Kawasaki Motorcycle Forums banner

1 - 8 of 8 Posts

·
Need more power Scotty!
Joined
·
20 Posts
Discussion Starter #1
Hi everyone! Well I am back with another issue with the 89 zx-10. Got it running with help from the dealer. Here's the deal, after pulling the plugs and checking they are very carboned up. The mechanic says that the jetting was not replaced, but he recommended maybe readjusting the jets to run leaner. Now, I have a full Muzzy header system on the bike. Would it be best to go with a jet kit or try and adjust stock jets? I have been reading about something called the "Flow Commander" and it sounds like it might be something worth trying. Anyhow I am at wits end with the beast as this last time I rode it I got at least 300-400 miles before the plugs fouled out and it would only run on 2-3 cyclinders. Can anyone offer any advice? Would be greatly appreciated. Thanks!
 

·
Registered
Joined
·
1,512 Posts
Are you sure your air filter/airbox are clean and free of obstruction?

I'm going to assume the stock jets aren't in the bike because there's no reason it should be running so rich as to carbon the plugs to the point they stop running, WITH an aftermarket exhaust. You can't "adjust" jets. They're either too big or too small. If the stockers are in it like your mechanic said there is another problem here.

Are you sure the plugs aren't oil fouling (bike is burning oil and oil deposits are fouling plugs)? That would make a lot more sense to me.

Alternatively you could try a hotter plug, and/or running regular gas. That's more of a band aid to the problem, though.
 

·
Navy Vet Search & Rescue
Joined
·
8,842 Posts
+100 I'm with JimmyD. I'd also suspect oil as the culprit if it indeed has factory jets installed. What mechanic suggested "adjusting" the jets? Unless thats his term for changing the jets I'm lost. Most bikes are set to run lean from the factory to comply with EPA emissions requirements and installing the aftermarket pipe normally makes it just a shade leaner. I don't see how the bike is running too rich with this unless you have severely restricted air flow on the intake.
 

·
The Cruising Gunsmith
Joined
·
1,459 Posts
+100 I'm with JimmyD. I'd also suspect oil as the culprit if it indeed has factory jets installed. What mechanic suggested "adjusting" the jets? Unless thats his term for changing the jets I'm lost. Most bikes are set to run lean from the factory to comply with EPA emissions requirements and installing the aftermarket pipe normally makes it just a shade leaner. I don't see how the bike is running too rich with this unless you have severely restricted air flow on the intake.
Ditto that aftermarket pipes will run lean with stock jets. You may want to actually look at the jets and see what they are to get a starting point. They may not be stock jets.

A jet kit is probably a good idea as you will get a selection of jets and save $$ from having to keep ordering more jets.

I think a rough ball park starting point for adding a full race header would be to go one size bigger on the pilot jet and one or two sizes larger on the main. See what that does and adjust from there.

If you are actually running rich (and not oil fouling) it sounds like somebody already installed some big jets and maybe overshot the mark. If it's oil, you need new valve guide seals.
 

·
Registered
Joined
·
1,199 Posts
maybe my 2 cents isnt worth 1 cent but ill throw mine in. i have a 91 zx11 and had a similiar problem. id ride the bike for about 500 miles sometimes longer and my spark plugs would foul out with carbon. it would start to run off maybe 2 cylinders. and i was thinking maybe it was running too rich but that wasnt the case it was fouling out from oil because soon after, she started blwing out smoke. valve stem seals are shot on mine. working on getting them fixed here real soon maybe that is what the problem is with yours. mine started acting just like yours. i would pull the carbs off and just take a peek at the intake valves and see if they are wet with oil.
 

·
Need more power Scotty!
Joined
·
20 Posts
Discussion Starter #7
Thanks for all the replies. Well I pulled the carbs after trying to start it on a cold day--40 degrees or so. I drained the carbs and have them in the house. The bike just turned 27, 000 miles and does not smoke like when burning oil. The valves appeared to be dry from oil just carboned. I do have an ignition advancer if that would have any affect. I will start with the jetting and see what I have and go from there. I was going to check the coils for proper output. Just getting frustrated with the bike. It's in darn good shape and is a blast to ride when she runs right. Will post as I check things and see what happens. Again thanks for the advice!!!!!!!!!!!!

Jim
 
1 - 8 of 8 Posts
Top