gas tank vacuum lock?

Hi I am still having problems with my bike shutting off or surging sometimes when ridding my XJ1100.
I have been ridding it this past week and took it for some long night rides. It ran great on those rides and no problems at all. Last night I changed the oil and cleaned the plugs and greased the shaft. Today is so nice so I wanted to go for a long ride. I filled it up and took off. About a mile down the road it bucked and seemed to be a bit low on power. I was on a back road and not pulling a lot of Rs. It did this a few times and I decided to head back home. I got on to the main road and about half mile down the road at about 3k and 40 mph the bike just quit. I rolled to the side of the road and tried to start it. No go. I took out one plug to see if it was wet. It was dry. I put it back in and after 5 min I tried it again and it started right up. Ran smooth and I babied it home. I thought about it and was thinking the tank screens might be dirty and was going to pull the tank and drain it and take a look. But then I realized that this happened last time I filled the tank! I did replace the cap seal a few years ago. I have been filling it up to the bottom of the rim. Or all the way full. Is there a tank vent somewhere on this bike? Let me know if you have heard of this problem.

 

The tank vent is in the gas cap.

How to: http://www.xj4ever.com/gas cap.pdf

 

Also check to see if fuel is flowing through petcock which operates off vacuum (I'm assuming the 1100 has same petcock as mine).

If you switch to Prime for free fuel flow through petcock does it run better?
If so, maybe petcock.

 

Well it must be the cap. I opened it and took it for a ride. No problems.... ran it like that for about 10 miles and then closed it. Ran it over 100 miles and no issues. I just won't fill it to the top anymore. Cgutz.... I removed the vacuum control on my bike last year. To many fuel lines for me lol.

 

it only takes about 20 minutes to dissassemble the cap and clean out the vent with some carb spray.
it is just a ball bearing and a hole which comes out under the chrome cover and you do not have to remove cover.

 

Yeah I will do that thanks!

 

By the way, My cap looks new no corrosion or rust in the tank at all.

 

The check-ball is tiny, as is the hole. It does not take much to clog it, or for the ball to stick.

 

sorry to hawk a 6 year old post....

but having a similar issue as the one mentioned at the start of this.

sputtering and low power in 3/4 gear. When throttle is stable, getting revs and jerks, and popcorn exhaust sounds.

my cap hissed at me one particularly hot day and my mechanic mentioned it was probably this issue. Trouble is, the problem 'shouldn't' be the cap seal, as my cap is literally 3 mon old. It's a cheap chinese piece of sh*t but it's at least new.

I took it all apart like the PDF...found all new and shiny bits and bots in there, did find a blue cellophane ring that was similar to the brand new cling film on the top of it when i unpacked it... thought maybe that was the problem...seemed to run better, but the issue returned.

my friend says to 'enlarge' or 'drill' the vent holes...but i have zero knowledge about how to do so, or how much...

thoughts? anything would be helpful

 

you wouls have to remove chrome shell to enlarge hole there is a spring and ball that opens when presure is building up in tank.

to test if it is the gas cap unlock cap this should open it up enough to prevent presure build up

 

Your Gas Cap and You

spray some cleaner in the vent hole see if it leaks out from under chrome cover this will tell you if it is clogged

looks easy enough to drill out the vent even without removing chrome cover
but use a carb cleaning tool to see if it is clogged

 

greased it up with carb cleaner and seems to be running better... i may still need to drill the hole out a bit, any tips, walk-throughs of that? it seems easy enough, but i don't want to go to deep, or to large a gauge bit.

 

you will have to drill compleatlly through the hole. see if you can run a paper clip through the hole or if you have the carb cleaning tool see what fits.
if passage is clean maybe consider leaving the ball out or looking at the area it goes into for defects.

before you modify the cap take a run with gas cap unlocked or open but not up. see if the same condition exists. this will help keep you from chasing your tail if it is not the cap.

 

check the condition and routing of your vacuum line 4 mm iD . it may be collapsing on you and cutting off fuel flow from petcock.
check the fuel line 6mm ID for same conditions.
are you using a paper filter they are known to cause issues.

 

Thanks for the advice.
One thing; don’t know where 4mm ID or 6mm ID are??

 

ID = Inside Diameter

 

don't know the 'map' of all the parts... so i don't know where the vacuum line would be.

would be GREAT to have some sort of schematic of where pieces and parts are. haven't found one yet.

 

You're right, there is no real good simple diagram that I can find. It really isn't too complicated though.

The vacuum line in question would be running from a vacuum port on one of the intake manifolds to the fuel petcock. The vacuum is what allows fuel to flow when in "ON" or "RES" positions.

What @XJ550H is suggesting is that if there is a problem with that vacuum line then it may not be getting enough fuel since the vacuum is required to "open" the petcock. It can get kinked, or if it is the wrong type of hose it can collapse under vacuum or melt.

Do you have a stock fuel petcock?

The paper filter problem would be a fuel filter made out of paper between the petcock and carbs that restricted fuel flow. The preferred fuel filter type is a sintered bronze.

 

Such things exist in the service manuals. Be mindful that each of the publishers have managed to leave things out, so to have a comprehansive manual you'll need both a copy of the Yamaha service manual and a copy of either the Haynes or Clymer manuals. Also note that there are erroes in all of the manuals, all of which have been corrected in various posts in the DYI section and in Chacal's forums.