Spark plug insulator around electrode broke off in the motor

[gasgasman]

Shop manual shows timing is adjustable.

https://www.dropbox.com/s/i93vw77r9k...anual.pdf?dl=0

[TGM_OFFROAD]

Originally Posted by gasgasman

Shop manual shows timing is adjustable.

https://www.dropbox.com/s/i93vw77r9k...anual.pdf?dl=0

Where? I have been through every page of the workshop manual several times and have never seen anywhere that shows it is adjustable. There is no stator plate, the pick up coil is bolted directly to the engine case.

[Zman]

Is there any play in the ignition pickup mounting holes or can you slot them? You could also add a thicker base gasket to drop a little compression.

[gasgasman]

Originally Posted by TGM_OFFROAD

Where? I have been through every page of the workshop manual several times and have never seen anywhere that shows it is adjustable. There is no stator plate, the pick up coil is bolted directly to the engine case.

Sorry.
You're right.

Did you have your CDI reflashed?
The new reflash retards the timing to prevent pinging at mid to wide open throttle openings.

[TGM_OFFROAD]

Originally Posted by gasgasman

Sorry.
You're right.

Did you have your CDI reflashed?
The new reflash retards the timing to prevent pinging at mid to wide open throttle openings.

I bought the bike used so I have no clue. When trying to find out through the local dealer they were no help and they no longer carry Gas Gas. I have a source who is going to give me a 19 cdi to use. Hopefully that does it. I took it out today and got the bike to run really smooth but it would still ping under heavy load like long hill climbs.

[hannesd]

did you measure compression with a guage (just to have an idea if its not +200psi? try double stacking 2 base gaskets to lower compression as previously suggested? it seems like you're getting close to more riding then wrenching keep up the good courrage !!

[TGM_OFFROAD]

Originally Posted by hannesd

did you measure compression with a guage (just to have an idea if its not +200psi? try double stacking 2 base gaskets to lower compression as previously suggested? it seems like you're getting close to more riding then wrenching keep up the good courrage !!

I havent checked compression since the most recent rebuild was done but I did check it before and it was 180psi. It should be even lower than that since previously I had the rk tek head on and now its the gp head and it has over 1mm more squish then before. I am 90% sure the cdi is causing the issue. This has been going on for a long time.

[Zman]

The squish is one measurement of clearance between the piston and head near the perimeter and the compression ratio is related to overall chamber volume. You can have a wider squish and still have higher compression.

[TGM_OFFROAD]

Originally Posted by Zman

The squish is one measurement of clearance between the piston and head near the perimeter and the compression ratio is related to overall chamber volume. You can have a wider squish and still have higher compression.

So you are saying a stock Gas Gas head, is too high of compression for 100 octane fuel?

[Zman]

I do not know what heads you have and if they have been modified. My point is that squish is independent of compression ratio.

I would assume that a stock unmodifed head should be fine for 100 octane fuel. I have been on this site for many years we have come across some factory built bikes that were machined differently than others and some bikes that were shipped with different parts.

Your detonation situation seems out of the ordinary so I would assume nothing.