Shortly my frywheel is damaged and now my hole engine is divided. I think about to built more cc and higher compression (12:1) on my engine. Can somebody say how much cc my stock crankshaft (+ carrillo rod) is still working and not damaged?
Is 760 cc bigbore and 12:1 to much for stock crankshaft or other oem parts?
Thanks!

 

Personally I wouldn't go any larger than the 727 kit unless you are building an all out drag bike. Its always a good idea to strengthen up the bottom end with all that money up top. And don't run a 12:1 ratio unless you want to spend the extra cash to run race gas all the time. Get in touch with Craycraft Racing and talk to them. They'll hook you up with some sweet ****..

 

He's in Germany, dont think Bob will be handling this one...

A 730 is as big as you can get on bore alone (105.5mm piston I believe), 760 requires a stroke (I want to say that's 4mm but dont know off hand). I've seen as big as 800, its certainly possible to go big.

The problem is reliability. The thinner the cylinder walls, the more likely they'll fail. The more hp you make, the more often you have to replace everything. The carillo will handle a bigger bore and stroke, its pretty solid. If you want to go bigger bore, go ahead and jump to a 105mm piston (727cc). If you want to stroke a few more mm into it at the same time, just understand it wont be as reliable or rideable on the whole. Big, big change in the feeling of a 686 to a stroked big bore.

 

OOPS.. I didn't even notice that he was in Germany. Sorry about that.

 

to add to that, putting more performance in one place will show you where the weak spots are. It's always good to try and evanly spread the upgrades, if you go more cc's you will need better intake and exhaust systems, then your looking at a better clutch and drive train. Just try to think of how much will be affected, and make sure to a LA design oneway bearing if you go up in compression.

 

Look at this link! That is possible here in germany.

http://www.gw-racing-parts.de/german.../Produkte.html
than click on "yamaha" > search on the right > "Yamaha Raptor-Grizzly 660" and you can look "yamaha" > search on the right > "Yamaha XTZ 660-5V" (it´s the same engine on motobike)

Is it rideable when I built a 727cc 105mm 12:1 and a stroke on the same time? Because of that the cylinder walls are big enough for a rideable engine and the stroke is stronger than stock plus more cc. Is that right?

GW-racing-parts offered to me that I can built 727cc 105mm 12:1, a long carrillo rod and a lower je piston 105mm. Is this the same effect of stroke?

 

A long-rod isnt the same as a stroker, there is no displacement increase. I've seen it in banshees, not so much in four strokes.

What are you doing with this bike? Is it a race machine, transportation, recreational bike, just playing around? Because what you use it for is going to determine how reliable it needs to be, and at what point it would no longer be comfortable to ride.

 

I drive only on the street and in the summer sometimes the 1/4 mile race. Only that!!!
What shall I do?

 

Craycraft Racing has done international Raptor work before.