250-500cc Cracked Jug !! AAAAHHHHHHH!! 02cr250

Well it seems ive solved my "falls off of an idle and dies/ air leak mystery- Damn,was just finishing her face lift too. Time to drop a couple more $$ i guess. anybody have a spare jug for a cr250 laying around ?
crack in mine is fairly small-wonder if repair is possible? any thoughts??

Thanx

You should be able to get it welded, if it does not go into the water jacket. If you do, then I would also have the cylinder base recut to be sure it is flat after the welding.

Paw Paw

Millennium Technologies can fix that ...had a customer with a '89 Honda CR250 that completely cracked thru worse than yours...look brand new when they got done with it...

That looks like an easy fix for an experienced welder.

halls has one sombuddy had a link to it posted up here a few days ago

This can be fixed. For now just wipe some silicone over the crack with a finger to seal it and keep diagnosing the idle issue. It certainly can be welded.

I had a Suzuki 500 quad many years ago that was ported so far for flat track racing, it cracked like that at the flats for the base studs on both sides and into the Reed cage inlet area of the casting just like that.

To repair it properly, It must be burred open with a carbide bit in a die grinder and welded while it's bolted down to a flat fixture base plate though. Which does make it difficult to weld where the studs and nuts are.

If you don't do this it will pull the base stud lugs up while welding and re-cutting the base gasket surface flat again on a lathe can change the port timing and TDC deck surface clearance enough that it will detonate and have engine problems. If the head isn't re-chambered.

My 2 cents.

I'm sure the shop "Millennium Technologies" mentioned knows what they are doing though.

DONT KNOW ABOUT JUGS BUT A PLACE CALLED RACERS TOY STORE DOZE CASES WITH SIMILAR ISSUES

I have a 01 WR250 jug going cheap

Don't put silicone on it if your getting it welded that shit makes inclusions in the ally, depending in how well they cut/ clean the crack.

The real question is why did it crack there are your base bolts to tight or your jug warped in the firstplace?

Is it poss a cracked or bent frame could cause this crack?

Besides what Big Timmy said, which is accurate, you also stand the chance of making the cylinder out of round when you weld it. I say weld what you can get to while it's still bolted to the engine and then finish it on the bench. Then dial bore the cylinder and if it's out of round then scrap it since you will have more tied up in it on a re-plate and machining than it's worth. If you can find a good cylinder at a fair price it would probably be the better way to go.

Silicone is so easy to remove. If I was welding this I would burr it to daylight so any silicone having been wiped onto it temporarily to sort your lean idle issue, wouldn't exist anyway after back cutting it for a full pen weld and then I would grind the inside smooth after welding it too.

Taking in consideration, as Doug says, Its a plated Nikasil bore and it's more vulnerable to warpage from welding. This amount of heat is enough to make it out of round most likely.

Even if welded as much as can be reached while bolted down to the cases.

The taller studs and nuts are in the way. That would not be the case if bolted to a fixture plate as the bolts could have the heads cut down and bolted onto that base fixture plate in the opposite direction to allow clearance to weld it but this would be only as a last resort.

I personally would get another usable, or just purchase a new cylinder altogether. This would be cheaper than having to go down the route to repair it back to a usable condition.

Jb weld that sucker n run it til it separates from rest of the donk!

sounds like a good way to blow it up.

Possibly but I'd be more confident in metal putty than sikaflex! Do it on bike, dremel out a bit along crack for it to adhere to. Cylinder is knackered really anyway so if wanted to try get bit more life outa it could try. He'll be buying new piston kit regardless.

I vote for silicone, but to make it a long term solution duct tape it down. Thats right, over the head and right around the frame rails, around six times will be right.
Thank me later.

You guys are starting to scare me.

Bush mechanics!

I'd run it with some sort of sealant(I'd have thought metal putty but silicone if yas reckon is better-both pretty strong id jus worry bout heat/fuel with the silicone) while waitin to buy/find a whole new jug. Probly wouldn't be doin any extreme rides into the desert or deep woods though

Macgyver woulda jus used some gum on that thing & still won the GNCC while diffusing a bomb.

You guys are bodging bastards if ya gunna run it till it grenades then use gorilla tape once round the frame n head really is overkill with that, and pu adhesive tiger seal job jobbed then worry when your 20k into your ride and have a seperated cylinder and a snapped con rod.

Or you could just buy a replacment cylinder an stop any more unwanted costs.

Jus carry an extra roll of duct tape n a couple of paddle pop sticks to splint the rod. Ez.