95 ZXR750L3 - it's driving me crazy!

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Guys,

I'm reaching out for some help with my '95 L3. I've had the bike for 15 years, and have ridden it only 12,000km in that time (total distance is 30k).

Lately it's developed a tendency to drop a cylinder, then only run on 3 for a couple of minutes before it dies. Then it can't be restarted without taking out the plugs (they appear a little 'wet'), cleaning, and reinstalling. I've had it looked at by a very knowledgeable mechanic here in Perth (he's done a strip down of the carbs etc), and when I've had it back from him it's run well, then a hundred k or so later it's developed the same problem. He thought it may have an intermittent problem with the points in the fuel pump, which he cleaned when it was last serviced. When riding the bike before the problem surfaces, a quick wind on of the throttle causes the engine to bog down, almost like it isn't receiving enough fuel.

Yesterday morning I took it out of the garage, started it and warmed it up. I then turned it off while putting my gear on. Then when trying to restart it the 3 cylinder problem resurfaced - I used my trusty infrared temp gun, and the far right hand pipe (when looking from the front) was cold in comparison with the others.

My first thought is to go and purchase a new fuel pump (they seem to be about $300 OEM, and $65 on eBay!). While I'm in there I also look to replace any fuel lines which look a little suspect.

Anyway, the point of this post is to find out if there is anything obvious that I may be overlooking. Any help is greatly appreciated!

Regards

Rob

[h.b.bear]

I am thinking you still having carby problems, how clean is your tank as it may be feeding some crap into the carbs (doesn't take much), but the guru will b along and b able to help more ( gos )

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Thanks - since posting this I've searched a bit more on the forum and found this post: viewtopic.php?f=46&t=41838&p=599638&hilit=zxr750+fuel#p599638 which is very similar!

The tank appears clean, and has a couple of week old 98RON in it.

Cheers,

Rob

[Gosling1]

My bet is that there is a spark problem somewhere - it could be as simple as needing new plug caps and leads ? The reason I think its an electrical issue - is the reference to the plugs looking 'wet' .......but the bike still starting once they have been cleaned ?

The plug caps and leads could be original - so 20 years old now. Coils can also break down, these need to be tested to see if they are still within spec (primary and secondary resistance measured).

Putting in a replacement fuel pump is probably good insurance anyway - but the best thing to do is only change one thing at a time.....then move onto the next. At worst, you will just end up replacing old stuff which could be likely to fail anyway due to age.

[photomike666]

First up - have you tried new plugs? I've had a similar issue & it was a dud spark plug.

If it was fuel pump it would affect all cylinders not just one. Plugs being wet suggests fuel but no burn.

[slocs]

Thanks for the quick response guys - really appreciate it.

Photomike, slightly hotter plugs were put in it at the last service, but I'll grab a new set. As Gos suggests go through it one item at a time, starting at the fuel cap and working my way down!

I was looking through the service records last night, and a bill from Sydney City Motorcycles reminded me it had an electrical problem just before the Sydney Olympics (as in the first week of September 2000)- the invoice suggests a voltage reg/rectifier problem which caused charging problems - I guess voltage spikes at the time might also have shortened the life of other components so I'll also methodically work through the electrics at the same time.

Thanks again,

Rob

[Gosling1]

good luck Rob - you will get it sorted