07 800R Rebuild

[Mountain Marty]

Hey guys, so I know this has probably been discussed before but wanted a fresh opinion. I am rebuilding my 800R motor and am wondering which pistons I should use. I rebuilt the top end before this season and used SPX's, put about 300 miles on them before a crank bearing seized on me. The pistons looked worse than the stock ones I took out the first time and they had 1700 miles on them.
I'm considering a dual ring piston on this rebuild, probably RK Tek or MCB, what do you recommend? Are the RK Tek pistons forged like Wiseco or are they cast?
Also, have you seen any issues with this motor losing oil, when I tore it apart everything looked really dry, didn't have much lube.
Thanks for your help, still hoping to get it going for spring riding!
Cheers,
MM

 

[maxwell]

go with rk pistons or mcb dual ring. check your oil pump adjustment or just run premix to ensure proper oiling.

 

[Slamnek]

X2 for Rk-tek

 

[team dirt]

u might want to look into the new pistons from the etech, they look like they will be a decent piston/ring combo. they will fit the 800r

 

[Mountain Marty]

Thanks for the tips guys, I have a set of RK Tek pistons on order. Anybody have an idea of how much clearance I should have between bearings and crankcase?

 

[Modman]

Thanks for the tips guys, I have a set of RK Tek pistons on order. Anybody have an idea of how much clearance I should have between bearings and crankcase?

None?

Which bearings and what clearance? Lateral or OD clearance?

 

[Mountain Marty]

None?

Which bearings and what clearance? Lateral or OD clearance?

OD. I checked the clearance because I hear some of these cases were machined too tight on the OD of the bearing. One of the inner bearings just seized on my motor. I checked and found .001"-.0015" on all of the bearings. Thx

 

[maxwell]

what cases do you have. check the casting for an R mark. some of them have the mark. these are ok. others were machined to tight although i have seen newer versions of the r bottom end without the r marking so it may be a myth

 

[Mountain Marty]

what cases do you have. check the casting for an R mark. some of them have the mark. these are ok. others were machined to tight although i have seen newer versions of the r bottom end without the r marking so it may be a myth

I had a look for the R and cannot find it. This is still the original motor as I haven't had an issue with the bottom end until now.

 

[Modman]

OD. I checked the clearance because I hear some of these cases were machined too tight on the OD of the bearing. One of the inner bearings just seized on my motor. I checked and found .001"-.0015" on all of the bearings. Thx

You'll have to call Doo for the specs or look in the manual, I don't know what they are supposed to be off the top of my head.

 

[tex78]

huh too bad u didn't go with the mcb's ..... i have many friends that have or have had rk tek's and even in doo talk they have had the rings locaters fall out.... fuges the motor..... i went with the mcb's and love them....

 

[HagmanMod1]

have an 0km rkt 860 complete engine for sale 780 305 9689

 

[DanoXRS]

have an 0km rkt 860 complete engine for sale 780 305 9689

Do you still have this engine?