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jack3140
03-23-2011, 01:30 PM
i have a briggs&stratton engine with an aluminum cylinder that is scratched due to a broken ring could jb weld be used for this or is a rebore needed thanks

airsmith282
03-23-2011, 01:54 PM
i have a briggs&stratton engine with an aluminum cylinder that is scratched due to a broken ring could jb weld be used for this or is a rebore needed thanks


rebor or replace the inner steel sleeve iam pretty sure there is an incert there .. jb weld is not suitable for that sort of a repair it does an even craper job trying to seal a block up that had a con rod wiped out of it..

you could also try if you want to hst 2000 or sutotec 78 i think it is and then re surface it you might get it to work that way as well,,,

steverice
03-23-2011, 04:44 PM
Sure, sand the scratches down so you finger nail doesn't catch, fill the cracks with the filler material, let dry and sand smooth.

jihe
03-23-2011, 04:52 PM
rebor or replace the inner steel sleeve iam pretty sure there is an incert there Actually I think many B&S engines don't have a sleeve. Instead they are supposed to be made of a silicon rich alloy which makes it possible to use naked aluminum as cylinders.

Hogridnfool
03-23-2011, 05:05 PM
i have a briggs&stratton engine with an aluminum cylinder that is scratched due to a broken ring could jb weld be used for this or is a rebore needed thanks
A guy on this forum claims it will work...http://bbs.homeshopmachinist.net/showthread.php?t=47200.
Of course that was in a cast iron bore, I don't know if it would work in an aluminum one.

winchman
03-23-2011, 05:40 PM
I'm a big fan of the stuff, but I think you're wasting your time trying to repair the cylinder wall with JB Weld. The heat will soften it, and the rings will scrape it away in short order. The hot oily environment won't help matters.

darryl
03-23-2011, 05:50 PM
I think it or some other high temperature formulation would work for awhile, but I agree, it will most likely get trashed and the repair won't have been worth it. You'll end up having to bore anyway. Might as well go that route now instead of later. My opinion anyway.

jack3140
03-23-2011, 06:00 PM
well it sure looks like i better rebore this thing too bad it is practically new i thought it would,nt work but no harm in asking thank you all for your input

hardtail
03-23-2011, 06:37 PM
Where is the scratch? Full length of bore.......worse in places than others?

Black_Moons
03-23-2011, 07:00 PM
... lol JB weld on a motor wall? thats the crazyest thing I have ever heard.

And I thought putting JB weld into the transfer ports of a 2 stroke was bad enough (To correct a bad porting job... Apparently it will hold there, But it won't hold in the exhaust ports)

Sometimes you can buy new cylinders/piston kits... depending on the engine.

Reboring it would work, if its not a lined cylinder. Make sure to hone it in to get the proper cross hatch pattren to reseat the new rings.

Btw, if the scratch isent too major, you could just lightly hone and put a new piston in.. Might burn a little oil, and lose a little power, but if its not a racing motor it should'nt be a huge deal.

wierdscience
03-23-2011, 09:11 PM
Aluminum bore BS engine = disposable.

You could bore it and sleeve it,but you will probably need to make up some valve seat inserts too,pretty easy to do,galvanized water pipe is three or four steps up in material quality:p :D

Ron of Va
03-23-2011, 09:16 PM
i have a briggs&stratton engine with an aluminum cylinder that is scratched due to a broken ring could jb weld be used for this or is a rebore needed thanks
Seriously, what do you have to loose? Go for it. Let us know how long it took to blow smoke.:D

Orrin
03-23-2011, 09:19 PM
... lol JB weld on a motor wall? thats the crazyest thing I have ever heard.
It has been done successfully many times; but on water cooled engines. Air-cooled engines run hotter, so a JB Weld repair is unlikely to be successful.

Orrin

jack3140
03-23-2011, 09:19 PM
lol JB weld on a motor wall? thats the crazyest thing I have ever heard.

thank you for your nice remark you have made my day i have never had to use jb weld before and i have heard many comments on this site lauding it so in my stupidity i thought i would ask for opinions and by job i got em thank you !!!!!!!!!!

Don Young
03-23-2011, 10:30 PM
It has been done successfully many times; but on water cooled engines. Air-cooled engines run hotter, so a JB Weld repair is unlikely to be successful.

Orrin
I am the one who posted about successful JB Weld repair in an auto engine cylinder. It would seem less likely to me to be successful in this case but it would be an interesting experiment. My repair was entirely in the cooler lower end of the cylinder and was basically four long narrow grooves cut by a loose piston pin. The engine was actually running fine before the repair as I only discovered the damage when removing the head for valve replacements due to a jumped timing chain.

It is necessary to have the surface rough and very clean for JB Weld to adhere well.

Iraiam
03-23-2011, 10:41 PM
A copy / paste from the JB weld website.

Q: Will J-B Weld work on an automotive exhaust?

A: Because of the extreme temperatures of exhaust systems, we do not recommend J-B Weld for use on exhaust manifolds and catalytic converters. Nor do we recommend the product for repairs within the combustion chamber.

jack3140
03-23-2011, 10:59 PM
A copy / paste from the JB weld website.

Q: Will J-B Weld work on an automotive exhaust?

