OK, this might sound a little half baked...
Sportbike pistons.
In five minutes I was able to find a dozen late model bikes that have either 75mm, 75.5mm or 76mm bore.
What I do know is that they are light weight (6ounces - CBR 954), pin is quite high (for better r/s), forged, typically flat top with no "dome".
Found some '97 gixxer pistons used for $75 for four pistons and pins.
Don't know the pin size or compression height. Pinsize could be fixed with some rod bushings.
Anyone have any specs on bike engines?
Any opinions?

 

this seems interesting. waiting for an educated reply also

 

Bump, bump, bump...

 

bump

 

i kinda want to know too. bumb for the D series

 

well it is a very interesting idea....but there are a few things that may not work

1. pin height.....to high or to low....to high could cause piston to not go up far enough, and to low could cause the piston to come out of the head at TDC...

2. number of valves, personaly i dont know anything about bikes yet soo....say its a 2 valve per cylinder, the pistons may not have the right valve recesses on top, if they have any at all....and depending on the pin height, do they need them?


a friend of mine and i were going over something like this when we wanted to make a b16 into an ls/vtec but we realized the deckheights(b16 is shorter than all other bseries) to stroke would cause a 6mm total difference in stroke, so 3mm each direction. Meaning that if the pin height was maintained from the b16 or Ls then the piston would go 3mm out of the block at TDC so we have to see if SRP(or another piston company) can make a honda piston with a pin height 3mm higher. But honda Pin heights are already pretty high....soo.

you see there is alot of variables, but you probably already know that....

maybe if the bore size is the same and you can get the pin height the same it would work....i would like to see it, its always fun to use something alittle out of the norm....its how new technology is started


[Modified by pornstarSR, 11:51 PM 1/29/2003]


[Modified by pornstarSR, 11:52 PM 1/29/2003]


[Modified by pornstarSR, 11:53 PM 1/29/2003]

 

Thanks for the response, pornstarSR...
The reason I was postng this up here was to gather a little info on sportbike pistons, such as pin height, pin size, and compression height.
As for the valves, late model sport bikes are a 4-valve head, with the exception of Yamahas (5-valve). But you're right, they may require a little massaging.
A little added info for you...
I was on the JE site yesterday and compared some weights. 81mm Suzook piston - 220grams, 81mm B-Series piston - 280grams.
Switching to these things, you would save half a pound off of the pistons alone. Half a pound is a lot at 9000rpm.
The more I look into it, the more I love the idea...need some specs!! Any specs!!

 

Are these street bike piston options press fit or circlip secured (free-floating) wrist pins? using bushings in press fit applications is not the best route as the bushing can rotate in its bore on the small end of the rod, which, in turn, induces alot of stress on the surrounding area on the small end of the rod. Incidently, this is why i don't favor using rebushed LS rods in dseries applications.




[Modified by GTI 1.8t, 4:49 PM 1/31/2003]

 

Thats a good question...I haven't had a chance to pick any pistons up yet.
I've never wrenched on a sportbike, so I don't have an answer.
I could only assume that an engine in that state of tune would be full floating.

 

Alright, the project has started. Picked up a d15 last night. Time to start hunting for the pistons.
The aim is a r/s ratio that is as high as possible without a deck plate, ITBs, rollerized valve train. Only going for revs on this thing. Probably won't have the torque to break out of a wet paper bag, know where I can get a 6:1 final drive?

 

well if you want to get all crazy....try swaping a 96-98 d16y8 head onto it....play with the R/S ratio.....see if you can track down 2 intake rocker arm assemblies from a 96-98 civic HX....they are the ultra fuel economy version with vtec only on the intake lobes....but the rocker arm assembly for that side is rollers from the factory.....maybe you can just use it on both intake and exhaust..... Something i have been thinking about....cause that would be pretty cool...and pretty cheap probably.

not trying to make things even more complicated but hey thats why we build these 4 cylinders right!!!

ok are you gona use the same crank from the d15???

whats the exact engine code...i can get bore and stroke numbers off of my Specs program at the shop....


about the final drive....you got to speak in a different language for hondas.....

like something that gets you about 70mph in 5th gear on the freeway at like 5-6 grand is a 4.9 final drive.....

what people also use is a 4.785 either one of those is made by a company called ATS i believe and also i think KAAZ has a few....for single cams too i think




[Modified by pornstarSR, 11:14 PM 1/31/2003]

 

ohh the other bitchen thing that people are doin now....is Skirtless pistons....

weisco or endyne is doing it now.....honda S2000 come stock with a skirtless piston....

something else to think about

high revs no skirt....sounds like a **** movie...sounds good to mee

less friction


[Modified by pornstarSR, 11:16 PM 1/31/2003]

 

there are 12 hx rollers per head, so if they line up corectly you could have a roller rocker assembly...but you'd need 2 sets of the rollers...dunno but the exhaust may fit in place of the one rocker which is only used to create the cvcc effect

 

Thanks for the feedback guys.
I dunno, I thought the HX rockers were totally different.
I'm thinking these bike pistons are skirtless in addition to the pin being quite high up under the ring pack. Probably find the ring pack fairly close to the crown as well.
Yup, will use the D15 crank. Going lightweight on the piston and rods, gonna balance the crap out of the crank, and spin it high.
This is a N/A project, I think the crank will stand up.

 

welp i just got my camshaft today i'll try popping in the hx rollers when i put in my camshaft