this is the same blaster me and my friend have been having probs with. saturday we put a new left case on, all bearings and seals, has a new hot rods crank, top end has been bored its all new. but we rode sunday for a few hours then we stopped for a while, he couldnt start it so i tried, it fired up but i noticed it was popping, blowing smoke from under the head, we were a long way from home so i left him there and went and got some tools, went back and tightened it back up, we rode 30 more mins and and it died, the head cam loose again, so we just pulled it home, i just dropped off 6 heads at the machine shop to have them all checked, but what could be the prob? warped head? warped cylinder? or the studs being stretched?
head coming loose
- Thread starter Reaper26
- Start date
Were they torqued down to the right spec AFTER heat cycles? Are they the right nuts? (Might not matter) I have never heard of that happening. Gasket on the right way?
If the nuts have been put on without using a tension wrench at the recommended settings, the nut/stud threads could be stretched.
Were heat cycles performed after rebuild?
Was a new head gasket used?
Was correct tightening sequence adhered to?
Were the threads clean and dry (no lubrication/Loctite) when tensioned at re build.
Were the studs Loctited into the cylinder?
A warped head usually shows its true colours at the time of re build and will leak from the onset.
Were heat cycles performed after rebuild?
Was a new head gasket used?
Was correct tightening sequence adhered to?
Were the threads clean and dry (no lubrication/Loctite) when tensioned at re build.
Were the studs Loctited into the cylinder?
A warped head usually shows its true colours at the time of re build and will leak from the onset.
yes, we used all the new parts, its pretty much a new motor! we did it sat, ran it here at the shop got it hot made sure it was guna open up and run right then went back over it all. it sat from 5pm till 9am sun morn then we rode for 2 or 3 hours stopped at the creek he couldn't start it when we got ready to leave so I got on it, it started right up and as I was revving it I heard it popping and he saw smoke cmin from under the head, we tightened it rode 30 mins tryin to get home an it died, came loose again, so I just pulled it home, ive been doin top ends for 12 or 13 years and never had one do that, but I just ordered new gaskests, guna check the piston to make sure its ok, and new studs and nuts.
It reads as if you did not perform the heat cycling that a copper head gasket prefers.
ive never done it the way some of the ppl here describe it, we have always warmed it up checked it good then rode fairly easy for about a tank, the heat cycles, if I do three do I need to check it after each one after it cools or after the last, im guna try this one that way when we get the parts for it.
After fitting a new gasket and tensioning down to 20 ft lbs run the motor by blipping the throttle until it gets to operating temperature and then switch off and cool for at least 30 minutes.
Do this 3 to 5 times.
Re tension head and cylinder bolts.
Solid copper gaskets require this process as the process of expansion/contraction crushes the gasket, therefore making it thinner and can cause it to leak, or in the case of stretched threads on the fastenings, cause them to loosen.
Do this 3 to 5 times.
Re tension head and cylinder bolts.
Solid copper gaskets require this process as the process of expansion/contraction crushes the gasket, therefore making it thinner and can cause it to leak, or in the case of stretched threads on the fastenings, cause them to loosen.
Inspect the studs very carefully, maybe even measure each with a caliper. Then write the measurements down so you can compare if it comes loose again. That way you'll know if the studs are backing out or stretching.
the studs were kinda loose when I changed them yesterday, only two of them were tight. we did one heat cycle last night, I just did the second, letting it cool of now. and luckily the piston wasn't really hurt, the jug had a light alum mark from the piston, I honed it, and got some polishing paper and cleaned the piston, took the rings off and checked them.
I checked the float, I cleaned it when I put it back together, changed the jet from a 350 to a 270 280 I did mine at the same time so I cant remember which jet I used in his. and I haven't moved the needle. were guna order a new kit for it so I can just go ahead and change everything, and get it jetted correct. I don't want any more problems with it for a long time.
