Could it be my gear ratio?

[alanscottj]

I have recently fitted a Mugello 198 to my GP, got it set up on the dyno at PSL (Liverpool), they sorted the timing for me and I have just run it in. It flies in the lower gears 1 through 3 and will easily hit 50+ in third. Now, I would of thought that if I am hitting 50+ very easily in third surely it will go a lot faster in 4th??? Not, the case, it will sit very comfortably at 55 at around half/three quarters throttle but at wide open throttle it doesn't want to go past 59/60 (gps) after a long run.

I am thinking, and I am by no means an expert, could it be my main running in jet is too big, currently a 98, should I drop it to a 96? Which is what CamLam recommend for my set up (198 Muggy, 25mm Dellorto, Ancillotti Sito exhaust) or could it be that I need to have a look at my gears???

Any thought much appreciated

[goldeneye]

if you've got a GP 150 gearbox and cogs in, then yeah, theres a long gap between 3rd and 4th. I"d put a GP200 gearbox and 18x47 cogs in, easily available. or LI 150 and keep the 15 x46 you already have.

[alanscottj]

Cheers Goldeneye, I have had a look at GP200 boxes on fleabay and there are only Indian ones available - are these any good?

[ktmh5]

Cheers Goldeneye, I have had a look at GP200 boxes on fleabay and there are only Indian ones available - are these any good?

Yup an Indian GP200 box will be fine, but buy from Scooter Resto's or another reputable dealer and not Ebay.

[Spanish Fly]

Do you know what box and final gear ratio you are running?
Did you get a dyno print out?
Did PSL run it through the gears and record road speed.
Maybe they could tell you what approx set up you have based on the dyno run? Revs/speed.

SF

[alanscottj]

Do you know what box and final gear ratio you are running?
Did you get a dyno print out?
Did PSL run it through the gears and record road speed.
Maybe they could tell you what approx set up you have based on the dyno run? Revs/speed.

SF

Nah, none of that as my kit wasn't run in. All I wanted them to do was set up the timing and sort my carb (jetting, air/fuel mix etc) out and get it running.

[alanscottj]

if you've got a GP 150 gearbox and cogs in, then yeah, theres a long gap between 3rd and 4th. I"d put a GP200 gearbox and 18x47 cogs in, easily available. or LI 150 and keep the 15 x46 you already have.

If I put the GP200 box in there and the 18x47 cogs - will I still keep the fast speed in the lower gears as I love how nippy it is now

[sydduckett]

I had same issue, make sure you get the Indian 200 box not the Italian. the jump between third and fourth is smaller is with the former.
you will notice the difference me thinks,

[sydduckett]

I had same issue, make sure you get the Indian 200 box not the Italian. the jump between third and fourth is smaller is with the former.
you will notice the difference me thinks,

forgot to say have to agree with 18 x 47 what I have, you may notice a gap between lower gears but it's barley noticeable, always a trade off with lam my boxes unless you go five speed

[alanscottj]

Righto - is this what I will need to buy then?

GP200 Clutch Sprocket 47 tooth
Chain GP200 (ltalian) 82 Pitch
GP200 Lower Chain Guide
GP200 Drive Sprocket 18 tooth
GP200 Gear Box (SIL) 4 Gears & Cluster

Have I missed anything? I got this list from Scooter Restorations and it comes to £221 - I don't want to miss anything