94 ZX-7 Will not idle after cleaning carbs...

lo cash john · 09-01-2005

So here's the deal...

I have a 94 ZX-7 that was running fine but it sat a while so I pulled the carbs and went through them. I fully stripped the carbs down (slides, floats, jets etc) but I did not remove the carb bodies from the carb rack. I then cleaned every last little bit and blasted carb cleaner through all passages, jets, emulsion tubes etc. I then reassebled the carbs, set the idle mix screws at 2 1/2 turns outand re-installed the carbs on the bike.

Note: The bike has a D&D muffler and DynoJet Stage I jet kit (used with stock air cleaner until now...) that I installed 7 years ago. Bike has always run fine with crisp throttle response.

Since I had the airbox off the carbs, I added a K&N air filter.

So the carbs are on the bike, all vacuum lines are hooked up, fuel line hooked up, a gravity feed tank is hooked to the inlet of the fuel pump (so I can sync carbs with stock tank off) and I put new plugs in the motor.

I crank the bike with some choke and she fires almost right away. RPMs com up with the choke on, so I back off on the choke to keep the revs down as it warms up. When I kill the choke completely, the bike dies out. I turn up the idle adjustment knob some and restart the bike. Same thing... Now understand that if you keep working the throttle, it hits on all 4 cylinders, revs good, all the normal stuff. But it just won't idel.
I figured, perhaps the air inlet for the idle jet emulsion tube was blocked so I pulled the carbs and checked each one. All are clean and clear. All idle mix screws have the tiny rubber O-rings and little washers. It just won't idle without some choke and that's just not right. So the only thing I can guess is that with the K&N air filter instead of that crappy foam filter that was in there , it's to lean at idle. What are you other guys thinking? Should I have upped the idle jet to go with the K&N air filter?

HELP!!!!!!

QKENUF4U · 09-01-2005

shouldnt have to be that drastic for a K&N filter. it should idle just like it did before ya pulled them apart.
i would start spraying some carb cleaner around each carb and see if the idle goes up/down etc. sounds like you have a vacumn leak somewhere.
good luck

lo cash john · 09-01-2005

I agree, it does seem like a vacuum leak but... I can imagine that on one carb, but that wouldn't cause it to not idle at all, would it? It would just idle on 3 cylinders and sound like crap. Besides, the rubber intake manifolds have never been off the head, the hose clamps holding the carbs on are tight (I even replaced the Philips head screws with Allen head) and I've disconnected the various stock vacuum hoses from the vacuum ports and installed brand new rubber caps to close off the vacuum ports. I'll try the old carb cleaner around the intake system trick and see what happens.

While I'm at it, do you or anyone have any recomendations on removing all the emissions crap having to do with the reed valves feeding air in the exhaust ports for less emissions? I'd like to reduce the amount of bull**** on the bike. You know, keep it all real simple and save a little weight.

Thanks,

John

lo cash john · 09-03-2005

Let me ask this of you guys. Has anyone ever heard of the stock hose clamps, for holding the carbs on, stretching? I am still having the idle problem and it does act just like a vacuum leak, but a leak on every carb. I have not tried to locate the leak yet with starting fluid or carb cleaner, I'm just tossing around ideas before I jump on this again tomorrow.

When I re-installed the carbs (the first time) I wiped out the insides of the rubber intake manifolds, then applied a very thin film of grease. Maybe the rubber is slipping and as the clamp tightens down, the rubber is arching very slightly somewhere around each carb. That would explain an intake leak on every carb...
What do you guys recommend as a prep procedure before reinstalling carbs to rubber intake manifolds?

Also, can anyone address my emissions equipment question?

09-01-2005	#1 (permalink)
lo cash john Newbie Join Date: Sep 2005 Posts: 4	94 ZX-7 Will not idle after cleaning carbs... So here's the deal... I have a 94 ZX-7 that was running fine but it sat a while so I pulled the carbs and went through them. I fully stripped the carbs down (slides, floats, jets etc) but I did not remove the carb bodies from the carb rack. I then cleaned every last little bit and blasted carb cleaner through all passages, jets, emulsion tubes etc. I then reassebled the carbs, set the idle mix screws at 2 1/2 turns outand re-installed the carbs on the bike. Note: The bike has a D&D muffler and DynoJet Stage I jet kit (used with stock air cleaner until now...) that I installed 7 years ago. Bike has always run fine with crisp throttle response. Since I had the airbox off the carbs, I added a K&N air filter. So the carbs are on the bike, all vacuum lines are hooked up, fuel line hooked up, a gravity feed tank is hooked to the inlet of the fuel pump (so I can sync carbs with stock tank off) and I put new plugs in the motor. I crank the bike with some choke and she fires almost right away. RPMs com up with the choke on, so I back off on the choke to keep the revs down as it warms up. When I kill the choke completely, the bike dies out. I turn up the idle adjustment knob some and restart the bike. Same thing... Now understand that if you keep working the throttle, it hits on all 4 cylinders, revs good, all the normal stuff. But it just won't idel. I figured, perhaps the air inlet for the idle jet emulsion tube was blocked so I pulled the carbs and checked each one. All are clean and clear. All idle mix screws have the tiny rubber O-rings and little washers. It just won't idle without some choke and that's just not right. So the only thing I can guess is that with the K&N air filter instead of that crappy foam filter that was in there , it's to lean at idle. What are you other guys thinking? Should I have upped the idle jet to go with the K&N air filter? HELP!!!!!!

09-01-2005	#2 (permalink)
QKENUF4U AZ's Official Mechanic BTK Expert Join Date: Sep 2004 Location: phoenix arizona Posts: 3,649	shouldnt have to be that drastic for a K&N filter. it should idle just like it did before ya pulled them apart. i would start spraying some carb cleaner around each carb and see if the idle goes up/down etc. sounds like you have a vacumn leak somewhere. good luck

09-01-2005	#3 (permalink)
lo cash john Newbie Join Date: Sep 2005 Posts: 4	I agree, it does seem like a vacuum leak but... I can imagine that on one carb, but that wouldn't cause it to not idle at all, would it? It would just idle on 3 cylinders and sound like crap. Besides, the rubber intake manifolds have never been off the head, the hose clamps holding the carbs on are tight (I even replaced the Philips head screws with Allen head) and I've disconnected the various stock vacuum hoses from the vacuum ports and installed brand new rubber caps to close off the vacuum ports. I'll try the old carb cleaner around the intake system trick and see what happens. While I'm at it, do you or anyone have any recomendations on removing all the emissions crap having to do with the reed valves feeding air in the exhaust ports for less emissions? I'd like to reduce the amount of bull**** on the bike. You know, keep it all real simple and save a little weight. Thanks, John

09-03-2005	#4 (permalink)
lo cash john Newbie Join Date: Sep 2005 Posts: 4	Let me ask this of you guys. Has anyone ever heard of the stock hose clamps, for holding the carbs on, stretching? I am still having the idle problem and it does act just like a vacuum leak, but a leak on every carb. I have not tried to locate the leak yet with starting fluid or carb cleaner, I'm just tossing around ideas before I jump on this again tomorrow. When I re-installed the carbs (the first time) I wiped out the insides of the rubber intake manifolds, then applied a very thin film of grease. Maybe the rubber is slipping and as the clamp tightens down, the rubber is arching very slightly somewhere around each carb. That would explain an intake leak on every carb... What do you guys recommend as a prep procedure before reinstalling carbs to rubber intake manifolds? Also, can anyone address my emissions equipment question?

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