Tm28 Jets

  • Cant seem to find any jets for the TM28 Mikuni need 250-260main etc. Fitted a dep expansion and now need to upjet to suit. Can anyone help? Know where to find them? Cheers

  • @CallumJ94 ???

    Standard Hex type jet. But check eBay! Search - '250 Mikuni Main Jet'

  • Dep themselves don't even say you need to rejet.

    So why do you think you need to can I ask?

    I ran dep pipe on my dtre, which came factory 210 main jet, and it was spot on. Nothing to be gained by increasing the jet size unecessarily.

    Remember engines run their best lean, which is part and part why they detonate. Injecting more fuel reduces this risk by various factors due to cooling, increased exhaust gases slowing combustion burn and impeding performance. That is at best very generic and not 100% accurate.

    Which is why I ask, why do you think you need to up jet.

    If it's not running right then this makes sense, but upjetting under the impression bigger jets = more power is a false assumption.

    If it's running lean and the only thing you have changed is the pipe then I would look at a possible air leak something. Or something else is a miss.

  • What he said^

    I've got a full dep system on my bike, standard jets and close to manual screw settings. And it runs fine - I thrash it everywhere!

    I even did a 20mile run at 70 on the M1 following someone on an FZ1, I was really paranoid all the way down so I pulled the plug and it was spot on colour wise.

  • @finnerz89 The key to two strokes and motorway journeys, NEVER shut the throttle off and coast. Every now and then pull the clutch in, blip the throttle. Try to go WOT for brief periods of time.

    It's mainly about oil and cooling.

  • I managed to find a company that makes precision jets for mikuni carbs (KMT Products) haven't fitted the 250 yet (240 standard I think) but have now reset then tweaked my mix screw and idle slightly and it is running much better in the lower rev range, no bogging when dropping gears etc. Feels slightly 'held back' in the midrange though and the same at the top end of the revs, with a slight 'cough' at full throttle. Hopefully will have time to fit the 250 main and raise the needle slightly this weekend and see how that does. It also feels as though it's revving extremely high in 1st & 2nd (pinned pv) then taking longer for the revs to reach 6.5K (hit the power band) in 3rd and upwards. Bit of a strange one, definitely a fuelling issue I reckon though...

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