ernestro
ArboristSite Lurker
Hi there!
first post i think. (to skip the story and go straight for the question, scroll down to the bottom)
Been reading here for a while, learned A LOT in the last two years. Had absolutely no clue about fixing chainsaws or anything 2-stroke before, but now i can do some maintence and fixing..
Thanks for all the info so far..the best forum around! Will contribute when i pull myself on a green branch.
So...i got a slightly beat up 365 Special for a good (200$) price 2 years ... got it running pretty good - the fine mesh filter in the carb was completely stuffed with oily wood dust residue. It was idling alright (although i don't know how it managed even that), but in the cut it would bog down completely.
Did a bunch of part replacements (fuel filter, flywheel bearing, sprocket, blade, x-cut chain ... ), so i', a bit invested in it, therefore i don't want to bin it straight away- or maybe at all.. i like the 365 sp... i'll just get another used one and have this one for parts..
It ran well enough for my needs, even though it had only 135PSI compression, as there was some slight scoring seen on the exhaust side, but still - ran enough to work with.
... but then i lent it to my inlaws ...
well... the result was that it wouldn't idle and run unless pushing the throttle....something was apparently wrong but they would keep on cutting
so i tore it apart, and voila...
scored piston, piston skirt chipped off (ok, the skirt might have happened before i bought it, as history was unknown
I decided to try to save the jug... i bought a new meteor piston and removed 99% of aluminum transfer in the jug (no acid) ...
Since the whole saw is a experimental first timer project, i decided to widen & smooth out the lower transfer end...(Not touching the science of port timing yet
I've got nothing to loose... If i messed up the cylinder, i'm most probably upgrading it to a 372 P&C anyway... WIN WIN
SO, finally getting towards the QUESTION.
Everything went fine (but as a first timer extremely slowly and carefully, also i have limited time for this new found hobby)
until i tried torquing down the cylinder.
In the workshop manual, it says 10nm.
Two screws clicked okay, on one i was getting suspicious, but one gave up on the thread.. .
Wrench was set in 10nm for sure...
How do you tighten your cylinders down?
Torque wrench or by feel? Till it's snug + one or two /16 of a turn?
I have 3 Torque wrenches...to work on the family cars...i bought them with the sole intention NOT TO STRIP threads or tear bolts (or o.t.o.h. have something come loose on the highway)
well...that's exactly what i did here...
I stripped the thread in the crankcase....after all that work
Still not sure how... tired material? Was someone before me there and overtightened already, so it was ready to get stripped on the next tightening?)
I read about possible solutions... i guess thread lock only is out of the question on such a critical part..
Thought about helicoils and/or timeserts (got no tools&experience yet)... but read somewhere that it might be worth to try
to drill and tap a new M6 thread.
So i do have taps, therefore i went this route. I read i can still put a helicoil/timesert, if the tap fails to work?
THE REAL QUESTION:
Can i get away with tapping just this one stripped hole... or should i do the same for all 4 cylinder bolt holes?
If i try to tighten by feel...will the clamping force be distributed evenly across the mating surface?
I always do tighten bolts in a circular (or other appropriate pattern) manner,
taking great care to increase force very gradually so i don't bend anything...
what's the worst thing that can happen?
I would like to keep the thing.... don't mind too much if i have to swap the P&C
... but would not be happy to destroy the crankcase...
Thanks a lot, for any kind of info!
first post i think. (to skip the story and go straight for the question, scroll down to the bottom)
Been reading here for a while, learned A LOT in the last two years. Had absolutely no clue about fixing chainsaws or anything 2-stroke before, but now i can do some maintence and fixing..
Thanks for all the info so far..the best forum around! Will contribute when i pull myself on a green branch.
So...i got a slightly beat up 365 Special for a good (200$) price 2 years ... got it running pretty good - the fine mesh filter in the carb was completely stuffed with oily wood dust residue. It was idling alright (although i don't know how it managed even that), but in the cut it would bog down completely.
Did a bunch of part replacements (fuel filter, flywheel bearing, sprocket, blade, x-cut chain ... ), so i', a bit invested in it, therefore i don't want to bin it straight away- or maybe at all.. i like the 365 sp... i'll just get another used one and have this one for parts..
It ran well enough for my needs, even though it had only 135PSI compression, as there was some slight scoring seen on the exhaust side, but still - ran enough to work with.
... but then i lent it to my inlaws ...
well... the result was that it wouldn't idle and run unless pushing the throttle....something was apparently wrong but they would keep on cutting
so i tore it apart, and voila...
scored piston, piston skirt chipped off (ok, the skirt might have happened before i bought it, as history was unknown
I decided to try to save the jug... i bought a new meteor piston and removed 99% of aluminum transfer in the jug (no acid) ...
Since the whole saw is a experimental first timer project, i decided to widen & smooth out the lower transfer end...(Not touching the science of port timing yet
I've got nothing to loose... If i messed up the cylinder, i'm most probably upgrading it to a 372 P&C anyway... WIN WIN
SO, finally getting towards the QUESTION.
Everything went fine (but as a first timer extremely slowly and carefully, also i have limited time for this new found hobby)
until i tried torquing down the cylinder.
In the workshop manual, it says 10nm.
Two screws clicked okay, on one i was getting suspicious, but one gave up on the thread.. .
Wrench was set in 10nm for sure...
How do you tighten your cylinders down?
Torque wrench or by feel? Till it's snug + one or two /16 of a turn?
I have 3 Torque wrenches...to work on the family cars...i bought them with the sole intention NOT TO STRIP threads or tear bolts (or o.t.o.h. have something come loose on the highway)
well...that's exactly what i did here...
I stripped the thread in the crankcase....after all that work
Still not sure how... tired material? Was someone before me there and overtightened already, so it was ready to get stripped on the next tightening?)I read about possible solutions... i guess thread lock only is out of the question on such a critical part..
Thought about helicoils and/or timeserts (got no tools&experience yet)... but read somewhere that it might be worth to try
to drill and tap a new M6 thread.
So i do have taps, therefore i went this route. I read i can still put a helicoil/timesert, if the tap fails to work?
THE REAL QUESTION:
Can i get away with tapping just this one stripped hole... or should i do the same for all 4 cylinder bolt holes?
If i try to tighten by feel...will the clamping force be distributed evenly across the mating surface?
I always do tighten bolts in a circular (or other appropriate pattern) manner,
taking great care to increase force very gradually so i don't bend anything...
what's the worst thing that can happen?
I would like to keep the thing.... don't mind too much if i have to swap the P&C
... but would not be happy to destroy the crankcase...
Thanks a lot, for any kind of info!
