RS34 Flatsides leaking

[Stugill]

Good evening.

The RS34's on my Lawson have started to leak a small amount from #4 carb overflow when the bike is running. The carbs are clean and as far as I can tell the floats are the correct height - 17mm. I will get a float height tool to check this but I have a few questions.

1. The photo shows the tip of #4 needle valve, it is slightly scored, deffo the worst of the lot. Could this be the issue?
2. If needed where can I get the direct replacement?
3. They are all metal, into the brass? housing, are there any replacements that have a rubber tip that would work?

Any other thoughts or pointers?

Cheers

Stu

[Al]

I was dogged by this for quite a spell. It turns out that having bought several eyewateringly expensive float needle and seat combos, it was just the 'O' rings that surround the seat part. A couple of £ each from Motocarb and all good again. Mine were like cork when i took them off!!
On the one occassion it wasnt that it was one of the needle plunger pin springs that had let go. Didnt spot it and again bought a needle and seat combo for which i had to sell the house. Not really but ask and you will see!!
No harm done i guess because these are genuine Mikuni and you cant buy the needle on its own as far as i am aware.
Broken or weak plunger pin springs do seem to ba a feature though. To test them push one plunger pin against another or against a known good one from a non leaking carb. As in; test the questionable one, against the others in the set or against a new one that you buy.

17mm may be correct but had no luck with that method myself.
I bought the alloy bottom cap as a spare part and converted it into a float level guage by drilling it and fixing a short length of copper brake pipe into it and then a length of flexi pipe to make a dynamic fuel height guage.

AL

[Stugill]

Thanks very much, I'll look into those bits you've pointed out.

Stu