Where can I get viton o-rings for carb rebuild

[koolaid_kid]

I am rebuilding my BS34 carbs on my GPz. I purchased the kit from cycleorings, but two of them do not fit, the air screw and the drain screw. I sent a pic to cycleorings, and his response was (applicable part of response) "I really have no advice for you. I've never seen these particular carbs before."
He thought they might be similar to the A & B orings from the VM carbs, so I sent him the dimensions of my orings, but have not received a response.
So, does anyone know where I might find an assortment of o-rings? This is keeping my rebuild of the carbs on hold (I want to do the first successfully before I start on the next 3) so any help would be appreciated.

 

[Nessism]

There are lots of places to get O-rings, try a Google search. McMaster-Carr is where I get my O-rings, but there are cheaper places out their that sell in smaller quantities.

If you have the old O-rings it's an easy matter to measure them and order what you need. I don't recommend ordering an assortment since there are too many specific sizes that won't be covered. Even if you don't have the size it's not that hard to figure out what size as long as you can measure the OD and ID of the interface parts. You want an O-ring with about 1mm smaller ID than the part it's installed on (unless you are talking about super small sizes). Ideally, there will be 1mm of crush on the OD when the part is installed.

BTW, Robert Barr doesn't use Viton O-ring, he used Buna-N. I prefer Viton and have put together my own carb kits for that reason although I'm sure Buna-N is fine unless you plan to keep the bike 20+ years.

 

[koolaid_kid]

I looked at McMaster-Carr, they had nothing close. I understand Googling, but that gives me millions of hits, most of which have no bearing on carb-sized o-rings. I was just wondering if someone could narrow it down a bit.

 

[Nessism]

I looked at McMaster-Carr, they had nothing close. I understand Googling, but that gives me millions of hits, most of which have no bearing on carb-sized o-rings. I was just wondering if someone could narrow it down a bit.

Nothing close? Doesn't sound right. They sell both metric sizes and Dash number sizes. Did you check both options - you often need to mix and match.

If you can measure the parts it fits on/between and I'll help you.

 

[koolaid_kid]

No, I only checked metric. It's pretty frustrating, b/c Z1Enterprises sells them in their rebuild kit, but its $22 bucks a hit:
http://www.z1enterprises.com/detail.aspx?ID=512
They are the two o-rings on the right. The top one goes on the air screw, the bottom one goes on the drain screw. Since I have a DynoJet kit, I would have to toss most of the kit, except for the needle and seat.
I'll get the standard caliper out and try them again.
The Air Screw measured as follows:
I.D. 3.35 mm
O.D. 5.55 mm
Width 1.80 mm
I had spares in the kit, so these measurements are pretty exact.

Drain Screw:
O.D. 7.25 mm
Width 2.0 mm
I.D. is probably around 5.90. I have not removed the existing o-ring in case I can't replace it.

 

[Nessism]

How are you determining the dimensions if the old O-rings are still in the groove?

Edit: just saw your comment about having extra air screws.

 

[koolaid_kid]

Just looked at standard sized o-rings at McMaster-Carr. Still no match.
Thanks for the assist, I appreciate it.

 

[Nessism]

No disrespect but your measurements don't add up.

I.D. 3.35 mm
O.D. 5.55 mm
Width 1.80 mm

With a 3.35 ID and 1.8 width, the OD would have to be 6.95mm.

EDIT: same thing with your drain screw measurements: the ID in this case would have to be 3.25 mm.

I suggest you go back and check the measurements. You will never find the sizes you need otherwise.

 

[tas850g]

i am rebuilding my carbs on a 1985 600zx and i just went thru the dealer as Robert Barr could not help. They are only about a $1 ea. for the fuel o-rings (4 o-rings) and about the same price for the fuel screws. The 0-ring that costs way too much is the float bowl 0-rings, about $14 each.

I didn't want to spend much time looking around for compatible 0-rings. Call me lazy.

