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Looking for some insite on next steps to determine cause of the bike falling on it's face only at WOT. Last ride was fine so whatever has changed did so while it was on the stand (I think).

History
2005 CRF, mostly stock, pipe, jetted years ago, no issues for long, long time. Main jet 170.

Bike doesn't sit for more than 2 months without being ridden.

Starts quickly (e-start), idles fine, power same as always except for WOT.

In AZ you used to have to emmision plated bikes. It failed so I adjust fuel screw to pass, and returned it to where it was after test. Now on decel it lean pops badly. Not sure if this is related to WOT issue...

Bike pulls good and abruptly cuts out at WOT. Either slowly rolling into WOT or just quickly opening all the way.

I pulled the main jet out, it was free of obstructions. I put a new spark plug in. The old one looked rich. When the tank was out I bumped the petcock and it flows just fine.

Don't think the clutch is slipping and hitting rev limit, but I could be wrong. Trans has rotella syn in it, for 3 changes (cheap f*@&er, yes I know). Once I back off throttle to 90% it pulls hard again. Headlight works, so stator is at least last functional. Air Filter and oil are clean.

Thanks

Year: 2005
Elevation: 1600
Temperature Range: 50-100
Smog (AIS): N/A
Airbox Modified Top: rubber removed
Airbox Modified Sides: both cut
Backfire Screen: still there
Air Filter: stock
Pilot Jet: stock
Main Jet: 170
Needle: JD red
Needle Clip Position: middle (3rd?)
Fuel Screw Type: stock
Fuel Screw Setting: 1 1/8
AP Modified: little o ring
Leak Jet: stock
AP Cover: stock
Exhaust Type: FMF
Exhaust Modified: n/a
Pink Wire Modified: no

You need a 165 or even 162 main, but that bike will still run fine with a 170.

Maybe a torn accel pump diaphragm? I would verify that you are getting a good squirt.

You need a 165 or even 162 main, but that bike will still run fine with a 170.

Maybe a torn accel pump diaphragm? I would verify that you are getting a good squirt.

Has this issue been happening all along ?? , or is this something new ??? , if so what changes were made around the time of issue (including carb cleaning ,etc)

Have you tried the needle on the 4th (from top) clip to see if that has any effect at WOT ???

If you were hitting the rev limiter , your bike would sound like Justin Barcia when he is jumping , so you would definitely know it was hitting the limiter

If your clutch was slipping the bike would run hot or overheat , and/or you would notice the bike holding back and rev-ving without gaining much speed and/or not having the ability to climb a hill

I also run Shell Rotella Synthetic in both motor and transmission and have not had any issues with slipping or any other issues

JimDirt wrote:Has this issue been happening all along ?? , or is this something new ??? , if so what changes were made around the time of issue (including carb cleaning ,etc)

Have you tried the needle on the 4th (from top) clip to see if that has any effect at WOT ???

If you were hitting the rev limiter , your bike would sound like Justin Barcia when he is jumping , so you would definitely know it was hitting the limiter

If your clutch was slipping the bike would run hot or overheat , and/or you would notice the bike holding back and rev-ving without gaining much speed and/or not having the ability to climb a hill

No this is new issue with no changes made to anything. Went for a ride last week and noticed a problem. Haven't touched carb in years.

Don't think its clutch just trying to keep open mind. Thanks for the input

You said last ride was fine , was this before or after you pulled the main jet to check it ??

If after , did you just pull the nut on the bottom of the bowl , or pull the entire bowl ??

did you notice any dirt flakes in the bottom of either ??

Have you checked the operation of your Hot Start Lever ??

Sounds like a problem I had once and it turned out to be an air leak between the carb and the engine. Turns out after I had the carb off to clean I failed to seat the carb properly in the rubber adapter. Cleared right up after I properly installed everything.
Just a suggestion........
Good luck!

RLPII wrote:Sounds like a problem I had once and it turned out to be an air leak between the carb and the engine. Turns out after I had the carb off to clean I failed to seat the carb properly in the rubber adapter. Cleared right up after I properly installed everything.
Just a suggestion........
Good luck!

Ok - When has your bike EVER seen wide open throttle...? hehehehehehehe

Was that when you had the carb off cleaning the spider webs out ?

JimDirt wrote:You said last ride was fine , was this before or after you pulled the main jet to check it ??

If after , did you just pull the nut on the bottom of the bowl , or pull the entire bowl ??

did you notice any dirt flakes in the bottom of either ??

Have you checked the operation of your Hot Start Lever ??

