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TOPIC: Aftermarket piston rings

Aftermarket piston rings 9 months 3 weeks ago #21746

  • StanG
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Kawasaki KZ1300 original stock top ring with bevel and the second ring with regular rectangular profile. (old used rings)

1982 Kawasaki KZ1300 A4
1981 Kawasaki KZ1300 A3
assembling engine, chassis & electrical from 79 - 89 parts
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Aftermarket piston rings 9 months 3 weeks ago #21748

  • Frank833
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My best guess is the bevel on the top ring is to reduce break-in time. It will provide slightly less drag, but if that was Kawi's intention, they would have either reduced the ring to 0.8mm OR done the same to the second ring.

The second ring will break-in easier since it does not have the chrome plating.

I would not worry about the bevel, and would just assume it will take a bit more riding to seat it.

For anyone concerned about their top ring not being chrome, this is a good read: hastings-piston-ring-set-composition-recommendations

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Aftermarket piston rings 9 months 3 weeks ago #21750

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There is another source for pistons (oversized) and rings (standard size). That is IMDPistons. There seems to be something up with their website at the moment. But you can contact Adrian Wright via:

Mill Farm, Beeston, Tarporley, Cheshire, CW6 9NJ
UK 01829 261641
Overseas 0044 1829 261641
This email address is being protected from spambots. You need JavaScript enabled to view it.

Their KZ650 pistons are sold by some vendors (in sets of 6) for KZ1300. Adrian tells me he has KZ1300 and ZN1300 standard ring sets in stock.

They have an eBay Store as well. Rings and pistons are a good bit more than the Crusin Image ones...

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Last edit: by Frank833.

Aftermarket piston rings 9 months 3 weeks ago #21751

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Just read the last article. A couple of excerpts:

"For typical light duty service where the vehicle Is not subjected to long periods of high speed or load operation and is run primarily on paved streets, plain cast iron is a good choice"

"When faced with continuous high speed or severe load conditions, the engine will be subjected to long periods of high temperatures. Moly is then a good choice because of its scuff resistance."

"In a dusty environment such as gravel pits, sand or rock mines, or operating on a dirt or unpaved roads, chrome is the best choice."


Now a quote from another one:

"Cylinder pressure forces the rings down in their grooves and, because of side clearance, gets behind the rings and forces them out against the cylinder wall. The top ring benefits the most, as there is much less cylinder pressure present at the second ring."

"Usually, the rings are bevel-cut to promote twisting. The top ring is often beveled on its top inside edge, which causes positive twist. That pushes the lower inside edge against the ring groove and creates an oil seal, while also allowing cylinder pressure to get behind the ring. The bevel of the second ring is machined in the lower inside edge to create negative twist and press the lower outside edge of the ring face against the cylinder wall for oil-scraping."

"The barrel face of the top ring is slightly curved, resulting in a very narrow contact point between the ring and the cylinder wall. Because the outward pressure on the ring is concentrated on a small area, the seal is tighter. The barrel-shaped face also allows the ring to maintain a proper seal as it rocks in its groove when the piston changes direction. As an added bonus, the barrel-face adapts easily to the cylinder wall during break-in and is able to maintain a positive seal as it wears."

My thoughts....

For both top and second identical rings, which basically would be the top ring shaped like the second ring.
The second ring is more porous for better oil distribution, the top is tapered for better seal against the combustion chamber (more pressure active surface less contact surface) during intake and combustion cycles, and metal treated for durability.

I guess cruising around on weekend in summer would fall in that 'typical light duty' category. I guess that would be around town and going to a park? While not off road usually and not racing, these 'muscle' bikes would be ridden harder than a moped, and extra stressed with load pulling all that weight wherever they go. Touring in mountains or countryside would go through dusty roads. Plus, these bikes have a general opinion of running hot. I'd say if installing a turbo in one of these, the engine would definitely appreciate those proper expensive rings.
1982 Kawasaki KZ1300 A4
1981 Kawasaki KZ1300 A3
assembling engine, chassis & electrical from 79 - 89 parts

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Aftermarket piston rings 9 months 3 weeks ago #21752

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1982 Kawasaki KZ1300 A4
1981 Kawasaki KZ1300 A3
assembling engine, chassis & electrical from 79 - 89 parts

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Aftermarket piston rings 9 months 3 weeks ago #21753

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I see Frank - IMD, that's the same company. You were a millisecond faster to post! haha

Final quote:

"All in-all when the engine experiences normal driving conditions and is properly maintained with respect to oil and air filter changes, any of the three coatings functions equally well. It is the installer's expert judgement in analyzing the primary use of the engine that should lead him in a direction of which ring set will be the best possible choice for that particular customer's engine."

With all the info, I guess we all will draw our own conclusion and perhaps there is no one ideal solution. I am leaning towards those beveled and chrome treated rings, when available.
1982 Kawasaki KZ1300 A4
1981 Kawasaki KZ1300 A3
assembling engine, chassis & electrical from 79 - 89 parts

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