KFX 450 HQ Forum banner
1 - 16 of 16 Posts

·
Registered
2008 KFX450r
Joined
·
16 Posts
Discussion Starter · #1 ·
Hey! I’ve had my kfx for almost 3 years. Rebuilt top end spring of last year then the rod bearing went out. Rebuilt the bottom end with all hot rods bearings and a hot rods +3mm rod and crank. I have an athena cylinder and wiseco piston. Stage 2 cams and kibblewhite black diamond valves. Wrapping up the rebuilt now and it cranks a time or 2 then stops. Tested the battery and turned out it was bad. Replaced it and still had the issue. Cleaned all my connections. (battery terminals, starter solenoid, and starter) issue is still there. I got my starter warrantied being it still didn’t crank that quick with no spark plug. Put the new starter in and issue STILL will not go away. I took my stator casing off to see if I put something together wrong. I don’t see anything out of place or incorrectly installed. I have not taken the fly wheel off yet but i plan of it to see if it’s something behind there. I would appreciate if someone on here knew what the issue is or could be. I’m out of thoughts about what it could be. I haven’t seen any threads on this exact issue.
 

·
Super Moderator
Joined
·
10,171 Posts
Hey! I’ve had my kfx for almost 3 years. Rebuilt top end spring of last year then the rod bearing went out. Rebuilt the bottom end with all hot rods bearings and a hot rods +3mm rod and crank. I have an athena cylinder and wiseco piston. Stage 2 cams and kibblewhite black diamond valves. Wrapping up the rebuilt now and it cranks a time or 2 then stops. Tested the battery and turned out it was bad. Replaced it and still had the issue. Cleaned all my connections. (battery terminals, starter solenoid, and starter) issue is still there. I got my starter warrantied being it still didn’t crank that quick with no spark plug. Put the new starter in and issue STILL will not go away. I took my stator casing off to see if I put something together wrong. I don’t see anything out of place or incorrectly installed. I have not taken the fly wheel off yet but i plan of it to see if it’s something behind there. I would appreciate if someone on here knew what the issue is or could be. I’m out of thoughts about what it could be. I haven’t seen any threads on this exact issue.
Welcome to the forum...!!

Have you turned the motor manually at the stator with a ratchet to check if the motor rotates with no issues...

Did you check the piston ring end gap before installing....? http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

Make sure the cam chain tensioner was installed correctly or the cam chain is too tight & will result in the motor dragging...!!
 

Attachments

·
Registered
2008 KFX450r
Joined
·
16 Posts
Discussion Starter · #3 ·
Welcome to the forum...!!

Have you turned the motor manually at the stator with a ratchet to check if the motor rotates with no issues...

Did you check the piston ring end gap before installing....? http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

Make sure the cam chain tensioner was installed correctly or the cam chain is too tight & will result in the motor dragging...!!
I have turned the motor manually over being I just did valves and had to set it at TDC. It seemed to turn over like it should and yes I did check the gap. Also when I installed the cam chain tensioner I followed the manuals steps. BUT today I noticed that the gear behind the flywheel can move back and forth. I’m not sure if I just didn’t get the flywheel seated all the way or if there’s something different hold it from seating
 

·
Registered
Joined
·
4 Posts
Hey! I’ve had my kfx for almost 3 years. Rebuilt top end spring of last year then the rod bearing went out. Rebuilt the bottom end with all hot rods bearings and a hot rods +3mm rod and crank. I have an athena cylinder and wiseco piston. Stage 2 cams and kibblewhite black diamond valves. Wrapping up the rebuilt now and it cranks a time or 2 then stops. Tested the battery and turned out it was bad. Replaced it and still had the issue. Cleaned all my connections. (battery terminals, starter solenoid, and starter) issue is still there. I got my starter warrantied being it still didn’t crank that quick with no spark plug. Put the new starter in and issue STILL will not go away. I took my stator casing off to see if I put something together wrong. I don’t see anything out of place or incorrectly installed. I have not taken the fly wheel off yet but i plan of it to see if it’s something behind there. I would appreciate if someone on here knew what the issue is or could be. I’m out of thoughts about what it could be. I haven’t seen any threads on this exact issue.

did you ever get this figured out?
 

·
Registered
Joined
·
1 Posts
Hey! I’ve had my kfx for almost 3 years. Rebuilt top end spring of last year then the rod bearing went out. Rebuilt the bottom end with all hot rods bearings and a hot rods +3mm rod and crank. I have an athena cylinder and wiseco piston. Stage 2 cams and kibblewhite black diamond valves. Wrapping up the rebuilt now and it cranks a time or 2 then stops. Tested the battery and turned out it was bad. Replaced it and still had the issue. Cleaned all my connections. (battery terminals, starter solenoid, and starter) issue is still there. I got my starter warrantied being it still didn’t crank that quick with no spark plug. Put the new starter in and issue STILL will not go away. I took my stator casing off to see if I put something together wrong. I don’t see anything out of place or incorrectly installed. I have not taken the fly wheel off yet but i plan of it to see if it’s something behind there. I would appreciate if someone on here knew what the issue is or could be. I’m out of thoughts about what it could be. I haven’t seen any threads on this exact issue.
Hi read ur post and found it to be very similar to my issue ( hav a 2009 Kfx450r ) put in new bat new starter and new starter solenoid. When I try to start it sound like the battery has no juice to crank kinda like the starter wants to turn but jams … then I’ll let go the start button and push it again and starts right up. Once started the quad has no issues runs great doesn’t stall has plenty of power and no black or white smoke from the exhaust. Would u be able to
Advise me of what the problem can be .. greatly appreciated
 

·
Registered
2008 KFX450r
Joined
·
16 Posts
Discussion Starter · #8 ·
what did the problem end up being I’m having the same issue now and I have a similar build setup
starter relay and my button was trashed which was probably my fault being I never cleaned and die electric greased it.
 

