Sprocket change on a GS450

[Anonymous]

How much should I expect to spend on parts to change sprockets? Right now, it spins about 6k rpm at 70 mph, I'd like to drop that to about 5k or so.

Any advice on what specific sprockets to get, and where to get them? I have no idea what's on there now. Can I just count the teeth and go up or down one from there?

Thanks!
Richard

[airportcop]

You should be looking in the neighborhood of between $15-$25 for the front sprocket and $25-$40 on the rear. You can order them through Dennis Kirk online or through their catalog or any generic cycle shop. As far as the # of teeth versus speed I do not know but keep watching because someone on this forum will know.

[Anonymous]

Thanks!

After some research, I've found out that from the factory it has a 16T/45T. If my math is right, a 17/41 should drop me to about 5150 rpm from 6k. Is that too drastic a change, or will the little 450 be able to pull it?

[jimcor]

I think that is much too drastic a change. 6K at 70... that's not bad. I think you'll be downshifting constantly trying to run at 5200. Just a gut feeling, but I'm pretty sure you'll be on the back side of the power curve with 17/41. Another thing, will a 17 physically fit under the cover? Adding a tooth might require a new chain. Subtracting a link or two at the rear might require you to remove a link to your chain.

I would do one or the other. 17 or 43. I don't think a 44 is available for your bike.

[bgmart450]

I think that is much too drastic a change. 6K at 70... that's not bad. I think you'll be downshifting constantly trying to run at 5200. Just a gut feeling, but I'm pretty sure you'll be on the back side of the power curve with 17/41. Another thing, will a 17 physically fit under the cover? Adding a tooth might require a new chain. Subtracting a link or two at the rear might require you to remove a link to your chain.

I would do one or the other. 17 or 43. I don't think a 44 is available for your bike.

Thats what I was thinking...

If your current sprockets aren't totally shot try one for a while then see if you really want to bog down your acceleration more.

My E which is even lower ratioed than L's and T's does not falter at 70mph for hour or so rides, even in the TX heat. If you are wanting higher mileage I can see wanting to do this (or bigger top speeds), but don't do it out of worry for your motor, it should be just fine at that RPM for distances.

[Anonymous]

So 6k rpm continuously is no big deal? That was my main reason for wanting to change it. I was hoping to pick up some gas mileage too, but it's getting about 61 mpg as it is. I can make it to school and back on one gallon If I left the front sprocket and just put a 41 or a 43 in back, (~5500 or 5750, respectively), would I see much improvement in gas mileage?

Also, what would I need to do in order to take a link or two out of my chain if that became necessary? I couldn't even find a master link...

[jimcor]

To remove a link requires a chain breaker. About $35 or preferably a breaker/riveter at about $75.

If you cannot find a master link, clip or riveted type, you have an endless chain. My 550 originally had one.

Not sure how much your mileage will improve. But I wouldn't change sprockets or chain till they were worn out, as you can see, there is a bit of expensive to this job that would take some time before your fuel savings equalled your parts/tools outlay. Chain alone will be close to $100.

[airportcop]

I seriously doubt you will do anything to get better mileage than 61. That is incredible. I only get 44 MPG in mixed driving on my 1980 GS 550L. 6000 RPM is not a problem at all for your bike. My Suzuki dealer told me that his 79 GS 550E didn't come to life until 7000 RPM. I just changed my sprockets and chain but because they were worn out. If yours are okay I wouldn't mess with it at all until they need replacing. I used cheap replacement parts and spent $84 on those three parts and installed them myself.

[Billm]

My E which is even lower ratioed than L's and T's does not falter at 70mph for hour or so rides, even in the TX heat.

2 weeks ago I drove my 79 GS550L from northeast Pa to Wildwood Crest, NJ. with my 15 yr old daughter on the back. Had no problems on the Pa Turnpike doing 70-75. Made two stops along the way which took about 4 hours total. Its all stock except for the aircleaners.

Bill

[IanFrancisco]

Thanks!

After some research, I've found out that from the factory it has a 16T/45T. If my math is right, a 17/41 should drop me to about 5150 rpm from 6k. Is that too drastic a change, or will the little 450 be able to pull it?

I don't think a 17 will fit on the front. My GS450S has 16/45 too. I think the E models are the same and the L models run 16/43. I wouldn't want to give up too much acceleration, these 450's are kinda quick compared to a Ford Pinto but any modern performance machine will beat a GS450 after about 30mph. You have to shift a GS450 too much. My buddy's 1985 V-Max will still do 60mph in 1st gear! I'm in 3rd already. I talked to a guy selling bikes at Bert's MegaMall who used to race a GS450. He said he never ran his bike below 9k rpm (redline) !! 8O and it held up. These motors are reputedly "unburstable" and as long as the oil's clean and the valves and carb mix settings are right, you should be able to run at 6k/70mph all day long without hurting the motor. 65 or 70mph feels OK on my bike, but 75-80mph = 7k rpm and the bike feels like it's working hard. The oil temp climbs too. One of these days I'll get out on a straight smooth stretch of deserted highway and see what the old girl will really do. Fastest I've ever been on a bike was 90mph on a 1976 Yam XS650 (Bonnie-killer). That was when I was young and foolish! I bought a copy of Cycle World July 1980 on fleabay and the performance numbers for the 1980 GS450S were 13.61 sec. @ 94.93mph in the 1/4 mile, 0-60mph in 5.3 sec., top speed of 105mph in 1/2 mile, engine speed at 60mph in 6th gear = 5327rpm (probably calculated, not actually tested).

[kkesler]

I changed my 81's 450S gearing to a 41 on the rear. Pulls it fine.

Kurt