T5 slow off the mark

Hi all,

I have a MK1 t5 with a 152 Polini, standard timing, PM exhaust & 4 plate Malossi standard 20T clutch. The problem is that it is slow off the mark. When I put it into 1st, it feels like it takes a split second before it takes off . All the other gears are fine. Until yesterday it had the standard 24/24G carb on it with a 118 m.j. I have tried 118-120 jets  in summer & 122-125 ones in winter & get similar results. Yesterday I put a 26/26G carb with a 116 m.j. in it & it's a lot better but still not perfect. Do you guys think a 21T Cosa clutch will cure this or is it something else such as timing? Also, does anyone know how many turns the mixture screw should be on the new type Spaco/Dellorto carbs? It seems to be more than the 1 & a half turns as on the old carbs.


Look forward to hearing from someone.



Ello mate

1 1/2 turns is only a guide, you will need to fine tune from there. It’s been written about hundreds of times before, but basically this is the drill.

Raise your idle speed to about 200rpm, then turn the mixture screw a little in and out (from 1 1/2 turns out) till you find the fastest idle. This is a good starting point. Then you lower the idle to a decent normal speed and try it. If it still bogs work out if it’s missing/popping (rich) or just lacking power(lean). Ride up and down the road very slowly testing pulling off with a screwdriver and note the changes you make. Make very slow changes to the mixture screw till you get the best pull away. Remember to make a note of the changes or your going to forget.

If you have to screw the mixture screw out more than 3 turns I would look at getting a smaller pilot jet. If it’s too far in try a larger jet.

Remember to fully warm the bike up first, and also remember that weather conditions will effect the mixture as well.

If you still can’t get it to pull away cleanly you might want to look at a different pilot jet or even slide (sorry can’t remember if you can change the slide on that carb - most you can though.

Hope that helps