what should be plugged?

on this project bike im working on, the vacuum operated petcocks were leaking something fierce, so ive decided to go back to a manual pingle petcock to simplify things. on top of that i have also chosen to take a performance air filter route by using k&n pod filters for my mikuni bs34's. ive already yanked that pesky emissions tube that plugs into the valve covers, but as far as what needs to be capped and what doesnt, im completely clueless. im under the impression if i dont do this correctly i can burn a piston up. also, with the removal of the vacuum petcock and installation of a manual, im not sure how to get my fuel to the carbs now? is there some insight as to how to do this or a guide or site of some sort. i know there are many kz's running pods and im sure a few with manual petcocks. -cc

Damn! After reading the title to this thread I was making a list but then I noticed it WAS about motorcycles. :woohoo:
All you should have to plug is the vac line that operated your petcock. You should run a hose off your crankcase breather (the one that connected to your airbox) up and where it can't dump on your back tire. They sell little filters you can put on the end. As for how to run the gas lines run them just like the vac petcock lines to the carb rack. If you got a single hi-flo pingle you might have to split the line. You can get splitters from most hardware stores. Now don't forget to TURN ON AND TURN OFF your petcock or you will get a rude lesson. If you are going from an airbox to pods you will most likely have to re-jet the carbs to run real good.

ccentralm wrote:

... mikuni bs34's....

Some excellent info is available by clicking > here .

Good Luck!

thanks locozuna! and patton, it sounds like i have to plug anything that isnt in use then? correct?

ccentralm wrote:

thanks locozuna! and patton, it sounds like i have to plug anything that isnt in use then? correct?

Except for the float bowl air vents which prevent vapor lock inside the float bowls. There are usually two vent nipples (one between carbs 1/2 and another between carbs 3/4) with each nipple having a tube attached which exits to open air. The tubes may be routed to under the seat in a stock bike, or routed around the swingarm to hang underneath the bike.

It's better to use tubes from the vent nipples rather than just leaving the naked vent nipples whereby water or other foreign matter could enter the nipples, or fuel leak from them onto a hot engine in event the bike for any reason goes down.

Here's the oem carb vent tube routing to open air underneath the seat on a 1976 KZ900-B1 LTD.

[Click on image for larger view.]



Good Luck!

ahhh, thank you, thank you!!

:woohoo:

ccentralm wrote:

on this project bike im working on, the vacuum operated petcocks were leaking something fierce, so ive decided to go back to a manual pingle petcock to simplify things. on top of that i have also chosen to take a performance air filter route by using k&n pod filters for my mikuni bs34's. ive already yanked that pesky emissions tube that plugs into the valve covers, but as far as what needs to be capped and what doesnt, im completely clueless. im under the impression if i dont do this correctly i can burn a piston up. also, with the removal of the vacuum petcock and installation of a manual, im not sure how to get my fuel to the carbs now? is there some insight as to how to do this or a guide or site of some sort. i know there are many kz's running pods and im sure a few with manual petcocks. -cc

Once again, don't plug anything except the emissions reed valve outlets on top of the engine. You do this by running one hose between the two outlets. The can on the bottom as everyone has been saying is what you DO NOT WANT TO PLUG as this will not be good but you either put a small air filter on it or leave it open but it is a really great idea to put a bent 90% angle hose on it if you don't put a small air filter because junk can get in it and well that wouldn't be too good either although most leave it open such as I but this season I will put a filter on it. Bugs have a funny way of getting in to things they shouldn't and road debris as well. The carb overflow tubes have long hoses and of course you know to leave those intact and routed away from engine. Other than that what are your worries? You eliminated the vacuum advance already on the petcock and put a pingle on it because you are a very smart man or have luckily done the right thing. Those old POS petcocks are useless and at best serviceable. I got rid of mine and haven't ever been happier cept that the reserve on the tank is about nil. If you run low you have less than a mile to make a pit stop or push.

My opinion on what needs to be done...

CARBURETORS
1. Carburetor vacuum fitting MUST be capped except for the one going to a vacuum petcock. If the petcock is manual/gravity, they ALL must be capped. ALWAYS use vinyl caps as rubber will crack within a month or two.
2. There are not overflow drains on a BS34 assembly so you won't run any hoses from them or cap them
3. SOME BS34 assemblies vent the float bowl through holes on the intake edge of the venturi. NOTHING should be plugged or capped. Some BS34 assemblies used on a Kaw have plastic tee fittings between 1&2 carbs and 3&4 carbs. These fittings should NOT be obstructed. It is a good idea to put a hose on these fittings and run the hose over the swingarm. In the even the bike overturns, gas will be routed away from your pant leg and the hot engine.

Emissions stuff
1. There was a vacuum canister which was previously attached to the airbox and the cylinder head reed valves and was operated by a teed vacuum line from the carbs. Remove all this junk; you have already capped the vacuum ports on 1 & 4 carbs where the vacuum line was connected. Use some black RTV silicon and fill in the ports over the reed valves. It is a good idea to leave them in place as they have effective gaskets.
2. You can use the RTV to seal the hole where the big hose went into the airbox or you can leave the hole alone. The air filter will catch air going through the hole and filter it prior to air going into the carbs. If you have pods, there is no issue here.

Crankcase vent
1. The crankcase vent is the cylinder shaped thing sitting on the engine cases behind your carburetors. It was previously connected to an airbox in the event any nasty stuff spewed out of your crankcase so it didn't go on the road. I guess the engineers figured that the air filters, being disposable, were a better target for blow-by. You have 3 options for dealing with the crank vent.
a. Leave it alone and exposed to the air. The chance of rain getting in isn't great but a bug could. I leave mine open on a couple bikes.
b. Put one of those hot-rod crankcase filters on that can be purchased at an auto parts store. As has been pointed out, if you have a lot of blow-by, this filter will clog and the crankcase won't vent. The next step is the engine blows up.
c. Put a hose on the vent and route over the swingarm. The only downside here is that if there is a MASSIVE venting (such as with a broken ring), you will have to deal with an oil slick under your tire. It is also possible that bugs can get in from here. Not joking about bugs. If a bike sits for a day or two in Texas, we are prone to get mud-dawbers crawl in any hole or opening and block it up with mud as they take up residence.

If I forgot anything, just ask here, please.