Mikuni 38 mm round slide

[Slow Pete]

Hi All,
         I have just put a new needle jet in my carb and it is not as long as the original, the main jet still goes in and is in the right place but there is no room for the round thing called the cup that fits above the main.   Anyone come across this before ?   Looks like it should still run without it but I assume its there for a reason.

Thanks

   

[tony27]

Sounds like you have the wrong series needle jet fitted. The cup you refer to acts as a baffle to minimize fuel surging from what I can see & if possible I'd use it as per how it left the factory

[bazza]

How much shorter is it? If it is not as the one that came out why use that type?

[mick25]

Unless the one you took out was the wrong one ? And the new one is right .

I have found this out with these old rockets we play with , some bikes have had so many owners over the years and funny things happen when the wrong parts are fitted and the new owner thinks that part is the right one .

[Slow Pete]

Could be Mick,   Its starts ok and revs out much better with the new one.   [It was running rich]   I will take it for a ride tomorrow and see how it goes.  If it doesn't work I will put the old one back in. 

[JohnnyO]

That needle jet you fitted is a different series for a different carb, you need the correct one and use the main jet baffle.. The series is stamped on the side of the needle jet

[ARN]

mikuni make a main jet extender piece that screws into needle jet before main jet  there on ebay

[bazza]

If have to use old needle jet (runs rich) try needle with same angles and length but fatter (to lean) ??