Coolant going to the expansion bottle

[Calum]

Bike will overheat, once the coolant has been evaporated.

The other one is faulty radiator cap. It's supposed to handle up to 1.3 bar of pressure. if it cannot maintain this, it will overflow into the expansion bottle.

Either get a new radiator cap, or switch to waterless coolant, which won't expand as much nor cause as much pressure on the system.

[Bananper]

@Calum any way to check the cap? The seals on it looks good

[Calum]

@Bananper Apply 1.3 bar of pressure to it and see if it opens.

[Bananper]

@Calum https://youtu.be/MoESLzTLdd8
I put pressure on it and it just leaked out water and air

[Bananper]

@Calum this explains why the overflow bottle is filling up right?

[Calum]

@Bananper Which end did you apply pressure. Obviously it protects from the radiator to the overflow, the other way around. Otherwise how would the water make its way back into the engine.

[Bananper]

@Calum applied it on the thing close to the radiator cap, where the line to the expansion bottle goes

[Bananper]

@Calum used this method https://youtu.be/QVQqqjkXjnA

[Calum]

@Bananper Fair, I wouldn't have thought that would work.

Well, looks like it's the radiator cap then.

[Calum]

@Bananper Besides, the spring preload isn't in that direction, It's in the opposite direction.

I don't know anything really about it, other than, when they go it will cause premature water to overflow.

[Bananper]

@Calum so it could be a gasket issue?

[Calum]

@Bananper Go path of least resistance. I'd be inclined to change the radiator cap first, and then the head gasket.

[Glynn123]

If you change the head gasket, skim your cylinder head cause it's likely warped.
This can be done easily at home, get a glass chopping board and put some 1000 grit sandpaper on it, rub the head around it in a figure of 8 motion. If the heads really bad I usually use a oil stone first. Repeat while adding water to the wet and dry paper until whole head surface is even and shiny. Torque the head down, run the bike up to temperature, and then torque it down once again.

[Bananper]

@Calum ordered brand new radiator cap, but i have to wait for at least a week. Would it work to plug the line to the overflow so it does not fill up the bottle, just as a temporary fix?
Or will this cause big problems?

[Calum]

@Bananper i wouldn't

[Glynn123]

Pick up a cap from the Scrappy, any car one with the same pressure will work aslong as it has the old style rad cap. You'll pay Penny's for it.