1984 Ninja 900 question - Sportbike Forum: Sportbike Motorcycle Forums
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post #1 of 23 (permalink) Old 05-14-2004, 06:02 PM Thread Starter
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1984 Ninja 900 question

Just brought home a very clean 1984 Ninja 900. Have taken it out for a few rides but cut them short out of fear it was getting ready to overheat. The temp gauge starts warming up within a few blocks, and heads for the far right of the gauge fairly quickly. Within 10 blocks of riding or so. That seems awful fast so I've been shutting it down. Coolant is full. I've always shut it down before it hit the red part of the gauge. What is the normal operating range on the gauge for this bike? Assuming this is abnormal behavior, wonder where to get started on it?

Thanks!!
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post #2 of 23 (permalink) Old 05-14-2004, 06:28 PM
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You said it definitely has water. Did you remove the radiator cap to verify that or just look at the plastic overflow bottle? If in doubt, when cold, remove the radiator cap and make sure that the system is truly full.

Then, is the electric cooling fan coming on. If not, often it's just the fuse or switch. Check the fuse first. If OK, find the switch. It should be located in one of the radiator end tanks. Most likely there's one wire to it. If so, that's a ground switch and disconnecting the wire, inserting a metal probe that will reach the contact, then touching to any metal that will allow it to ground, should bring the fan on. If by slight chance the switch had two wires to it, disconnecting the plug and putting a jumper wire in it should bring it on. If the fan comes on then the switch is bad. Replace it. Note: Make sure you have the key on when testing. Some circuits will run the fan even with the key off, but most are wired through the key. I'm not sure on yours.

If not, further trace out the wiring to the fan, checking for troubles. If still nothing, the fan motor could be bad. Hotwiring it from the battery should bring it on. By now, if it's still not working, you should know the whole fan system pretty well and sort it out yourself with logical thinking.

Always the possibility that a thermostat is bad but from my experience that's highly unlikely.

Still another possibility would be that you're being a little too afraid of seeing the gauge go up a little bit. This would be the easiest as it would mean nothing's wrong. Without knowing what the typical gauge range is on your specific bike, I can tell you that it's not uncommon for them to get up there a bit when in traffic, although never in the red. The fan should be kicking on by about 3/4 of the way up the normal span.

If you're still not sure, have someone look at it who knows. No sense hurting it by overheating when the problem is likely an easy fix. Hope that helps.

Keeping the "Hap" in "Happy Holidays"!

Regime change begins at home.

Blind patriotism is worse than no patriotism.

Last edited by Dad; 05-14-2004 at 06:32 PM.
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post #3 of 23 (permalink) Old 05-19-2004, 03:18 PM
 
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i've always heard the 84 900 ran hot. Mine doesnt seem to run to hot though so i dunno. got any pics of the bike?
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post #4 of 23 (permalink) Old 05-20-2004, 06:51 PM Thread Starter
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Thanks for the great tips. I'll try and post a picture, maybe this weekend.

The bike does have a full radiator. I checked to make sure there wasn't any air in the system per the manual. The fan does come on.

I've a theory that the running hot is not coolant related. The bike has a Vance and Hines system on it that appears to have no packing in it. So that would cause the bike to run a bit lean, which would be hotter than it should.

Plus, the bike has the idle set at 2,000 rpm. I discovered that the bike runs fine above 2,000 rpm, but if I try and set it lower it runs like crap.

So, I'm thinking that sitting at a few stop lights, running at probably twice the recommended idle, plus running a little lean, that is possibly what is causing the bike to run so hot.

Is this likely or am I way off base here?

Then how to fix it is a different story! Would have to figure out what packing to order, and I guess get the carbs done. Anyone know any good places to mail carbs to get the cleaned?
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post #5 of 23 (permalink) Old 05-21-2004, 04:23 AM
 
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You will probably need to rejet your carbs to take care of the lean. With a V&H on my 86 1000 it ran hotter than normal until I rejetted. But mine would idle fine at lower RPM's.
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post #6 of 23 (permalink) Old 05-21-2004, 08:03 AM
 
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Holy crap Dad. Do you know everything?
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post #7 of 23 (permalink) Old 05-21-2004, 08:45 AM
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Quote:
Originally posted by granitesun


I've a theory that the running hot is not coolant related. The bike has a Vance and Hines system on it that appears to have no packing in it. So that would cause the bike to run a bit lean, which would be hotter than it should.

