5hp chrome rings???

Fisher1983

Active Member
#1
Whats the deal with chrome rings for a Kool Bore 5hp? I was reading that they dont require a hone or deglazing. My 5hp has a nice bore, no ridge whatsoever at the top, but the last time I reassembled a Briggs that was this clean it smoked like a stack. Since the bore and piston are in great shape, I dont want to bore it. Anyone have a part number? Its a 1991 with the old style rings (1 piece oil ring.)
 
#2
What makes you think it needs reboring or new rings? When you say "nice bore" I am assuming that you mean no significant visible scoring. That is only PART of the story, however. The bore could still be worn oversize, tapered, out-of-round, or all of the above. The ONLY way to tell for sure is to take precise measurements of the bore at the top, middle, and bottom.
Michael
***Edit- "Chrome" rings are a band-aid repair to extend the lifespan of an engine that has lost power and compression and/or burning oil. It is actually a legitimate procedure to buy some more time and extend the use of the engine and postpone the inevitable which is an overbore with an O/S piston/ring set. My son and I have done it on a couple of Briggs 3 HPs and 5 HPs with good success. It works fairly well provided that the cylinder bore is still round (not tapered or out-of-round), and is just worn oversize only by not more than .005". The additional (wavy)"expander" rings installed behind the chrome piston rings push the rings toward the cylinder wall with more "bite". The part # for your engine is Briggs 299742. If you purchase them I would recommend OEM NOS Briggs only which are becoming hard to find.
 
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MB165

Active Member
#3
even if it looks good, most likely there is some excessive wear in the bore. unfortunately most all aluminum bores do. if you cant precision measure it try a new ring to check the end gap. compare it to factory specs and itll give you a good idea, check it in different areas of the bore, you will find some taper, with the lower part of the bore almost perfect and opening up towards the top. check the valves/ guides for wear and check the breather to see if its working properly, if it is smoking really bad it may be more than the piston/ cylinder causing it. if you can get ahold of one, do a leakdown check.
if you go as far as a rebore, they wear so fast its frustrating. I have tried different grit on the final hone operation. wear rate doesn't change, its just the fact that the aluminum is not optimal for a cylinder.....
 

Fisher1983

Active Member
#4
I spoke to a kart engine builder today and he said the same thing. He convinced me to sleeve the block and fit a Raptor piston in it so thats what im going to do. This engine has a nice looking bore...yes. I didnt measure anything yet. But as stated here, he said to sleeve it for racing/not stock chipper useage LOL! Doesnt matter the engine is lower hours....if Im this far into it might as well do it right, and its still less money than a Raptor block. Creia, what made me think chrome rings was wanting reassemble it with the stock bore and piston and have no chance of it smoking. But if aluminum bores wear that quickly too bad for me, Ill cough up and sleeve it. Furthermore, the iron bore runs with a closer piston to wall clearance leading to less piston rocking and longer bore life in the sleeve. He said closer clearance with a kool bore results in galling. Makes sense.
 
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