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When I bought my 82 XJ650 it had a wide open header on it. I just hit the start button and it started right up- no choke. I didn't care for the loud noise at high rpm's so I bought the stock exhaust and put it on. Now it has to choke which may not be a problem. Did this go lean or rich ? My plugs are pretty clean. The insolators are white with a little tan. I'm guessing this is good. The stock plug calls for a BP7eS. When I bought it the man used a BP8eS, colder plug for NGK. Should I stay with that plug or go with a hotter plug ?

Ron

I'm not the mechanical genius but I believe that when the open header was put on, the carb had to be re-jetted. I would think that to go back to stock exhaust, you would have to reverse that process as well.

That's really ... weird.

You have to use the choke ... which indicates you went lean

The old exhaust needed no choke, shich indicates rich...

But you went back to stock, which should, by normal standards, make the bike run RICHER if the jet sizes were increased...



Your description of the plugs sounds like it's ok ... i would take it to a place with an exhaust gas analyzer to tell you what's up ... Was the stock exhaust used??? Maybe it's been hollowed out ... or maybe while you were tinkering you knocked something loose and have a slight vacuum leak?

no, the exhaust isn't hollowed out. It is pretty quiet. Any suggestion about which plug to go with to help the leanness ?

It MAY be lean ... it may be just fine. Since your plugs are yellow and not ashy, you're probably ok. You can safely go back to the stock plugs, I don't think it will drastically change matters but it might.

Ok, I'm thinking about going back to the header and endure the noise with some ear plugs for the present time. My reason is that I have read it is better to run rich than lean for the motor. Does this sound reasonable ? I don't have blued pipes from the leaness so it seems to have not running real hot.

I wanted to also add that when the header was on there was no problem with the plugs.

Well, after changing plugs and puting the header back on I drove to NY this weekend and back. Over 400 miles. Today I pulled a plug and the insulator was white, no tan at all, just white. The plug with the stock dual exhaust was white with a touch of tan mixed in.With the header and the white insulator, doesn't it sound like it is running more lean than with the stock pipes ? When I first got the bike and it had the header I never paid attention to the plugs except to see they weren't carboned. Now that I have read more it seems the whiteness indicates "lean" when the header is on.

One more observation. When I took off the stock pipes I noticed it was sooty in the pipes and where the pipes go into the engine which makes me think "rich" even though it required choking to start. Does this seem correct ?