Lexmoto again, probably

[Nac]

Hi all. So my son has recently bought a 2016 Lexmoto venom. It had an engine swop, by the previous owner, for a 2019 efi engine that he had converted to carb. From day one the bike had issues as follows. Wouldn’t rev past 8k and was as lumpy as hell. It also cut out when hot or cold and would lose spark. So far we have changed the cdi for a brand new unit which immediately improved the running, revving to the red line and no longer lumpy. We’ve fitted a new carb which made no difference at all. Changed the coil, again brand new unit. And also fitted a new stator and pick up coil which seemed to resolve the issue of it cutting out for almost a whole day but it again cut out and lost spark. There was plenty of juice in the battery but refused to start again. We’ve checked the spark with a brand new plug, a spare from his pit bike, and there was still no spark. This morning the bike is refusing to start at all. What else is left that could cause the issue? Any help will be gratefully received.

[kgm]

Why was it converted from EFI to carb? Seems and odd decision, most people would rather go the other way. We're other medications made for 'performance' reasons and the carb fitted as an easier way of tuning?

[Nac]

The original engine was knackered and needed a new one, apparently. The guy had an engine but it was the efi variant. I’m guessing he didn’t have the ancillary components to make it work on the non efi chassis.

[MilfHunter]

My best advice would be to set light to it and claim off the insurance as you are finding out it will just be one problem after another leading to more frustration.

Put it down to bitter experience. Never buy a butchered Chinky bike no matter how cheap it maybe.

Use the pay out to get a real mans licence if he's a young spunk confined to Loser plates buy something Japanese.

[Easy-X]

Eaten an engine in only 3 years?! Previous owner should be reported to the motorcycle police for abuse

One must ask: why buy a bike in such a state? Unless you in fact got paid to dispose of it.
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Robby]

The problem is more likely to be down to the mismash of parts controlling the engine than the engine itself. I doubt any changes were made between the two different engine years.
That said, are you sure its 2016? I'm fairly certain that Euro4 killed off carbs on 125s in 2014, so a 2016 model should also be FI.

Anyway, I'm assuming you have a 2016 model engine and carb, with a 2019 CDI and spark control. Possibly a lambda sensor plumbed in too. This would make it have all kinds of problems if it runs at all, because the ECU is trying to control fuel injection and ignition, but isn't getting any response from the throttle body and injector.

You might have some luck sourcing the correct CDI to go with a carbed bike, or fitting the fuel injection side of things.

Come to think of it, it might still be running the high pressure fuel pump for fuel injection too.

So, yeah, you'll probably need to replace half the bike.