Bike has little to no power.

[Calum]

This symptom sounds like the reed switch, but I've never had to derestrict one myself.

Have you got a compression tester to check the engine's health?

The easiest way to derestrict these bikes is to simply get an aftermarket CDI and then you don't have to worry about the reed switch.

[YYHpilo]

I looked for the reed switch behind the speedo but there was none. I can attach a picture to be shure. I have a compression tester, and i will test today and let you know. I also orderd a zeeltronic cdi unit So hopefully that resolves the problem.

[YYHpilo]

It gets about 90 psi compression with throttle fully open

[Calum]

@YYHpilo Yeah that's too low. There is something wrong with the engine and it needs dismantling and investigating.

[YYHpilo]

Ok, i will look into rebuilding the top end. I will also check the squish, do you know what the normal squish is on these bikes? Also, it got the 3bn head could that be a problem for the compression?

[YYHpilo]

Also do you know someone who could get that 3bn head ristriction out?

[Calum]

@YYHpilo Mick Abbey will rework the head for you, used to charge £30, but last time I used him he said he was going to have to up his prices.

[YYHpilo]

@Calum i have found a 3mb head, would you know the squish for this head?

[Rallyfinnen]

I usually aim för 0,7-0,8mm squish for these engines, I think that would be good for the 3mb head too. You could also use a Athena cylinder head (they have inserts), I've seen those sold separately somewhere before. Check that the profile of the piston dome matches the profile of the squish area in the head.

[YYHpilo]

Thank you very mutch, i will be looking for one of the Athena ones. I have managed to get hold of a 3bm head but it is badly damaged on the inside so i will send it back and switch it for a Athena head.