How does the fuel flow through the T on vm26's?

[andler2008]

i have a somewhat rigged setup right now just trying to get the gs 750 to fire on all 4 and i notice both the outside exhausts (1&4) are still cool. so i'm sure it's the carbs so i was wondering if the fuel needs the extra pressure from a full tank to fill the bowls or the bowls just fill up once the one before it gets filled.

[Steve]

If the fuel level is anywhere above the float bowl (that includes an almost-empty tank), and the passages are open, there will be no problem feeding fuel to the outboard carbs.

Why are you so sure it's the carbs? Both of the outboard cylinders are fired by the same coil, have you checked that?

Have you checked valve adjustment? Probably not likely, in this situation, but needs to be done at some point.

.

[andler2008]

i figured it out. just needed more gas. i guess i didn't feed enough in. and my petcock was doing it's job as well by leaking all over my lift. so they just didnt fill up correctly. now my question is, what are the ports on the bottom of the bowls? as soon as the 1 carb filled up it overflowed out of said tube. is that a stuck fuel needle? or maybe the float is set too high?

[Steve]

i figured it out. just needed more gas. i guess i didn't feed enough in. and my petcock was doing it's job as well by leaking all over my lift. so they just didnt fill up correctly. now my question is, what are the ports on the bottom of the bowls? as soon as the 1 carb filled up it overflowed out of said tube. is that a stuck fuel needle? or maybe the float is set too high?

Could be, on either one.

Have you bothered to properly clean the carbs and replace all the o-rings yet?

A thorough, PROPER cleaning of the carbs will go a long way to ensuring the carbs are doing their job properly.
It also lets you set all the adjustments to where they are supposed to be, so you KNOW where they are.

.

[andler2008]

yeah the guy i got them from said he cleaned them so i just said okay and went on my way. got home did some minor work like oil and filters and plugs and what not then tore the carbs apart. i took some guitar string and carb cleaner and went through as many ports as i could. put everything back together and put them on. don't have rebuild kits, but assuming that the needle valves are original, they probably just need to be replaced anyway. then i honestly never checked float levels, but as soon as that happened, i kinda assumed that that could be a possible problem.

i've worked on quite a few sets of carbs from kz400 to kz1000 and my gsxr1100 and it's unbelievable how different, yet so similar they are. so now i just have to get used to working on this set of carbs and get more comfortable with them and how they work.

[Steve]

Too many questionable items there, I will just highlight them for you.

yeah the guy i got them from said he cleaned them so i just said okay and went on my way. got home did some minor work like oil and filters and plugs and what not then tore the carbs apart.
i took some guitar string and carb cleaner and went through as many ports as i could. put everything back together and put them on.
don't have rebuild kits,
but assuming that the needle valves are original, they probably just need to be replaced anyway.
then i honestly never checked float levels, but as soon as that happened,
i kinda assumed that that could be a possible problem.

Do you see any pattern here?
- Never trust what the PO said.
- Guitar string and carb cleaner are no substitute for a proper "strip and dip" cleaning.
- You don't need "rebuild kits", just a set of o-rings from cycleorings.com.
- You should know about "assuming". Just follow the advice in tkent's signature: "To measure is to know."
- Checking float levels is one of the most-critical parts of putting the carbs back together.
- There you go assuming again.

Too many times, people will say "the carbs have been cleaned" when they have simply sprayed off the outside to make them look good, or they have dropped the float bowls and sprayed a little bit in there. Neither situation will clean out the important passages that are buried deep in the carb body.

Guitar string might help poke some crud out of the holes in the jets, but it will only stuff crud deeper in those 'important passages'. You need an overnight soak in carb cleaner dip (Berryman's or GUNK brands), followed by a HOT water rinse, then a couple spritzes of carb cleaner spray and some compressed air through the passages.

"Rebuild kits" typically contain inferior-quality brass pieces that you don't need and not nearly enough of the o-rings that you DO need, so are generally a waste of money (usually about $25 each). All you need is an o-ring kit from cycleorings.com. The guy that runs that site is our own member, Robert Barr. Be sure to get the o-rings for your intake boots. While you are there, splurge, spend the extra penny and get the o-rings for the drain screws. Not sure why they are not included, but they are worth the extra cost.

If you feel you need new needle valves, the best place I have found is Parts-n-More. $8 per set, so $32 for all four. Browse their site, they have a decent assortment of aftermarket parts for the bike.

Checking float level is critical, because ALL the circuits in the carb depend on the proper fuel level. Besides measuring the height, you should also verify that there are no holes in the floats, which have allowed gas to get inside, which will change their "float" height. Holes can be patched, but it's a tricky process.

It is also recommended to verify the actual fuel level with a clear tube that is connected to a modified drain screw, so you can see how the fuel level compares to the specified height.

.

[cowboyup3371]

Just follow the advice in tkent's signature: "To measure is to know."

You getting tired already Steve? Especially since that's Ed's signature; Tom's is Learn to ride fast, you'll never know when you'll need to.

[tkent02]

Twice in one day. I should buy a lootery ticket.

[chuck hahn]

As for the petcock leak...wipe off the bolts and instantly take a look and see if the fuel is getting them wet again. Then look at a parts fiche and notice there are special seals that go on the bolts to seal them against fuel migrating down the threads and dripping.

[1_v8_merc]

Check your Float needles and needle valves.
If they are binding up, or have friction, they won't open and close properly as the fuel level fluctuates. And you'll run too rich or too lean.