42mm manual petcocks for XS750 tank

[scott s]

I need manual petcocks (or rebuild kits) for an XS750 tank.
Mine are LH and RH, and have 42mm mounting holes. I can't find an exact match. Either the gasket surface is different, or the holes are 46mm apart. I found some TX500 petcocks that are LH and RH and 42mm, but the valve bodies look slightly different than what I have (not that it really matters, I guess).
Where can I find these:

 

[scott s]

Any reason why these wouldn't work?

https://www.ebay.com/itm/3039348119...w4Pl01JTi2&var=&widget_ver=artemis&media=COPY

 

[nj1639]

They should be fine and look like ones that I had purchased some time ago.....been used on a '78 xs650 tank AND an xs750 knee dent tank.......won't work on a '77 xs650 tank due to the smaller spacing on the '77.

I'll add that the fuel input option of left or right to the petcock is nice. The fact that the levers only work one way is moot (left points forward, right points back).........with these 38's I could probably run just the one side anyway.

I'll go check the spacing......stand by......

Knee dent and the Standard xs650 '78 tank are 46mm spaced. '77 xs650 tank is 42mm spaced. That's the view from here.

 

[scott s]

I measured mine and they are definitely 42mm.

 

[nj1639]

It is what it is no doubt.
As long as those petcocks state 42mm spacing you should be good to go.

Just like the spacing between the '77 and '78 Standard tanks are different, so too must the spacing on the different year xs750's must be. I have no idea what year my knee dent is.

 

[jetmechmarty]

https://yamahaxs650.com/product/petcock-left-hand-oem-type-1970-77-xs650/
https://yamahaxs650.com/product/petcock-right-hand-oem-type-1970-77-xs650/

I have an XS750 standard tank and I have each of these petcocks. I set my caliper to 42mm. Looks like a match to me.

The best part is that these are left and right.

 

[scott s]

Well, I went to install these and they are not 42mm as described. I get 40mm.
I have checked the hole spacing on the tank and the old petcocks a hundred times and they are definitely 42mm. Every petcock I see that looks like the old ones are 46mm (note the difference in the gasket mating surfaces).
For example, these look just like what I have, except they are 46mm: https://www.mikesxs.net/yamaha-xs650-petcock-non-vacuum-type-oem-447-24500-02-00.html
I am 100% positive that 46mm would be too wide.
I'm thinking about checking the internals on these to see if I can rebuild the old ones.

 

[WideAWAKE]

What’s keeping you from just rebuilding them???

 

[scott s]

I just figured out today which rebuild kit is correct. By the time I order rebuild kits, I can get new ones. I have another pair on order that I am going to try.

 

[Grimly]

Jeez, just file the inner sides of the holes, and use a sealing washer on the bolts.

 

[scott s]

Jeez, just file the inner sides of the holes, and use a sealing washer on the bolts.

It's not the inner sides that would need filing....it's the outer, and that would get into the groove for the sealing ring.

 

[vr3506]

I meassured XS1’s, they are exactly 42mm

 

[nj1639]

I'd probably be trying to fit the guts of the 40mm into the stock 42's......just because.

 

[Grimly]

It's not the inner sides that would need filing....it's the outer, and that would get into the groove for the sealing ring.

Sorry, I meant the 46mm ones. My reply seems quite snappy, not that it was meant to be.

 

[nj1639]

Sorry, I meant the 46mm ones. My reply seems quite snappy, not that it was meant to be.

Yeah, I drilled a Pingle 46mm base to fit my '77's 42mm spread when I ran that tank with a set of bs34's. The critical eye was in me own head, it worked.

 

[jetmechmarty]

What was the final resolution to this?

 

[scott s]

Different petcocks that didn't measure 40mm! LOL

It's kind of odd....the old petcocks measured 42mm, but the spacing on the tank was some weird, in between.....like 44mm. I finally found a set that fit.