Question about tanks and petcocks

[stevendefense]

I am trying to figure out what tank I am going to run on my xs400 project and I think I have decided on a tank from a xs750.

My question is this, my bike only has one fuel petcock, feeding the left carb. The tank I want to use has two petcocks. If I do run this tank should I use two petcocks (I would have to make a fuel inlet for the right carb) or should I seal the extra opening in the tank? And If I do seal the other opening what is the best method, welding or glassing?

 

[Ease]

You can run the two petcocks together into one line, then split into the normal connection on the 400 carbs.
Just use a y-connector.

 

[mysta2]

One way or another you have to get fuel from both sides of the tank. If you sealed one of the petcocks you'd have to drill a crossover into both sides.

 

[stevendefense]

Yeah I didn't even think about running both petcocks into the one carb. Sometimes I tend to over-complicate stuff. Thanks for the help.

 

[rudy]

Repro petcocks can be had from Mike's XS if they're the same as the 650. I have two on the 650, and I'm using one on my 400 as well. They're the same size. The only thing I don't really like is that it doesn't flip all the way to reserve as the handle is too long. I can measure to see if it fits if you like.

The new petcocks are pretty slick, since they don't leak like the old vacuum operated ones all do by now. Not a cheap fix by any means, but I think it's worth while. Just gotta get in the habit of turning off the petcocks when you shut off the bike.

 

[stevendefense]

I'm not really sure if I am going to use this tank or not. I saw one on Ebay and it kind of got me thinking about what tank I am going to put on this bike, I think it would look cool with the original knee dents deepened. I'm not really a fan of the vacuum operated petcocks, seems like it is way to complicated and problem prone for the small amount of convenience it provides. I was tempted to go ahead and buy that tank, but I want to make sure that I can get the bike to run first before I spend any more money on it. That running problem is about to make me pull my hair out. The only thing else I know to check for is a weak valve spring but it might be a week or more before I have the time to work on it again.

 

[rudy]

Whats the engine doing (or not doing)? What all have you done to it?

 

[stevendefense]

Its only running on the left cylinder. With a vacuum gauge hooked up I have about 5 in/hg on the left cyl (not really sure if that is good or not) and on the right cyl the needle flutters all over the place. I have checked compression and that was good, had the carbs cleaned in n ultrasonic cleaner, tested the coils. and most recently adjusted the valves, thinking that one was too tight, causing it to not close all the way. I had no change after that, so now I am thinking burnt valve or weak valvespring. The bad think is it might be a week or more before I have the time to pull the head off and check.