Yosh Race Pistons: 2V 1000?

[dardoonk]

Good thought on the copies, even if I had them add a third ring. Sure, it'd be nice to have some brand new. lightweight pistons in there, but the whole point of buying these was to see if I could snag a deal. If they're nice and For $50 bucks, I should be able to spend a little extra on pins, rings & clips & still be under the cost of a Wiseco kit & get maybe another 1 point in cr. I called the tech guy at Total Seal today & explained what I dealing with having only 2 rings. Basically, he told me not to sweat it, keep my tolerances on the tight side & they can hook me up with the correct rings after I get them the measurements... Hopefully it works out better pricewise than a Wiseco kit for $429.

Ray, just so I know, whats the plus side for the added $250 I'd be looking at on the CP kit? Obviously, you could offer a higher cr than Wiseco, but other than that, can you offer some comparison? If my bargain yosh replica's fall thru, I want to be able to consider all my options.

[rapidray]

The CPs are a better forging, better alloy aluminum, WAAAAYYYY tighter tolerances in the machining, narrower wrist pins so the PINS are lighter too, better pins, newer better ring style, anti-detonation grooves, lateral gas porting, & the pistons are lighter just due to the design shape & live longer & make more power! To me, for the $250.00 more to get 30 YEARS of better technology, it's a no brainer. If you can get a set of good, usable pistons for 50 bucks, go for it. Are the correct length pins available? Do they have an old style, DISCONTINUED ring groove sizing? Are the skirts collapsed? Two ring design pistons are designed strictly for RACING, not street use! They use a low tension ring set to reduce drag to free up power but on the street don't seal well for sustained mileage use. They were designed to be changed often. Do you want to replace rings often on a street motor. I know yours are a 3 ring design but I want others to know the purpose of 2 ring design pistons. My point is, used pistons are a crap shoot at best. If you get lucky & they are usable, they are still ancient in engineering respects. Way more power & durability is available with the new piston designs. Wisecos are still old design & heavy. Custom made & lighter pistons will make more power & your engine will live longer due to less weight reciprocating around inside. Ray.

[Tarbash 27]

How do these CP's compare compression wise to the wiseco's? What size are they?

[dardoonk]

So, If I wanted 73.5mm pistons an 11.25:1 cr cut for 1mm os valves, or say, I wanted the largest piston I could get into a stock block (bored and sleeved of course), then you could whip up a set of 76 or 77mm pistons with a 9.5:1 cr for our bikes? (or whatever it was that fit)

Basically all a custom deal?

[rapidray]

73.5 I don't know if rings are made for as it's an odd size but I KNOW I can get 83.5 rings because I have a set right now. All of your other questions, YES! Ray.

[49er]

The CPs are a better forging, better alloy aluminum, WAAAAYYYY tighter tolerances in the machining, narrower wrist pins so the PINS are lighter too, better pins, newer better ring style, anti-detonation grooves, lateral gas porting, & the pistons are lighter just due to the design shape & live longer & make more power! To me, for the $250.00 more to get 30 YEARS of better technology, it's a no brainer. If you can get a set of good, usable pistons for 50 bucks, go for it. Are the correct length pins available? Do they have an old style, DISCONTINUED ring groove sizing? Are the skirts collapsed? Two ring design pistons are designed strictly for RACING, not street use! They use a low tension ring set to reduce drag to free up power but on the street don't seal well for sustained mileage use. They were designed to be changed often. Do you want to replace rings often on a street motor. I know yours are a 3 ring design but I want others to know the purpose of 2 ring design pistons. My point is, used pistons are a crap shoot at best. If you get lucky & they are usable, they are still ancient in engineering respects. Way more power & durability is available with the new piston designs. Wisecos are still old design & heavy. Custom made & lighter pistons will make more power & your engine will live longer due to less weight reciprocating around inside. Ray.

Take heed guys. Ray is right. The modern forged ali pistons are superior to our 30 year old technology. Custom pistons, be they CP's , JE's and some others are lighter, stronger and more durable than OEM and Wiseco.
JE produced my pistons 2mm OS and at 10.5-1 CR to within 11 grams of my stock pistons (198 grams). Their piston pins weighed 9 grams heavier than the stock ones. You could have fitted them to a diesel piston. They were designed to run with pistons of varying CRs, probably up to 15-1. I replaced them with new stock pins and ground them back to match the circlip clearances. Saved 11 grams against the JE pin weight, leaving less metal removal off the pistons. The end result was a set of oversized pistons that were exactly the same weight as the stock 850 ones. The stock ones are a very light design anyway.

