Scooterotica

Sticky' book says they aren't too good but does anyone have any experience with them? The ratios don't look terrible to me. It's going to be for a GT186, using a BGM Clubman

I assume you mean the Series 3 li150 spanish box, yes they have a huge 3rd to 4th jump. Spanish Series 2 li150 boxes though are the same as the italian ones.

Yes the S3 one. I know it says that but when you look at the figures it doesn't seem that bad

I have no empirical experience.

The torque curve for a GT186 looks pretty flat between 4500-6800 so if you change gear at 7500 you will come in right about 5500 which is right in the middle of the flat curve.


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https://www.youtube.com/watch?v=avPGLg1iSPc
(Sorry I've given up with the youtube video insert voodoo. Just open it your self.)

It is after all the gearbox you have. So unless you want strip it down?
There is a fair chance I will end up with a Vijay Mk1 which has a large gap between 2nd and 3rd.

If you live or ride somewhere where there is a long hill you might be at a disadvantage riding two up but only for the duration of the hill. If it is a two lane road you will be limited to the speed of the other traffic anyway.

It is what it is, just ride and enjoy.

I am running a Spanish LI150 GB in my machine. Originally a Serveta LI150, had the spigot opened up to accommodate a Rapido 225 classic.
Running with a 28mm Delly and an Ancillotti exhaust. Had to change out the front sprocket to bring it to a 4.9 ratio as it would rev and shake-the-poop-out-a-yah. (maybe its the LI silent blocks???)
My original intent was to use the MRB Big Box as well but every time they are available I have no funding available, strange how that works.

I submitted a similar question to yours in Scootering mag and Sticky himself replied. June 2012 Issue.
You can read it here if you like: http://servetalambrettarebuild.blogspot ... -jump.html

I do notice the jump btwx 3 & 4th when I'm in town but its not like it is un-ridable. You just 'manage' it differently.
A reed kit coupled with the MRB should be no real issue me thinkith.

Have a thorough look to your gearbox. Some early spa ish S3 had an S2 engine and gearbox.

As others have already said, yest there is a jump between 3 and 4 but providing you don't go too long on the final 4th gear ratio by fitting a large front sprocket, then you'll be fine. These gearboxes are well made and strong so it isn't a bad option if you just want a decent ride. Whilst they might have a bit of lag between the 3-4 gear change, whilst revs build to get it back on the power, you would not suffer any negative side-effects unless you're intending to get top sprint times.

I run one of these in an iron 175 and the wide powerband of that motor means that this with 15/46 is a far better option that the original Italian TV box as the revvier clubman pipe has pushed the power that little bit higher up the rev range. 15/46 sprockets for 5.2 4th ratio works a treat for this motor. Don't forget that both the Italian and SIL Stg IV GP200s use 5.2 final ratio to allow that extra rev revs that the original TV couldn't reach, and even AF recommend 5.2 for their TS1 and RB 225 when used with revvy pipes, so don't assume that you'll need to go any higher than the standard 15/46 sprockets, although your motor may work OK with a 16 tooth front... but this is when the big gap of the later Spanish box will show most noticeably.

Best of luck with it.

Adam

I've got a Spanish 150 special with 185 kit,,gearbox is pretty poor on inclines two's up on a hill and its third gear most of the way ,,I'd recommend sorting another box,
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My old 71 special with a mikeck tuned Suzuki 185 was much the same went like stink 1-3 but you had to ring the neck off it to get it in to the power in 4th

I have recently changed gearboxes on my GT186 with MB Clubman. I had a Spanish S3 in, 16/46 sprockets. Yes you did have to rev it hard in 3rd to change up to 4th but it wasn't unrideable.

I have now a Spanish S2 gearbox in and it's much better.