·
Registered
2008 KFX450r
Joined
·
16 Posts
Discussion Starter · #9 ·
Hi read ur post and found it to be very similar to my issue ( hav a 2009 Kfx450r ) put in new bat new starter and new starter solenoid. When I try to start it sound like the battery has no juice to crank kinda like the starter wants to turn but jams … then I’ll let go the start button and push it again and starts right up. Once started the quad has no issues runs great doesn’t stall has plenty of power and no black or white smoke from the exhaust. Would u be able to
Advise me of what the problem can be .. greatly appreciated
I noticed that Sometimes if The starter tries spinning the motor at top dead center it struggles but starts once it gets a “run up” is i guess what to call it. I don’t know if that’s a KFX thing or maybe just how it is after my modifications
 

·
Registered
Joined
·
4 Posts
starter relay and my button was trashed which was probably my fault being I never cleaned and die electric greased it.
I feel like my problem might be different because the quad won’t even start if I try to bump start it in any gear
 

·
Registered
2008 KFX450r
Joined
·
16 Posts
Discussion Starter · #11 ·
I feel like my problem might be different because the quad won’t even start if I try to bump start it in any gear
Possibly a shot battery? I just went through that with mine. Got the starter relay issue fixed and then my battery crapped out. Throw a battery tester on it and see how it is taking the load or if the battery is just low. If I’m correct these machines are very picky on how charged the battery is. I don’t know exactly where they should be for voltage but anything above 12 volts should be allowing it to run. Also with bump starting I use 3rd gear and that’s the lowest I can get it to bump start with. But weight wise I’m rather small.
 

·
Registered
2008 KFX450r
Joined
·
16 Posts
Discussion Starter · #12 ·
Hi read ur post and found it to be very similar to my issue ( hav a 2009 Kfx450r ) put in new bat new starter and new starter solenoid. When I try to start it sound like the battery has no juice to crank kinda like the starter wants to turn but jams … then I’ll let go the start button and push it again and starts right up. Once started the quad has no issues runs great doesn’t stall has plenty of power and no black or white smoke from the exhaust. Would u be able to
Advise me of what the problem can be .. greatly appreciated
Pull the starter gears cover off and double check all of the gears to be moving correctly if you had that side apart. I put it together wrong once and had to tear it all apart to figure out what gear Installed wrong. First and last time I did not use the manual instructions to assemble anything in that motor lol.
 

·
Registered
Joined
·
4 Posts
Possibly a shot battery? I just went through that with mine. Got the starter relay issue fixed and then my battery crapped out. Throw a battery tester on it and see how it is taking the load or if the battery is just low. If I’m correct these machines are very picky on how charged the battery is. I don’t know exactly where they should be for voltage but anything above 12 volts should be allowing it to run. Also with bump starting I use 3rd gear and that’s the lowest I can get it to bump start with. But weight wise I’m rather small.
I’ve tried everything bro i haven’t pulled the valve cover off but I tried charging the battery and using a jump starter, tried bump starting it, took out the new spark plug and it cranks just fine, put it back in and it’ll only crank once or twice.
 

·
Super Moderator
Joined
·
10,171 Posts
I’ve tried everything bro i haven’t pulled the valve cover off but I tried charging the battery and using a jump starter, tried bump starting it, took out the new spark plug and it cranks just fine, put it back in and it’ll only crank once or twice.
Make sure the battery is fully charged...12.8 volts standard...!

Check if the decompression spring is on the exhaust cam...

Does your F.I Dash light remain ON or flashing when trying to start...If yes.. Check for error codes...

Does your fuel prime when the key is turned ON...!

Check for spark & Fuel...If good...

Check if your Throttle positioning sensor/TPS is in range...

Check your valve clearance for being a close gap preventing your valve to close completely causing compression loss...

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.)
 

Attachments

·
Registered
Joined
·
2 Posts
I have somn similar happening also with mine wants to struggle starting almost like it's getting hung up while starting like it turns over once or twice then kinda sounds like it's dragging so I stop .. I can put jump box on it an starts fine or I can push start it an starts right up, I just got the bike so idk what if anything's been done internally with the motor all I know is what I've done too the bike an that's hmf 3 button fuel pro.. fci an yosh exhaust
 

·
Super Moderator
Joined
·
10,171 Posts
I have somn similar happening also with mine wants to struggle starting almost like it's getting hung up while starting like it turns over once or twice then kinda sounds like it's dragging so I stop .. I can put jump box on it an starts fine or I can push start it an starts right up, I just got the bike so idk what if anything's been done internally with the motor all I know is what I've done too the bike an that's hmf 3 button fuel pro.. fci an yosh exhaust
Check the battery's voltage 12.8v standard..!

Check if the decompression spring has fallen off the exhaust cam.!
 

Attachments

1 - 16 of 16 Posts
Top