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Kodiak ATV won't start

5337 Views 11 Replies 7 Participants Last post by  Fish0rDie
I have a 2000 Yamaha Kodiak 400 that I have had since 2002. I have ridden lots of miles and done (I am sorry to say) virtually no maintenance to it. Late last fall (nearly 2 years ago), I was using it around the farm and it was running fine. After shutting it off for a few minutes, I went to start it and it backfired, blowing the boot off the carburetor (between the engine and carburetor). Try as I might, I could not get it to start after that.

Fast forward (past a shoulder surgery, and many months) and I have been trying to get it going again. I have replaced the carburetor (with a cheap ebay carb) and the spark plug. I have replaced the gas with brand new, super unleaded (non-ethanol). I changed the oil and took off the valve covers and they appeared to be working.

It turns over fine and the spark plug sparks when grounded to the frame or engine.

When I put my finger over the spark plug hole, it is pushing air out when I turn it over and it is pulling air through the carburetor. The carburetor is taking fuel, and (assumedly) injecting it into the engine. There is air (and gas smell) coming out the exhaust.

When I remove the plug, it is not very wet, and only faintly smells of gas (sometimes) and other times smells more like vanilla (yes, like a candle and I have had a friend verify this).

The connections between the carb and engine have been checked for leaks, cracks, holes and are tight.

I have tried pouring gas into the spark plug hole. I have tried spraying starting fluid into the plug hole and into the carburetor. I have tried the starter, for minutes at a time, with the choke on, or the choke off.

Nothing that I have done makes any difference at all.

The only exception to that is when I have sprayed a LOT of starting fluid either into the carburetor, or directly into the head (with the carb removed), after a couple minutes of turning over, it will finally ignite the starting fluid on top of the engine, or in the air cleaner box (depending on which way I did it). The engine never, pops or lets out exhaust smoke, not at all.

A google search suggested the following things:

Incorrect valve clearance "as the engine gets some hours on it, the valves may seat deeper in the valve seats and need adjusting".

The timing is off/the flywheel timing key is sheared. (I'm not even sure that it has one of these.)

So, any thoughts/suggestions?

Thank you so much!
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Maddevill, thank you so much for your response and advice.

I am pretty novice at this stuff, so I have some questions. (I will also try searching for the info online.):

1. What is a Leak Down check? How do I do it?
2. How do I check the valve clearances? Can you recommend a good video, or instructions on how to do this?
3. It seems that the jets are an unlikely culprit, given that it was doing the same thing with the stock carb/jets. Do you disagree?
4. It seems to be sparking well (I think). How do I know if the spark is "strong"?

Thank you so much!
1. get a compression tester tool, BETOOLL HW0130 8pcs Petrol Engine Cylinder Compression Tester Kit Automotive Tool Gauge: Industrial & Scientific

remove spark plug, install tool and crank the engine while holding the thumb throttle all the way in, your compression should be between 170-220

if its on the low side, add an oil cap full of oil to the cylinder through the spark plug hole, wait a min or so and do the compression test again, if numbers are higher you need to change your rings, possibly piston.

2. I do not have a video of the valve adjustment on a 400 yet, but this guy does a really good job. the intake valves should be at .0024-.0039in. and exhaust at .0063-.0079in.

3. Agree!

4. Remove the spark plug and install it in the spark plug cap. touch the engine (away from the spark plug hole) and crank the engine. you should see a bright blue almost white spark. Do it indoors away from the sun or outdoors once the sun goes down.

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by the way, you dont have to pour gas down the cylinder to try and start it you can either soak the spark plug itself in gas or any flammable liquid and reinstall spark plug


buy something like a seafoam can and spray straight into the carb.

when you re-installed the new carb, how is the butterfly position in the carb, you have to make sure it is in the almost closed position, there should only be a tiny gap as thick as a piece of paper.

there should be about 2-5mm of free play in your throttle cable or else it may not start.
The throttle cable needs to be resting in A, end of it in B and it should be touching the idle control rod.


looking forward to you reply
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