Scooterotica

My t5 was having issues with cutting out when under load and was over heating. This was diagnosed as a failing oil pump so I have disconnected the autolube and am now running it pre-mix. Now runs with no cutting out issues however it's struggling to hit 50 now whereas before it would hit 65 flat out and happily cruise at 60. Question is should I change the jets now as its no longer autolube? And if so what ones and what sizes?

Cheers

probably a new piston and bore might be needed,,,,,,,,,,,,,,,,,,,try the bigger jets anyway you have nout to lose.............
good luck

When you say cutting out and overheating do you mean seizure as in back wheel locking up or just cutting out like knocking off the key for a second or two and the engine coughing and continuing as normal? If your T5 barrel has heat seized then you'll need a new barrel and piston or have the barrel replated. Every T5 heat seizure I've had has damaged the barrel badly. It's the big disadvantage of alloy barrels. Is it hard to start?

Back wheel would lock up, luckily managed to get the clutch in so kept it upright. Have had the barrel off and can't see any damage, piston and rings look fine also. Not hard to start, starts first kick. Will cruise along happily at 40 and sounds like it should but after that it struggles. I'm stumped, was hoping bypassing the autolube and going premix would solve it but obviously not. Was clear the pump had failed as the cogs on it were rounded.

You did well to clutch in time and stay upright! I'm stumped myself. I think 110 is a standard main jet. Maybe you could try a 112 and as shamrock express mentioned, you've nothing to lose. Your sure the piston is ok? A new piston isn't too expensive and on a T5 you're expected to change it every 7 to 10,000 miles anyway if I remember right. The piston wears, not the barrel. When my standard pistons got worn the engine would develop a piston slap which is a clicking noise. The T5 barrel has a nicosil coating which is like hard chrome. It's hard to scrape grooves in it as happens on an iron barrel sometimes after a seizure but it's easy enough to lose pieces of the coating when the barrel seizes. I'd check the barrel again for missing coating. Good luck with it!

you should deffo up jet to allow for premix ,as the addition of say 3% oil means at least 3% less petrol in the mix ..hence it would run weaker ..i would go up on the main jet by prob 5% as a starter...
Also ,I cannot imagine that there has been NO damage to the piston/rings and maybe the bore if as you say it siezed enough to lock up the rear wheel ...i,m pretty sure that at least you would find that the rings are stuck in the grooves,prob on exh side ..
this may account for the lack of performance since ,although it is odd that it starts ok !

Thanks for the advice guys. I'll order a bigger main jet and while I'm waiting on it to come I'll get the barrel off again and check the piston again too. I never thought to check if the rings were stuck.

Cheers again, will let you know how I get on

Likely the nicosil lining and piston will be Donald ducked after numerous nips.

I'd check your plug colour and do a few plug-chops to check your jetting and if you've got the inclination a pressure test would be wise.....

sounds very strange that it would lock up, but no barrel damage, did you instpect the crankshaft, maybe the big end is locking up, not the top end ?