 

[koolaid_kid]

I did make a mistake on the width, it should have been 1.6 mm, not 1.8mm. But that is the width of the slot, not the oring. Again, I can't take it off w/o breaking it. The other measurements on the air screw are correct, but it is also an old oring, so the od is most likely no longer accurate for a new one (flattened by age).
Sounds like I'll make a trip to the dealer Tuesday (closed on Mondays in Indy).
I'll repost if I can't order them. Thanks for the help.

 

[koolaid_kid]

Wow. $10.32 for 2 o-rings. That hurts.

 

[Nessism]

I did make a mistake on the width, it should have been 1.6 mm, not 1.8mm. But that is the width of the slot, not the oring. Again, I can't take it off w/o breaking it. The other measurements on the air screw are correct, but it is also an old oring, so the od is most likely no longer accurate for a new one (flattened by age).
Sounds like I'll make a trip to the dealer Tuesday (closed on Mondays in Indy).
I'll repost if I can't order them. Thanks for the help.

For that air screw you can use a 3.0 mm ID and 6.0 mm OD O-ring. You want a little stretch to put the O-ring on and a little compression on the OD when you install it.

http://www.mcmaster.com/#o-rings/=77pk0q

Going to the dealer is fine, but I can assure you that you CAN find the proper size on McMaster-Carr.

 

[koolaid_kid]

Excellent. What do I need to do for the drain screw? If removing it will give you the measurements you need, that won't be a problem. Sorry, but my brain has been fried by all the issues this bike has presented me.

 

[koolaid_kid]

Wow, my brain is more fried than the eggs I had for breakfast. The drain screw measures:
ID 4.10 mm
Width 2.10 mm
So I can order ID 4 mm and OD 6 mm, correct?
Thanks for putting up with my lack of cranial functions this morning, Nessism.

 

[Nessism]

Wow, my brain is more fried than the eggs I had for breakfast. The drain screw measures:
ID 4.10 mm
Width 2.10 mm
So I can order ID 4 mm and OD 6 mm, correct?
Thanks for putting up with my lack of cranial functions this morning, Nessism.

Is 2.1 with width of the groove or the width of the flatten O-ring that's on there now?

EDIT: You want an O-ring with slightly smaller ID than the mating part. I'd try 3.5mm ID for the O-ring. Pick the width based on the OD needed, again, you want about 1mm compression when you fit it to the mating part. They sell 3.5 x 1.5 wide, this will be close but again, double check everything and be an engineer to make sure you get all the measurements right.

 

[koolaid_kid]

That is the width of the groove, I moved the o-ring out of the way to measure the ID.

 

[Nessism]

That is the width of the groove, I moved the o-ring out of the way to measure the ID.

What is the ID of the O-ring seating hole the drain screw fits into?

 

[koolaid_kid]

Be an engineer, argh. I feel like all my engineering bits got toggled this morning.
I can't measure the width of the hole, it is recessed into the bowl and my caliper won't fit down in there.
If I go 3.5 ID, width 1.5, that will yield OD of 6.5, although it will be larger b/c the o-ring is stretched, correct?

 

[Nessism]

Be an engineer, argh. I feel like all my engineering bits got toggled this morning.
I can't measure the width of the hole, it is recessed into the bowl and my caliper won't fit down in there.
If I go 3.5 ID, width 1.5, that will yield OD of 6.5, although it will be larger b/c the o-ring is stretched, correct?

Yes, stretched. You are learning fast! Slight stretch to install, and about 1mm compression on the outside of the O-ring is just about perfect - although super small sizes can have less compression.

 

[koolaid_kid]

Thanks. I'm not usually this slow at picking up new concepts, but I guess I just had to get into an o-ring state of mind. The 3.5mm should work, the 3.8mm is definitely too large OD.
The part you selected for the air screw should work also, I went back and double-checked your work.
Thanks for the assist, it is much appreciated. And the best part - McMasters-Carr delivers to my door in one day.
And I cover all the carbs (6 times over) for the price of one set from the dealer.