Plus, the bike has the idle set at 2,000 rpm. I discovered that the bike runs fine above 2,000 rpm, but if I try and set it lower it runs like crap.

So, I'm thinking that sitting at a few stop lights, running at probably twice the recommended idle, plus running a little lean, that is possibly what is causing the bike to run so hot.

Is this likely or am I way off base here?
The high idle is what's doing it although the cooling system can probably handle it. Not much more, though.

At that vintage and clean as you described, the bike has probably sat at some point in its life, long enough to gum up the carbs. That sounds like a plugged idle circuit in one or more carbs. They are very tiny and plug easily.

It's not a tough job to clean out and you already made reference to the "manual", so I assume you have one. Follow the directions carefully and take the bowls off, jets out, and pilot mixture screws out, blowing out each passage. It's convenient to use an aerosol carb cleaner because it affords you the pressure and also you can see when it flows nicely through the ports. When removing the pilot screws, first screw them in gently seating, counting the turns, so you can return to that adjustment on reassembly. The manual will also advise number of turns out and is usually sufficient for a final setting, especially if you get widely varying turn counts from one carb to another, indicating that someone was messing with them. An additional quarter to one half turn out from recommended usually doesn't hurt either.

You shouldn't have to break the carbs apart, losing the sync. Everything you need to access should be able to be done with the rack assembled.

Before to reassemble the carbs to the bike, take a careful look at the intake manifold rubbers. They can become hard with age and have cracks or just be so hard that they won't seal well, causing an intake leak. Same goes for the diaphragms that operate the slides. Look at them closely for cracks. An intake leak will cause idling problems, too.

You'll likely want to fix the pipe too, but that shouldn't be causing your temp problems. It's just obnoxious.

Good luck.

Keeping the "Hap" in "Happy Holidays"!

Regime change begins at home.

Blind patriotism is worse than no patriotism.

Last edited by Dad; 05-21-2004 at 08:50 AM.
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post #8 of 23 (permalink) Old 05-21-2004, 08:57 AM
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Quote:
Originally posted by Gideon777
Holy crap Dad. Do you know everything?
No, I'm just old and have been a machinery addict since I was knee high to a crotch cricket. Throw that in with cracking a book once in a while and you learn "tings".

Thanks though..... I think.

Keeping the "Hap" in "Happy Holidays"!

Regime change begins at home.

Blind patriotism is worse than no patriotism.
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post #9 of 23 (permalink) Old 05-21-2004, 09:53 AM
 
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There are two air bleeders for the cooling system on that bike. One is the top most bolt on the water pump. It's located low on the engine on the left side. Crack the top bolt open and leave it open until coolant dribbles out. Tighten it up again. The other is on right side of the thermostat housing, above and behind the carbs. It is a brake bleeder. Crack it open until coolant seeps from it and tighten it back up again. This may be the only problem with your bike.

That said, I'd look into why it won't idle at less than 2000 RPM. Sounds suspiciously like a vacuum leak to me if it runs great otherwise.

You ought to adjust the valve lash on that engine too. They are known for soft intake valves that use up clearance quickly.

One other thought, the ignition modules on those bikes can fail in such a fashion that the timing goes to full advance. This'll make it run like total crap at low RPMs and then fine above a certain threshold , like say 3000 RPM. It'll also make it run very hot. the module (ignitor) is used on several Kawasaki models (it's even used on 1986 through 2004 Concours) so a used one should be easy to come by.

Godd luck
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post #10 of 23 (permalink) Old 05-31-2004, 02:40 PM Thread Starter
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OK Thanks Dad, Stoinky, for the great advice. I just happened to have an ignitor from a 99 Concours in the garage, so I swapped that today in hopes it would be an easy fix. Unfortunately, it was not to be. Looks like I get to go into the carbs.

The Clymer manual that came with the bike had the instruction sheet for a Dyno jet kit in it. Anyone know what the stock size jets are, or what size the Dyno jet kit sizes are, so I can tell if the kit ever made it into the bike?

Thanks!!
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