If you make a spacer to be placed in the piston smaller in diameter than the bearings and press them both out at the same time they can both be removed.
I believe that the rings are thicker on the LRB piston.
McCulloch Chain Saws
- Thread starter Bruce Hopf
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I believe that the rings are thicker on the LRB piston.
DOT3/4 brake fluid (or your equivalent) is good for stiff diaphragms. I just revived a nearly hardened NLA Homelite oil pump diaphragm with it. Took a couple of days and some slight flexing of the diaphragm over the course of the soak, but worked surprisingly well in my particular case. There's a YouTube video out there of all the different home brews for softening rubber and diaphragms and the only thing that seems to work better is a wintergreen oil.
That's disgusting! I would be ashamed to to do something like that.The oil rod button was broken too,they put a 2 + in.deck screw in it to hold it together.Needless to say it didn't oil.Lol
I did exactly this with the wristpin/bearings and a 7-10 LRB piston/rings. FYI the LRB wristpin did NOT work, it was slightly too small and would just fall out. I pulled the bearings out of the original piston with a long bolt and a socket. The piston and new rings seemed to fit/work well otherwise. Haven't put it through a hard workout yet, but assembly went well and it fires/runs, and compression feels good.
Have you checked Caber for rings? As for the bearings, if you can, look at the ones you have and (hopefully) they will have a manufacturer's name and part number. On a 1-4* mac I was able to find dozens of new wrist pin bearings using the Torrington part number I saw on a n.o.s. Mac-numbered bearing.
This guy claims to have some. They are aftermarket but are the ones you need. https://www.sawsalvage.co/products/new-oem-style-mcculloch-610-605-700-sp81-pm850-802-pin-bearings
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I find that when working with the wrist pin bearings in the 10 Series saws the needles frequently fall out. It is possible to put the needles back in with a bit of grease to stick them in place but it is tedious work. I have also had the needles fall out when I pressed the wrist pin out so be ready, have the area cleaned up, and if possible put a piece of paper or a clean shop towel down when you remove the wrist pin to catch any that fall out.
I have heard from several sources that the LRB wrist pins are too small and just fall out, evidently they were intended to be fixed in place with circlips but they didn't bother to put the grooves in piston for the clips. The one I purchased did not have the ring grooves cut deep enough and the rings bottomed out and would not fit in the bore. I made a fixture to hold the rings and ground the I.D. until they would seat fully. After that I elected not to put it in a saw and still have it in the attic.
Mark
I have heard from several sources that the LRB wrist pins are too small and just fall out, evidently they were intended to be fixed in place with circlips but they didn't bother to put the grooves in piston for the clips. The one I purchased did not have the ring grooves cut deep enough and the rings bottomed out and would not fit in the bore. I made a fixture to hold the rings and ground the I.D. until they would seat fully. After that I elected not to put it in a saw and still have it in the attic.
Mark
My favorite sp81 has a lrb piston in it. Been there for quite a few years. The saw runs great. I used the original wristpin though for the reasons mentioned. The rings fit fine for my puston and the bearings came with it. I havent bought one since so maybe now they dont come with bearings. I did get one from bob johnson last year for a 70cc mac. He sent bearings though. I had to press them in pkace and used the old wristpin again. Sp70. It worked out fine and runs very well.
54 degrees. Turkey delayed until 5:00. Hope I can wait that long.Looks nice over there, whats the temp right now? Its not quite so pleasant in Northern Idaho, cold and snowy. But while the snow is flying I got the model 47 running alright and put up on its own shelf. The bar I got from Mark is a nice touch! Still have to and get some chain for it though. Also finishing with a super 55. Had a local machine shop bore the cylinder .030 over and found a nos piston for it. Going to try some new paint on a couple parts and will be about done. Anyone have a flywheel screen they want to part with? I'd like to put one on this thing.
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Ron
Drumsticks and turkey breast(s) are in the smoker now, brisket was done yesterday afternoon, lunch will be at noon...you are all welcome to come if you can make it in time.
In order to keep this thread on track, I will post a photo of my twins when they were younger.
Mark
In order to keep this thread on track, I will post a photo of my twins when they were younger.
Mark
I've just been informed that I'm about to exceed my permitted off-brand usage for this year, but I sold all of my confirmed Mac runners off. So, I've gotta get my 10-10 running. It has a new carb kit and good spark but, depending on where I set the carb screws at, it just loads up, pops, and emits a cloud of white smoke or it doesn't pop at all. Thoughts, suggestions? I will do a compression test and check the piston condition soon and report back, fyi.
Attachments
Timing / Points? Think I'd check f/w key and points condition/gap and go from there..
Thats an oxymoron, all McCulloch saws are runners!
Yeah buy a chip and start from there.
Any idea who bought this? It ended with 1 bid if I understand correctly.
McCulloch BP-399-T, Vintage Snowmobile Engine, Vintage Kart, Collectors | eBay
Mark
McCulloch BP-399-T, Vintage Snowmobile Engine, Vintage Kart, Collectors | eBay
Mark
fechtichmac
ArboristSite Operative
Brief update, the saw has 130lbs of compression and the piston looks clean, but there are shiny patches on the exhaust side. Also, while I was putting the spark plug back in I noticed that the plug wire is bare right below the boot, so a new coil wire is in order.
It's a good possibility that the bare plug wire could be causing your problem of not starting.I had a Homelite XL-800 this past summer that had the same problem.Only thing was I found out the hard way after I'd started the saw,got knocked on my keister.Lol I dropped the saw from waist high & it landed as if I sat it down & just kept running.
The other thing is your compression might come up some after you get it running.Your test was done on a dry cylinder.I wouldn't be surprised if it came up 5-10 lbs.,maybe even more.
Can anyone tell me whether the coil wire is 5 or 7mm?
Thats correct. It had 1 bidder. Likely a buy it now or best offer auction. Someone gave the buy it now price. The only one who knows who bought it is the seller. He/she gets the name of the buyer for shipping when the auction ends.
No it wasnt me.
I've used 7mm accel racing wire,with the copper core. Must be metal.
