Motorcycle Questions? Ask a Mechanic.
Hi, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, have you drained tank and replaced with fresh fuel?Could you please check and post back with the burn color of the spark plug tip?And have you checked/ensured that the air box and filter are fitted correctly with no possibility of an air leak?
Can you try checking the spark plug burn color?
It would helps us narrow down suspects; lean, rich, air or vacuum leak.
I understand and would look forward to an update tomorrow or when able.
Appreciate the update / information.
With fresh fuel and all others that have been tried/done, it would appear to still be a fuel delivery/starvation issue.
Let's go back to the basics, dis-assemble the carb (again if necessary). Soak and clean all metal parts using a solution similar to the product shown HERE.
In some instances, it may be necessary to use special cleaning brushes such as those featured HERE.
Of particular interest would be the bowl, float height and float needle & seat condition.
Please post back results / observations of the above once tried.
Sorry to hear the lack of developments.
Let's consider "...spark plug...dark and gray..." and work on to make it light brown.
Consider / try:
The please have the compression or leak down test.
For video insight, please click on compression check and leak down test
Yes please; click on the links above.
Ensure air box and filter are correctly in place with air entry only through the designated opening (no air leak).
If have not been done, check the air/fuel mix adjustment screw. Try 1½ from fully in.
Install back the air box and filter. (Is it an original?)
For some reason, it would appear that the air filter is 'not enough' and/or too coarse.
Add a layer (or more) of generic filter foam/screen to 'further restrict' air intake something like the product shown HERE. This add-on air filter should be placed between the air box's entry slot and the original filter (not before the carb).
If the old/original is still available, try it back (even if just for test purposes).
Otherwise, consider the above add-on filters.
If of interest, I use (when trying/needed) modded vacuum cleaner bags.
Incidentally, my wife reminded me that there was a time I used a layer or more disposable medical/dental face mask.
Actually any material that would 'further restrict' air intake/flow.
It can be tried raising the needle 1 notch at a time. If no clip notch, then inserting a small spacer/washer would also serve the same purpose.
Appreciate your kind understanding on the limitations of remote (not seeing) diagnosis.
Still, good luck and thank you too for the opportunity to exchange information.