Changing Gears?

[Anonymous]

Has anyone ever tried adding bigger gears or swapping trannies from one gs to another. Here is what I am after,

I have a 1983 Suzuki XN85 Turbo that I have been making to push 200bhp. The motor is ready to put back togeter but I think I do not have enough gears for what I want to do.

Before you ask how can I get so much from such a small motor well I enlisted the aid of Horse Power Unlimited and my motor has been seriously worked including a 7mm over bore and tons more but thats another story.

Stock internal gear ratio from a 1983 Suzuki XN85 Turbo:

1: 3.166
2: 2.187
3: 1.684
4: 1.380
5: 1.173

Overall Gear ratio
1: 14.875
2: 10 .277
3: 7.909
4: 6.486
5: 5.514

Final Drive No. 530 chain, 2.40.1

Stock was 16 tooth front sprocket with a 39 tooth back. I have added a 17 tooth front for a little more top end 140 mph up 8 from the stock 132 but with all this bhp I was hoping to get more mph from a bigger transmission.

The stock lower end on this bike was a gs 1000 crank and used a gs 650 tranny with 1,2 gears shorter than a stock gs 650 and 3rd the same but 4, 5 taller so I am wonder if another gs would slap right in. If anyone has changed gears out or even used after market point me to the right resource.

Oh yeah I run www.xn85turbo.com which is where you can learn all about the rare factory turbo charged gs 650.

xn85turbo

 

[saaz]

Yes I have checked out the XN site. The problem is that not many will have experience with doing such swaps. I think the closest you will come is people with GS650 experince, which is not common. If it has the GS1000 crank do you know if the gearbox is off a GS1000 as well? Or gears intercgangeable? It would make sense if it was given the power output of the turbo.

If we can establish what the gearbox is off, the rest is simple given drag and racing experince around here.

 

[Anonymous]

Everything I have ever read said it was a GS 650 tranny with a different gear ratio. I listed that in my post. This was a concept bike from them with tons of development stuff in it.

xn85turbo

 

[Anonymous]

The stock lower end on this bike was a gs 1000 crank and used a gs 650 tranny with 1,2 gears shorter than a stock gs 650 and 3rd the same but 4, 5 taller so I am wonder if another gs would slap right in.

If I'm reading you right, why not use your tranny and put on a smaller rear sprocket. The shorter gears for 1,2 should make starting out easier and the taller for 4,5 should give you more top end. Or - did I miss something?

 

[Anonymous]

I need taller gears all the way around in every gear 1-5. the main problem with the bike was the gear selection they made them to short and you ran out of gear by the wime you really started boosting. I was hoping that suzuki made most of the parts interchangeable as they released bigger bikes, and just added taller gears. Hence why i want a bigger tranny gear set from say a gs 1000 or 1100.

xn85turbo