Petcocks spacing

[Mikey]

From what Mikes XS website says that the mounting screw holes from petcock to tank is 42.5 mm and can be used for a 70-77
I just want to swap the petcocks from the 75 I just bought to the 77 I have
Does that seem correct

 

[willis]

There are some differences in early and later. I don't recall where the change was made, but I am pretty certain the 75 and 77 are the same.

 

[Mikey]

I did a really quick measurement the other day and I was getting like 33 - 34mm with them still on the bikes
So they should work
Thanks !!

 

[nj1639]

Looks like ‘78 brought in the wider spacing.

 

[Mikey]

I went out to the shop the other day when the sun was out and there the same spacing

 

[gggGary]

Spacing changed when they introduced the vacuum petcocks in 78.
They needed more room between the screws to clear the vacuum diaphragm housing.

 

[MaxPete]

True that about screw spacing, and it is important to note that the two different types cannot be interchanged.

Fortunately, for those who have problems with their vacuum petcocks, there are manual variants that fit fine and work just like old-fashioned manual petcocks.

 

[Mikey]

Ok what I dumb shit I are
Here I was so proud of myself because I thought it would be a great thing to put the petcocks from the 75 I bought over to the 77 I've had for awhile
Got the petcocks from the 75 tank all cleaned up and ready to put them on the 77 and SOB the hole spacing is way differen't from one to the other
The tank on the 77 is from a special and if I would have paid attention to what the cap looked like and when the bikes were side by side it's obvious there different
So the petcocks are back on the 77 and the 75 tank is downstairs soaking in vineagor to get a little rust out and it's petcocks are ready to go
So just a warning
DON'T BE A DUMSHIT LIKE ME

 

[gggGary]

yeah that's not a 77 tank, that's a MikesXS replacement tank.
LATE model spacing with the mikes retrofit manual petcocks.

 

[MaxPete]

Ok what I dumb shit I are
Here I was so proud of myself because I thought it would be a great thing to put the petcocks from the 75 I bought over to the 77 I've had for awhile
Got the petcocks from the 75 tank all cleaned up and ready to put them on the 77 and SOB the hole spacing is way differen't from one to the other
The tank on the 77 is from a special and if I would have paid attention to what the cap looked like and when the bikes were side by side it's obvious there different
So the petcocks are back on the 77 and the 75 tank is downstairs soaking in vineagor to get a little rust out and it's petcocks are ready to go
So just a warning
DON'T BE A DUMSHIT LIKE ME View attachment 364598View attachment 364601

....maybe some chewing gum to seal the gaps Mikey....?

 

[Mikey]

Well I've learned another thing new to me
It was a fun way to kill some time in the shop anyway

 

[MaxPete]

BTW - those Mike's manual replacement petcocks for late-model tanks work just fine.

 

[Mikey]

I've never had a problem with them I just thought it would be nice if both were in sync with each other
But I have on the handle bars a little diagram indicating which one should be facing foreward and which one faces to the rear to shut the fuel off
So not a problem

 

[MaxPete]

I've never had a problem with them I just thought it would be nice if both were in sync with each other
But I have on the handle bars a little diagram indicating which one should be facing foreward and which one faces to the rear to shut the fuel off
So not a problem

Yup, same deal on my '78E - but after a while, it becomes second nature to shut them off as I ride down the street and then let the bike idle till it stops.

 

[jetmechmarty]

BTW - those Mike's manual replacement petcocks for late-model tanks work just fine.

Well.... sort of. I don't find the quality anywhere near that of OE. For me, they are not futz free. Now that I know how to properly fix the vacuum tap, I believe that's my preference.

 

[Jim]

Now that I know how to properly fix the vacuum tap, I believe that's my preference.

Same here. Fixed mine about 6-8 yrs ago. it works like it should with no leaks.