Fuel Mileage Part II

My 1985 Maxim XJ700 is still getting around 25 mpg. After my last post, I checked and realized the plugs that came with the bike were wrong. I have since changed them and it starts much better, it idles and drives fine, but the economy sucks. Upon pulling the plugs I found 3 of 4 carboned up, my assumption is that I'm still running too rich. I have ran Gumout and now am part way through a tank mixed with Seafoam. I've checked the air filter and it does not seem impeded. So here's my question.. Do I now have the carbs removed and cleaned? I assume the Seafoam and Gumout would clean ports that gas passes through but not ports for air. Anywhere else I should look first?

Thanks.

 

Is your enrichment circuit getting stuck open by the cable restricting it? That is REALLY bad milage. Seafoam helps, but won't remove hard deposits and anything that got by the filter (or the lack thereof).

 

Thanks, can you help direct me on how to check on this? I've only had the bike for a couple months and am not that familiar with it. Also would the hard deposit lead to it running rich, it would seem that that would restrict the gas flow and cause a lean condition.

 

Search for a plug read thread.
It has a great link that explains why your plugs are black.

 

It is hard to say where it could get stuck. A bad float valve will cause a rich condition, a bad petcock can cause a rich #3 (or where ever your vacuum hose is connected). The 4 into 1 will also zap your milage some from what I experienced with bad mufflers. In replacing mine with H-D mufflers, I went from 35 mpg to 45+ just by going back to factory style.

Your plugs should be a light tan color with a good air:fuel mixture. If they are white or bone white, you are running too lean. If they are black and sooty, your are running rich. If they are oily, well, you could probably figure it out but you have oil control issues. If they are wet and gas smelling, you have a dead hole.