KTM ATV HQ Forums banner
1 - 10 of 10 Posts

·
Registered
Joined
·
430 Posts
Discussion Starter · #1 ·
Well, im looking to have some work done on the engine for next year. Looking for some input if anyone has any. I race mostly XC. Here's what im planning to do to the 450.

High comp weisco piston 13:5:1

806 cam

Port and Polish head

Possible carb bore, if it improve anything?

Thats all i got for the engine right now, if you think i should do anything else worth while, let me know.
 

·
Administrator
Joined
·
4,264 Posts
that will be a strong runner for sure, good an punchy, the 806 runs real nice in our 450. Look at exhaust also.

I'd hold of on the carb bore thats more for top end (and can make low end jetting more fincky due to the lower velocity - has been our finding on the YFZ anyways)

Have you done any suspension work ?
 

·
Registered
Joined
·
430 Posts
Discussion Starter · #3 ·
that will be a strong runner for sure, good an punchy, the 806 runs real nice in our 450. Look at exhaust also.

I'd hold of on the carb bore thats more for top end (and can make low end jetting more fincky due to the lower velocity - has been our finding on the YFZ anyways)

Have you done any suspension work ?
Im currently running the FMF 4.1 full exhaust. And i have Rocket Rons $400 upgrade done to the shocks, i may go with the $700 one. Good call on the carb, ill take that into consideration. Thanks
 

·
Registered
Joined
·
430 Posts
Discussion Starter · #4 ·
would it be better to run a piston with 13:5:1 compression or 12:1?
 

·
Premium Member
Joined
·
968 Posts
If you're running XC type stuff a 13.5:1 should be fine. Just run good race gas. You can do other things to help with heat if it becomes a problem. I ran an XC race and I have 14.25:1 compression.
 

·
Registered
Joined
·
500 Posts
If you're running XC type stuff a 13.5:1 should be fine. Just run good race gas. You can do other things to help with heat if it becomes a problem. I ran an XC race and I have 14.25:1 compression.

I have also added a KBS Racing crank case evac valve. It doesn't do a lot for increased HP but it does help create a vacuum in the crank case in which creates better ring seal. I have also put a filter on the end of it and routed it to ambient air and blocked off the carb port so as not to route any blow by oil into the carb.
 

·
Registered
Joined
·
430 Posts
Discussion Starter · #7 ·
I have also added a KBS Racing crank case evac valve. It doesn't do a lot for increased HP but it does help create a vacuum in the crank case in which creates better ring seal. I have also put a filter on the end of it and routed it to ambient air and blocked off the carb port so as not to route any blow by oil into the carb.
I did somthing of the sort minus the KBS Racing crank case evac valve. I had trouble with oil getting sucked into the carb and really making a mess of things. Where can i get one of those valves?
 

·
Registered
Joined
·
430 Posts
Discussion Starter · #8 ·
If you're running XC type stuff a 13.5:1 should be fine. Just run good race gas. You can do other things to help with heat if it becomes a problem. I ran an XC race and I have 14.25:1 compression.
what is the stock compression in these engines? and does just the piston change the compression, b/c im also looking at running a 806 cam, but i dont think the cam has anything to do with compression
 

·
Premium Member
Joined
·
968 Posts
what is the stock compression in these engines? and does just the piston change the compression, b/c im also looking at running a 806 cam, but i dont think the cam has anything to do with compression
It might be around 11.5:1. I know the new SX has higher compression. The cam won't have anything to do with compression.
 

·
Registered
Joined
·
500 Posts
It might be around 11.5:1. I know the new SX has higher compression. The cam won't have anything to do with compression.
11.1:1 is stock compression. This is the information for the crank case evac valve.

KDS Racing
685 Hope Rd
Floyd, VA 24091
NEW PHONE 540-818-9154
Paypal; [email protected]
 
1 - 10 of 10 Posts
Top