Gear reduction

[anasasisxenophontis]

I'm trying to figure the proper ratio for my buggy. I'm using a ninja 600cc engine...it has a 15t stock front sprocket on it. I'll be using 20" height rear tires, which is a 4:5 reduction compared to the 25" 180/55ZR17 rear tire on the bike originally. So that's a little bit of reduction. The stock rear sprocket on the ninja is a 40t...would going up to a 60t be about right for my application? Just for calculation's sake, let's assume this thing weighs 900lb; the bike weighed 377lb dry.

[boostinjdm]

Ball park would be drop 2 teeth on the engine and go from there. The four wheeler and buggy I put MC engines in both had to lose two teeth on the engine to get them good enough.

[Bugpac]

keep the 15 if at all posible, longer chain longer life, id presume a 60 would work decent, i think somewere in the 70 would be ideal tho....

[anasasisxenophontis]

Ok so all things considered, the gearing would be 5.83:1 (with the 70t sprocket and compensating for smaller tire size as well) as opposed to the bike which was only 2.66:1. That would bring my top speed down to around 72mph, and theoretically allow the engine to pull 825lb of weight with just as much ease as it pulled the bike before at 377lb with its original gearing. Sound about right?

[Bugpac]

I dont believe it will seem to pull as equaly as it did in the bike.. I believe it will work ok, but a teeper reduction would be better, IMO i think somewere around 7:1 would be supreme....

[anasasisxenophontis]

Well I said that theoretically... So why do all of those gearboxes come in ratios of like 4.7:1 and 5.5:1 if 7:1 would be superior?

[Bugpac]

Originally Posted by anasasisxenophontis

Well I said that theoretically... So why do all of those gearboxes come in ratios of like 4.7:1 and 5.5:1 if 7:1 would be superior?

you can do whatever you like, but all gear boxes do not come with that high off reduction, rpm has one thats 9:1...Therotecially speeking, buy an extra clutch for the motor as well, you will need it, Busa has good torque they can run the 4:1 or whatever they do...they are a one of a few breed of engine as well...

[anasasisxenophontis]

Well, I think I'll go with the 70t. The beauty of chain drive is I can always drop a tooth or two off the front if need be.

[Bugpac]

Yes you can, like i said, id try to maintain the 15 at all cost, i dont believe id drop less than a 14 no matter the cost myself....

[anasasisxenophontis]

Yeah if I'm bogging down because of the gearing being too high with the 15t front and 70t rear, it's time for a hayabusa. That'll kill two birds with one stone.