Is the matching main jets a problem?

[Bizzy13]

The carbs on my 81 were built by a custom shop a year ago, before I owned the bike. I tore down the carbs for a good cleaning yesterday and while putting them together today I noticed that the main jets in each carb are 137.5's. aren't these carbs supposed to have different sized main jets?! And I also noticed that the mixture screw on the right carb was shimmed, left was not. Why would this be? Is that stock?!!

 

[Scorpio1963]

If your bike is a sohc then both mains would be the same size and your numbers are correct for stock jetting.
As for the shim on the misture screw the spring may be weak and this was done to increase tension to balance each side.

 

[Bizzy13]

137.5 is stock jetting?!!! Damn that's huge!! This thing has open pipes and pod filters. I'm beginning to think this custom shop dunno what the hell they're doing

 

[Scorpio1963]

what year and model of your bike?Its a maxium then the jet size would be different sizes and smaller.
If its xs400 sohc that size is not realy that big.

 

[Bizzy13]

It's an 81 xs400 single cam. I just read another post here on this forum that says stock jets on this bike are 135, which would mean my main jets @ 137.5 are 2 1/2 over, which should be good. BUT! I read in a Yamaha forum that the sohc xs400 had 142.5 mains stock?

 

[xschris]

The 77 model had 142.5 as stock.

 

[Bizzy13]

And the 81? 135?

 

[xschris]

Yes. 80-82 sohc 135 main

 

[Bizzy13]

Bad ass, thanks bro!