Question about 1985 Yamaha XJ 700 X Maxim
Have 4 lines that just hang down but there 3 lines 1 off the number 1 carb and 1 off the number 4 carb and 1 comes off between the number 2 and 3 carbs where do the 3 top lines gcarbss
Posted by Anonymous on
There\'s no "fuel line diagram" for the Maxim-X that I\'m aware of but the fuel lines aren\'t all that complicated.
Let\'s start at the gas tank. The petcock has 2 hoses coming from it - the smaller of the two is not a fuel line - it\'s the vacuum line to trigger the petcock valve and it connects on the hose nipple at the top of the #2 intake manifold. Some people have petcocks where the vacuum hose leaves the petcock toward the back of the bike before doubling back to the #2 manifold. Others have petcocks where the vacuum hose leaves the petcock toward the front of the bike before connecting at the #2 manifold. Either way works. It\'s not important which way as long as the hose doesn\'t get kinked and cut off vacuum from the manifold.
The larger hose from the petcock is, of course, the main fuel feed. From the factory there was not an in-line fuel filter in that hose but there should be. In fact, it\'s one of the first things I recommend to people who are tinkering with their X fuel system. Install an inline fuel filter right behind the petcock as shown here:
http://www.maxim-x.com/fuel_filter.html (there are pictures midway down the page)
The end of the hose emerging from the fuel filter has bends in it in order to neatly find it\'s way to the fuel T between the #2 and #3 carbs. The T is just above the tops of the bowls. Don\'t be afraid if you see the fuel T rotate while pressing the hose onto it - that\'s fine.... unless it rotates too freely in which case the seals might dried up and you might experience some seeping or even full blown leakage around the T fitting where it enters the #2 and #3 carbs. Oh... one more thing about the main fuel hose - there is a guide loop bolted to the carb rack on the rail joining the top-back of the carbs, between the #2 and #3 carbs. The main fuel hose is meant to be held in that guide loop.
Two down - two to go.
There are only two remaining and identical fuel hoses - they are actually float bowl vent/overflow hoses. There are 2 more T fittings on the X Mikunis - both are at the same level.... just a bit higher up than the fuel T for the main fuel hose. There is one vent/overflow T between carbs #1 and #2 and another between carbs #3 and #4. Just like the main fuel inlet, these T fittings also rotate. But unlike the main fuel inlet, if they rotate too freely and imply that the seals may be dried up, it\'s of little consequence because they\'re only vent/overflow fittings anyway. If the carbs are setup right and the float valves aren\'t sticking then there should never be any fuel in those hose at all. Seriously - they should remain forever dry and fuel-free if everything is correct. It\'s only when the float valves stick or if someone incorrectly sets the float levels too high that you\'d ever expect to see any fuel coming from those fittings through either of the vent/overflow hoses.
There is one caution about connecting the 2 vent/overflow hoses. Make sure they aren\'t directed UP from the T fittings and draped over anything before heading down again. The hoses should leave the T fittings in a downward direction, otherwise, if there\'s some kind of condition that causes float levels to be too high, draped hoses will allow the fuel levels to get much higher in the carbs before draining away and that can lead to other unhappy things.
So to sum up - there are only 4 hoses involved in the Maxim-X fuel system (unless you\'re in California in which case there\'s an extra bottle and lines). 1.The petcock vacuum hose, 2.The main fuel feed which goes to a T between carbs #2 & #3 and which should have an inline fuel filter installed, 3.The left float bowl vent/overflow hose which connects to a T between carbs #1 and #2 and should be directed down, and 4.The right float bowl vent/overflow hose which connects to a T between carbs #3 and #4 and should be directed down. That\'s all there is.
Posted on Aug 21, 2014
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Posted on Jan 02, 2017
yes, the breather line hooks to the petcock on the line facing the back, the fuel line hooks to the larger one. the line from the breather is actually a vacume line that turns on the fuel, without it you will not get fuel out of the petcock unless it is in the prime position.
Posted on Jul 04, 2009
Are you saying that 2 & 4 got gas with external tank but not with gas tank? If so something else has happened ,if gas is getting to the carb it cannot by-pass 2 to get to 1. Take the tank back off ,connect to external, again. See what happens.
Posted on Sep 11, 2009
I'm guessing that the fuel block you refer to is the inner side of the petcock assembly. If this is so, the larger line is the fuel supply and connects to a swivel pipe in between two of the carburetors and feeds all four through internal piping. The second smaller hose is a vacuum line to operate the petcock and runs from one of the rubber carb mounts to the petcock. My 85' model also has four vent hoses running from the top front part of each carb back and down between each one. I hop this helps.
Posted on Oct 27, 2011
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