Scooterotica

friend of mine has just stripped down his smally motor due to various probs /none performance...
and has found that amongst other things it may have been slightly over geared.
its an ET3 main case ,although it has a missmatched outer case half...
running a polini 135 kit on 4 speed gearbox ,cut crank...approx 180 degrees of inlet timing..24mm carb and PM pipe.
cases have not been matched or ported .so std.
primarys are 29/68...hence 2.34:1
i assume this is way out myself and have advised him so (maybe std primmy pimarys would be better or others to give maybe a 2.55/2.6 :1 ratio) but would appreciate some advise from others just to give him a second oppinion as hes very confused about it all.

Match the casing, and a 2.56 for road use, a 3.00 for race.

And you can put a DRT gearing shaft to mount both around 2.86



For me 2.34 is to long for an "small" engine, and you can never pull the 4th...

sean brady scooters wrote:friend of mine has just stripped down his smally motor due to various probs /none performance...
and has found that amongst other things it may have been slightly over geared.
its an ET3 main case ,although it has a missmatched outer case half...
running a polini 135 kit on 4 speed gearbox ,cut crank...approx 180 degrees of inlet timing..24mm carb and PM pipe.
cases have not been matched or ported .so std.
primarys are 29/68...hence 2.34:1
i assume this is way out myself and have advised him so (maybe std primmy pimarys would be better or others to give maybe a 2.55/2.6 :1 ratio) but would appreciate some advise from others just to give him a second oppinion as hes very confused about it all.

Hi Sean,

Either standard primmy primarys 24/61 or 27/69 should give you around 2.55
24/61 = 2.54
27/69 = 2.56
Tell him to get a short forth too

Sean if you run 27/69 you have a 3 further options of drt primaries that will interchange. 25,26 and 28.. in fact he may even do a 29 now.. wayne is right with the drt 4th.. this sounds good with the 27/69

Robi.. that gearing for race is way too low for the uk tracks btw.

Ive not seen the 29 yet, but I'll be buying one to play with soon Tony

ps DRT also do a 24 for use with 27/69

24/69 = 2.88
25/69 = 2.76
26/69 = 2.65
27/69 = 2.56
28/69 = 2.46
29/60 = 2.38

tony wrote: Robi.. that gearing for race is way too low for the uk tracks btw.

Oups

I forgive you run on long track

In france, we race on short track (approx 1/1.5 km)

thanks for the replys everyone