If you want an increase in performance with reliability, don't risk running second hand, high CR pistons.

[Billy Ricks]

A little off-topic, but here is a photo of one of my Cosworths I intend to use one day. I had a tough time sourcing rings for them so I sent the set to Total Seal and they recut the grooves to accept a set of their Gapless rings.

[rapidray]

What bore size are those Billy? I have a set of Cosworths also, BRAND NEW, flat tops, 80 mm bore, 18 mm pins for 16 valve. Ray.

[dardoonk]

A little off-topic, but here is a photo of one of my Cosworths I intend to use one day. I had a tough time sourcing rings for them so I sent the set to Total Seal and they recut the grooves to accept a set of their Gapless rings.

Good thought. I might have to consider talking to them about that on my "FleaBay, I sure hope they work" pistons

[Billy Ricks]

What bore size are those Billy? I have a set of Cosworths also, BRAND NEW, flat tops, 80 mm bore, 18 mm pins for 16 valve. Ray.

They are for a 700/750. 67mm with a .05 overbore. Not a typo there, .05mm. I got my set from Britt Turkington who had his engines built by Kelly Roberts back in the '80s. Kelly had the distributorship for Cosworth at the time. He had a few other sets at one time, not sure if he still has any or not. They were doing some pretty crazy stuff to the engines Britt roadraced. Center bored cams to lighten the valve train was just one of Kelly's tricks.

BTW Ray, I have two blocks with one liner missing in one and another with a busted liner skirt. I need to have one of the blocks made whole and probably nothing more than a clean-up to meet piston specs. Would you be interested in doing the work?

[rapidray]

PM me your # Billy & I'll give you a call. Ray.

[Big Jay]

One of the problems with these older pistons is rings. All of that old stuff used very wide rings. They are no longer available. Total Seal doesn't even have them. The guys over on the KZ boards just went through this.

We had a new set of Yosh GS pistons in house last month to have the block bored. I remember thinking "Hope this guy doesn't break a ring while putting this together".

Back in the beginning of this big bore thing, we had to build the pistons around existing piston rings.

If my memory serves me correctly, the 73 mm rings were Honda GL1000 Goldwing 4th over. Anyone with these old cast 1085s that can't find rings might want to try the Honda dealer.

Jay

[first timer]

One of the problems with these older pistons is rings. All of that old stuff used very wide rings. They are no longer available. Total Seal doesn't even have them. The guys over on the KZ boards just went through this.

We had a new set of Yosh GS pistons in house last month to have the block bored. I remember thinking "Hope this guy doesn't break a ring while putting this together".

Back in the beginning of this big bore thing, we had to build the pistons around existing piston rings.

If my memory serves me correctly, the 73 mm rings were Honda GL1000 Goldwing 4th over. Anyone with these old cast 1085s that can't find rings might want to try the Honda dealer.

Jay

thanks for the tip Jay, I'll be carefull installing my rings.

Could you have total seal recut your pistons for fit newer rings?

[Billy Ricks]

thanks for the tip Jay, I'll be carefull installing my rings.

Could you have total seal recut your pistons for fit newer rings?

It depends on the width of the grooves now. The Cosworths I have are new and never used. They had narrow grooves and Total Seal was able to recut and set me up with a set of their patented Gapless rings. The compression ring is actually two rings that you set the gaps up 180 apart to virtually eliminate leakdown past the rings. I don't know if he still works for Total Seal but I spoke to a guy named Ed Law when I had my pistons done by them probably 8 years ago. You might call Total Seal and see if Ed still manages the shop.

[first timer]

Yeah my pistons are the ones Jay talked about and are brand new with rings. I just wanted to know what my options were encase i did have to replace my rings. You think if i sent them a set of my rings (brand new) they could copy them? Maybe I'll give TS a call just to chat with them and see what can be done. I'll just be extra carefull installing the cylinder for now