Plain bearing big ends

[Craig in France]

The article I mentioned in an earlier post is on this site. Go to articles index and scroll down to Kevins Bevel Article. It is full of good info about cranks and other stuff.

Thanks for the link wdietz186. I haven't heard of this (oil starvation caused by poor return flow) being touted as a possible cause, but I can see the sense in Axtell's observation and Kevin Bracken's remedy.

Like he says, "Roller cranks need oil volume."

Good.

Cheers,

Craig

[BevelDave]

I think the reason the roller big ends fail is because of the lack of proper filtration. Most Jap bikes have a paper filter after the pump that filters ALL the oil to the crank and cams. 1970's Kawasaki's changed quite a bit from roller to plain and back to roller. They tend to believe that their roller cranks are "indestructible" compared to the plain bearing cranks, the problem with them being the oil pump with such a low pressure.
Dave

[rwhc80]

Interesting read guys,
So if oil feed and flow are critical to the roller end, surely these can be rectified on the bevel engine ? flow could be restricted to non critical points, gearing can be changed for volume and flow and couldn't the line to the almost useless bypass filter be re-routed to have full flow filtration ?

Any thoughts guys ? or am I wavering in la la land ? would be nice to think a remedy could be found other than a major and costly plain bearing conversion.

Cheers
Rick

[Craig in France]

Interesting read guys,
So if oil feed and flow are critical to the roller end, surely these can be rectified on the bevel engine ? <snip>
Cheers
Rick

Yeh, Rick. If I read it right, this is essentially what Kevin Bracken's mods achieved. Here's the link, http://www.ducatimeccanica.com/kevin_race_engine.html

Ing. Taglioni also did it - on the Mille. Took a bit more re-engineering, mind .

Ciao

Craig