Piston Help
Thread Starter
|
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,078
Likes: 2,150
From: Ohio
Piston Help
Brought a 82 Tour Glide home from Michigan, got the bike home getting it running and aware of new Cometic head gaskets was on it at purchase. Engine oil smoked badly with characteristics of bad valve seals, pulled it down noticing it had new pistons and valve guides installed, pulled the cam revealing a L3 so knew right away it had crushed valve seals from the new guides not correct for the Leineweber cam. Pulled the springs, both intake valve seals was pushed down 1/8" further than exhaust with one of them being crooked and the valves fell out with little resistance so believe that problem was found.
Pistons was rocking excessively in the bore, removed them from the rod checking clearances with base stuff at home, dial bore gauge at work. Calipers and feeler gauge both came in at .007 piston to cylinder wall clearance, ring gap was excessive @ .030 plus the rings aligned during cylinder removal.
New pistons have markings of 41637 PR 927 .020, they are forged and can't find any name on them, searched the internet with no success of information. Has anyone heard of a possible PR piston and would excessive ring gap and slight cylinder wall clearance cause a piston to rock as bad as these pistons did? I'm going to keep this bike and not to keen on not running name brand pistons.
Pistons was rocking excessively in the bore, removed them from the rod checking clearances with base stuff at home, dial bore gauge at work. Calipers and feeler gauge both came in at .007 piston to cylinder wall clearance, ring gap was excessive @ .030 plus the rings aligned during cylinder removal.
New pistons have markings of 41637 PR 927 .020, they are forged and can't find any name on them, searched the internet with no success of information. Has anyone heard of a possible PR piston and would excessive ring gap and slight cylinder wall clearance cause a piston to rock as bad as these pistons did? I'm going to keep this bike and not to keen on not running name brand pistons.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
forged pistons for street is a thing of the past - they cheeped out and had worn used cast pistons but just installed a un branded import forged set - then used maybe the used rings for the other pistons - that 30 pack went down just as expected
moronic thing is install a cam that comes with specific directions about the valve travel from the bottom of the top retainer to the top of the seal - BUT you need to not only know how to read BUT understand whats going on - none of that was any concern
check the valves with a magnet if it sticks to them even a little bit - well that's china stainless that actually rusts if you can believe that < throw that $hit away - kibble white valves we set them as max .003 exhaust and .002 intake - valve to guide - the tin seals are junk but the blue rubber may need to machine the tops of the guides to get the travel distance - and 82 you have the correct lower retainers for the blue seals - the top retainers may need the andrews blue .060 off set - for that cam dont have the spec in front of me but .450 lift and more its in play - you want 125 pounds on the seat in pressure and 275 open to 320 is also going to happen with performance springs NO more then this - yes hyd lifters will work - we use a rimac machine to do springs
just re bore the cylinders .030 Yes its getting thin but the 80 jugs are thicker in spots the 74s are not but do not do .040 get new barrels - we re correct re pop jugs and make them .010 but they are then straight and correct .003 piston to wall - < this is what we use .003 with the cast piston JCC is the best ones - as a set they are .0001 close to one another
cometic MLS head gaskets are best - but we went back to paper base gaskets sprayed with hylomar < more forgiving then the tin base gaskets -- good luck moving forward
moronic thing is install a cam that comes with specific directions about the valve travel from the bottom of the top retainer to the top of the seal - BUT you need to not only know how to read BUT understand whats going on - none of that was any concern
check the valves with a magnet if it sticks to them even a little bit - well that's china stainless that actually rusts if you can believe that < throw that $hit away - kibble white valves we set them as max .003 exhaust and .002 intake - valve to guide - the tin seals are junk but the blue rubber may need to machine the tops of the guides to get the travel distance - and 82 you have the correct lower retainers for the blue seals - the top retainers may need the andrews blue .060 off set - for that cam dont have the spec in front of me but .450 lift and more its in play - you want 125 pounds on the seat in pressure and 275 open to 320 is also going to happen with performance springs NO more then this - yes hyd lifters will work - we use a rimac machine to do springs
just re bore the cylinders .030 Yes its getting thin but the 80 jugs are thicker in spots the 74s are not but do not do .040 get new barrels - we re correct re pop jugs and make them .010 but they are then straight and correct .003 piston to wall - < this is what we use .003 with the cast piston JCC is the best ones - as a set they are .0001 close to one another
cometic MLS head gaskets are best - but we went back to paper base gaskets sprayed with hylomar < more forgiving then the tin base gaskets -- good luck moving forward
Thread Starter
|
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,078
Likes: 2,150
From: Ohio
Thanks John, I'll check items mentioned because short cutting engines isn't something I'm known for. It had the tin valve seals and can clearly see where the intake valve seals was smashed on the valve guides. Kinda funny they put a new Mikuni 42, 2000i ignition system and money in areas but short cutted the main area of focus on a engine. Do know the valve springs had some serious pressure removing them so something else to check.
The L3 cam runs solid lifters and has solid lifters in it, the rollers will get cleaned and inspected, cam looked good
Last edited by 1997bagger; Aug 17, 2020 at 09:18 PM.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
it could have leinweber springs - they are over the top strong and not in my opinion a street bike set up
you need to test /. check it with a rimac and calipers - dont guess its oj as i do not believe it is
you need to test /. check it with a rimac and calipers - dont guess its oj as i do not believe it is
Thread Starter
|
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,078
Likes: 2,150
From: Ohio
Did some more measuring, L3 cam is .486 lift and had .570 from the valve retainer to the top of the valve seal so has enough clearance. Valve seals was screwed up, going to go with John's 30 pack build and maybe a few shots of Tequila.
Looks like Kibble White guides, valves are new(black) and a magnet didn't stick to them so heads need valve springs checked, TLC with good seals, bore job and check over items and a go. Springs have doubles with a small inner winding so possible overkill for the street.
Looks like Kibble White guides, valves are new(black) and a magnet didn't stick to them so heads need valve springs checked, TLC with good seals, bore job and check over items and a go. Springs have doubles with a small inner winding so possible overkill for the street.
Thread
Thread Starter
Forum
Replies
Last Post
Bagger_Vance
Engine Mechanical Topics
87
Jun 6, 2015 03:24 PM
