Electric fuel pump yes/no??

[Snow]

XVS650's have fuel pumps and carbs afaik.

[HobbyMan]

I know somone out there makes a vacuum operated pump for things like mowers and such. Two would run a coupla psi. You could tap the vacuum from the intake manifolds. I have never used them except on really small ones for RC engines. I will try to do some searching.

[goldcoastguy001]

Great info guys, I think after what was said bout the Busa pump i might try to look into the XVS650 pump and the vaccum pump as suggested, (although the thought of a mower pump on my beloved xs is daunting....lol..) I have a XVS Shadow i might raid the pump if its not too hard to fit and try to save some bucks if it works i'll buy one for the XS, didnt think to look at the shadow always heard the buzz from the bike when i switched on key but didnt think it was a fuel pump....I'll keep you informed as to how it goes..with pics if it works..

[Crazcnuk]

I think the big question on everyone's mind, is WHY you want a fuel pump on the XS to start with...

[AlanB]

Hi Goldcoastguy

If your taps are not supplying enough fuel, you have a fault!..... Don't fit a pump to get around it; find the fault. Either your tank breather is part-blocked, a hose is kinked, or you have a choked gauze somewhere.

Check to see if the problen still happens with the tank cap open. If it is no better, check the screens in the fuel taps.

Some carbs (don't know about the diversions!) have a small screen on top of the needle valve (fuel inlet valve?) which can cause problems.

My bike supplies enough fuel for GSXR carbs, but during high speed runs on the dyno, it gradually leaned out, due to the cap vent not keeping up; I had to modify it to flow more air......... I would start by looking there!

AlanB

[Crazcnuk]

Hey Alan, I think this thread shows why your tag line is wrong!

[AlanB]

Hi Crazcnuk,

I have modded all sorts of bits of my bike (and every vehicle I have owned!) but always to find an improvement - Or at least to try to find one.

However, I am not in favour of adding bits for no good reason; it is hard to believe that of all the bikes on the forum (Tuned, big-bored, gas-flowed, etc.) ONE might need a fuel pump.....When all the rest manage with gravity.

If you doubt my commitment to modifying, there are some pics of a couple of my bikes in an earlier thread on the forum here;http://www.xs11.com/forum/showthread...7964#post97964 There are three more in the shed, including a Trike and a hardtail chop. The SG (orange one with the little fairing!) is currently getting the back wheel changed for a 4.00x17 three-spoke, and a big brace added to the swing-arm. Pics when it is finished.

AlanB

[Crazcnuk]

heh, wasn't bugging YOU, just the sentiment, considering we are in a discussion about a mod that no one seems to think is necessary.

If you want to get into mods, the Monte Carlo in my sig is a 1983 with a 502cuin big block, w/ narrowed Ford 9", TH-400, reinforced frame and home made crossmember...I am just waiting to afford the blower kit!

Mods are fun, to a point.

Personally, however, after a vehicle gets to be 20+ years old, I no longer want to mod, I want to restore. Nothing irks me more than some guy gutting a 57 chevy to make a hot rod.

[goldcoastguy001]

Okay looks like some people reading this thread are gettin' icthy?? Now as far as i know let me know if ANYONE has an XS with Diversion carbs on it. now the carbs have been sync'd (by yamaha), the hole bike was originally stripped to the frame and bolt for bolt rebuilt, F/tank was cleaned and sealed and new petcocks installed with new tubes etc. the bike runs FINE under ALL normal and some extreme riding habits.......after reading the lastest replies I went to the garage to check the tank flow from the petcocks before replying. both petcocks empty the tank within a matter of about 6-7mins. and the carbs are spotless if I take out the drain screws in the carb bowls on all four carbs i can empty the tank in about 10 mins give or take a few (via a cat litter tray jimmy'd up with a tube in the corner to collect the fuel)....by the way what a waste of fuel but worth it to prove a point a to myself. I just got back from a test ride with the fuel cap open and no difference. I am assuming that the carbs flow a higher volume of fuel (maybe even the carb bowls are slighty smaller?? but not by much. Therefore the 1100 is drawing more fuel than can be supplied to the carbs to keep the level constant. I run excellent color plugs and I spose i am being picky bout the fact that a run that constists of redline revs from start thru all gears and then the bike sems to drop off at about 265kms. I know it wont go faster but i am sure it will get there faster if the fuel level is more constant to keep up the mix and stop it leaning out, my lasty 1/4 mile run was 10.24 an it feels like it has more to give...

[Crazcnuk]

Awesome performance.

However, if the carbs can drain (through the drains) the entire tank in 10 minutes, I think they are supplying more fuel than the engine could burn in that same amount of time, as a group.

Have you tried the same drain test with 4 large pickle jars and a stop watch, just to make sure you don't have one 'slow' carb? Maybe you just have one lazy carb that is holding you back?

[goldcoastguy001]

crazcnuk, you might be on to something, I wouldnt have any idea how to test that? I thought that if the carbs are sync'd they should be drawing the mix evenly. I assume you mean to fill a jar to a set level from the drain plug of each carb bowl and time it, then do the same test for each carb to see if they all match. Will try this shortly.

Cheers

[81xsproject]

I think he just means drain individual carbs into jars while timing to see if all the bowls are receiving fuel at the same rate.

On a side note, I think that is the fastest quarter time I've seen reported here. Be careful, you may create a high demand for 900 diversion carbs

[Crazcnuk]

exactly 81XS, if you have 4 jars that will fit under the carbs, you turn off the inlet fuel, take out the drain plugs, thenlet the fuel go.


If you have less fuel than will fill the 4 jars, you can just let it go and see if they are all the same, if you have more fuel than the jars will hold, just watch the jars. If one is way out you should be able to tell easily.


BTW this has nothing to do with 'synching'. Synching the carbs makes sure that all the carbs are creating the same vacuum, so they will DRAW the fuel the same through the venturis.

This test makes sure that all the carbs can get fuel into the bowls at the same rate. May point out bad hoses, plugged screens, or a sticky float/valve.

[goldcoastguy001]

well to cut a long experiment short, with the jar method it seems all the carbs are draining reasonably close to the same rate.....on a dangerous suggestion from a mech at the track (and the availablity on new parts if i messed it up...lol..) I took the carbs off and removed the float bowls and fuel float needles...now i found my needles have a rubber type stopper on the end to seal the hole, what we have done is drilled this hole ever so slightly and set the floats to compensate for the extra height caused by the needle seating a little more deeply than before....we did this by drilling the first one and refitting the floats to it and one that wasnt drilled and used the difference(bout 1mm) to bring the float back up to the right level. After the test ride I dont think i have gained any major increase in power but it has stopped the leaning out........I spose only a test at the track will tell for sure, but i do thing i have as much out of this XS as it will give.

On the side note from 81xsproject, I have read so much about how fast some of your guys bikes are i thought i was missing out...lol.....I didnt think the 1/4 time was that much better than standard....0-100kms is consistent 3.4secs with the slowest run after the rebuild at around mid 12's now with the tuning finished and its all working it runs consistent low-mid 10's it also tops out at about 265kms on a long top speed run, but i dont know what that is in mph? but i can say that Diversion carbs are readily available here in Aussie..

Cheers

[81xsproject]

We are glad to hear that you found the bottleneck. I was wondering if there could be some sort of slow-down from where the fuel entered the carbs to where it entered the bowls. Good job