Posts
131
Joined
7/14/2011
Location
CA
Edited Date/Time
9/3/2014 3:16pm
Sorry for tossing it in here but I know this gets more traffic than the race shop, I barely go there myself. Anywhoooo I swamped my 2006 CRF 450R a while back and ripped it apart to dry it out and inspect stuff. Think I kicked it w/o the plug grounded and fried some ‘lectrical components. Now the spark is all good but it is sputtering in the mid-high range. It sounds a bit like its bouncing off the rev-limiter. I mostly notice it when I rip it up/down the street and get on the throttle to run through the gears. It’ll accelerate and then mid-RPM it will start to sound like ass. Neighbours love me… Any thoughts dudes?
New stator
New ignition coil
New plug wire and plug
New CDI (computer, whatever its called)
New head gasket
Carb cleaned (by myself and a mechanic)
New gas
Timing OK (99% sure)
Valves OK (one intake valve is 0.004 – spec is 0.006-/+0.001in)
Passed leakdown test
Compression at 60PSI
New stator
New ignition coil
New plug wire and plug
New CDI (computer, whatever its called)
New head gasket
Carb cleaned (by myself and a mechanic)
New gas
Timing OK (99% sure)
Valves OK (one intake valve is 0.004 – spec is 0.006-/+0.001in)
Passed leakdown test
Compression at 60PSI
When the plug gap gets to great the ignition has to jump a bigger distance and can mimic your symptoms . Make sure the coil to plug cap is good. And your grounds are good.
Next,buy a digital ohm meter and test your ignition system. All the test values are in your service manual
Good luck& stay with it and you will get it covered.
Cheers, Pat
What color is the plug after one or 2 of these hood rips?, is it black and sooty? Or still looks new?
You are sure the new plug wire is screwed into the coil and plug cap good.
The plug condition,color will tell me the most info here.
You say 99% sure on timing, is that spark timing or cam timing?
Since you had the head off you are sure that the cam is not off a tooth .
It will clear the valves if off one tooth in one direction but not the other.
Remove the inspection plug on the crank cover and remove rocker cover.
Line up hash marks on cam with top of head,look at crank marks,the 3 of them will be in line if correct.
The Shop
If the leak jet is clogged or has trash in it will also cause this issue.
As others have stated, cam timing off one tooth can do it.
A coil with too low primary resistance can do it.
A stator that is breaking down can do it.
A float set too low can also do it.
Paw Paw
You really need to look good at the crank arrows ,plus I take a length of metal coat hanger with tape wrapped around it and stick it in the plug hole to feel out TDC.
Hillbilly - plug is BLACK, super black.
Confirming timing again but I lined it up at TDC by a screwdriver, with the valves pointing to the rear, clutch side marks lined up and the magneto marks lined up. Bit of play in the cam chain tho.
For the o-ring on the slide, any pics or links to that? Not sure what that is.
Thanks again dudes, times running out for this summer here....
Paw Paw
Here's the plug after a ride yesterday. I'm going to put a bullet in this bike soon. Retarded the timing one tooth, still doesn't run right. Advanced it a tooth and it won't start and just about bucks me off the bike when it nears tdc.
Went up/down 2 main jet sizes and moved the needle jet clip around. Questioning the new CDI but who knows.
Sounds like it's hitting the Rev limiter but the rpms will increase after it starts sputtering.
Pit Row
Are the vent tubes on the carb clear,none plugged up?
It can suck fuel backwards out of the bowl vent at the rear of the carb.
It even looks oily,was there water inside the cylinder? You could of broken a ring but the bike would smoke blue.
If you put in a new plug does it cure the miss for a bit or does it still miss right away?
Did the engine hydraulic lock? Couldn't kick it thru till the plug was removed?
With that cold water hitting the very hot aluminum I'm not sure you aint got a small crack something.
The plug looks oily and oil fouled which would make it miss.
The valve bowl is the thinnest part of the casting but if it hydraulic locked the valves would be closed and it would do things like bend the rod,break a ring,eh,crack this piston,dunno,they are pretty hefty but it could.
A leak test can lie because the oil seals the crack.
Rub that black off the plug on your finger,if it is sooty then its carburetor if it is oily and smears you are pulling oil in somewhere.
Or,vent tubes plugged with mud and engine vacuum is sucking fuel out the bowl vent on the rear of the carb.
The silencer never came to mind good call
Thanks a ton guys for all your inputs, massively appreciate the knowledge shared! Baaarrraaaaaappppp
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