How to bleed a coolant system? + Some other questions

[5v3d3b0]

I need to fill my coolant system and bleed it...How do i do this? Also, when I removed my cylinder to replace it(havent put the other one on) the sheared cylinder was fillend to the top with compressed coolant which came gushing out the top when I took a bolt off...Ive got the Yamaha TZR 50 (2005).

Also: How do I attach the choke to the carburetor? My last carb didnt have a choke, it has like a switch... Ill provide pics tomorrow if necessary

[stinkwheel]

Could you repost that with regard to the following diagram. It is a trifle confusing.

Where exactly did the water come out?

What exactly was broken?

It sounds like something fairly serious happened to your engine. It also sounds from your description like it was badly fluid-locked, in which case it may not be as simple as just replacing the top-end.

A more detailed description would be helpful.

[5v3d3b0]

Well, I was riding, and i felt the engine shear. It had already happened once, so I immediately knew it was sheared. When I started taking it apart, I just uncrewed the bolts on the cylinder head and there was a big hexagonal screw with some kind of gasket around it which I unscrewed, and when I removed it coolant (I think) came gushing out. I then took off the cylinder and the piston (deeply scratched) and my piston ring is loose.

[stinkwheel]

No sheared, SEIZED.

Something that has sheared would have snapped in two. Something that has seized would be stuck.

When you said you'd sheared the cylinder, I though you had cracked the liner of the barrel which could have lead to more serious problems.

So there was no coolant in the actual barrel? (over the top of the piston?)

A simple seizure, you should be able to get the barrel reconditioned providing it isn't too deeply scored. They are probably nikosil plated so this can be pretty expensive. Then it is a case of fitting a new piston kit and putting it all back together again with new gaskets.

As to filling the coolant system. If it is like any normal bike. You take the radiator filler cap off and fill it to the brim with coolant. Replace the cap and top-up the expansion bottle to between the max and min lines. You then run the engine for a few minutes to remove any air bubbles, top it up again and you're done.

[5v3d3b0]

The thing is Im selling it, so im changing it back to original parts... What do I use to stick the the cylinder head together with the barrel?
What two caps are you talking about? Here are pics of what I think you mean.

[jay_666]

i think your're supposed to re-fill coolant through the radiator cap.
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[Paddy Blake]

When you are putting the head back on you just need to put the gaskit
on and bolt the head down.

[5v3d3b0]

Ok thanks alot guys. So the coolant goes into the cap on the second photo I posted? And the cylinder is held together with the barrel with gasket? Right?

[stinkwheel]

[cagiva gezzer]

Now, while we've got a few minds here.

That coolant expansion bottle. Please convice me it's worth having. My manual says i should have it 1/3-1/2 full. It connects onto the filler neck above the pressuirised valve of the filler cap.

How the hell will any coolant in this bottle back feed into the system (past the one way valve).

The only purpose they serve is to catch over flow from overheating or HG failure, so why the "low" line?

Or am i looking at this in the wrong way?
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"because one stroke isnt enough and four strokes waste two"

[5v3d3b0]

[stinkwheel]

[Whosthedaddy]

[stinkwheel]

[5v3d3b0]

Ok ok ok. I live in Barcelona, Spain, so I doubt you can help me XD. Anyway, Ill just put the piston on and ask the local mechanic (who I know) to tighten the bolts for me. He'll probably do it for free cause I've spent about 700 quid in their shop so far. The coolant I'll just do by myself. Thanks a bunch everyone

[finpos]

cagiva gezzer -

When your engine heats up, The water in the rad heats up and expands, creating pressure. This is good as it stops it from boiling, but at at a certain pressure the valve in the rad cap opens and lets some water out into the expansion tank, to prevent the hoses from blowing off. This is normal - not overheating.

There's another valve in the cap which works the other way round. So as the water cools, it sucks some water back in to the rad from the expansion tank.

So if you look at the levels in the tank with the engine hot/cold, you'll see they are different.

You can run without the tank. just fit a long tube which will spit the expanded coolent out somewhere safe. But now, when the engine cools, it will draw air back in. So, you might find yourself topping up the radiator every time you go out

finpos.

[5v3d3b0]

The bastards at the mech want 20 quid just to put the friggin cylinder on! How long would that take a pro mechanic with the other one already off!? It's the piston and a few bolts for gods sake!