which gearbox

[bazza3004]

i everyone , im after some advice on which of 3 available gearboxes would best suit my GT186 running with a 28mil dellorto and a stearling pipe.Would it be the gp 150 (currently in) a Li150 or a gp200 . Thanks for any help on this matter, Baz.

[sean brady scooters]

well deffo not the GP 150 lol

[Muttley McLadd]

Do you want a 4.6 final drive or a 4.8?
I'd go with the Li150 and 17x46. You might need to biff your stearling pipe if it doesn't pull and go for something a bit longer.

[bazza3004]

Do you want a 4.6 final drive or a 4.8?
I'd go with the Li150 and 17x46. You might need to biff your stearling pipe if it doesn't pull and go for something a bit longer.

can you explain what the difference in the 2 ratios would be eg is it mainly top speed ? thanks.baz.

[storkfoot]

I'm still messing with the gearing on my GT186. At present I'm on a 4.9 fourth gear ratio but I'm on a clubman and not the PM copy pipe that you have. I suspect that with the clubman it probably will pull 4.6.

Your exhaust has entirely different characteristics. If you want to keep that pipe, and especially if you have a 46 rear sprocket anyway, I'd recommend the Li150 gearbox. If you get an 81 link chain and 16 and 17 front sprockets, you can try them and see what you think feels best.

[roadrunnerian]

hi bazza
try the li 150 box i use one with the 16x47 sprockets goes like s**t off a shovel m8

[nelson pk]

The difference between 4.6 and 4.8 is that the lower value (4.6) will have a higher top speed but its not just as simple as that as your engine/exhaust set up has to be strong enough to pull the final drive that you have otherwise the scoot will just die in a headwind or up a hill.
It also depends on your riding style.....do you mind constantly changing down to 3rd and thrashing to go up hills and against headwinds (and also making the engine work extremely hard and get very hot) or do you want something that will pull in 4th up most hills and against winds and not labour the engine.
It is a case of trying an initial final drive (from recommendation) and going from there to improve on it if needs be.
On which gearbox to use......i would choose one where the jump from 3rd gear to 4th gear isn't huge.
What this means on the road is that if the jump is big you'll be thrashing the nuts off it in 3rd to get it to pull in 4th when you change up.
A lot of people like the Italian LI150 box and thats why prices for these boxes are high. The Indian GP200 box is ok and good value for money but make sure it is original SIL. The Italian GP200 box has a bigger jump between 3rd and 4th than the Indian so thats no good.
Hope this helps.

P.s Stickies book has a wealth of info on different gearbox's and formulas for working out your final drive.

[bazza3004]

The difference between 4.6 and 4.8 is that the lower value (4.6) will have a higher top speed but its not just as simple as that as your engine/exhaust set up has to be strong enough to pull the final drive that you have otherwise the scoot will just die in a headwind or up a hill.
It also depends on your riding style.....do you mind constantly changing down to 3rd and thrashing to go up hills and against headwinds (and also making the engine work extremely hard and get very hot) or do you want something that will pull in 4th up most hills and against winds and not labour the engine.
It is a case of trying an initial final drive (from recommendation) and going from there to improve on it if needs be.
On which gearbox to use......i would choose one where the jump from 3rd gear to 4th gear isn't huge.
What this means on the road is that if the jump is big you'll be thrashing the nuts off it in 3rd to get it to pull in 4th when you change up.
A lot of people like the Italian LI150 box and thats why prices for these boxes are high. The Indian GP200 box is ok and good value for money but make sure it is original SIL. The Italian GP200 box has a bigger jump between 3rd and 4th than the Indian so thats no good.
Hope this helps.

P.s Stickies book has a wealth of info on different gearbox's and formulas for working out your final drive.

Thanks for that info its a big help,cheers , Baz.

[Muttley McLadd]

The third/fourth gap is less of a problem with a GT as it's more of a torquey kit than a revvy one. I've never found myself revving the nuts off it in third before dropping into top.
Saying that, if you've got a long hill, you're two up (or the sort of shape that draws people into your orbit), you might be in third gear. This isn't a huge problem - mine will sit at 60ish in third without making you deaf. Third is probably as high as tuned for hp engines' fourth.

A 4.8 would likely have more of an urgency to it than 4.6. I prefer the way my GT rides with 4.6, but I do more motorway riding than twisty roads riding.

[bazza3004]

[quote="Muttley McLadd"]The third/fourth gap is less of a problem with a GT as it's more of a torquey kit than a revvy one. I've never found myself revving the nuts off it in third before dropping into top.
Saying that, if you've got a long hill, you're two up (or the sort of shape that draws people into your orbit), you might be in third gear. This isn't a huge problem - mine will sit at 60ish in third without making you deaf. Third is probably as high as tuned for hp engines' fourth.

Thanks for that, I have only done a few miles on the original set up so far due to it being feckin freezing but even though I haven't give it any hard running do to running it in I find it copes with the 3rd - 4th gap ok and im sure it will rev out in 4th quite easily , so for now I thought about about putting a 16t front sprocket on . I am going to see a chap tomorrow about either a Li box or maybe a GP200 box so which gearing route I go down will depend on the out come of that. Thanks again,Baz.