Help! Losing coolant after WR 400 to 430 supermoto build

[Supernoddy100...]

I'm having a lot of trouble after resleeving my wr with a 430 piston and sleeve from wiseco. It keeps dropping coolant.

I took her for a second short spin today on the road to test her out. Seemed fine untill five minutes after parking her up I hear a gurgling sound and see that the remote coolant reservoir is filling up with coolant

I checked the radiator and the level had dropped. mayonaise found behind the clutch basket cover

Previous to this when I first got the bike it was running fine untill it overheated one day and seized.Main bearings went and some swarf damaged the barrel and piston. That's why I went for the wr 430 conversion

it's been a nightmare since. i've had the engine out a few times.

I replaced the water pump seals and bearings and put a OEM head gasket in

I've a few questions for now and I'd REALLY aprreciate some advice

1. Why does the remote reservoir fill with coolant? and where is the likely problem?
2. AFAIK the barrel was not skimmed by the engineering company who ftted the sleeve...should this have been done?

Again any hints tips, jokes apreciated...I'm near the edge here

[Frost]

Skimming may or may not have been needed so it's impossible to say if they should have done so or not. At very least they should have checked it.

As above you should have used a fresh head gasket and torqued the bolts down the correct amount and in the correct order, typically a criss-cross pattern.

The coolant bottle is an expansion bottle and will fill when the engine is warm then drain back down again.

Make sure you squeeze all the hoses and make use of any bleed points to get all the air out of the system, or this will expand and push out coolant.

[Robby]

Looks like a blown head gasket to me. If the sleeve is sitting ever so slightly proud or low of the mating surface then you'll be constantly blowing gaskets until its sorted.

Water pump seal is a possibility, as is a knackered thermostat leading to HG failure, but if the remote resevoir is gurgling violently and filling fast then exhaust gasses leaking into the coolant is a potential reason.

I would whip the head and barrell off and check both for straightness with a steel rule and feeler guages. I enjoy stripping singles.

[finpos]

contrary to the above - I'd say not the head gasket. It's just overheating. The 5 minute gap is the key.

With a blown gasket, you tend to be loosing fluid all the time - gas is entering the cooling system and blowing out the equivalent amount of fluid. So you come back from a ride, it's gone.

But What's happening here is that when you stop the bike, the coolant stops circulating. The stuff that is near the hot barrel soaks up all the residual heat and eventually boils, turns to gas and that pushes the fluid out into the expansion chamber. This process takes those critical few mins.

So, in this case, I'd look for reasons for overheating, e.g stuffed thermostat, blocked rad, running stupid lean etc. Seems this is what killed it to start with and the problem has not been fixed.

Of course if it runs hot too much you might end up with a warped head as well!

[Supernoddy100...]

Thanks gents I really appreciate all the replies

I've had a think about it & I'm not so depressed now Just want to get down to it

Before I go mad with stripping the cylinder off again I think/really hope
finpos is right. The only problem here is the mayonnaise behind the clutch basket cover??

It may well be running way too lean. I think the jetting may be too small

Just to clarify it was a new OEM gasket, the water pump seals & bearing were all replaced.

So how would I determine if it was way too lean other than the plug condition??

Would you guys know what jets a 430 conversion should have.?

I have the jet numbers written down some where

[Frost]

Generally lean running might mean a little bit less peak power, and flat spots in the rev range.

[finpos]

Small amount of gunk in the clutch housing is not unusual, it could just be condensation and once it forms it's pretty hard to get it all out again.

f.

[Supernoddy100...]

[Supernoddy100...]

It was a fair bit of mayo BUT you could be right finpos.

I know what I could do.

The reservoir was exactly at the full level line and the rad was totally topped up before the last run.

So I will drain the reservoir to just at the level line. Measure the volume, and add the same amout to the rad...see if it comes up to the top of the rad and then I might know if coolant is actualy getting in

Never be that lucky would I?

[iooi]

Totally drain the coolant out and then reverse flush it to make sure there is no crap in the system. Do both the rad and the engine on their own. Then fill it back up squeezing the rubber pipes to make sure all the air is out. Then run with the rad cap off to allow any trapped air to rise to the top.
Once you have done all that top the system fully up via the expansion tank to the correct level.

Was the mayo there before you had the problem, of has it started afterwards...

Change the oil/filter and clean the mayo out.

Unless water is getting into the oil, you should not get that at this time of the year, as its caused by condensation forming as the engine oil is hotter than the cases, due to the outside temps. Air temp is high enough now for the cases to cool at roughly the same rate as the oil, unlike winter were they cool a lot quicker.
____________________
Just because my bike was A DIVVY, does not mean i am......

[finpos]

If you're worried about the head gasket, do the easy thing - pressurise it when it's cold. Make sure it's topped up, bodge an old tyre valve onto the nipple on the radiator neck that the expansion tube attaches to, pump it up to 15PSI with a footpump then go have a cup of tea.

If you come back and the pressure has gone and your sump or cylinder is full of water, you have a world of pain. Simple as that!

f.