A: Because of the extreme temperatures of exhaust systems, we do not recommend J-B Weld for use on exhaust manifolds and catalytic converters. Nor do we recommend the product for repairs within the combustion chamber.
thank you that is the kind of answer i was looking for now i know regards jack

Boostinjdm
03-23-2011, 11:47 PM
Aluminum bore BS engine = disposable.

You could bore it and sleeve it,but you will probably need to make up some valve seat inserts too,pretty easy to do,galvanized water pipe is three or four steps up in material quality:p :D

I get the feeling you don't have any experience here. B&S aluminum bore is referred to as a "cool bore". Very common and have survived racing environments. Nowadays, the IC blocks are more desireable with the cast iron sleeve, but cool bore engines are still in use.

Black_Moons
03-24-2011, 06:16 AM
I get the feeling you don't have any experience here. B&S aluminum bore is referred to as a "cool bore". Very common and have survived racing environments. Nowadays, the IC blocks are more desireable with the cast iron sleeve, but cool bore engines are still in use.

My motorbicycle has no sleeve. But it does have a (Nickel?) plating on the inside of the cylinder that is reasonabley hard.

JCHannum
03-24-2011, 08:08 AM
JB Weld has temperature limit of 600*F, and has been used for minor cylinder repairs with success. I used it on a hit & miss engine and it held up well, so this question is not a stretch at all.

The main consideration is to clean and degrease the repair area. The greater expansion of aluminum over that of iron might present a problem, it would have to be tried. That said, depending on the severity of the scratches, I would consider just cleaning them up and reassembling with new rings. Unless there are very deep gouges, there will probably only be minimal effects on performance.

JoeLee
03-24-2011, 08:20 AM
JB weld is garbage............ It will never hold in a small scratch in a cyl. You need a substantially deep gouge in order for the stuff to stick, remember it's just putty. I have people bring me stuff all the time to weld that they tried to patch up with that crap.

JL........................

J Tiers
03-24-2011, 09:01 AM
Lots of violent opinions here......

The epoxy may or may not hold up, I suspect not, in general.... but might be surprised.

I believe it matters a lot how deep, where in the bore, and what direction the scratch....

Likely it is parallel to the stroke. if not very deep, you might ignore it, it may fill up with carbon anyway. Depends on how hard the engine will work. Since it is parallel the ring will slide over it

if really deep, you might have a problem anyway.

if the ring broke and a piece twisted and made a wide sideways gouge, it's likely toast.

if low in the bore, JB may work fine to "fill it up", because lower part of cylinder doesn't get as hot.

If up near top, it will get pretty hot, but JB could still work "OK" if not over the max for the material.

For-sure it will not work for cracks in the head,.......

hardtail
03-24-2011, 11:32 AM
I've seen it successfully used for lower cylinder nicks below the ring travel......if it's 4 stroke the rpms will be lower but still not as good as the hit and miss canidate......LOL But way better than 2 stroke......the gouging may be worst at the top and bottom where the broken ring wiggled as the piston changed direction thats why I wanted to see pics or a better description. I wouldn't by any means call it a recommended repair but it might work.....depends on the area and extent of damage.......if it's minor the gouge should just fill with oil down the cylinder anyway providing somewhat of a seal........

Jack you need a thick skin around here........LOL

jack3140
03-24-2011, 11:43 AM
thanks for your input and suggestions i,ll try the new rings approach and see what happens might take a while though it is still a little cold in the shop to play with that take care jack

vpt
03-24-2011, 01:29 PM
Lets see a pic of the scratches. Did the piston get damaged? You have to replace the rings already and if you have to replace the piston there is no reason not to go the next size up and bore the scratches out. If it is within .010" that can be brought up just by honing.

jack3140
03-24-2011, 05:50 PM
Lets see a pic of the scratches. Did the piston get damaged? You have to replace the rings already and if you have to replace the piston there is no reason not to go the next size up and bore the scratches out. If it is within .010" that can be brought up just by honing.
at this stage only the head is off so pictures are not really possible i will investigate this further when the weather warms up a little no fun freezing your fingers lol besides it is only an 11 hp motor so no big deal i was just curious about using jb weld since i have never used it take care

Black_Moons
03-24-2011, 06:15 PM
Lets see a pic of the scratches. Did the piston get damaged? You have to replace the rings already and if you have to replace the piston there is no reason not to go the next size up and bore the scratches out. If it is within .010" that can be brought up just by honing.

If its a lined cylinder, you don't really wanna bore off the lineing.

vpt
03-24-2011, 06:17 PM
Have it rechromed. ;)

CCWKen
03-24-2011, 06:56 PM
The cylinder is NOT part of the combustion chamber. :eek: Besides, way back when I was racing karts the cylinder head itself never got above about 525 degrees. And that was on 6000rpm Briggs. If it did, it meant you were running too lean. You then run a quarter lap with the carb control turned out to dump in more fuel (methanol) to cool it off. Then ease it back in. All the while fighting for position, driving hairpin turns, negotiating the switchbacks and getting ready for the straight. While watching the temperature gauge of course. :cool:

These were all Cool-Bore engines back then. They were all aluminum alloy--No sleeve. The piston was nickel plated though.