1100E gear ratio for 1/8th mile racing?

[Anonymous]

First off, my '81 1100E is at a stock level of tune with a MAC Anniversary 4 into 1, an 1150 INNER clutch hub and springs, and Barnett fibres. The rear tire is a stock size Dunlop K491.

My friends have some 1/8th mile racing set up at a local track. The rules are that the lights change colour and the first person across the 1/8th mile line wins. There isn't a clock or a radar or anything, they decided that getting to the end first is what counts. What would be a good sprocket ratio be for this sort of thing? I have to race R1s and RC51s and anything else above 800CCs SOOOO I need something controllable and quick. What would you guys recommend? From what I remember the track is pretty slippery and starts off on concrete. Will it matter if I stick to 630 chain?

Thanks, Steve

 

[gsbill]

By adding teeth to your rear sprocket you will get the bike moving quicker...Your shift points will come up quicker...If you cut good lites, you will surprise those newer sport bikes, which come on strong down track in the 1/4 mile. If you decide to go bigger on the rear, you may have to add links to your chain..Ideally, it would be wise to try several different ratios to see what works best.

 

[rosco15]

We need racingjake to get in on this one. He's the big 1/8th mile guy.

 

[Anonymous]

Cool, I just ordered an RK 630GSV x 98 so I will leave the two extra links on if it will fit the bike like that. I can always cut it later. I ordered a couple stock Sunstar sprockets for daily riding but the plan is to get some cheap ROC sprockets for interchanging at the track. The track is actually a 1000 km round trip from my house so I won't be racing too often. Probably every second week. I don't want this to become an expensive hobby so I won't look for anything closer.

I had thought about going 1 tooth down in the front because it is the easiest thing to do but I'm concerned that my bike doesn't have the low end power to run it. If I don't rev the engine up a little it will bog out as the clutch hooks up rather quickly. Once I'm fully engaged in 1st gear I have lots of power and can lift the front wheel a touch. This could all be in my imagination too since I drive a diesel car. It'll torque its way out of anything.

The next week will be fun but require some serious work to make my bike competitive. I'll have to see how the bike works with/without the muffler baffle. Then there will be the tire pressure and suspension. Then a carb sync and tune. It is running leanish at the moment and won't redline in 5th gear. It's supposed to right? She'll redline in 4th I think. I'm usually too busy looking for traffic when I'm doing that sort of speed. 8)

Steve

 

[Anonymous]

It is running leanish at the moment and won't redline in 5th gear. It's supposed to right?

I won't comment on the other stuff, the racers will be better than I, but if it is running lean you need to fix it first. Running hard at the track in that condition is begging for a burnt exhaust valve and/or a holed piston.

My 82 with pipe and pods will bury the tach in 5th (it RAGES past redline) and feels like it would easily do the same with 2 less teeth on the back. Yours should be similar...


Mark

 

[Anonymous]

No dice getting the 98 link chain on with stock sprockets. The adjusters were at the max so I cut off a link which brought it very close to the other extreme. That makes me think there won't be enough slack to put on a bigger rear so smaller fronts is what it will be. Too bad I stripped the countershaft nut while putting it back on. :? Hopefully the 4th part revision will be a bit tougher. 8)

Steve

 

[Anonymous]

Deleted by me :wink:

 

[RacingJake]

I would run the 42 rear and install a 14 front that should make a differance. Then strap that front end down