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Discussion Starter · #1 ·
Hi Everybody;

Can anyone tell me what’s burning in my 1992 Bayou 4x4. It’s a small piece of metal about 4” long X 3” wide and 1” thick with cast fins on the outside-it has a couple of wires going in and coming out. It bolts to the side of the air-intake box and gets really hot after a few minutes of riding-Is it the part or a symptom of a larger problem?

Thank you.

Ranchand Mark
 

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That would be the rectifier. That's what shaves off the extra current produced when the system is producing more than what is needed.

Is it actually burning or smoking or just getting hot? If it's just getting hot, well, it's supposed to do that. Those fins are for cooling, just like with the cylinder cans.

However, if it's smoking or smells like it's burning, then it's likely you have some fried wiring or need to replace the rectifier completely.
 

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...and about $100 to replace. :shock:
Well, it is essentially a big slab of machined metal...the only way to get something that thick placed on your vehicle more cheaply is to call up the kid who will eat dirt for a nickel and have him get on it.
 

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Discussion Starter · #5 ·
Hi Everybody;

Can anyone tell me what’s burning in my 1992 Bayou 4x4. It’s a small piece of metal about 4” long X 3” wide and 1” thick with cast fins on the outside-it has a couple of wires going in and coming out. It bolts to the side of the air-intake box and gets really hot after a few minutes of riding-Is it the part or a symptom of a larger problem?

Thank you.

Ranchand Mark
Thank you CTRider; it was definitely the unit smoking a toxic odor. The wires probably got just as hot too-however did not melt casing. I found an item on Ebay that appears to match the KLF300 model and it was listed for $60.00 new-It’s on its way to me now. I don’t think that it will solve the problem of shedding too much electricity, so I should look at the generator/alternator-voltage regulator?

Your thoughts welcome-

Ranchand Mark
 

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If you can add a piece of aluminum for the new piece to mount to, it might help in heat dispersal. Get some heatsink compound from Radio Shack(looks like the white goop people put on noses for sunburn protection) It will fill the really small gaps between the new part and the aluminum sheet.

A lack of cooling air can easily overheat rectifiers/regulators too.
 

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Discussion Starter · #7 ·
If you can add a piece of aluminum for the new piece to mount to, it might help in heat dispersal. Get some heatsink compound from Radio Shack(looks like the white goop people put on noses for sunburn protection) It will fill the really small gaps between the new part and the aluminum sheet.

A lack of cooling air can easily overheat rectifiers/regulators too.
Thank you MFolks for your reply;
Wow! I would never have thought of that. So to be sure I understand, I should mount a piece of aluminum sheet between the mounting surface and the new unit to act as a “heatsink” to collect the excess heat. How thick do you propose the aluminum sheet? Then I should smear a product called heatsink as a gasket material to seal the mounting. Right?
P.S. The existing unit looks clean.

Thanks for all your efforts.

Ranchand mark-
 

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1/8" or if you can get it, or 3/16" should be more than thick. You'll probably have to get longer mounting bolts too as what you've got may run out of threads.

The heatsink compound(or sometimes called thermal compound) has been used for many years in the electrical power conditioning industry when mounting high powered stud and pressure packed SCR's (Silicon Controlled Rectifiers) (more like a electrically controled on-off switch) in large finned fan cooled heatsinks.

Computer manufacturers use the thermal compound/heatsink compound for maximum heat transfer/dissipation in the processor(s).

If you're in the U.S., Ace Hardware stores, Home Depot, and Lowes sell small pieces of aluminum. The metal can be cut and driled to fit your needs easily.

A brand I've used is K&S metals sold at some hobby stores.
 

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Discussion Starter · #9 ·
1/8" or if you can get it, or 3/16" should be more than thick. You'll probably have to get longer mounting bolts too as what you've got may run out of threads.

The heatsink compound(or sometimes called thermal compound) has been used for many years in the electrical power conditioning industry when mounting high powered stud and pressure packed SCR's (Silicon Controlled Rectifiers) (more like a electrically controled on-off switch) in large finned fan cooled heatsinks.

Computer manufacturers use the thermal compound/heatsink compound for maximum heat transfer/dissipation in the processor(s).

If you're in the U.S., Ace Hardware stores, Home Depot, and Lowes sell small pieces of aluminum. The metal can be cut and driled to fit your needs easily.

A brand I've used is K&S metals sold at some hobby stores.[/QUOTE

Thanks again MFolks-I'll post my results.
 

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The thermal compound is not a gasket, but more like a heat transfer medium. It does not have to be applied very thick, more like a thin film. It will fill in the small imperfections between the aluminum and the replacemnt part.

A brush used to apply solder flux(clean one) can be used to apply the thermal compound, also a tongue depressor will work too.

The aluminum should be large enough to act like an additional heatsink. If possible make it twice the size of the rectifier.If not, try to make the aluminum plate/sheet a little larger than what the rectifier is.

Electronic packaged parts like this have a finite life, voltage fluctuations, and heat are the main causes of failures. Sometimes the package can fail from vibration, but since most are sealed up or "Potted" it's a remote possibilty for why yours failed.
 

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The thermal compound is not a gasket, but more like a heat transfer medium. It does not have to be applied very thick, more like a thin film. It will fill in the small imperfections between the aluminum and the replacemnt part.

A brush used to apply solder flux(clean one) can be used to apply the thermal compound, also a tongue depressor will work too.
I wouldn't even do that. Your right about the first statement, but the tools you suggest may leave too much of it on the part.

