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Discussion Starter · #1 ·
Hi guys new here. I need a new top end for a 2013 kfx 450. Compression is 49psi cold. What should be done? I just bought the wheeler, rode it 1/2 mile and it backfired and wouldn’t start. Had a HMF full pipe w/wiseco controller that the previous owner didn’t tune correctly. The plug was white as snow.
 

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Hi guys new here. I need a new top end for a 2013 kfx 450. Compression is 49psi cold. What should be done? I just bought the wheeler, rode it 1/2 mile and it backfired and wouldn’t start. Had a HMF full pipe w/wiseco controller that the previous owner didn’t tune correctly. The plug was white as snow.
Welcome to the Forum...!!!

Do you have the stock intake tube. If yes, remove the wiseco fuel controller you don't need it... ...see pic (stock is circled)

What's the valves clearance..? If too close will prevent the valve from closing & lose compression..????

Valve Clearance: between cam and valve lifter
Standard:
Exhaust 0.17 ∼ 0.22 mm (0.0067 ∼ 0.0087 in.)
Inlet 0.10 ∼ 0.15 mm (0.0039 ∼ 0.0059 in.)
 

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Discussion Starter · #3 ·
Stock intake
Exhaust clearance 18-19
Intake 10.5-11
11-11.5
I also noticed a lot of oil, I may have put an extra 4-6 oz in after I changed oil. Would that cause a compression/no start issue?
 

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I just tried starting again, all kinds of fire, plug is wet when I pull it out, (yes new fuel). Only thing that is off is compression 45 psi closed throttle, 54 wot.
With a stock intake disconnect the wiseco fuel controller & hook it up back to factory...!

(Intake .105 .110mm) This might be your problem for low compression & not starting...???..Shim both intakes to 0.14mm for best performance..

Is it burning oil & is your sparkplug wet with oil..??

Double check your Cam chain timing......see pic

Here's a copy of the service manual to help you
 

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Discussion Starter · #7 ·
What is the next step? I did take the wiseco controller out of the equation with the same result in the no-start.
With a stock intake disconnect the wiseco fuel controller & hook it up back to factory...!

(Intake .105 .110mm) This might be your problem for low compression & not starting...???..Shim both intakes to 0.14mm for best performance..

Is it burning oil & is your sparkplug wet with oil..??

Double check your Cam chain timing......see pic

Here's a copy of the service manual to help you
Thanks Dust Devil. I’ll check it. Would a lean tune burn the rings? I drained the oil and no debris in it.
 
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