First thing I did was check the valve lash. I loosened the front plastics to get access to the exhaust. Both valve were good, no adjustment needed.
I pulled the carb to check it out. It always seemed to want just a touch of choke to stay running. I thought maybe the pilot jet was partially clogged. Surprisingly, it looked really good in there. Just a touch of debris in the float bowl. All jets were clear. I removed the 2 diaphragms and then cleaned it out with carb cleaner and made sure all the openings were clear by blowing thru with my air compressor.
After putting it back together, it does not run right. It misses at all RPM. The spark plug goes black after just a few minutes of run time. I have to give it throttle to keep it running. It is not driveable in this condition.
Here is a video link of what it is doing.
EDIT, Can’t post the link yet. Need 10 posts
I figured that I must have messed something up with the carb teardown since it ran fine before I touched it. I took it off and checked it 3 times since. I’m no carb expert but, I’ve been into enough of them to know my way around and not be intimidated. I’ve done a number of carb jobs on street bikes (vmax) which is a similar CV design but, there are 4 of them instead of 1.
The diaphragms are both in good shape (no holes), installed correctly as are their covers. All jets are clean and clear. All passageways are clean and clear. Choke plunger is operating properly. I did a wet check on the float level by attaching clear hose to the float drain tube. I marked the carb body at 4.5mm. Fuel level is spot on.
After checking the carb multiple times and not finding anything wrong, I started checking electrical items. I replaced the plug multiple times with no change. New OEM coil. New NGK 5 Ohm plug cap. I even tried a different (known good) CDI unit. No change.
I checked to make sure the timing chain did not jump while rotating the engine during the valve check. With the flywheel on the "T", I took the cam cover off and the "I" on the sprocket lines up the pointer cast in the head.
I did resistance checks on the stator and pickup coil. Stator was good. White/Red-White/Green resistance on pickup coil was good. Red-White/Blue resistance was .208 vs the manual range of .085-.105. I’m not sure if 1/10 of an ohm is enough to call it bad?
About the only thing I can thing of that I haven’t done is put a timing light on it.
Open to any and all suggestions.
Thanks,
Mike
’07 Grizzly 450 Stock
