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Discussion Starter · #1 ·
Hey guys new to the forum here! I'm having some problems. I replaced my rings as was blowing blue smoke. My cylinder and piston are in spec my head was good replaced valve springs and valve stem seals. Ok I got it back together and torqued to spec. Now my problem... it starts great when cold but when hot it will start but very very hard and moat of the time it wont start. My valves are adjusted right..18mm exhaust .15mm intake. I am stumped as to why it wont start. I bypassed my crank breather tube with a small filter. I have stock cams hmf slip on custom intake didn't change tube from efi also have lexx controller please help guys I'm stressed out and cannot figure this out please help a newbie.. I am very mechanically inclined! Piston tdc cams are facing away from each other timing marks are what manual states 29 pins from exhaust to intake. Just don't know what to do. Thanks mike
 

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Mikeman11,

First thing you may want to check is your battery voltage, should be 12.8 volts. After that, you might want to check your TPS sensor voltage and see were it's set at. Also, it may sound dumb but I've done it, make sure your cold start knob on the side of the throttle body isn't pulled out. Just the first things that came to mind, I'm sure some of the more experienced folks will jump in here and helped get you sorted out.

Tony
 

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Yes! make sure your battery is fully charged...

Hard starting when HOT is usually the symptom of your valve clearance/lash is too close...Are both the intake measuring 0.15 & both exhaust measuring 0.18mm...???

Make sure your TPS voltage is in range...see picture below

Make sure the spark plug gap is proper & the color of your spark is white & not orange...!

Test your water temp sensor it might be faulty & will cause such symptoms when faulty... see picture below
 

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Discussion Starter · #4 ·
Mikeman11,

First thing you may want to check is your battery voltage, should be 12.8 volts. After that, you might want to check your TPS sensor voltage and see were it's set at. Also, it may sound dumb but I've done it, make sure your cold start knob on the side of the throttle body isn't pulled out. Just the first things that came to mind, I'm sure some of the more experienced folks will jump in here and helped get you sorted out.

Tony
Thanks I will try that. My multimeter took a crap on me and I will have another Tuesday. I had my battery fully charged but that doesn't mean anything for me as I have replaced batteries multiple times.
 

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Discussion Starter · #5 ·
Yes! make sure your battery is fully charged...

Hard starting when HOT is usually the symptom of your valve clearance/lash is too close...Are both the intake measuring 0.15 & both exhaust measuring 0.18mm...???

Make sure your TPS voltage is in range...see picture below

Make sure the spark plug gap is proper & the color of your spark is white & not orange...!

Test your water temp sensor it might be faulty & will cause such symptoms when faulty... see picture below
Thanks for the info! Valves are... exhaust both sides .18mm intake both sides @ .15mm I will try the water temp sensor also will try the tps adjustment. I haven't messed with it and it possibly could have moved a little!
 

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Discussion Starter · #7 ·
Finally got it figured out today! No more hard to start problems. I checked codes wasn't throwing any. Checked battery voltage was 12.8. Checked my relays all good fuses all good. Tapped into my tps read 5.01 volts. Checked the output. Read .589 wide open throttle 3.66 so I changed it to .64 wide open 3.75. Double checked it stayed the same started let it get hot fan came on (this is when it wouldn't start) started right up! Thanks for all ur help!! Now I can ride again!
 

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Glad to hear you got this sorted out, and thanks for posting up what you discovered was the problem. It's always nice to hear about a problem getting resolved and what the culprit was. Time to go ride!!!

Tony
 

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Make sure the spark plug gap is proper & the color of your spark is white & not orange...!



I thought plug should be chocolate in color?
The spark...Bright white is strong (normal)..If the spark is orange..your ignition coil is weak...!! Yes the spark (plug) electrode should be a coffee color showing a proper air/fuel mixture burn...!!! Yea! checking the TPS was the next item on the list...
 

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Discussion Starter · #10 ·
Glad to hear you got this sorted out, and thanks for posting up what you discovered was the problem. It's always nice to hear about a problem getting resolved and what the culprit was. Time to go ride!!!

Tony
Thanks! Anything to help next person having same problem! Ready to ride now!! Gotta parade to show my baby off next weekend! I forgot to mention I did switch plugs out for a new one! The old one was about 5 yrs old so idk if that helped or not sure it did in some way.
 

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Discussion Starter · #11 ·
Make sure the spark plug gap is proper & the color of your spark is white & not orange...!



