A good case for knead-it?

[tony27]

Reckon some liquid metal will fix this?



Pulled barrel to replace base gasket in hopes of getting bike running right before Mr VMX starts next weekend & found this slight problem, had been welded in the distant past.
Unfortunately I don't have a 1st oversize piston to fit my spare barrel & don't think I can get 1 sent over quick enough 
Hopefully the welder thats been recommended to me by a friend who builds roadrace bikes(GSXR600s running 3 cylinders) can make a better job of it

[DR]

  ouch!...max oversize I assume? the liner looks awfully thin, think I'd be busting my butt trying to find that 1st over kit for the other barrel

[tony27]

Only third oversize, still another 5 rebores left in theory seeing as wiseco do up to 2mm over
Problem is any piston kit I could source will be in oz or the us & will take more time than I have to arrive although quite often thngs arrive quicker even from the uk than if sourced locally in nz

[Lozza]

If you make a drill jig and dowl it with roll pins and smear JB Weld over it before you hammer the roll pins in ,all will be sweet.

[tony27]

Now that the pieces are clean I can see that it's been welded through the transfer port & at the front with a bracing weld to the exhaust port, to do the job properly would have meant removing the liner as the break is at the transition point of the main body & flange. I'll see what the welder thinks he can do but I'm not holding my breath that I can have it back together & running by saturday seeing as it's a holiday tomorrow

[tony27]

Been thinking about another possible option, how hard would it be to swap liners & get the barrel welded properly while the liner is out.
The clymer manual I have talks about fitting a new liner but as new they're undersize & require boring out to standard bore size, is the bore size likely to alter if I did remove the liner & refit it to the other barrel?
What sort of temp do you need to heat the barrel to?

[POM]

Removing a sleeve from a barrel  can be a tricky task,particularly if its the original sleeve.
Be aware some manafacturers actually cast the barrel around the sleeve and somtimes the sleeve also has ribs around the outside of them,making removal and saving the sleeve almost impossible...very dependent on the manafacturer and model.
I am just in the process of resleeving a yz250 (39x) barrel which had the aforementioned ribs around the sleeve...and yes the original sleeve had to be destroyed to get it out....I have pictures of this and when i'v finished it, i will post pics if anybody's interested.
To fit a new sleeve you need to heat the barrel to approx 400degs (apparently).

[Lozza]

200degC is hot enough, another problem with pressing sleeves out (is pretty obvious on this one) that the spigot is way to thin to take any sort of pressure unless there is a mandrell slipped into the sleeve to press on.

What is the cylinder off BTW?

[tony27]

Cylinder is off my 73 CZ380, the spigot is definately thinner than the main part of the sleeve-2mm or so with the main part another 4mm thicker. I can throw it in our heat treatment oven at work which we don't use much anymore & should be able to make up a mandrel to push with although I was reading an old post where ShakeyCZ reckoned his basically slipped out under its on weight when he did his.
This is all new territory for me & I'm still not sure about whether there is any chance of the sleeve warping

[Lozza]

sleeve won't warp not hot enough for that

[john d]

Tony,
 I have had good luck using my oven at home.
 Clean the cylinder up first. We use a cookie sheet and some red brick . Space the cylinder off the cookie sheet enough so the liner will fall free of the cylinder. Heat the oven up to 400 to 450 Degs F or so and the liner will usually fall out on the sheet. It take about 1/2 an hour. We have done KTM and Honda 500/600 XR liners like this. Some times a tap with a hard wood hammer handle if their is a burr from handling on the cylinder or liner.
 Get the cylinder grease free and then wash with hot soap and water and the oven will have no lasting effects.
john d.

[tony27]

Thanks for that John, just easier to do it at work & won't have the wife complaining about stinking out the house.
Lucky my boss looks on homework as being a good way of broadening our skills base.
Did a similar thing a couple of months ago with a urethane coated stainless roller although that was from scratch & I had material to remove to finish

[GMC]

If you make a drill jig and dowl it with roll pins and smear JB Weld over it before you hammer the roll pins in ,all will be sweet.

I know a lot of guys on here like this play doh shit but there’s no way that would hold a repair like this together, with or without dowel pins.
There are way too many forces going on inside the crankcase for that to hold together.
It has already broken the casting and the previous weld so it needs something substantial to hold it together.
It just wouldn’t be worth the grief of traveling a couple of hours (or days) to a race to have a DNF through a budget repair.

To weld it properly it would be best with the liner out, and the machinist is going to want the liner out when he does the surface as well.

[Lozza]

Worked fine in much harsher environments.

[tony27]

Liner is out & cylinder is at welders, been told to ring during the afternoon to make sure it's ready for collection after work