Cafe Racer Forum banner

1 - 20 of 39 Posts

·
Registered
Joined
·
1,426 Posts
Discussion Starter #1
anyone care to make a judgement on whether or not it's okay to rering a stock engine with .25 oversize rings and file them down to basically stock size to run a tighter ring gap for better compression? I've been told this is a good idea on race motors, but for a stocker it will cause irregular wear on the cylinders and will cause problems over time (not a big deal for racing, but a big deal for a street bike)
 

·
Registered
Joined
·
3,086 Posts
Since you have a motor that is easy to get spares for, I'd try to find the right size first. I don't think I'd ever run the wrong size rings on the track. They are not super flexible, squeezing in is as bad as spreading out. I've cracked them during installation being very careful. I'd find the right size for the bore, or go up on the bore if it's between sizes.
 

·
Registered
Joined
·
3,086 Posts
Since you have a motor that is easy to get spares for, I'd try to find the right size first. I don't think I'd ever run the wrong size rings on the track. They are not super flexible, squeezing in is as bad as spreading out. I've cracked them during installation being very careful. I'd find the right size for the bore, or go up on the bore if it's between sizes.
 

·
Registered
Joined
·
3,475 Posts
It's different with a 4" bore and wide rings.
I imagine trying to 'file to fit' 3 piece oil rings on a CB360/350 is going to be difficult?
 

·
Registered
Joined
·
3,475 Posts
It's different with a 4" bore and wide rings.
I imagine trying to 'file to fit' 3 piece oil rings on a CB360/350 is going to be difficult?
 

·
Registered
Joined
·
4,721 Posts
If the rings that are actually for your bore size don't require filing to obtain a SAFE gap....

they are probably crap anyhow


lemme give ya a million dollar clue


Total Seal Gapless second ring and top if likely available....


Do you understand why conventional rings must have an adequate gap? My guess is you do not or you'd realize it's more important on a race engine.
 

·
Registered
Joined
·
4,721 Posts
If the rings that are actually for your bore size don't require filing to obtain a SAFE gap....

they are probably crap anyhow


lemme give ya a million dollar clue


Total Seal Gapless second ring and top if likely available....


Do you understand why conventional rings must have an adequate gap? My guess is you do not or you'd realize it's more important on a race engine.
 

·
Registered
Joined
·
1,426 Posts
Discussion Starter #8
i was planning on filing to the lower clearance spec per the shop manual, pj's right, the rings I got were probably crap and too loose. I do understand the different expansion rates of the cylinder, piston and rings...

I looked at total seal's design, it's really genius, the article they wrote up on the dyno seems the proof is in the pudding, I'll have to see if they have rings to fit the 350
 

·
Registered
Joined
·
1,426 Posts
Discussion Starter #9
i was planning on filing to the lower clearance spec per the shop manual, pj's right, the rings I got were probably crap and too loose. I do understand the different expansion rates of the cylinder, piston and rings...

I looked at total seal's design, it's really genius, the article they wrote up on the dyno seems the proof is in the pudding, I'll have to see if they have rings to fit the 350
 

·
Registered
Joined
·
681 Posts
I've heard some people praise Total Seal gapless rings, and others pan them. One of these days I'll get a set for my mini...
 

·
Registered
Joined
·
681 Posts
I've heard some people praise Total Seal gapless rings, and others pan them. One of these days I'll get a set for my mini...
 

·
Registered
Joined
·
4,721 Posts
I've run them currently in two engines and have built several using them. Old engines love them.

Next clue.....

Dial bore gauge and learn how to use it.....

ya really gotta have virtually error free cylnders not only with respect to being a near perfect cylinder.... but also with respect to how it's located with respect to the rod, its journal and those of the crank as well

They aren't cheap.
 

·
Registered
Joined
·
4,721 Posts
I've run them currently in two engines and have built several using them. Old engines love them.

Next clue.....

Dial bore gauge and learn how to use it.....

ya really gotta have virtually error free cylnders not only with respect to being a near perfect cylinder.... but also with respect to how it's located with respect to the rod, its journal and those of the crank as well

They aren't cheap.
 

·
Registered
Joined
·
681 Posts
Because of how my cases were tweaked to get a 60mm bore between the studs, my bore centerline does not pass through the axis of the crank, but is shifted down by nearly 2mm. Does this make my motor a poor candidate for gapless rings?
 

·
Registered
Joined
·
681 Posts
Because of how my cases were tweaked to get a 60mm bore between the studs, my bore centerline does not pass through the axis of the crank, but is shifted down by nearly 2mm. Does this make my motor a poor candidate for gapless rings?
 

·
Registered
Joined
·
4,721 Posts
Not enough data.... by a long shot

to render an opinion.

How about some rough sketches with all vital dims.

So the bore is 0.080" to one side of the rod journal center and everything else is perfect?
 

·
Registered
Joined
·
4,721 Posts
Not enough data.... by a long shot

to render an opinion.

How about some rough sketches with all vital dims.

So the bore is 0.080" to one side of the rod journal center and everything else is perfect?
 

·
Registered
Joined
·
681 Posts
When I get my hands on the appropriate measuring gear again I'll sketch it up and start a new thread. My bore itself was true when assembled, but other than knowing it's 2mm off center I can't verify for certain the exact alignment of the bore to the crank. When I looked into the rammifications before all I came across was increased wear on one piston skirt, reduced wear on the other, the motor would tend to act like a long rod going up and a short rod going down, not that the amount of offset I'm at would be enough of a change that I could feel AFAIK. Never considered how it'd affect the rings.
 

·
Registered
Joined
·
681 Posts
When I get my hands on the appropriate measuring gear again I'll sketch it up and start a new thread. My bore itself was true when assembled, but other than knowing it's 2mm off center I can't verify for certain the exact alignment of the bore to the crank. When I looked into the rammifications before all I came across was increased wear on one piston skirt, reduced wear on the other, the motor would tend to act like a long rod going up and a short rod going down, not that the amount of offset I'm at would be enough of a change that I could feel AFAIK. Never considered how it'd affect the rings.
 

·
Registered
Joined
·
4,721 Posts
So its not offset to the center of the rod journal....


But actually offset fore or aft of the main journal centerlines?
 
1 - 20 of 39 Posts
Top