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Discussion Starter #1
Hi,

My motorcycle is Kawasaki VN800, 1995.
Recently changed oil, oil filter, sparks plugs, air filter, adjusted the valves, cleaned coil ignition cables, and cleaned carburetor.
And until it reaches 70 mph, bikes works great, it's very powerful. But, when it reaches 70 mph, it's looks like that's all she can do, is has no more potential. It looks and sounds like when it reached 110 mph last summer, only that now is 70mph.

I cleaned the carburetor, and checked for vacuum leaks.
I don't know if this might help you find the problem, but one exhaust warms a bit faster than the other, just a little bit faster.

I live in a country when it's nearly impossible to find a good mechanic near to me. Any idea would be more than helpful, thank you.
 

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When you hit 70 does it feel like its starving for fuel (kicking and sputtering) are you sure both cylinders are firing? and back to my original SHIFT are you hitting 5th?

All things that would cause loss of power or speed
 

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I'm really leaning towards a coil or cylinder not firing. But really sounds like ignition and not fuel.
 

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Discussion Starter #7
No, it does not feel like it's starving for fuel. It's feels like it has no more potential.
Just like when you reach the maximum speed limit in your bike.

And yes, I hit the 5th gear.

And, I am not that sure, but I guess both cylinders are firing, because otherwise I don't know how the bike would have all that power until it reaches 70 mph, if one cylinder was not firing.
 

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Discussion Starter #8
I will add something else, maybe this will help something.

Last night I removed the spark plug cable from the exhaust side that was getting hotter a bit faster, and when I did that, the engine shut down. I tried to start it up, and it started with difficulty, and shut down immediately.
 

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Mine didnt want to fire on 1 cylinder when I woke it up over the winter. I yanked the enrichment valve (choke) and it was hitting on one cylinder and I rolled the throttle till i heard the second cylinder cracking and popping in. then you could tell the difference. First ride it stumbled a couple times when that cylinder would miss fire. Changed plugs and yippie smooth as a babys butt again. You can definitely feel the difference by hand at the exhaust tip when its not firing.

If I were to guess I'd say same situation but its not trying to come in at all. Not saying hold her at WOT sitting in the drive way but getting the rpms up and see if she starts popping like shes trying to fire up that other cylinder. Disconnect a spark plug. if she doesnt start the shes not firing on the other cylinder. if it does start does it sound the same? reconnect does it sound the same? If so you have no spark on said cylinder.


Best help I can give from the back of the screen here.
 

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Discussion Starter #11
I hope that you are right. I really do.
Anyway, I will check it after 2-3 hours, as soon as I get home,
and will keep you informed. But, if hypothetically the problem
lies there, why the bike would have all that power until it reaches 70 mph. Do you have any answer that it makes sense, because I am an amateur on these issues.

Sorry for my bad English, thank you a mil!
 

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well its a 400cc when its not hitting that cylinder. It would have all the power of a single thumper. Mine sounded and would idle fine on one cylinder but throttle roll was delayed and it didnt pick up rpms as fast. But once CYL 2 came back to life she was a different animal again.

Best of Luck I'll check back after work!
 

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Discussion Starter #13
Let's hope you are right. And, actually, It makes sense. If it's just a coil malfunction, or something similar, and nothing more serious, I would be more than happy. Thank you again,
and as soon as I test it out, will inform you.

Regards,
 

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I'd suggest trying to run the same rpm in 4th gear. Do you also lose power in that gear?

I also would lean toward ignition. Luckily for you that is often a cheap fix. Start at the plugs (you replaced but did you verify the gap?) first and replace parts back to the ignition control.
 

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Throwing parts at a problem is a fast way to lighten your wallet and a slow way to repair a bike.

1. How many miles on it?
2. How long have you owned?
3. Did the problem just start one day, or?

Post back.
 

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Discussion Starter #17
1. Bike has 63,000 kilometers.
2. I owned the bike for a year and a half.
3. Yes, the problem stared one you. Actually, bike has been staying in garage for more than
4 months, because during the winter I don't use it. And during this time I have done some work on her, like I mentioned
in the original post. The last time I rode her, 5th of December, the bike had no problem whatsoever reaching 110 miles per hours.


So, last night, I checked again the motorcycle, and one exhaust warms a bit faster then the other, and always is hotter than the other, and it is more louder. And, after lubricating the spark plug cables, I managed to reach 85 miles per hour.
With third gear I managed to reach 50 miles per hour, with 4th gear I managed to reach 70 miles per hours, and with 5th gear, 85 miles per hour, with difficulties. It's really killing me, I love that motorcycle, I had to work a lot of years to buy it. Maybe I am just overreacting. I don't know.
 

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Discussion Starter #18
Thank you for your advice, last night I put the old spark plug in the side of the engine that
exhaust warms slower, but no change. So spark plug is not an issues. Tonight I will check the ignition cables, and ignition coil with an ohmmeter, If I can find one.
 

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Discussion Starter #19
In the picture below, is the new spark plug that I removed from the engine side, where the exhaust warms slower. I don't know if it can be seen good, but it was wet, different from the other one, which at the top was dry.
 

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Some questions:

1. It ran fine before you worked on it over the winter?
2. Which cylinder is the wet plug from...front or rear?
3. What did you mean by "lubricated spark plug cables"? What did you use?
 
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