Western Massachusetts new guy

[FJmonkey]

There might be something causing the diaphragm valve not to close.

While were on petcocks, what would it take to set this petcock up.

http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3A89-93petcock&cat=34

The diaphragm is missing in the photo, so a new one seems to be in order... But new ones are not a FRU (Field Replaceable Unit). Finding the same material and cutting a new one could be done. Considering how long the original one lasted, just get a new petcock and move on to the next issue.

Not sure what the clear looking material is just right of the safety wired barb fitting is. The color and shape makes me thing it is silicone or RTV sealant. Gas dissolves that stuff. Then it can get into the carbs  .

If the diaphragm is still good then the spring is likely weak from age. Good luck finding a new spring of the same size and rate. You can buy some time by stretching it out just a touch. But due to age it will fatigue quickly back to where it is now.

The last part of the equation is the O-rings, find an exact duplicate and replace it.

It can be done, how much money and time do you want to spend?

[rktmanfj]

While were on petcocks, what would it take to set this petcock up.

http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3A89-93petcock&cat=34

IIRC, a later model tank to go with it... the spacing is different on the mount holes.   

[Joe Sull]

The diaphragm is missing in the photo, so a new one seems to be in order... But new ones are not a FRU (Field Replaceable Unit). Finding the same material and cutting a new one could be done. Considering how long the original one lasted, just get a new petcock and move on to the next issue.

Not sure what the clear looking material is just right of the safety wired barb fitting is. The color and shape makes me thing it is silicone or RTV sealant. Gas dissolves that stuff. Then it can get into the carbs  .

If the diaphragm is still good then the spring is likely weak from age. Good luck finding a new spring of the same size and rate. You can buy some time by stretching it out just a touch. But due to age it will fatigue quickly back to where it is now.

The last part of the equation is the O-rings, find an exact duplicate and replace it.

It can be done, how much money and time do you want to spend?

Sorry Monkey, I was just showing John what the diaphragm looked like. I did use silicone and it did brake down and stopped the valve from sealing. The last time I took my carbs apart there was chunks of silicon on the float seat screens. My petcock is working good NOW. I was just wondering what it would take to fit the cheap petcock up and I see that Not at Lib answered that.

[FJmonkey]

No worries from me, just calling it as I see it. I want what is best for our members. If mistakes happen, then get it fixed ASAP... I make mistakes, when called to the carpet, I fess up. Simple as that. Truth is the Truth.... Don't mess with it, it can bite you in a bad way if you twist it...

[John322]

Hi all,

I've been pretty busy going through the bike to get it ready to ride.  I took apart the petcock and nothing seemed clearly wrong so I cleaned it up and put it back together hoping something was stuck.  It didn't dump out fuel anymore but when it should have been closed there was still a very slow but steady drip so I will bite the bullet and order a new one.

I cleaned the carbs and noticed what I believe is a dynojet kit has been installed.  The main jets have the number 114 stamped on them and the needle is adjustable.  The pilot jets are still stock so I'm thinking about stepping up to a 40 or 42.5.  From the comparison chart in the files section it appears that the 114 dynojet is actually smaller than stock.  There is also a post saying the chart isn't accurate so I'm not really sure.  Any recommendations for jetting the bike with the foam filters and a V&H 4 into 1 exhaust?  I will probably order mikuni jets through Randy since I need a few other parts.

Thanks again.  Can't wait to get the bike on the road.

[movenon]

Hi all,

I've been pretty busy going through the bike to get it ready to ride.  I took apart the petcock and nothing seemed clearly wrong so I cleaned it up and put it back together hoping something was stuck.  It didn't dump out fuel anymore but when it should have been closed there was still a very slow but steady drip so I will bite the bullet and order a new one.

I cleaned the carbs and noticed what I believe is a dynojet kit has been installed.  The main jets have the number 114 stamped on them and the needle is adjustable.  The pilot jets are still stock so I'm thinking about stepping up to a 40 or 42.5.  From the comparison chart in the files section it appears that the 114 dynojet is actually smaller than stock.  There is also a post saying the chart isn't accurate so I'm not really sure.  Any recommendations for jetting the bike with the foam filters and a V&H 4 into 1 exhaust?  I will probably order mikuni jets through Randy since I need a few other parts.

Thanks again.  Can't wait to get the bike on the road.

If it has a dynojet kit the diaphragm springs might be different also. Possably lighter spring.  (running richer in mid range?)
Here is a picture. The left side spring is a stock Yamaha FJ spring.

George