Malossi 172 top end

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Dek
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Posts: 9
Joined: Tue Mar 24, 2020 11:51 am
Main scooter: Vespa T5 classic
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Sun Oct 18, 2020 1:08 pm

I run the following T5 malossi 172 with a si 26/26g carburettor, 125 main, bgm big box, 21 tooth clutch and kytronic ignition smart booster set at 24 btdc on curve 1.
It accelerates in 1st 2nd and 3rd very well but when changed into 4th doesn't make much difference in speed 60 mph on GPS flat out.
So I suppose my question is that the expected top end speed for that setup, I thought it would be more.
Also pulls up hills very well.
Cheers

Dek
registered user
Posts: 9
Joined: Tue Mar 24, 2020 11:51 am
Main scooter: Vespa T5 classic
Contact:

Sun Oct 18, 2020 1:45 pm

Oh, also has a pinasco race crankshaft

paul d
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Posts: 294
Joined: Thu Jun 30, 2011 10:00 am
Main scooter: T5 172 Tv 240
Location: Galway Ireland
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Mon Oct 19, 2020 12:50 am

It should be quicker. I've a feeling the bgm big box might not rev enough but has boosted your low down torque. If the scooter is reving out the same in 4th as in 3rd then the exhaust might be the problem. I think it'll pull a 22 tooth clutch with that set up which would give an extra 5% ish top speed. A sito plus exhaust would allow it to rev higher with the 21 tooth which would give more top speed too. Maybe the first experiment I'd do is to remove the kytronic and set the timing to 15 or 16 degrees. In my very many miles of 172 experience, the kytronic isn't needed on a standard 172 set up like yours.

Dek
registered user
Posts: 9
Joined: Tue Mar 24, 2020 11:51 am
Main scooter: Vespa T5 classic
Contact:

Mon Oct 19, 2020 9:58 am

Thanks for the reply, I was wondering about the kytonic iI, will give it a try. Thanks

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