Xs650, VM34s, low end seems rich, acts lean

[ProSimex]

Right,

So low end at idle to 1/4 throttle puffs of black smoke seemingly indicating rich, however popping and lack of power at 1/4 throttle without en-richer indicating lean. I just richened it up mix screw is at 1/2 turn. 2.5 slide, 25 pilot, 185 main, needle at 3rd, needle and needle jet I cant remember but they're the ones what everyone recommends. At 1/2 turn throttle response in better and no popping.

New cam chain, exhaust gaskets, 650central intakes, no leaks, XS pods. Valves adjusted, cam chain adjusted, timing is good, new plugs. I'm begining to suspect the pilot jets and main jets that I got from 650direct(MikesXS) are just poorly engineered mikuni rip offs. Needle and needle jets are genuine mikuni. Anyone think I should just go get some new pilot and main jets?

God I love motorcycles ;D

 

[Tim]

I'm running the same 25 pilot and 2.5 slide with a 190 main. I have 6F9 needles and P6 needle jet and my clip is 3rd from top.

Did you remove the air jets? There are little jets in the intake bell.

My air screw is 1 1/8 turn out from closed.

This setup ran well on the stock 650 engine and is now also running nicely on my 750 rephased enlarged valve high-lift cam motor so it was likely rich on the stocker, but it did run very nicely for a couple years.

I get all my Mikuni bits from my local Mikuni dealer - might be worth buying some new mains and pilots, double check your needles/needle jets and make sure the air jets are not there.

 

[Kanticoy]

Are you kidding me Tim? You got lucky enough to not have to change you're jetting in your carburetor? Some guys get all of the breaks!

 

[ProSimex]

Yeah Tim I based everything off of your jetting set up, the 190s seemed a tad rich for my rather restrictive cans. Needle and needle jets are the same as yours. And yeah the I binned the air jets as per your recommendations via text.

Im gonna toss the cheap mikes jets next weekend and put proper Mikuni brass in, I know better then to buy cheap shit, but I keep doing it.
And yes you have all the luck.

 

[Big R]

I have faith in Tim and Kanticoy, but I just want to add: have you confirmed your float height too? I know even new carbs can get banged around in shipping.

 

[ProSimex]

You what, no I haven't. For some reason I have no problem tearing a motor down but I have some sort of phobia of checking float height. How the hell do I do that? What should it be set at? Is there a pill to fix my fear?

Me and my short cuts.

 

[Big R]

I know the exact procedure is in the tuning manual. But basically flip the carb upside down, leaving it at a slight angle. The float should just barely be touching the float needle.

 

[ProSimex]

cool thanks, I have that manual in PDF.