Posts
6153
Joined
1/31/2018
Location
Mansfield, OH, USA
Looking for some experienced help because im out of ideas. Just finished building this bike and cannot get it to start. It ran perfectly fine before.
What its doing:
Gets gas, gets spark, every few kicks it blows flames out of the exhaust. - sounds like a valve timing issue..but the cams are correct. Have reinstalled them at least 10 times. Even tried rotating a tooth both directions to be sure...
Valve clearance is .15mm on the intakes and .2mm on the exhaust which is hotcams’ spec for their cams.
Leakdown test is showing zero leakage past the valves and 10% leak through the piston.
Cylinder is replated from powerseal and was matched with a new piston.
I reset the TPS resistance according to the service manual - this didnt make a difference.
The carb’s jetting is the same as it was before teardown. Fuel screw is 1.5 out & the slide height on the air box side is .125”
The flywheel key is not sheared - i just put it together.
The cam gears do not appear to have rotated on the shaft while they were sitting in a box over the duration of the rebuild.
The decompressor on the exhaust cam is functioning properly.
Pretty lost at this point. Im hoping someone can suggest something i havent tried yet. The bike sounds like it wasnt to catch, but doesnt.
What its doing:
Gets gas, gets spark, every few kicks it blows flames out of the exhaust. - sounds like a valve timing issue..but the cams are correct. Have reinstalled them at least 10 times. Even tried rotating a tooth both directions to be sure...
Valve clearance is .15mm on the intakes and .2mm on the exhaust which is hotcams’ spec for their cams.
Leakdown test is showing zero leakage past the valves and 10% leak through the piston.
Cylinder is replated from powerseal and was matched with a new piston.
I reset the TPS resistance according to the service manual - this didnt make a difference.
The carb’s jetting is the same as it was before teardown. Fuel screw is 1.5 out & the slide height on the air box side is .125”
The flywheel key is not sheared - i just put it together.
The cam gears do not appear to have rotated on the shaft while they were sitting in a box over the duration of the rebuild.
The decompressor on the exhaust cam is functioning properly.
Pretty lost at this point. Im hoping someone can suggest something i havent tried yet. The bike sounds like it wasnt to catch, but doesnt.
Are you getting fuel to the carb?
Using correct timing marks for cam timing?
Fuel screw set too lean?
I have always found the valve settings from Hot Cams to be too tight and give starting issues. You may want to try stock settings.
New cam chain?
Bright Blue spark?
Paw Paw
-no it looked nice and clean before i cleaned the carb
Are you getting fuel to the carb?
-Yes, the spark plug gets plenty wet
Using correct timing marks for cam timing?
-Yes. Its the two marks on the flywheel next to each other, and im using the most clockwise mark if those two marks.
Fuel screw set too lean?
-Im not sure, 1.5 turns out is more screwed in than before i took it apart. Before i believe it was 3 turns out or so.
I have always found the valve settings from Hot Cams to be too tight and give starting issues. You may want to try stock settings.
-stock is .10-.15 on the intake and .15-.2 on the exhaust. My clearances are at the loose ends of those ranges. Additionally, these clearances are what i ran before teardown. The bike always started 1st kick.
New cam chain?
Yes, OEM.
Bright Blue spark?
Yes. It seems like a strong spark, it jumped from the plug to the frame over a 1/2” gap
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
You can have a brand new clean pilot in it, if the body passage is still blocked no fuel or little.
Clear passage
Backfire, could be timing
Pit Row
Went through, 2008 model 2009 model and 2010 model
Back when D-K was king of thumpertalk.!!!!
Trust me the stator will spark even if its bad!
Neutral switch wire does not have continuity to the frame.
I have continuity from the wire to the harness connector.
I have continuity from the harness connector to the CDI harness plug.
I have continuity from the proper lead in the CDI harness to the frame if i jump the connection without the CDI installed. This is from the terminal on the neutral switch all the way to the frame.
I do not have continuity to frame if i plug in the CDI box.
I do not have continuity on the male cdi box pins either.
Not sure how the cdi went bad from sitting on the shelf, possibly from condensation from heating the garage in the winter?
Old thread, new to the community hello everyone. I am 31 y.o and have been in the industry since 17 y.o. long story short I finally decided to create an account and share my knowledge they way you all have not just here but on other sites as well. In my experience I ran into a 07 kx250f for tuning the carb and some aesthetics. Turned out to be a nightmare. I even met the previous mechanic and shared knowledge with the next. All very knowledgeable and knew exactly what they were doing. Idk how to explain this but I figured out the problem to be a bad frame. I don't even know how to explain this but I've come across certain black spray paints because the majority of people do that 😐 even on new bikes and for some reason it affects the engines electrical
For the love of God it doesn't make any sense to me. I've cleaned contact points to the state of a brushed aluminum finish and I've seen the problem on the kx250fs of 06-8 and on raptor 700s 14 and up also banshees. The case on the banshees have been after powder coated frames and or engine cases. Fixed by simply retappi g the frame and sanding for a better ground to not just frame but engine as well. On the kx250fs and those years of raptor when ever I've come across some one spray painting it with a certain black paint your lucky if the bike even fires up once per 50 tries.
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