Crank Question?? BAD WEEKEND!!

[screaminta]

So this weekend I went out riding and had a great day of riding was a little cool (about 20 degress!!) but the bike was running great!! On the way home, all of a sudden there was a loud screeching noise and then complete lock up!! The cylinder was locked up beyond the point of forcing the kicker or try to put it in gear and moving it.. I was worried that it went lean and heat seized. Long story short, i went home and tore her down, the only good thing was that it wasnt a lean condition, but the big rod bearing in the crank blew apart and seized up. When this happened the bearing bits came up through the ports and tore apart my new ESR310 top end!!! So yes I am a little upset. Anyway I am going to go ahead and redo the entire motor obviously and have one question. On the ESR website it says that with a long rod crank (thats what Im going with new from honda) you have to use a spacer plate with their pro-x cylinder?? I dont understand this because if I use the long rod crank and a 87-89 piston wouldn't that be fine? The only reason I could think of is if all the Big Borepistons were '86 style? Can anyone clarify this?.........BTW those little bearing bits did a number on the wiseco piston I had in there!!!!! I wish I could get you guys some pics!!!! thanks

[number5]

Look like this.

[number5]

And this?

[number5]

I was wide open in 4th racing when this happen. So I just rebuilt my engine with the $99 bearing and seal kit of ebay and a hot rod crank. Broke it in and it runs like a brand new motor. Going to see how long this lasts with cheap parts. I have about 5 more races left so I will let yall know.

[screaminta]

Are you sure that you just didn't take pics of my engine!!! Thats exactly what it looks like, my piston may be a bit worse though and it still has some bits of bearing inbedded iin it haha (its now a paperweight on my desk at work!!) Thing that stinks is that I need to get the cylinder bored and that puts me on the last bore for a 310 (73.5mm) Any word on the crank? I really want an oem crank without a doubt because I want this next motor to last a long time!!!

[Aceman]

Big bore pistons are all 86 style as far as I know.

I'm curious about your crank though. How fresh was it when you put the new topend on it? Did you stick a feeler gauge down there and check the rod side clearance every time you bored it? What's your premix ratio?

[skyhighatv]

whats with the dome being cut like that?

[screaminta]

My premix ratio is 40:1 with amsoil dominator and VP C12 Fuel. The last time I put a topend on it the rod was a little loose, but I wanted to go riding that weekend, so I threw it all together, but that was about 6 months to a year ago. I guess I had it coming knowing that it had some play. Anyway, so is this true that all the big bore pistons are 86 style? thanks

[number5]

Originally posted by skyhighatv
whats with the dome being cut like that?


Gives ya like .027 hp. I dont know I guess the theory is with the velocity of the fuel going mach 1.9 its going to have time to cork screw into the plug to give it one last little whirl. I did have a big bore cylinder and I think thats just a little more weight my crank doesnt need on the lower bearing. My 68mm bore ported out seems to be very close to the 295 if not the same. So for the money and reliability I asked myself do I really need it?

[screaminta]

on the nacs website it says that 87-89 style are available in a 73.5mm bore. If this is true would I be able to run this setup with no spacer plate?

[C-LEIGH RACING]

Originally posted by screaminta
on the nacs website it says that 87-89 style are available in a 73.5mm bore. If this is true would I be able to run this setup with no spacer plate?

If the intake side of the cylinders not opened up to wide you can, the big oval hole in front of the reed.
The 87/88/89 model pistons have a full skirt on the intake side so when you bore it in you need a good tight piston to cylinder clearance.
Somewhere around 0.0025 would be ok with a good intence break in time. after the INTENCE break in time is finished & with it set up that tight, run it rich & warm it up real good before you do any riding at all, dont just crank her up & blast off or ELSE.
I've used the late model pistons in the Pro-x cylinders before, but you dont want it flopping around in the cylinder.
Neil

[screaminta]

Hey thanks c-leigh thanks for the reply I guess I am going to go with a spacer plate setup then.. I also left you a message on the "other" forum. I was wondering what the lead time was for a new bore and hone job? Also maybe a new port job...(while im in there i may as well do it right haha!!))

[skyhighatv]

i agree with you 100% . my old ported stock 68mm bore cylinder was just as powerful as the unported 295 i have now,im hoping when i have a little extra cash around i can have neil port it and see some gains.

[number5]

My next top end I will open it up a bit more and show pics.