Mikuni Carb
Posted by Garenne on Aug 27, 2020; 5:06pm
URL: http://silk-motorcycles.221.s1.nabble.com/Mikuni-Carb-tp5001990.html
Has anyone tried a Mikuni carb on a Silk? A new 34mm Mikuni carb came with the boxes of bits that I have eventually managed to turn into a reasonable representation of an early working Silk. I have not seen any mention of Mikuni carbs in this forum and assumed that I was on my own trying to sort it out. I was too miserly to lash out on a new Amal carb having already spent more than intended but it would have made life a lot easier as it turned out. If anyone is interested I have so far come up with the following settings although work still needs doing to get it more to my satisfaction.
I had hoped that the previous owner when buying the carb had it set up to emulate the 34mm Amal but it proved to be set very lean in the middle range. It still runs very hot according to the temp gauge and I am still richening it up although I now have a nice brown colour on the plugs at last. In light of recent posts on the forum I have yet to try diluting the radiator content from the present 50/50 antifreeze. It needs a bigger needle jet to get the needle down to the middle range of adjustment. It is just that it isn’t as easy as with the Amal going to the next number, Mikuni offer a much greater choice. The main jet isn’t yet finalised as not many miles have been put on the new pistons and bores. However it was worth the wait and exasperation as it is performing better than expected if a little more loudly than I would like.
Mikuni Carb VM34-275 34 mm bore
Slide 2.5
Needle 6FJ6 Clip Position – 5 (Came with original carb)
Needle Jet 159 Q – 5
Main Jet 350
Pilot Jet 30
Carburettor Float Height 23mm