How reliable is the late model Raptor 660 engine with a 105mm bore and 10.5:1 piston? This would actually be a big bore project for a Yamaha Rhino, with an LA Sleeve 105 mm sleeve (installed by LA Sleeve), and would be combined with a low RPM torque cam. The engine would not be seeing a lot of RPM, but rather, would be a torque motor for chugging around in the Rhino, with hopefully better ability to turn the 27" tires. Thanks.

DV.

 

Way to many variables. Plenty have been running a long time on low compression setups but with upgraded rods. Try to saty as light as you can on the piston. Why not use a liittle higher compression? We have run 93 octane in some 12.5 (rated) pistoned raptors with no preignition trouble.
Not sure if the cranks are the same but Hot rods has an inexpensive stroker set up w/102mm bore. Barker makes a crank/rod setup that will work with off the shelf pistons of any size. A +4 stroke with the 105mm will yield 760. That with a stage 1 cam should yield some very good tourque. Try Craycraft racing. Bob has alot of 105mm piston options as well as info on the stroker cranks.

 

The end of the crankshaft where the clutch bolts on is different on the Raptor than it is on a Grizzly/Rhino, ... different enough that you could not modify the Hotrods +4 crank to work in a Rhino. I'm just trying to build a cruiser with more torque than stock. What I am looking at now is:

11:1 stock bore piston with a torque cam
11:1 102mm piston with either the stock sleeve bored 2mm or a LA Sleeve 102mm sleeve, with a torque cam
10.5:1 105mm piston and a LA Sleeve 105mm sleeve, with a torque cam

Which is going to work best for a cruiser Rhino?