[atengnr]

3000 miles ago, 95" build was completed with SE Heads, SS570 cam. Since then, the rear spark plug has been considerably darker than the front (front looks good IMO). Im aware that the rear runs richer, but this is a big difference. The rear plug has a sooty appearance to it, while the front is white to slightly tan. I checked for an intake leak with WD40 and found nothing.

I also noticed that engine has used about 1/2 qt of oil in that time.

Could valve seals be defective on the rear cyclinder or would engine consume more oil if they were bad?

The bike starts and runs well and no smoke is visible at any load/engine speed.

Thanks.

 

[HIPPO]

1/2 qt in 3K is normal consumption with synthetic IMO, actually low consumption with the regular oil.

 

[atengnr]

1/2 qt in 3K is normal consumption with synthetic IMO, actually low consumption with the regular oil.

Thanks. I use synthetic, though the stock motor didnt use any oil in 3000 mile intervals (always full on dipstick).

Any explanation for the rear cylinder plug looking sooty??

 

[HIPPO]

Pure speculation, but with the fuel these days on bikes where the AFR is correct you hardly see any color on the plugs. Like you say, there usually is a difference from one to the other, perhaps it's just rich overall.

 

[atengnr]

Pure speculation, but with the fuel these days on bikes where the AFR is correct you hardly see any color on the plugs. Like you say, there usually is a difference from one to the other, perhaps it's just rich overall.

Thanks. The problem is the front plug is nearly without color, just a bit of tan, while the rear is sooty.

Should I expect that this build might burn more oil than when it was stock??

 

[jim t]

95" Build oil consumption valve seals

just a thought, but if you had an intake leak in the front cyl. and a rich carb, that would create that reading