air filter height

[jeffro1954]

I bought an air filter on ebay and I think it's too tall, the air box won't close. Threw away the old one so can't measure that one. What is the height of a air filter for a 1978 XS1100?

[TDodge7]

i had the same problem , the air filter likes to get caught on the top half of the air box when you put it on , lean over the bike and grab the bottom half of the air box on each side and pull up , eventually the filter will pop over the edge of whats holding it back (i think it's the edge of the posts that the wing nuts screw in to) it took me a while to figure out that that's all the problem was . i keep looking at the half inch gap and saying to myself there's no way this is the right filter . push hard , you'll hear a pop when it's right and then after that it'll be easy to take the air box bottom on and off , the filter just has to stretch over the obstruction . oh , and make sure you have the air filter fully seated around that raised portion on the air box bottom half (this may also require some stretching) if you've done it right you should be able to turn the air box bottom over without the filter falling out .

[Lamric]

62mm high (excluding the foam)

[jeffro1954]

air filter

Hey thanks, wondered if that was the case, I've pulled pretty hard, just have to stay at it.
wondered about another thing. No 2 and 3 cylinders are running cooler than 1 and 4. plugs are a little black on those two cylinders. compression on all 4 are the same. carbs were just cleaned. Can float height do that? Other suggestions where to look.
just got it running. Bike was sitting in a farmers shed for 5 years.

[TDodge7]

on some years the carbs were jetted differently in the middle two cylinders to keep them cooler , like on my 80 carbs the middle two emulsion tubes are different . or your mixture could just be off . keep trying with that filter , mine is a k&n and it took some serious fighting to get it on the first time , now it slips on and off like it should .

[skids]

You really need to know what range is running rich for those two carbs. The emulsion tubes are more for the main jets at the higher ranges of rpms and the pilots are more for the low ranges. The float heights can affect all ranges except I think very low idle rpms. The idle mixture can be adjusted via the pilot screws to compensate for differences with the pilot jetting. If you think your floats are adjusted good and you are noticing that the two inside head pipes are a noticably cooler at idle, you can screw-in the pilot screws about an 8th of a rotation to make the mixture less rich.

Of course you should not even think about any of that if you have not balanced the vacuum with manometers (aka carb sticks). The reason I say that is because when you make "vacuum" adjustments, it positions the butterfly plates differently, affecting the air+fuel supply to that particular carb. As the plate is adjusted more open, the 3 pinholes have a bigger influence into the mix.

That said, never make more than one type of compensating adjustment to carbs at a time so you can check the affects, or you'll just end up chasing your tail!