Once and for all, GK76a SP carb O-Rings

[Jaicen]

Can anybody confirm the correct size required for the main jet holder O-Ring on a GK76a SP, with the 35mm carbs?

I've tried it unsuccessfully using the specified BS010 rings. They seem to be too fat to allow the jet to seat correctly without splitting. The rings I took out seemed much thinner.
Any suggestions as to what to use, given that I can't now find the original rings

[Jaicen]

I just went out and pulled out the carbs again, only took 40 minutes this time, not three days like the first time!
The main jets are not seating in the carb body because of the excess sized o-ring, which is causing the erratic idling. The O-ring I was supplied with is at least twice as fat as it needs to be, so i'm taking the damn thing with me to the shop tomorrow!

Incidentally, the jets themselves are 110, is that the correct size??

[Jaicen]

Ok, this is an example of how the BS010 ring looks in the carb body:



And on the jet:



If your O-Rings look like that, something's wrong!!

I took the jet to a local shop that specialise in seals, and they measured it up for a perfect fitting ring, which should look like this:



Having fitted those rings to the carbs, the bike now appears to rev perfectly. It screams through the revs, although i've only run it on the stand so far.

In conclusion, if you have 35mm GK76a SP carbs, you may have to tweak the O-ring sizes to get your bike healthy again.

[stripes1976]

yes the o.ring size is correct. And yes 110 is also correct. When fitting the o.ring you need to lubricate it with silicon spray to allow it to slip in without damage.

[Jaicen]

Those o-rings seem to be much too big to sit in. I know about lubricating them to make them slip in. The new size I used appear to be working just fine, and are closer to how the originals looked when removed. If you look at the top and middle picture, you can see that the O-ring is sitting on the thread when it's compressed, so is obviously much too fat to fit into the space available.
Also, the jets are 100, rather than 110. I think I was a bit confused when I posted that.

[stripes1976]

don't worry i read it as 100. I can't say i've ever had any problems with the o-rings not fitting. Make sure they are viton or they will rot out very quickly

[Variablevalves suck]

Stripes is correct. If you try and fit them dry you will have problems with them rolling up and pinching. Carb cleaner is the best stuff and at the worst use fuel.
There is some confusion over the o'rings as Tonys list of sizes is for imperial sized ones and as we all know Suzi use metric. The ones i supply are as Suzi sizes and some are a little thinner than tony's.

[Jaicen]

As I said, I use lubrication to get the rings in. Even the thin ones wouldn't go in without it.
The rings my supplier were giving me simply will not go in, they're probably 0.6m too wide.
To be honest, I was going to get in touch with VariableValves to get a set of rings, but I couldn't remember your name! Does the third picture above loook right, because that's the set i'm using.
Hopefully, i'll be able to give the bike a shakedown today or tomorrow, so if it's working i'll be happy.