projects and I've NEVER seen a number that massive for a rear sprocket.

Wow. Guess it's a good thing you looked into that.

Hey, would you mind posting a pic here? I'm curious how that looks on the bike.

 

[Old Colt]

A 112 tooth sprocket would be 22.28" diameter.

112X.625/3.14159

 

[MelodicMetalGod]

Is it possible that there's a non-standard chain and sprockets on the bike that would include more but smaller teeth on the sprocket?

 

[Old Colt]

The original 48 tooth sprocket would have a PCD of about 9.5", that would be an OD a bit over 10".
If he double counted the teeth he might have a 56 tooth on the back. That would rev a bunch more than we are used to on these bikes.

 

[MelodicMetalGod]

Well, looking at the pic in GQRod's sig, it looks like a normal sized rear sprocket. Something doesn't add up here. That's why I was wondering if there might be a sprocket chain combo that would have a rear sprocket with 112 much smaller teeth...?

 

[GQROD]

I counted each tooth ( now three times. ) HOWEVER i looked on the sprocket and saw 48-530 ! stamped on it.

It must be a front sprocket that is too small. I will take the cover off tomorrow and see.

Measured the widest points and got 10 inches wide :-k

I'll post pics tomorrow

The math in the prior post has me thinking maybe i'm counting it wrong. But that's what i counted.( ok now i'm weird ! )

 

[Old Colt]

Use a paint marker or a sharpie to mark one tooth on the sprocket.
I could see the chain having 112 teeth but the sprocket will not be far away from the original 48. A quick look at the picture of your bike shows it to not be something radical.

 

[GQROD]

Thanks everyone i edited my prior post to show i saw 48-530 stamped on the sprocket.

Must be the front one is smaller.:-k

Can the front sprocket being smaller by only one tooth really make that big a difference?

Should i go with a smaller rear sprocket and front combo?? for better mileage and top end ? Any recomendations on which brand and vendor ?

Thanks all

 

[p_s]

112 is the stock number of links on the chain. Maybe that's what you were counting?

 

[GQROD]

I was counting the teeth at the top of the links. While rotating the wheel in neautral.

I used this link below to a calculator and the numbers for a 14-48 are almost exaclty what i'm seeing it's off by about 10 mph.

I entered all the ratios taken from the factory manual.

Which means i'd have to run the RPM's to almost 8000 to be at 65 MPH ????????? YIKES !

I'm definelty going to have to find a better combination. I don't think one tooth size up alone on the front sprocket is going to cover it.

http://www.gearingcommander.com/ - 2k

I'd like to do 65 mph in 6th gear at 4000 to 5000 RPM max am i deluding myself in thinking this is practical????

 

[GQROD]

Did more reasearch by using the search feature here and found great info.

From what i got using the calculator i got two sets of numbers

16/44 gets me in the ball park.

18/35 Being ideal ratio to do 65-70 mph in the 4000-5000 RPM range.

or just go with a 18 tooth front sprocket ( this reduces according to the +1 front = -3 rear formula to 18/35 )-providing i don't have clearance issues etc.

I know about the 16 valves not having gobs of torque, don't mind downshifting to pass and i don't intend on doing more than 80 on the highway. So i can live with sacrificing roll on power to shift less and have a less buzzy vibration free ride.

I'm not a math wiz so feel free to chime in with advice it is appreciated.

 

[p_s]

I wouldn't trust the numbers you get from 25 year old analog gauges. Trust the numbers from the back page of this:
http://junkyman.org/gs550es/Cycle_World_83.pdf
or this:
http://junkyman.org/gs550es/cycle_83_review.pdf
and you'll see you don't need such a drastic change to get to 5k at 65 mph.

And if you up the gearing by 10% you'll have to shift more, not less, to make power.

 

[Old Colt]

The original front was a 14T, If it had a 13, Rare, that would be a big difference.
I expect many of us will recommend getting 15 or 16 for the front. I would say just get a 16 tooth and run that.
This way you do not need to change the chain or anything else.

 

[Calvin Blackmore]

Did more reasearch by using the search feature here and found great info.

From what i got using the calculator i got two sets of numbers

16/44 gets me in the ball park.

18/35 Being ideal ratio to do 65-70 mph in the 4000-5000 RPM range.

or just go with a 18 tooth front sprocket ( this reduces according to the +1 front = -3 rear formula to 18/35 )-providing i don't have clearance issues etc.

I know about the 16 valves not having gobs of torque, don't mind downshifting to pass and i don't intend on doing more than 80 on the highway. So i can live with sacrificing roll on power to shift less and have a less buzzy vibration free ride.

I'm not a math wiz so feel free to chime in with advice it is appreciated.

47-14 is about 7000 at 70 maybe im wrong

 

[GQROD]

I wouldn't trust the numbers you get from 25 year old analog gauges. Trust the numbers from the back page of this:
http://junkyman.org/gs550es/Cycle_World_83.pdf
or this:
http://junkyman.org/gs550es/cycle_83_review.pdf
and you'll see you don't need such a drastic change to get to 5k at 65 mph.

And if you up the gearing by 10% you'll have to shift more, not less, to make power.

You are right i will have to downshift more but i don't mind and thanks for the links they were a lot of help. And finally makes sense of this.

Thank you all again for your help. I think it makes sense as you have suggested to go with a 16 and test it. I can always go higher if this is not enough.

Old colt and calvin thanks for your suggestions,

I wonder though would i have to add links to the chain?? to make it longer to keep it in the slots for adjustibilty?

 

[Old Colt]

Not with changing just the front.

 

[Commodus]

Um. Earlier in the thread you were saying something about really bad fuel mileage, no? I think you should fix the bike before modifying it. Find this problem and deal with it and then you may find there's no need to play with gearing.

 

[GQROD]

Um. Earlier in the thread you were saying something about really bad fuel mileage, no? I think you should fix the bike before modifying it. Find this problem and deal with it and then you may find there's no need to play with gearing.

I have already cleaned the carbs, and tuned it. The main jets are stock, the pilots are one size up from 35 to 37.5 and the valves were adjusted.Plugs are new. Electrical is all new.

I'm not sure what else could be cuaseing such high consumption and the gearing is driving me nuts.

 

[GQROD]

Not with changing just the front.

Sweet, thanks old colt i will definetly order the front gear and try it. Are these available through z1 enterprises or is there another vendor i should try?