I thought plug should be chocolate in color?
The spark...Bright white is strong (normal)..If the spark is orange..your ignition coil is weak...!! Yes the spark (plug) electrode should be a coffee color showing a proper air/fuel mixture burn...!!! Yea! checking the TPS was the next item on the list...
Ok I've got another problem. Spark plug electrode is a coffee mocha color. Ok I had top end rebuilt new valve springs piston rings etc. Ok I replaced base and head gasket with oem kawi parts. I'm having a problem with the head gasket leaking on the right side of engine in front by the head bolt. It leaks at start up until I let it set and get hot then it stops it. Is it a bad head gasket and what could I do for this to completely stop it's not a lot maybe like a drop running down the cylinder just above the oil filter.
 

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The spark...Bright white is strong (normal)..If the spark is orange..your ignition coil is weak...!! Yes the spark (plug) electrode should be a coffee color showing a proper air/fuel mixture burn...!!! Yea! checking the TPS was the next item on the list...
Ok I've got another problem. Spark plug electrode is a coffee mocha color. Ok I had top end rebuilt new valve springs piston rings etc. Ok I replaced base and head gasket with oem kawi parts. I'm having a problem with the head gasket leaking on the right side of engine in front by the head bolt. It leaks at start up until I let it set and get hot then it stops it. Is it a bad head gasket and what could I do for this to completely stop it's not a lot maybe like a drop running down the cylinder just above the oil filter.
Simply re-torque the head bolts to spec's, that usually fixes it after a rebuild..... Torque - Cylinder Head Bolts (M10): 59 N·m (6.0 kgf·m, 44
ft·lb)......Torque - Cylinder Bolt [A]: 12 N·m (1.2 kgf·m, 106 in·lb)
Cylinder Head Bolts (M6) : 12 N·m (1.2 kgf·m,
106 in·lb)
 

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Discussion Starter · #13 ·
Ok I've got another problem. Spark plug electrode is a coffee mocha color. Ok I had top end rebuilt new valve springs piston rings etc. Ok I replaced base and head gasket with oem kawi parts. I'm having a problem with the head gasket leaking on the right side of engine in front by the head bolt. It leaks at start up until I let it set and get hot then it stops it. Is it a bad head gasket and what could I do for this to completely stop it's not a lot maybe like a drop running down the cylinder just above the oil filter.
Simply re-torque the head bolts to spec's, that usually fixes it after a rebuild..... Torque - Cylinder Head Bolts (M10): 59 N·m (6.0 kgf·m, 44
ft·lb)......Torque - Cylinder Bolt [A]: 12 N·m (1.2 kgf·m, 106 in·lb)
Cylinder Head Bolts (M6) : 12 N·m (1.2 kgf·m,
106 in·lb)


I had broken one off inside the head the longer 12mm bolts and I had set it to 44 ft lbs it never clicked as it kept turning and turning and finally snapped. Brand new oem head bolts.
 

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Simply re-torque the head bolts to spec's, that usually fixes it after a rebuild..... Torque - Cylinder Head Bolts (M10): 59 N·m (6.0 kgf·m, 44
ft·lb)......Torque - Cylinder Bolt [A]: 12 N·m (1.2 kgf·m, 106 in·lb)
Cylinder Head Bolts (M6) : 12 N·m (1.2 kgf·m,
106 in·lb)


I had broken one off inside the head the longer 12mm bolts and I had set it to 44 ft lbs it never clicked as it kept turning and turning and finally snapped. Brand new oem head bolts.


"Sorry to hear" your not the only one who has broken or stretched the OEM head bolts...To prevent any head gasket problems in the future I recommend to you KMS head studs...
https://www.kmsperformance.com/shop/item.aspx?itemid=622


  • Increased torque
  • Replaces all 4 stock bolts
  • Allen broach for easy install and removal
  • Cost effective upgrade
  • A must for race engines
  • Increase clamping forces to reduce head gasket failures
  • (4) 10mm ARP studs, nuts and washers
  • ARP2000 grade, stronger than the ARP 8740 chromoly!
 

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Discussion Starter · #16 ·
Ya I've seen them bolts. The next rebuild I do I'll definitely get me a set!! Thanks for info helps out a ton! I'd be selling my kfx450r if it wasn't for u!!
 

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Finally got it figured out today! No more hard to start problems. I checked codes wasn't throwing any. Checked battery voltage was 12.8. Checked my relays all good fuses all good. Tapped into my tps read 5.01 volts. Checked the output. Read .589 wide open throttle 3.66 so I changed it to .64 wide open 3.75. Double checked it stayed the same started let it get hot fan came on (this is when it wouldn't start) started right up! Thanks for all ur help!! Now I can ride again!
Having same problem, hopefully this is the fix, Thanks!! Great post.
 
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