Heat sync compound (i.e. thermal grease) should be applied lightly, then you essentially wipe it off. Your finger will work for that. The idea is not to create a layer of the stuff, but to fill in the imperfections in the metal for a smooth surface contact. The less you leave on, the better. It's not like joining parts with silicone adhesive, where you want to create a sandwich with it between the parts.

Essentially, you want what amounts to bare metal to bare metal, with the thermal compound only there to smooth out the scratches and pits in the parts.
 

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Discussion Starter · #12 ·
Thanks for the great advice-
a new rectifier is on the way. It is my hope that just replacing the part will do the trick-I understand that it is more likely to be a symptom of a greater problem. I'm not sure I want to attempt to rebuild the entire system. It's a stupid question but does the machine really need such a complex electrical system. I can do without turn indicators and headlamps, horn and etc. All I want/need is a starter.
 

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Thanks for the great advice-
a new rectifier is on the way. It is my hope that just replacing the part will do the trick-I understand that it is more likely to be a symptom of a greater problem. I'm not sure I want to attempt to rebuild the entire system. It's a stupid question but does the machine really need such a complex electrical system. I can do without turn indicators and headlamps, horn and etc. All I want/need is a starter.
That's actually why you need a rectifier. It's not a complex system.

The problem is, as you ride, the battery charges. The more RPMs, the more it charges. Eventually, it doesn't need any more power, but the bike is still producing it.

Each time you stop, you burn a little off since the bike really doesn't charge the battery at idle (at best, you might break even, but older ones actually start draining the battery below about 2000 RPMs). However, between stops, the battery usually tops off and that extra power has to go somewhere or you'll blow up your battery.

That's where the rectifier comes in: it eats that power, kind of like a transformer. The problem is, doing so generates a lot of heat (like a transformer gets hot) and that's what the metal plate with the fins is for: as you ride, it dissipates heat as air passes over it.
 

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Discussion Starter · #14 ·
That's actually why you need a rectifier. It's not a complex system.

The problem is, as you ride, the battery charges. The more RPMs, the more it charges. Eventually, it doesn't need any more power, but the bike is still producing it.

Each time you stop, you burn a little off since the bike really doesn't charge the battery at idle (at best, you might break even, but older ones actually start draining the battery below about 2000 RPMs). However, between stops, the battery usually tops off and that extra power has to go somewhere or you'll blow up your battery.

That's where the rectifier comes in: it eats that power, kind of like a transformer. The problem is, doing so generates a lot of heat (like a transformer gets hot) and that's what the metal plate with the fins is for: as you ride, it dissipates heat as air passes over it.


Dear CT rider, Thank you again for your comments-

Yes-I think I now better understand the general concept of the rectifier. My thoughts now are to strip the quad of all wiring and just replace what is necessary. A heavy wire from battery to starter, small wires to voltage regulator, rectifier, switch & fuse. No onboard computer system, no horn or lights-Then I'll know the condition of the components.
So if it's Okay to ask another question: When I view the back of the battery box where the computer is mounted I also see two additional components, the one on the left is a small cylinder which I believe to be the voltage regulator from the regulator is a small short bundle of wires that lead to something that I’m not sure what it is (maybe a fuse) from there another bundle of wires leads forward to places to be determined. (my guess starter solenoid) By now I'm sure you are aware I’m no Mechanic or electrician 

Ranchand Mark
 

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Can you tell us what wire colors go to these components? There are some members more experianced with this model than others.

Some Kawasaki's will have color striped wires(like BLACK with YELLOW stripe, usually a ground circuit). If you can get a wiring diagram, it will make figuring out what wires to leave or remove.

Unfortunately, if your vehicle has Fuel Injection, a computer is needed to make all the fuel/air mix adjustments for the engine to run
 

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If you can add a piece of aluminum for the new piece to mount to, it might help in heat dispersal. Get some heatsink compound from Radio Shack(looks like the white goop people put on noses for sunburn protection) It will fill the really small gaps between the new part and the aluminum sheet.

A lack of cooling air can easily overheat rectifiers/regulators too.
Just a word of thought, but by filling those gaps with heat sink compound and covering fins with a solid sheet of metal by slapping a thick piece of aluminum to the top of the rectifier fins, you're actually reducing the amount of surface area available for cooling.

That's why CPU heat sinks, cooling coils, air-cooled heads, and a myriad of other devices have a finned surface instead of a solid surface - it's for heat transfer.
 

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I'd think by adding an aluminum plate with heatsink compound under the package, the affected cooling area would be increased for higher heat dispersal.
 

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I'd think by adding an aluminum plate with heatsink compound under the package, the affected cooling area would be increased for higher heat dispersal.
At first the solid aluminum plate idea made sense, but I was thinking about it and this is what I've been taught through various schools throughout my time in the Navy:

Take a piece of aluminum, say 3" x 3". That gives you 9 square inches.

Now add a 1" tall fin right down the center of it. That gives you the 9 square inches of cooling, and then an extra 3 square inches on top of that.

You get a total of 12 square inches of cooling surface on a package that only takes up 9.

Add one more fin, so now you have two fins. Now you're up to 15 square inches of cooling in a 9 square inch package.

Add a third - now you've got 18 square inches in a package that takes up 9.

Add another fin...and another fin...you can see where this is going.

Adding fins gives you more surface area for heat dispersion in a small amount of space. ;)

Now, if anything, a painted heat sink would impede heat transfer.
 
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