Vacuum Advance Question

[AndyHartvig]

I am trying to get my xs11 that I just got from my father in law running and he seems to think that there is a leak in the vacuum line for the vacuum advance. Now I don't know much about these bikes YET but I'm learning. I think what I want to do is just replace all the vacuum lines. Can anyone tell me what to get and possibly where to get it.

Thanks

[crazy steve]

There's only two or three vacuum lines on the whole bike (depending on which model you have), but there's other places that can leak vacuum.

The vacuum advance wil be the hose coming out of the left-side engine case and going to the #2 carb. If you still have the vacuum-operated petcocks, you have two lines (standard) or one (special), going to the carb boots. But more likely leak points will be the rubber caps on the unused carb boot vacuum ports, the boots themselves if they're badly cracked, or the throttle shafts on the carbs.

If you can post a description of what the trouble is, and the year/model of the bike (with changes from stock, if any), we can probably point you in the right direction. If the bike has sat without running for any length of time, it very probably needs the carbs overhauled.

[3Phase]

Welcome to the forum, Andy!

For replacing vacuum lines I bought a package/coil of the orange high temperature silicone vacuum line. It looks ... orange but it's relatively thin and easy to work with. It doesn't burn or harden as it ages and it doesn't collapse and close up under vacuum when it's exposed to engine heat.

[James England]

Vacuum line is readily available on eBay. As Scott has said, vacuum line doesn't collapse under vacuum. The inner diameter is quite a lot smaller than the outer. As cylinder 2 sucks, it transmits the suction to the vacuum advance. If the pipe is just normal rubber pipe, some of that suction (vacuum) is lost because it's wasted on pulling the sides of the tube in (well, technically, allowing atmospheric pressure to collapse it..!), instead of pulling the vacuum advance unit. You want as little loss as possible, hence the vacuum pipe. It's really cheap and comes is several diameters

[motoman]

Add to Scotts reccomendation that came to me from him origially is that hose is a metric size and the hose he reccomends will apparently fit tighly to keep moisture out where it goes through backside of case. The regular vacuum hose of "looks like same OD" will be a bit oversized and could pinch off vacuum drawn.