Author Topic: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation  (Read 1027 times)

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dgundlz

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Hello everyone, and thanks in advance for any advice you may have...

I have a 1979 Kawasaki 440 Intruder, engine was recently rebuilt (three years ago). Ran great all last season and this season, up until now.

After running for about 20min at normal trail speeds (not more than 50mph, usually more like 30-40), the engine will start to bog severely, to the point of sputtering and sometimes even quitting. In the midst of the bogging (as I am working the throttle to keep it going), it will surge dramatically for an instant, and then continue bogging. If it quits, it won't start for a few minutes, then will run fine for about 5-10minutes before doing the same thing. If I stop and let it idle for about 5 minutes, it will, again, run fine for a few minutes before bogging/bucking again. This just started happening -- there was nothing unusual about performance until this suddenly started happening.

At first I thought "fouled plugs?" -- I pulled the plugs and they are dry and a nice brown color. With the plugs out, I checked compression, which measures ~160. So now I'm suspecting a fuel flow problem -- it seems as if it is running out of fuel. This one doesn't have a fuel filter, otherwise I'd suspect a clogged filter... Sludge in the fuel tank, clogging the pickup (tank was flushed when engine was rebuilt)? Bad fuel pump? Sticking fuel inlet needle/float arm/floats in the carb (carbs were overhauled with engine...)? Has anyone experienced this, and suggest a good place to start?

Let me know.

Vader440

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #1 on: February 18, 2018, 05:39:16 PM »
Is the vent tube on the fuel tank kinked?

kawhead

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #2 on: February 18, 2018, 07:43:53 PM »
those had a dime sized filter in the fuel pump,thats were id look

dgundlz

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #3 on: February 18, 2018, 08:16:55 PM »
thanks for the tips kawhead and Vader440 -- I'll check the vent tomorrow. If that's fine, guess I'll pull the fuel pump.

dgundlz

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #4 on: February 19, 2018, 02:02:10 PM »
Thanks again for your responses. There was nothing wrong with the vent tube, however, I pulled the fuel pump and upon disassembly found that the filter material was embedded with ~40years of debris, and the filter screen had a small tear in it. The rest of the pump (diaphrams and gaskets), looked just fine. I think this may be the culprit.

Does anyone recommend eliminating this internal filter, and instead adding an inline filter before the pump? Or running both an internal, and an inline filter? Seems to me that an inline filter would be much easier to change on a regular maintenance schedule...


kawhead

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #5 on: February 19, 2018, 03:26:14 PM »
I remove, way to small of surface area, run an inline

gixxer6

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #6 on: February 19, 2018, 05:14:06 PM »
I always run both. 

Interceptor398

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #7 on: February 19, 2018, 07:13:04 PM »
I've been running both but I NEVER put the last quart of gas from a can into the sled tank.  That's where all the crap is that can cause a plugged fuel line.

dgundlz

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Thanks everyone for your input. I just wanted to swing back to this thread and update with the solution to my problem, in case someone else stumbles on this thread with a similar problem.

I put the fuel pump back together with the filter screen in, but without the filter material -- it was shredded/deteriorated and embedded with debris, it couldn't be cleaned without destroying it, and there is no part number in the manual or elsewhere for replacement filter material. So I omitted the filter material and installed an inline filter before the pump, instead. This solved the problem. Now I just need to add fuel filter replacement to regular maintenance schedule.

mswyka

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Glad to hear that the problem has been rectified.   It is wonderful when they run!
Intruders:  1978, 1979, 1980, 1981 Custom
Invaders:  1979 340, 1980 440, 1980 440 TOC Custom
Projects:  1979 Invader 340, 1980 Invader 340, 1979 Intruder 440, 1982 Intruder 440, 1980 Drifter 340 F/C, 1972 Panther 303 ...

Vader440

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #10 on: March 06, 2018, 09:41:35 PM »
Good to hear you got it fixed and thanks for sharing the solution.

kawhead

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Re: '79 440 Intruder, engine bogs/bucks severely after ~20min of operation
« Reply #11 on: March 07, 2018, 08:23:21 AM »
I believe that filter was deleted on newer models, an inline is fine