Yamaha TRX850 Enthusiasts Forum

Here is the info on Kennys fuel tap mod

Hi Its actually very simple I removed the spring from the vaccum diaphram and replaced it with washers to make sure the o-ring seal sealed the back part of the tap then reassembled the vaccum side. I then removed the tap side retainer ring with the ON-PRIME-RES and simply rotated it 90 degrees clockwise so now ON is forward OFF is down and RES is backwards JOB done it really is that simple.

Here are some photos of a fuel tap mod that I have done today

1st remove vacum spring



2nd replce the spring with washers or a 5mm spacer



3rd file off the lug



this is the position for fuel on



reserve



and finally the off position

If it is what i think it is, then it's interesting... But to be clear, what is the result of the mod?

When my fuel tap goes again I'm just gonna buy a PINGEL Hi-flow unit to go with the FCRs

Bob

HansJ wrote:If it is what i think it is, then it's interesting... But to be clear, what is the result of the mod?

+1????

Another thing, is it just me or have any of you actually ever managed to put tap onto reserve on the move, I've never managed it yet and now just refuel before it ever hits reserve

The reason for this mod is to stop the tap leaking when it becomes faulty. I only posted the pics of this mod as some one asked how to do it on another thread it is a quick and simple fix for a faulty tap that works, it turns the tap into an on/off and reserve tap with on vacum needed.

SDN wrote:Another thing, is it just me or have any of you actually ever managed to put tap onto reserve on the move, I've never managed it yet and now just refuel before it ever hits reserve

touch wood, i haven't had a drama with my TRiXie's tap yet . . . . and yes i can select reserve on the go . . . woo hoo.......
cheers
fung

dixonj wrote:The reason for this mod is to stop the tap leaking when it becomes faulty. I only posted the pics of this mod as some one asked how to do it on another thread it is a quick and simple fix for a faulty tap that works, it turns the tap into an on/off and reserve tap with on vacum needed.

Excellent, i suspected that was the purpose, but it wasn't clear to me at least! No criticism whatsoever!

SDN , selecting reserve at speed ? No problem ...
Just reach in behind your left knee and the tap is there !!

Its never been there when I've gone on reserve (last meet!!)

Dave E

I am doing the fuel tap mod described here so that I do not need the vacuum line to the tap but have a question about the small spacer that is put in place of the diaphragm spring.

I may be wrong but it appears to me that in the original tap the spring closes off the fuel flow when there is no vacuum provided by the inlet tract.

When the motor is running the vacuum would pull against the spring force and lift the diaphragm allowing fuel to flow past the spigot/O-ring seal on the opposite side of the diaphragm to the spring.

If the spring is removed and replaced with a spacer on what was the vacuum side of the tap, would this not hold the diaphragm in the closed position preventing all fuel flow?

I must be missing something here because the mod obviously works; I just can't understand how it works.

Can anyone explain for me?

Thanks

Wombat wrote:When my fuel tap goes again I'm just gonna buy a PINGEL Hi-flow unit to go with the FCRs

Bob

Anyone checked wich tap to choose, i saw their vacuum one but are there a straight fit for us?

misterdimwiddy wrote:I am doing the fuel tap mod described here so that I do not need the vacuum line to the tap but have a question about the small spacer that is put in place of the diaphragm spring.

I may be wrong but it appears to me that in the original tap the spring closes off the fuel flow when there is no vacuum provided by the inlet tract.

When the motor is running the vacuum would pull against the spring force and lift the diaphragm allowing fuel to flow past the spigot/O-ring seal on the opposite side of the diaphragm to the spring.

If the spring is removed and replaced with a spacer on what was the vacuum side of the tap, would this not hold the diaphragm in the closed position preventing all fuel flow?

I must be missing something here because the mod obviously works; I just can't understand how it works.

Can anyone explain for me?

Thanks

Re fuel tap mod replacing the vacuum spring with a spacer or washers is to seal the vacuum part of the fuel tap off this prevents fuel leaking through the vacuum part of the fuel tap and running down the vacuum pipe. if you read the first part of this thread it is explained that you also modify the front of the fuel tap to change the flow through the tap. if i am wrong someone be along to correct me.


have a look at this thread
viewtopic.php?f=37&t=7021&p=71082&hilit ... mod#p70408

All is clear thanks.

I now see that the diaphragm is disabled by the spacer and over looked the fact that flow is now redirected by the altered tap orientation.

I'll give it a go.

seems like a good mod to do whilst i'm at this stage of my build. Think i will also cut down the main fuel pipe inside the tank closer to the reserve, comes with the obvious risk of less reserve but hey ho, needing to turn on reserve whilst leant over on aroundabout isnt a lot of fun.