We had a similar problem on a 2022 YZ250f, had everything checked, all came back good. Problem still existed. What we found in the end was unbelievable. The metal bracket that holds the spark plug cap to the head cover, was causing a ground for the HT lead, which gave weak spark, the bracket itself didnt seem to be the problem, more the HT lead is allowing the electrcicty through and making some level of contact with the bracvket which then grounds. Full inspection of plug cap, and nothing wrong. Replaced cap with a brand new genuine one, still same problem. to fix it, i wrapped the bracket in insulation tape, problem has gone away. This had us baffled for a while.
@@TepcoCycleRepair The worst part was the problem was hidden when testing for spark, as at that point the bracket was not on there, so spark was good. We identified the issue purely by mistake, as I forgot to put the bracket back on trackside and the bike fired up no problem, remembered and put the bracket back on and there we go the problem re-occured
@@CarrieCole-v5u stock sizes are on the parts diagram on any parts website and the mixture screw depends on the bike but a good starting point is 2 turns out. What bike do you have and what elevation?
I'm having a similar issue, but 15 450 efi. Very Good leakdown results, replaced coil, plug cap, top end fully refreshed. Starts fine 1st moto, then not so great afterwards. Any suggestions?? My thoughts this evening is setting the tune back to all zeros, see if anything changes.
We had a similar problem on a 2022 YZ250f, had everything checked, all came back good. Problem still existed. What we found in the end was unbelievable. The metal bracket that holds the spark plug cap to the head cover, was causing a ground for the HT lead, which gave weak spark, the bracket itself didnt seem to be the problem, more the HT lead is allowing the electrcicty through and making some level of contact with the bracvket which then grounds. Full inspection of plug cap, and nothing wrong. Replaced cap with a brand new genuine one, still same problem. to fix it, i wrapped the bracket in insulation tape, problem has gone away. This had us baffled for a while.
@@jadereynolds6963 Dang, that's a good find!
@@TepcoCycleRepair The worst part was the problem was hidden when testing for spark, as at that point the bracket was not on there, so spark was good. We identified the issue purely by mistake, as I forgot to put the bracket back on trackside and the bike fired up no problem, remembered and put the bracket back on and there we go the problem re-occured
@@jadereynolds6963 Ha. Awesome sometimes we get lucky diagnosing things
Is there any way that I can get info on correct Jet sizes And fuel mixture screw adjustment
@@CarrieCole-v5u stock sizes are on the parts diagram on any parts website and the mixture screw depends on the bike but a good starting point is 2 turns out. What bike do you have and what elevation?
Great video 👍. How many turns out did the mixture screw end up at?
@@danielwoodhouse1870 Thanks 1.75 turns out.
I'm having a similar issue, but 15 450 efi.
Very Good leakdown results, replaced coil, plug cap, top end fully refreshed.
Starts fine 1st moto, then not so great afterwards.
Any suggestions??
My thoughts this evening is setting the tune back to all zeros, see if anything changes.
I always say check valve lash, then try a different map. Something else I would look at if it was touched is the TPS, make sure it's set properly.
I found a loose connection at the thermo sensor , error 21 on tuner, would this cause warm starting issues ??