Project Project SRX250

To be honest... it shouldnt be an issue. The engine cases dont get ultra hot... the barrel will be the worst affected I would think. @my67xr would be the better person to comment though... far more knowledgable and experienced them me on anything to do with paint.

 

As long as the etch primer is a decent brand it'll be fine,
i have rarely used primer between the etch and engine enamel, thicker paint is easier to chip

I wouldn't have paint stripped the engine back as far as you've gone, i'd have just feathered out all the edge's of the chip's etc but it does take longer

 

You should be able to turn it upside down and rattle it out... or look in there with a torch and a magnetic pickup tool...
the joys of motorcycle ownership... NOT

 

That poor engine looks to have been running very rich or using a lot of oil.... lol
You wont need a rivet tool.. just slide the oil feed tube out (looks like you have already) and take the cam chain off.. no need to break it when you have the head off...
That piston is a .5mm oversize already do it has been bored before...the barrel looks like it could do with a good hone and then check for sizing... mainly on rings (for end gap). You can get new rings... look in Impex.jp under XT250 1987 model... same basic engine.
As for the valves... use an old appropriate sized socket and cut a decent window in it with a grinder.. then with a big G clamp you should be able to get the collets on or off easily. I would soak everything that has lots of carbon on it in 3 Bond and then give it all a good clean with a wire brush (carefully).
Forget suction cups.. use a bit of hose on the end of the valve on the other end in a slow speed reversible drill.. then lightly pull on it while spinning (slowly) using your grinding paste.
Make sure you have new (viton) valve stem seals too..
https://en.impex-jp.com/catalogs/mo...witzerland-8773/crankshaft-piston-357047.html


The second oversize ring set is 30X-11610-20-00 which is the same as TTR250. Shown as $101.15 at Trooper Lu's (Yamaha Dealer in Sydney) so you should be able to get a set if you need them.
Dont buy cheap Cam Chain... they are rubbish for the twin cam engine..

 

There is a 0.5 on top of the piston, well it looks like that.
Yep, you should take the rings off the properly clean the piston anyway. Slide the ring in square using the piston and measure the end gap. Specs are in the manual.
The cam chain will come out. There is a removable oil feed tube in the area where the oil filter is. It feeds oil into the cylinder to go up to the head for the cams. Once that is out and the guides you can easy change the chain.

Hopefully the Piston is fine and you might not need new rings either. Personally, if you have gone this far, I would probably go for a new set of rings.
Depends on the measurements etc too.


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What suburb are you in?
I might be able to recommend a machinist to hone your cylinder ready for the new piston and ring's
He can also get decent piston's and ring kits in if you want him to

 

That would help, he could measure it all for you as well. No guessing then.


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I'll pm you a name and number tomorrow morning

 

Yep... that is typical of the earlier heads... unfortunately that head is toast.. you could try getting it welded but it rarely works.
Dont be tempted to go for the $12 cam chain... ask me how I know lol.
I wouldnt do anything on the piston until the bore has been measured.. it looks to have a couple of deep marks but it may just be shadows in the pictures.. really hard to tell.
The piston looks to be pretty good from the pics, dirty but good. If the ring end gaps are ok you might well get away with a light hone.
Your biggest issue will be the head... I will check out in the garage later but I am pretty sure I have a spare head.

 

There is a legendary head shop in Adelaide, that another member posted about.
https://www.adelaidecylinderheads.com.au/products-cat.aspx?Id=28
I would go and see them and ask them if they could repair it. You want to remove the helicoil, weld it all up and re-machine for a smaller diameter plug. Of course they are going to have to do new seats too. That will solve the cracking to seats problem. Will not be cheap.

Oh, another engine running rich. What a surprise. If I ever see one that is lean I will have a heart attack and die and yet all that owners ever do is fit big jets. Coz they wanna go faster. Not having a go at you Edwardo

 

Sorry @edwardo, just pm'd you the detail's