Mixture Settings and Main Jet Sizing

[iBoesen]

Hey guys,

long time lurker of the forum. I have a question today about sizing that I have not been able to find a definitive answer for.
Bike is a 1978 XS400

Many time I'll read "you have to go up a size" or "go +2 sizes on your main jet"
My question is, what exactly is "1 size"?
For example with my current build; it had a stock 142.5 Main jet, so is one more size up 150? 155?

My second question is a question about settings for my bike. I have gotten my bike to run before, but as of right now it is not. I picked up a project bike and it did not have the stock housing. So I went ahead and threw the classic pod setup on it, it is also running shorty mufllers.
PODS: http://www.ebay.com/itm/191766276310?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
Mufflers: http://www.ebay.com/itm/NEW-YAMAHA-...-MUFFLERS-SHORTY-CHROME-/262452743899?vxp=mtr

I can get the motorcycle to sputter for a little bit, some of the time when it is chocked.
I cleaned the Carbs from top to bottom, and I went ahead and threw a #155 Main jet in it.

Like I said, I could kind of get it to run, but not anymore. Does anyone have experience with this setup? What kind of settings did you run?

On my left side currently, the plug looks wet with gas, is this because the main to be too large?

Thanks for the help

 

[BBS360]

Those look like pretty cheap pods. It's quite likely that they are blocking ports in the carb mouth.
Do you have the stock intake tract that would have been between the carbs and filters? The rubber/plastic H-pipe?
Use it if you have it.

I believe jets go in increments of 2.5, so 1 up above 142.5 would be 145. I've seen it posted pretty recently.

 

[iBoesen]

Those look like pretty cheap pods. It's quite likely that they are blocking ports in the carb mouth.
Do you have the stock intake tract that would have been between the carbs and filters? The rubber/plastic H-pipe?
Use it if you have it.

I believe jets go in increments of 2.5, so 1 up above 142.5 would be 145. I've seen it posted pretty recently.

I do still have the intake tract, I will go ahead and put that on and give it a try. Although they are cheap, is there really much discrepancy between a $15 pod and a $40 pod?

Thanks for the answer to the main jet question.

I think I may go back to the 142.5 Jet and give a try to see what it does. Does the Main Jet affect idling/ startup? Or is that controller by a different jet?

Like I said in my previous post, my left plug is wet with gas, so I am not sure if it is getting too much fuel or what.