KFX 450 HQ Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
Hello so I have a 09 kfx450r with FCI PCV and auto tune and it seems to run perfect when I start it when it's cold no bogging but after 10-20 min after riding I get this nasty bog at 3/4 throttle my fan is wired to my high beams and battery is perfect anyone know what the issue could be thanks
 

Attachments

·
Super Moderator
Joined
·
9,627 Posts
No replacing the water temp and map sensor first ordered oem ones today
Valves needs adjusting....!!!!

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.)
If the valve clearance is not within the specified range,
adjust it.
 

·
Registered
Joined
·
1,967 Posts
The fan and high beans would be too much draw together.

I agree with DD.

You have a valve getting tight
 

·
Registered
Joined
·
365 Posts
Yes, the fan gets it's own relay because it draws so much current. If the lights are halogen instead of led they draw a good bit as well. The power for the lights run through the ecu where as the fan does not normally. The ecu is a cdi as well and is initializing the coil to fire. In theory the fan running through the ecu could potentially be drawing the ignition down to the point that its having a hard time keeping the spark plug lit under full throttle turbulence.

Just brainstorming

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Registered
Joined
·
365 Posts
And keep all parts you are replacing so once you figure it out then you have good parts for troubleshooting in the future

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Registered
Joined
·
365 Posts
I just looked at the wiring diagram for a while after writing my last post and I'm not sure if I'm right about the power for the lights having to pass through the ecu at some point but it does pass through the same relay that the ignition feeds from. Where it would only feed the fan relay 5 volts to turn on the 12 relay, instead of supplying the fan a full 12volts through the same relay along with the Amos the fan requires while its running

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Registered
Joined
·
9 Posts
Discussion Starter #10
With the fan off or on it does the same thing I replaced the map and water temp it still seems to spit flames if I Crack the throttle so I'm going to adjust the valves next see if that fixes the problem
 

·
Registered
Joined
·
365 Posts
To spit flames there has to be....

1 too much fuel
2 too late of ignition point (ignition retard)
3 mechanical timing is off (meaning the camshaft/shafts are out of time with the crankshaft... or an exhaust valve is getting stuck open past the point of where it should be...either expanding because it's hot and sticking in the valve guide, or maybe when it heats up it's not landing back in the correct valve seat position allowing it to stay open all the time. In this case it would only be open staying open a tiny bit, the same could happen if your having valve float( the spring is wearing out and at high rpm the spring isnt strong enough to get the valve all of the way shut on each revolution and if it gets to staying open too far the piston will hit it)boom!!
(spring gets weaker as it heats up)

If I had to guess...the fan wired to a switch wasnt coming on as it was supposed to and it got a little, or a lot, too hot many times. The heat will make a valve spring weak or it can cause a valve to slowly warp over time and land in a valve seat offset causing it to land offset in the valve seat more and more over time and at higher rpm when hot. I would sell it unless u want to replace some or all of the top end just too be sure you found and fixed everything that was wrong.... could fix it for cheap and be fine, or could end up in a money trap for trying to save money... it's always a gamble.

Any way I see it, I think I would have the head removed and the valves checked if you find no problem with it yourself. Because left like this is sure to cause damage every time it occurs.

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Super Moderator
Joined
·
9,627 Posts
To spit flames there has to be....

1 too much fuel
2 too late of ignition point (ignition retard)
3 mechanical timing is off (meaning the camshaft/shafts are out of time with the crankshaft... or an exhaust valve is getting stuck open past the point of where it should be...either expanding because it's hot and sticking in the valve guide, or maybe when it heats up it's not landing back in the correct valve seat position allowing it to stay open all the time. In this case it would only be open staying open a tiny bit, the same could happen if your having valve float( the spring is wearing out and at high rpm the spring isnt strong enough to get the valve all of the way shut on each revolution and if it gets to staying open too far the piston will hit it)boom!!
(spring gets weaker as it heats up)

If I had to guess...the fan wired to a switch wasnt coming on as it was supposed to and it got a little, or a lot, too hot many times. The heat will make a valve spring weak or it can cause a valve to slowly warp over time and land in a valve seat offset causing it to land offset in the valve seat more and more over time and at higher rpm when hot. I would sell it unless u want to replace some or all of the top end just too be sure you found and fixed everything that was wrong.... could fix it for cheap and be fine, or could end up in a money trap for trying to save money... it's always a gamble.

Any way I see it, I think I would have the head removed and the valves checked if you find no problem with it yourself. Because left like this is sure to cause damage every time it occurs.

Sent from my SAMSUNG-SM-G935A using Tapatalk
Thanks For Sharing That Information
Blayzin212 has a point...But....!!!!

It wouldn't run for 20 min then bog when hot...or restart until the motor cooled off...Which is the sign that your valves need adjusting....!!!

Check the valve lash/clearance first.....!!!!!!!!

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.)
If the valve clearance is not within the specified range,
adjust it.
 

·
Registered
Joined
·
365 Posts
Not to argue dust but if the valve guide or valve itself being made of metal were to expand as heat is applied (which all metal does) it could potentially not allow the valve to slide through as it normally would and that would explain the running while cold and bogging when hot, as well as the spitting flames.

With that being said do what dust devil says first. I am just applying general engineering. His knowledge on this particular engine is far greater than mine.


Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Super Moderator
Joined
·
9,627 Posts
Not to argue dust but if the valve guide or valve itself being made of metal were to expand as heat is applied (which all metal does) it could potentially not allow the valve to slide through as it normally would and that would explain the running while cold and bogging when hot, as well as the spitting flames.

With that being said do what dust devil says first. I am just applying general engineering. His knowledge on this particular engine is far greater than mine.


Sent from my SAMSUNG-SM-G935A using Tapatalk
Yes...the heat will expand more with common steel & less with titanium due to it's high melting point...Thus the heat will travel up to the stem and expand the cam lobe & valve shim/cap closing the gap of the valve clearance...thus run cold & starts to stall when hot....

valve guide not so much to heat but excessive valve wobble will cause the valve seal to leak...Thus burn oil at startup after sitting for awhile...
 

·
Registered
Joined
·
365 Posts
Damn man, well said. I'm not sure how I missed that but most definitely right!

Sent from my SAMSUNG-SM-G935A using Tapatalk
 
1 - 16 of 16 Posts
Top