I'm at the last stages of putting my CPL back together. The replacement Villiers magneto plate is producing a nice spark. However, it was as I was turning the flywheel by hand that I realised that it seemed just a little too easy to turn. As the piston came up, it didn't 'bounce' back if didn't get past TDC. The CPL still does have compression, but clearly not as much as the WSPCL next to it, which is very 'bouncy'. Should I have replaced the piston rings? I don't have a compression tester anymore, unfortunately.
It'll be a bit of pain to strip it back down again, but what else am I going to do with the motor.................
New piston rings?
Moderators: John@sos, charlesp, Charles uk, RickUK, Petergalileo
Re: New piston rings?
I kind of think you have answered your own question, I guess it depends what you want to do with the motor, if you want it good, solid and reliable you may have no choice than to check the bore and maybe fit a set of rings, if you just want to keep it maybe sell it I wouldn't bother, these motors suprised me as they run on such low compression so if it starts and runs ok it will probably do so for a little while longer. I have a couple of motors with low compression, they run well in the tank but would I trust and depend on them out at sea? No.
If you do fit rings I would give the bore a quick hone just to remove the glaze and clean up rhe surface, this makes a big difference to a rebuilt motor as it ultimately raises compression and evens out heat dissipation due to increased ring/bore contact, strange enough, not many people seem to do it.
Hope this helps some, Rene.
If you do fit rings I would give the bore a quick hone just to remove the glaze and clean up rhe surface, this makes a big difference to a rebuilt motor as it ultimately raises compression and evens out heat dissipation due to increased ring/bore contact, strange enough, not many people seem to do it.
Hope this helps some, Rene.
Re: New piston rings?
Well, I got a new pair of ex WD rings from John that took a good soak in petrol to get the grease off. I took the block off the crankcase, removed the old rings and put in the new. He advised that these rings may need to be gapped, but they fitted the bottom of the bore well enough so I just put them on. I did deglaze the bore with some 280 grit paper before putting it back together. The compression is better, just by feel, though I actually don't think the old ones were that bad.