Sprocket size on 7-11

[Slabby]

I’m running a 1100f engine a 750 slab by frame does any body know the best size sprockets to run on this set up?

[DAZ]

I would say 16/48 which is std 1100 gearing or drop it to a 15 on the front for a "livlier " feel 

[wraith]

I'm running 15/52 

[dupersunc]

15/48 works well.  

[DAZ]

10 hours ago, wraith said:

I'm running 15/52 

Yeah but I bet you hardly need to replace your front tyre !!! Probably set off in 3rd ,that's a big gear on the back

[Dezza]

A bike built round a 750 slabby frame is going to be several tonnes lighter than a stock powerscreen, a bike that's fairly low geared as stock. As far as I know, all the 11/12 oil cooled engines have the same gearbox ratios, although there is some slight variation in the primary drive ratio. I think the powerscreen p/d makes the gearing overall lower, as does it's relatively low final drive ratio as OEM: it has a large rear sprocket. Therefore, you'll probably be able to go higher (smaller rear sprocket) than a 48 rear. What rear tyre size are you using? Try some of the gearing calculators online as they will give you a good idea where to start. You'll need to find the gear and p/d ratios and rear tyre circumference first. I have these written down somewhere as I have a powerscreen engine waiting to go in my bike as they are a good 20 bhp up on a 1200 Blandit and can dig these numbers out if need be

[wraith]

2 hours ago, DAZ said:

Yeah but I bet you hardly need to replace your front tyre !!! Probably set off in 3rd ,that's a big gear on the back

Standard gearing for the gsx1100f power screen is 15/52 but they also run on a 34mm carb 

I'm running 38mm and you it will lift the front in theard gear.

[DAZ]

3 minutes ago, wraith said:

Standard gearing for the gsx1100f power screen is 15/52 but they also run on a 34mm carb 

I'm running 38mm and you it will lift the front in theard gear.

Jeez that's 7 teeth up on a std b12 but then I suppose the 1100f was supposed to cope with two fat tourists and a fortnights luggage  nice that it'll lift in third just right for overtaking Greta in her prius 

[Dezza]

The powerscreen also had a 16 inch rear wheel as stock so depending on tyre profiles may further have reduced the final drive gearing compared with other oil-cooled 11/12 machines.

[Slabby]

Ok cheers lads will try a few and see what’s best she will lift the front in second as she is but the bike has been made out of random Suzuki bits left in garage so I can’t be that far off.

[wraith]

You should not be far off with a 15/47.

If you go for a 16T front you will need to grind a bit of the sprocket cover out where the rear bolt goes through 

[clivegto]

I run 16/43 on my 1216cc turboed 750 slabby frame. Not that helpful for you right now but it might be in the future 

[DAZ]

1 hour ago, clivegto said:

I run 16/43 on my 1216cc turboed 750 slabby frame. Not that helpful for you right now but it might be in the future 

Bloomin eck! So that's geared for elvington  then 190 ish? ,mind you it'll help load the turbo a bit 

[clivegto]

43 minutes ago, DAZ said:

Bloomin eck! So that's geared for elvington  then 190 ish? ,mind you it'll help load the turbo a bit 

That's exactly what it does, loads the engine and turbo to make them work. Stoppes it spinning & wheelieing every where.

Edited January 11, 2023 by clivegto