Kawi2strokes.com Forum

This beautiful piece just returned from a trip to southern england.
Notice the choice in bearings.

PK

Polyamide cages and C4 clearance... Better longevity?

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http://kawatriple.com/wtf/

Yep ...the work of H2CHRIS is beyond reproach.

Higher tolerance for overreving.
One missed shift can be enough to destroy a steel caged bearing.
It's more about the polyamide cage than the clearance, however, this combination seem to be the most common in modern 2-strokes (KTM, Cagiva etc...).

PK

Good to know, thanks!

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http://kawatriple.com/wtf/

Anything special with the installed rod bearings? (The stock non silver plated needle cages have been reported to break above about 10,500rpm).

Steel main bearing cages can spot weld a pit on the ball, usually as a result of free acceleration combined with high rpm (missed shift). With time the pit then turns to a crater and bearing failure results. I suspect most main bearing/cage failures start from a corrosion pit (rust).

Why did you choose rubber seals? (It seems lab seals are all the rage these days)..

J

Don't know anything about the rod bearings other than all parts are new.
I prefer Vesrah rod kits over Toko. According to Chris these are named Long (hopefully they are std length ).

What you say about bearing failure is pretty much the same Leo is preaching.
According to SKF; polyamide caged bearings are specially suitable for applications where there are high acceleration, as in very rapid RPM changes.

The biggest enemy of rubber seals are aging. I never had a crank that lasted more than 4 years and I'm doing approximately 6000 miles per year.
So I figured the rubber seals would outlast other parts of the crank.

PK

When we used to spin the TZ engines past 13,000 rpms, especially the 700/750, we used to fracture the steel ball guides, so, I used to use these plastic ball guides, subbed them into the Japanese bearings, taken from the FAG/Norma and SKF bearings they came in, and I reused them for years, as they never wore out, nor fractured.

I think all the TZ's, and Kawasaki racers/street bikes I have that I have done the cranks for, have these guides in them, along with all the transmission ball bearings as well. I've been using these guides since the very late 1970's. Good stuff.

Sweet Chris made my main seals for my crank as they are very top knotch and thanks again for making them.

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Comfortably Numb )