Viton v/s metal tipped float valves

[JTGS850GL]

Lately I've been having issues with float's sealing even after replacing the complete inlet valve assembly. I noticed that Yamaha and Kawasaki both used BS34 carbs of the same era but with one difference... Suzuki used metal tipped float valves while the others used Viton tipped valves. Just curious if anyone has tried to use the complete Viton tipped assembly on their bike. It looks like you can transfer the entire float seat and needle assembly into our carbs. I know that most manufacturers switch to the Viton tipped needles in later years.

No comments on "why not use OEM" please. This is simply an exercise in seeing if the newer, more up to date, components would retrofit into ours or if there are any drawbacks to using them.

[jbthomp]

If the float heights are set right and your petcock doesn't leak the inlet valves don't leak.....

[tkent02]

If the float heights are set right and your petcock doesn't leak the inlet valves don't leak.....

Transposed a bit, if the inlet valves are leaking the petcock needs to be fixed.

[Nessism]

Sounds like a good plan. Viton tipped needles will seal better. Not as durable as all metal needles though.

There are lots of small detail differences between Suzuki Mikuni's and Kawasaki Mikuni's for example. Mix and match the best from each might be ideal.

[JTGS850GL]

If the float heights are set right and your petcock doesn't leak the inlet valves don't leak.....

They sure can if the float valves are not perfect. Even with a working petcock, the needle can still cause the engine to be very rich when running.

The problem I'm trying to address is the OEM valve assembly is $$$$ and the aftermarket valves seem to be having problems even when new. Looking for a reliable alternative to the aftermarket metal tipped needles. The Vition tipped needles seem to be a good possible alternative. There are good reasons that many manufacturers switched from metal tipped valves to the Viton tipped ones. They do tend to seal better and are just as compatible with ethanol infused fuels.

[tom203]

"...the needle can still cause the engine to be very rich when running"

I doubt it- if engine is running ,it's using fuel-small dribble but something.

[JTGS850GL]

Doubt all you want but I've seen a valve leak bad enough to fill a cup of gas in a matter of a minute or two. If the float is leaking more then the engine is consuming then the float level will rise higher then its set point.

[derwood]

probably not what you want, but ... It can be the brass seat that is damaged and leaking, not the steel needle. Have you tried carefully seating the steel needles in the brass seats with a hammer and punch? (depending on the needle you may have to use a hollow punch to avoid damaging the spring or use a sacrificial needle) this works quite well. . Can't do it with viton needles.
and no, I haven't tries fitting viton needle valves.

[tkent02]

I have heard of people lapping them in like intake valves….. Seems completely ridiculous to me.

[mikerophone]

The problem I'm trying to address is the OEM valve assembly is $$$$ and the aftermarket valves seem to be having problems even when new. Looking for a reliable alternative to the aftermarket metal tipped needles. The Vition tipped needles seem to be a good possible alternative.

+1

I need to replace mine and am considering the Viton tipped versions of the the aftermarket steel ones. Curious if anyone has actually done it?

[philosopheriam]

I just replaced the OEM steel needles in my VM26's with a set of Viton tipped ones - I have no idea which bike the ones I used came from...

My buddy works on a variety of Italian/British/Japanese bikes and he has and entire box full of different Viton tipped needles. In essence, pick one that isn't too tall and doesn't bind in the seat. Then, do a preliminary setting of the float height with a ruler or caliper. Lastly, you MUST check the float height using a set of clear tubes inserted into the float bowl drain screw holes - this will tell you definitively if the float need to go up or down.

The viton tipped needles I am using are the same diameter yet a smidge taller than the originals. No problem, I just bent the tabs on the floats a bit to get them in spec.

[Crankthat]

Rebuilt the carbs on my sisters Honda CF? 450 a few years back.
It has the Viton tipped needles.
Took them apart one week and went back the next to rebuild and reinstall.
Spent most of a day trying to figure out why they would overfill and run out the overfill drains.
When it started to get late I gave up with the carbs still on the bike and went home.
Was going to stop by the following weekend and chase the problem again.
They had stopped leaking by then.
I had rechecked the float level A few times.
Ran my fingertips in the needle seats to feel for debris or scoring.
Even used one of the wire Dremel tools that looked like a paint brush in the seats to no avail.
I still do not know the cause.
My two guesses would be.
Guess 1- The tips dried in the wait and then while sitting in the gas while on the bike softened.
Guess 2 - A weird air pocket-bubble.

I really think it was guess #1
If I ever rebuild a set with them again they will sit in a container with gas until ready to install.

[JTGS850GL]

Good to hear. I'll be getting ready to set up some BS34's with Viton tipped valves in a few weeks. I'll post results.

[mikerophone]

Think I'll do the same with my BS32's soon.

Adjusted the float levels a few weeks ago and since adjusting the valves I now have an overflow problem. I noticed one of the stock needles has a slight score where it seats so Viton it is...


philosopheriam - do you just find clear tubing slightly larger than the 6mm drain bolts to press or twist in? I've searched high and low (locally at nut and bolt supply houses) for a .8 pitched 6mm bolt that I could then drill out the center of and cement/glue/epoxy tubing to but no one has the right thread pitch in town.

[philosopheriam]

Well, I ran into a hiccup with my viton tipped float needles...

Reassembled everything today and for love or money, I could not get the damn things to seal correctly. The bowls consistently overflowed or they would not hold their levels correctly.

I thought I paid attention to everything, however, I think I overlooked one critical detail - the taper of the tip on my viton needles is different than the taper of my original needles.

So, just as a FYI, I don't see this as a problem with the viton needles themselves, more of a problem with the ones in particular that I selected.

Just a heads up...