FZRSupport: the FZROnline Archive

Jim with Wiseco was at the rack yesterday and we talked in length about why they have not given me the pistons and barrels as promised.

The reason is a technical one (Not a financial one) I wanted some in put on this.

I guess they can nto get a 2 ring set up but they can provide a piston with a single ring.

I asked the pros and cons which Jim stated he will send a white paper on that.

Basically he said for racing its fine I may need to replace the rings more often than I would on a duel ring piston.

Ok I am fien with that. its for a race bike not a srteet bike.

Just curious on other opinions and what they know about this issue.

prolly not enough room between the piston pin bore and the oil control ring to allow lands for two compression rings(and keep the upper ring a decent distance from the crown).

As they go up on piston bore size they need to keep the piston weight similar to the stock bore. This usually means they shave the skirts down in the area on the sides of the pistons ("slipper pistons"). And, the crown height usually gets reduced as compression increases rapidly as bore goes up. I've seen big bore Harley pistons (made by JE) which run the oil control ring through the top of the piston pin bore....is wiseco scared of that?

And, big bore "kits" usually depend on a flat land around the periphery 'cause the combustion chamber/head will have a huuuge squish band.

If it's the crown height/compression that is the concern and which is limiting ring space....can you ask that they allow you to enlarge your combustion chambers in order to allow them to keep the crown height up?

Single ring....not a bad thing. If they plan on selling those publically, they may find some resistance in street riders wanting them at all.

Ohh, and passalong for me my irritation at the prices Wiseco wants for their stuff

reelrazor wrote:prolly not enough room between the piston pin bore and the oil control ring to allow lands for two compression rings(and keep the upper ring a decent distance from the crown).

As they go up on piston bore size they need to keep the piston weight similar to the stock bore. This usually means they shave the skirts down in the area on the sides of the pistons ("slipper pistons"). And, the crown height usually gets reduced as compression increases rapidly as bore goes up. I've seen big bore Harley pistons (made by JE) which run the oil control ring through the top of the piston pin bore....is wiseco scared of that?

And, big bore "kits" usually depend on a flat land around the periphery 'cause the combustion chamber/head will have a huuuge squish band.

If it's the crown height/compression that is the concern and which is limiting ring space....can you ask that they allow you to enlarge your combustion chambers in order to allow them to keep the crown height up?

Single ring....not a bad thing. If they plan on selling those publically, they may find some resistance in street riders wanting them at all.

Ohh, and passalong for me my irritation at the prices Wiseco wants for their stuff

+5 on their pricing, that said:-
1} the matelurgy of their pistons is such that the boring & expansion limits are completly different to OEM.

2} The second ring thro the pin land is OK on very slow revving H_D's but for high reving Japanes bikes none too wise

3} to stop the excessive bearing wear they must keep the piston near OEM weight

4} the down side of 3 is that reduced piston height with just 1 ring allows the piston to rock in the bore at slow speeds & flutter at higher speeds.

5} on a multi piston engine the weight difference in piston + pin + ring has to be extremely close tolerence for obvious reasons

Wisco are afraid that their reputation will be on the line if ever their "race pistons" were smuggled on to a street bike without due care and attention by some squid & he ends up dead or sueing for a new engine.

yamaha_george wrote:+5 on their pricing, that said:-
1} the matelurgy of their pistons is such that the boring & expansion limits are completly different to OEM.

2} The second ring thro the pin land is OK on very slow revving H_D's but for high reving Japanes bikes none too wise

Umm, the maximum piston accelerations on a built HD engine are as high-if not higher than our FZR's. Four years ago, I built a 120 cubic inch HD twin cam usinga Zipper's kit. The engine produces 145hp at the rear wheel. Break-in redline was 5500 rpm. The ECU was then set to allow 8500rpm. At 8500....this combo has numbers of 5996.8 for a mean piston speed, 179,154 ft/sec2 max piston acceleration.....(comparision=FZR in stock trim at 11500rpm...has MPS of 4390.7 and MPA of 172.812ft/sec2).

That engine just got put to bed for the winter with 44000 miles since it was built. It has done a bunch of full tire long burnouts at redline(seriously-bouncing the rev limiter the whole time-like 10 minutes), has exploded two "race clutches" while drag racing (and hasn't been beat) and gets ONE oil change per season "whether it needs it or not".
It has pistons exactly as I described(made by JE)....oil control ring has a top land surface above the pin....no land on it's lower side in the area by the pin. It's skirts extend only about a half inch below the oil control ring(and have cut-outs on each piston's 'inner V' side so they don't collide at BDC.

3} to stop the excessive bearing wear they must keep the piston near OEM weight

4} the down side of 3 is that reduced piston height with just 1 ring allows the piston to rock in the bore at slow speeds & flutter at higher speeds.

5} on a multi piston engine the weight difference in piston + pin + ring has to be extremely close tolerence for obvious reasons

Wisco are afraid that their reputation will be on the line if ever their "race pistons" were smuggled on to a street bike without due care and attention by some & he ends up dead or sueing for a new engine.

I think it has to do more with Wiseco's quality control than anything.....they go back and forth between making excellent stuf, to barely capable and back to excellent in bouta five year cycle in my experience

RR,
@ 8.5 max out on the H-D, the FZR is hardly warming up hence my concerns.

I have used wisco stuff and as you say it is very hit & miss. I used them primarily in 2 stroke engines where the red line was 11.5 K + and all the warnings that went with those revs apply to 4 stroke reliability as well.

yamaha_george wrote:RR,
@ 8.5 max out on the H-D, the FZR is hardly warming up hence my concerns.

5996.8 FEET PER SECOND for a mean piston speed on the 120" harley @8.5k revs......4390.7fps for the FZR @11,5k revs...

179,154 ft/sec2 for maximum piston acceleration on the HD @8.5k revs.....172.812ft/sec2 on the FZR @11.5 k revs...


The math is pretty simple.....the HD is exceeding any possible piston acceleration/mean speed/bearing loading/material concern/construction issue than the FZR can possibly create....unless you were to take the rev celing of the FZR up to about 15,500rpm(and far before that point parts other than the pistons would become the limiting factor)

reelrazor wrote:

yamaha_george wrote:RR,
@ 8.5 max out on the H-D, the FZR is hardly warming up hence my concerns.

5996.8 FEET PER SECOND for a mean piston speed on the 120" harley @8.5k revs......4390.7fps for the FZR @11,5k revs...

179,154 ft/sec2 for maximum piston acceleration on the HD @8.5k revs.....172.812ft/sec2 on the FZR @11.5 k revs...


The math is pretty simple.....the HD is exceeding any possible piston acceleration/mean speed/bearing loading/material concern/construction issue than the FZR can possibly create....unless you were to take the rev celing of the FZR up to about 15,500rpm(and far before that point parts other than the pistons would become the limiting factor)

RR,
Sorry the meds are taking their toll today, missed the math bit entirely in the 1st message :-{