[shwine617]

I just put K&N air filters on my 82 GPZ750. Now if I go past 1/4 throttle it breaks up. I had to remove the air box from the bike to put the 4 K&N's on. There was 2 hoses that were going to the airbox. One went to the crank case right below the carbs and the other went to the vavle covers. I think it was causing a vaccum leak so I connected them together with a PCV valve. The bike still won't run right. I think I need to re-jet the carbs. I am not sure what size jets I am going to need and I don't know what would be the right thing to do with the two hoses that went to the airbox.
Thanks for the help !
Cory

82 GPZ 750

 

[UngaWunga]

Air hose from the crankcase to the airbox is the crankcase breather hose, to vent off extra oily air from the crankcase to a safe place, the airbox.

The hose from the valve cover is also a breather. For releasing extra pressure. Don't connect the two, route them to a catch bottle of some sort. Otherwise the pressure has no where to go and you might blow a seal...

Taking off an airbox to put on individual filters leans out the mixture through the whole range. You'll at least need to go up a mainjet size or two (maybe three). Might find that you need to either put small shims under the slide needle to richen up the midrange and to either open up the fuel screw another 1/4 - 1/2 turn or close the airscrew by the same amount, depending on what your carbs have, to fatten up the idle to 1/4 throttle response.

 

[shwine617]

If I put like a valve cover breather on the crankcase and left the pcv valve on the valve cover, would that work?
I am going to get the number of the jet and see if I can ones that are a few sizes bigger. I also have a kerker pipe on the bike if that makes a big difference.
thanks for the help again!

82 GPZ 750

 

[UngaWunga]

quote:
If I put like a valve cover breather on the crankcase and left the pcv valve on the valve cover, would that work?

fuck if I know. Why use a pvc valve? Its not a car. Route both hoses to a catch bottle and be done with it. Use a small sode plastic bottle or somthing.

quote:
I am going to get the number of the jet and see if I can ones that are a few sizes bigger. I also have a kerker pipe on the bike if that makes a big difference.
thanks for the help again!

Yeah, a kerker will make it even leaner as its a freer flowing pipe.
Oh how to jet the thing: buy this:
http://www.pro-flo.com/proflo_mikuni_tuning_manual.htm

It'll set you straight on jetting.