'93 750, Carb Question - Vacuum

[brgaulin]

Hello KatRiders, brgaulin here, pretty new but I have a quick question.

At the end of last year I got myself a Katana. The guy who was working in it before I knew about it did some weird things to it and just wow. He had the coil wires wrong, carb is all messed up and many other things. Needless to say it didn't run.

After putting the cables on the spark plugs in the right order I could get it to start up, but it was running rough, like real rough. My choke wouldn't stay on unless I held the choke on the handlebar(cable is good), then it takes forever to warm up, like 10-15 minutes on choke. Then if I ride it, if I come to a stop sign it stalls on me unless I keep the throttle on. So lots of things going on, so I figured I want to overhaul these carbs and get the back up to snuff.

So yesterday, now that it is nice out, I pulled the carbs out and dismantled them. I found many o-rings that need replacing because they are cracking, and I am already on that. Also my air screws were 3-4 turns out each, so there is always that.


My question,
Should there be a vacuum line between carbs 3&4? And if not, what should I be doing with those vacuum lines. The manual isn't helping me too much with this.
Picture:

[92xjunker]

The only vacuum port is on the right side of carb 4, the upper T fittings between the carbs is a vent for the bowls. Hoses from those route over the air box threw the fittings on the filter housing then to the bottom of the bike. There are 4 additional vac ports, they are for syncing.

[Kreylyn]

Take that line off, and put caps like the other 2. That's how the sync ports should be covered.

Krey

[92xjunker]

What, that's not balanced? Hehe

[brgaulin]

Thanks guys, I figured no matter what that was, it was wrong. So those four ports are what you use to sync then plug them. Will do =)

[Purplehaze]

Wait.... Is that a fuel filter? Get that off there.

[brgaulin]

PurpleHaze -

I do want that on there for a bit. The bike sat for years and I haven't yet cleaned the tank. When I emptied my carbs there was a ton of gas in them, or at least I found it to be a lot, so it is definitely flowing just fine, but ya, eventually.

Is there any serious advantage to not having one?

[Kreylyn]

PurpleHaze -

I do want that on there for a bit. The bike sat for years and I haven't yet cleaned the tank. When I emptied my carbs there was a ton of gas in them, or at least I found it to be a lot, so it is definitely flowing just fine, but ya, eventually.

Is there any serious advantage to not having one?

Yes, in that there is absolutely NO advantage to having one, and having one will cause problems.

If you have a petcock screen, that's going to filter out all the larger particles the in line filter you have installed would.

If particles can get by the petcock screen, then the fuel filter isn't going to filter them well enough to stop your carbs from getting gummed up. If the filter could, it would not flow enough fuel for the bike to run right.

If you feel there is an issue that you would consider a fuel filter for, forget the filter... fix the issue. Cleaning and rust removal on the gas tank is simple and cheap. Clean it.

Krey

[arsenic]

As far as having an in-line filter. It won't stop any of the small particles from getting in your carburetors, so there is no point to have it. On a pre 98 intake system, there are 2 fuel lines going to the carbs. Unless the filters are 100% straight up and down, which is nearly impossible on a two line intake, it will cause fuel starvation. Again, keeping the fuel filter on because your tank is rusty isn't helping a thing.

[brgaulin]

Sounds good to me. Where can I pick up some fuel line? Would a hardware store have any?

[e30bradley]

any good hardware store should have a nice selection. Make sure to get a kind that is nice and flexible.. NOT EFI line, way to stiff.. your fuel lines have just about no pressure in them.

[brgaulin]

Silly question, what size ID is the fuel lines on a pre(93) 750 kat? US, not Cali

[Kreylyn]

Silly question, what size ID is the fuel lines on a pre(93) 750 kat? US, not Cali

8mm is OEM. 1/4 is really tight (slightly larger than 7mm) but can be made to work. 3/8 is a little loose (slightly larger than 8mm) but with good clamps can also work. Most auto shops will only care standard sizes, but if you can find the 8mm... get it.


Make sure it's reinforced fuel line (cross cut has the white string in it).


Krey

[41 Redhawk]

Some places will have 5/16s fuel line which should be just right (as Goldilocks said).