JB Welding holes !!

Oct 8, 2011
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nova scotia
I bought my bike off of a friend that blow it up. There was a hole the size of a bottle cap just under the crank and there was tranny fluid coming out of it, so that wasent good. after tearing the topend off we found out what had happend. the bottem half intake side of the piston had broke off and when it fell into the bottom of the motor the crank forced it through the case. aswell as busting a crack through the tranny side of the case. the crank bearings were all good. i dont have any pictures of the hole but i do have some of our fix for it. 2 packs of JB Weld and alittle bit of fiberglass. we used asetone and a file to rough it up before applying.
left side case
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right side
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The case can now be repulled apart if needed to, the way we did it was by sealing the cases togeather and using electrical tape between them, then build our jb up in layers on each sides of it. after pulling the cases and tape off minor touchups are needed to make sure it seals after. aswell as fileing was needed to be done on the inside to make sure the crank will still pass it.
This dos look abit sketchy and if applyed wrong can be problem prone. but after installing a new piston/bore this motor runs like a top. i have been running this bottom end in my bike since and havnt had a problem with it. i also did an air leak test on the motor a year after this fix and still held air fine.
lol and yes This is rigging it up at its finest
 
how's it holding up. Well, assuming if you had a chance to run it.

he said he's been running it that way.

I would have put a new set of cases in there...just couldn't trust a repair like that long term. maybe get me through a weekend, but definitely not a permanent fix
 
he said he's been running it that way.

I would have put a new set of cases in there...just couldn't trust a repair like that long term. maybe get me through a weekend, but definitely not a permanent fix

when i bought the blaster there wasent much for parts around so we made for what we had. This was done over a year ago and i have been running it since, i run my bike hard. the bike just had a topend rebuild and is workin awsome.
 
he said he's been running it that way.

I would have put a new set of cases in there...just couldn't trust a repair like that long term. maybe get me through a weekend, but definitely not a permanent fix

we have the parts and cases now to build new motors so im not worried much. Just kinda running it for now cuz it works. ill try and get a video of the bike up one of these days. As for JB its pretty strong stuff if its used right.
 
You've got balls to post those pictures!
Mere mortals cannot stand the sight of such things.
It makes their heads spin and explode. They see you as crazy and heretical.

I see my join date is Dec 2010 so it was before that. You got me into Blasters.
This motor has had the 30hp DT200 top end on it, and now has the modified head and lowered cylinder.
We have been on some good all day trail rides but usually it is a couple of hours of hill climbs and jumps.
We have them out at least once a week even in bad weather. Gotta have over 100 hours on it by now?

You didn't mention or show how you roughed up the case with a coarse file before the acetone and epoxy.
Just barely visible in some of the picts is the fiberglass mat that is an important part of this.
Not bad for a first time repair. Not pretty, but with the careful filing and case lapping it hasn't leaked.
 
See, I had to come and check it out (AGAIN?) because I'm going to do a repair on a Warrior that got chain wacked. I was thinking of imprgnating fiberglass cloth with JB and using it like a bandage. 2 layers w/2nd larger than first. I haven't seen the job yet so I can't really say if there is a chance :eek:
 
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See, I had to come and check it out (AGAIN?) because I'm going to do a repair on a Warrior that got chain wacked. I was thinking of imprgnating fiberglass cloth with JB and using it like a bandage. 2 layers w/2nd larger than first. I haven't seen the job yet so I can't really say if there is a chance :eek:

I have done one of these repairs to a 250x motor that had a chain slip off an bust around the sprocket. Hardest part is cleaning all the oil from the aluminum, asetone and rough file maarks dos the trick well.

As for these holes i repaired over 21/2 years agoo ^^^^^. Jb has held fine leak tests pass everytime...... Dont believe the hype, i spent something like $15 to fix these cases an have put 100`s of hours on it since.....whos laughin noww B)
 
Larry, getting the metal clean is the biggy, whether with welding or epoxy.
Clean it all up as best you can, then the acetone, then I'd suggest sand blasing if you can, to give it some tooth to hold on to.
A thin coat of the original JB Weld epoxy (not the Qwik Set stuff) and lay your fiberglass cloth on. Saturate it.
Keep laying more cloth on and saturating it to build it up if you need to.
You can cover it with plastic and box it up to mold it to shape if you want.
Let cure 24hrs and file or grind to shape.

It won't work everywhere, but for unstressed areas it hold remarkably well.
I have been sticking it inside my intake ports for over 30 years, without failure.
I have sealed cases with it even longer than that, and had failures, usually from inadequete prep, dirty aluminum.

It won't take the heat of the exhaust side, it needs a lot of rough surface area to hold, and it needs to be clean.
It ain't a miracle, but pretty darned close... :)

Steve
 
Im a fan of JB weld or in other words epoxy. It can be a damn good fix and I have actually used it to to fix to date and still going strong:
A drag ported 27cc weed wacker motor- I ported through the intake transfer roof on one side.
A busted 79' YZ400 case where the clutch rod boss was hit and split from a chain.
A busted 79' YZ400 case where who know what cracked the case after a big end bearing let go.
A stripped Banshee carb idle adust screw- it worked for the 2 years I ran stock carbs.

If you do the stuff to properly prepare the surface for it to bind to (clean and rough its not that hard) it's a big time and $$$$ saver.
What sucks is it always gets a bad rep because people don't do that- which is the reason I avoid buying anything that has been repaired by it unless I did it myself.
Another thing worth mentioning is there are many kinds of epoxy. They vary in the times they take to dry and the viscosity they are (thickness) like loctite, educate yourself on which is right for your repair.
 
Year and model ??

1979 250 Qualifier. It runs, compression is good. It has an unusual aluminum swing arm. I've picked up a second bike for spare parts and should have enough to put together a complete bike. I've moved so I don't have my shop so I'm working in an unheated, unpowered, unlit shop. Feels like I'm 16 again!

Cleaning 38 years of grease and stuck bolts. So far haven't broke anything. Brakes, spokes, stuck axles, hardened rubber, brittle plastic, rust, luckily no cracks found yet. In my search for parts I picked up a 1977 as well. Hardly any of the chassis parts fit. Those were years of rapid change in the competitive dirtbike world.

To keep on topic, I haven't had to resort to JB Weld so far, and it's a good thing. Temps in my shed hav been down in the -10c range. JB Weld wouldn't set properly in these temps. Also working on a woodstove and solar lights...
 
See, I had to come and check it out (AGAIN?) because I'm going to do a repair on a Warrior that got chain wacked. I was thinking of imprgnating fiberglass cloth with JB and using it like a bandage. 2 layers w/2nd larger than first. I haven't seen the job yet so I can't really say if there is a chance :eek:

I am here to say that I have successfully repaired my blaster 200 that was chain slapped. I used sand paper and roughed up the area I needed to apply to it has held and with no leaking. I just need new seals now. And I had a neighbor pour mountain dew in my tank so I drained my tank and cleaned the carb a little but I gotta do it again. I got a carb rebuild kit and a new gas valve for turning the gas on and off. I am new to all this and have been doing nothing but research.
 
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