Hi guys, new to site and I am glad I found you folks. I have a question for the oracle here. I just rebuilt my Husky 55 with a HiWay piston and cylinder and I used the ring that came with it. After running the saw for about 4 hours this weekend, compression is 110 which sounds pretty low to me. The saw seems to run fine for my purposes (cutting deadfalls in my woods for firewood) but I was hoping for better compression. Had I done my homework properly, I would have installed a Caber ring. Should I go ahead and put one in at this point or just leave it alone?
Is your tester accurate? I would recommend caber rings If your tester is accurate, you should measure your squish clearance before you install new rings and end up with same results. Hope that helped
IIRC the Hyway Kits come with 'split groove ductile iron' rings which are known to take quite a while to seat. So you can wait or pull the jug and put a Caber in it, its' your choice. The corners of the Hyway ring top and bottom are square to the cylinder wall the Cabers have a radius. Some folks believe that the Cabers have less chance of hanging up on a port. I have used both and have never experienced this however that does not mean it cannot happen.
Cabers take a long time to break in also. I have seen compression just as high with the meteor rings as caber.
Thanks for the replies guys. I believe my tester is fairly accurate as its readings coincide with the gauge on my compressor. To further illustrate how much of a novice I am, I didn't know about squish until I read about it here. I will definitely check that. And, thanks for the explanation about the Caber rings. I was trying to determine why they are so well regarded.
Mike, Caber, I believe is a subsidiary of Meteor and all Meteor pistons come with Caber rings. Correct me if I am in error.
I think Randy Watson does that. I'm not positive on them being the same. They look a little different if I remember right. I have some extra cabers at home along with meteor pistons. I need to check them to see.
http://www.meteorpiston.com/default.aspx Check out the Meteor web site, it says that Meteor and Caber are one in the same. Caber makes rings from several types of materials MATERIALS • STD CAST IRON • I CAST IRON (GH. I.) • NODULAR CAST IRON (GH SF) • F CAST IRON (GH. F.) • L CAST IRON Not clear which type is used for gardening equipment. Further reading on the Meteor/Caber web site indicates that the F-Cast rings are specific to plated cylinders, contain no chrome.
Since F-Cast is the only ring Caber makes for a plated aluminum cylinder, I would think they do ship them with Meteor pistons for chainsaws. Reading further it appears that the other four types are for 4-stroke gas and diesel applications. Some internet sellers may make a big deal of 'giving' you Caber ring(s) for free when they actually come with the Meteor piston and you pay for them, know it or not.
Pull the muffler & look at the piston. If the Hyway wasn't chamfered at the ports it might have seized the ring. If you are using reformulated/alcohol gas that could seize the piston. 110psi is way too low, somethings wrong.
Thanks milw, I did pull the muffler. The piston and and the jug looked good as far as scoring go. The ring looked good and flexible as well. That's why I am concerned.
But the saw runs fine? My compression tester is basically 120 psi on my saws, rather useless aside from a go/ no go standpoint. Did you check your tester up to >150psi with your compressor? If yes, then start suspecting any adapters that aren't in line when checking against compressor. Maybe squirt some soapy water around the fittings while on the saw?
Couple things: Sometimes as a tester ages, the o-ring can get soft and blow out at pressures over 100psi. Testers without retaining grooves for the o-ring are especially prone to this. Also, if the Schrader valve for the tester is not located at the very end of the line, this will have a negative impact on your readings. Your gauge may be perfectly accurate relative to your compressor, but that does not mean your tester isn't adding volume to the combustion chamber and lowering the reading. Unless the saw is a total dog in the wood, something is up with your test readings. 120 psi on a good tester would be a very sluggish 55.
Good ideas - thanks guys. I will focus on my testing method. My old tester went fubar so when I was at Harbor Freight the other day I picked up one of theirs. I'll stop by at my friend's shop and use his. I can always use my HF tester for skeet practice if it turns out to be bad
I would do that Fred, as others have said they can read low....as I found out with a VW diesel many years ago. If you have a good accurate read at 110psi I would pull the jug & look for a cracked ring etc.
A ring that has lost tension will also give poor compression. If you pull the jug & everything looks ok the ring probably has failed. Put in a steel ring(or recommended one) like Caber or OEM & that should solve it in that case.
