Question-------------------------
Followup To
Question -
I have a 1987 CR250. When I put in a new stock plug BR10ES it fouls within the hour. Runs great while it lasts. Doesn't matter if I idle or rev up hills. It looks oily. When I put in BR8ES it never fouls instead it pings under extended heavy load like riding in sand. I guess this is to be expected as the plug is too hot. It looks white. Any suggestions? Don't say get a BR9! Then I'd have the worst of both? Too rich? Adjust needle clip? Old 2-stroke oil? Mix less than recommended?
Thanks in advance,
Steve
SBright33@mindspring.com
Answer -
Hi Steve,
Change either air or fuel to adjust a bit leaner. Make changes a step at a time to know the effects the change has made.
What air filter is being used and what is it condition? Is it over saturated with oil? Is the air intake restricted by any means?
What tweaking has been done with the carburetor if any?
What fuel/oil ratio premix is being used?
How old is the oil and fuel?
What is cylinder compression?
Any engine modifications or performance mods?
mshively1@woh.rr.com
Respectfully,
Mark Shively
Brand new air filter. Same problem with old filter. The premix oil was sealed in original bottle. Bel-Rey? 15 years old. New gas 91 octane the CA junk. I moved the clip one step to make it leaner many years ago. No performance mods.
AnswerHi Steve,
I tried sending carb tuning files to your email. I received a reply email that you must add my email to your email preferences (security measure) before you can receive my emails.
I would like to know cylinder compression when engine is cold, and when when problem occurs. It's like the doctor taking our vitals.
If the ignition is not breaking down and causing the problem, I suspect the oil fouling may be caused by one of the following:
1. Lugging the engine while riding.
2. Age of oil; unstable burning.
3. Engine overcooling.
4. air-fuel screw adjustment.
Did this problem occur with fresh two-stroke oil?
You may try lowering the needle a notch. Undo the change if performance is not improved. Also, replace the fuel oil with new. Try these and we'll go from there.
Mark