Before, pulled jet after issue to inspect for clog.

Carb nut only, clean, no gum or flakes.

Hot start lever seems to operate properly.

Back2-2 wrote:

RLPII wrote:Sounds like a problem I had once and it turned out to be an air leak between the carb and the engine. Turns out after I had the carb off to clean I failed to seat the carb properly in the rubber adapter. Cleared right up after I properly installed everything.
Just a suggestion........
Good luck!

Ok - When has your bike EVER seen wide open throttle...? hehehehehehehe

Was that when you had the carb off cleaning the spider webs out ?

Yup - and the spider webs are still there!
PM Sent.......

Out of ideas I checked the carb to head coupler and it was slightly loose. pulled the tank and tightened, but no change. I rode about 12 miles yesterday and it seems to be doing much better. I put some sea foam in the fuel so perhaps it has done something. The throttle was slow to return to closed so I removed air filter and sprayed some carb cleaner into the carb bore. It seemed to help.

As for the popping on decel, I farted around with the fuel screw. It was at 2 turns. I tried 1-1/8, same, then 3 turns out. At 3 it doesn't pop and idles fine. This seems like it is too far out. perhaps this is masking another issue like restriction in the idle circuit.

Richening up your fuel screw to get rid of the decel pop can mean you need a larger pilot jet. Im at 6000' and use a 42 or 45. One of those is stock, i cant remember off had which one. These bikes seem to be lean from the factory. I think a lot of guys run 45 or 48 at lower altitude. Start with the right pilot jet and tune the clip and main jet from there.

When I WAS riding in AZ - mainly out at Wildcat North of Scottsdale, I ran:

Pilot: #48
Main: #165
Fuel Screw: 2 Turns Out
Needle: JD-Red, 4th Clip

And it ran pretty good (no comments from you Neil!)

When I first got my 2005 it was from CA and had the smog stuff on it, and the decal pop was really bad. I removed the smog stuff and used the Baja Designs Block Off Kit - no more pop!

Here in NV we ride from about 5,000 ft. up to about 8,000 ft. and I just change the jets to:

Pilot: #45
Main: #162
Everything else stays the same and while I have not ridden it since leaving AZ (Injury Time Out), it ran good like this before I moved to AZ.....

Hope this helps,
Bob

RLPII wrote:When I WAS riding in AZ - mainly out at Wildcat North of Scottsdale, I ran:

Pilot: #48
Main: #165
Fuel Screw: 2 Turns Out
Needle: JD-Red, 4th Clip

And it ran pretty good (no comments from you Neil!)

When I first got my 2005 it was from CA and had the smog stuff on it, and the decal pop was really bad. I removed the smog stuff and used the Baja Designs Block Off Kit - no more pop!

Here in NV we ride from about 5,000 ft. up to about 8,000 ft. and I just change the jets to:

Pilot: #45
Main: #162
Everything else stays the same and while I have not ridden it since leaving AZ (Injury Time Out), it ran good like this before I moved to AZ.....

Hope this helps,
Bob

Dang !!! I had so many things I could have added to this

Arizona X wrote:Out of ideas I checked the carb to head coupler and it was slightly loose. pulled the tank and tightened, but no change. I rode about 12 miles yesterday and it seems to be doing much better. I put some sea foam in the fuel so perhaps it has done something. The throttle was slow to return to closed so I removed air filter and sprayed some carb cleaner into the carb bore. It seemed to help.

As for the popping on decel, I farted around with the fuel screw. It was at 2 turns. I tried 1-1/8, same, then 3 turns out. At 3 it doesn't pop and idles fine. This seems like it is too far out. perhaps this is masking another issue like restriction in the idle circuit.

Carb cleaner is bad to spray in the throat , you can damage the slide plate seal , also , if you need to turn the screw to 2 turns or more ,means either the pilot jet is slightly clogged (if you dont have the correct cleaner tip tool , then just replace the jet), or you have the wrong size pilot jet for your elevation , but i doubt its the jet size , i would bet on the pilot jet being clogged , the jet is about $6 , that should get your fuel screw back to where it needs to be , between 1 1/4 - 1 3/4

As for throttle binding , check your cables for binding , and if you removed them , then most likely they are mis-adjusted , as the throttle should "snap" back with the bars turned in any direction or full turn either direction , if it does not , then the cable is bound or mis-adjusted , or there is dirt in between the throttle tube and the bar , or there is dirt down inside the carb where the cap is that covers the slide/needle access , you need to fix this ASAP to avoid a stuck throttle