electrical / carburetor problem

[rekako]

Hello to everybody,
I live in Bilbao, in the north of Spain. Excuse my English, it´s not good enough.
In the year 2004, I bought a ZXR400h2 imported from France, registered in April 1990.
I drove 124 miles more or less and one valve was broken which broke the piston, the cylinder and the cylinder head.
In Spain mechanical professional don´t want to repair this type of motorbike (there is a lot of CBR = Easier and faster money).
Finally in a workshop dedicated to classic engines with new pieces (valves, valves seats, pistons ...) brought in France the engine was repaired.
In another workshop the carburetors were repaired with new pieces (main jet, needle ...).
A few months ago I started the engine without trottle the engine goes O.K., the water temperature is O.K., good sound of the engine during a lot of minutes. The problem comes when I go to the road, in a few miles the bike begin to fail and it stops.
The spark plugs get dirty a lot, it becomes completely black. If I clean them or I put new ones the motorbike starts perfectly, but in some miles the spark plugs get dirty again.
I have spoken to the person who repairs carburetors and he told me that problem could be electrical because carburetors are in original sizes (main jet ...)
I have changes coils, HT wires, new spark plugs, spark plugs caps, new battery, CDI, pump fuel, pump fuel relay, and the problem continues.
I am fed up with the bike.
I attached some photos of spark plugs with 4.97 miles.
Is there any suggestion to this problem?
P.S.: My mechanical knowledges are limited.
Thanks in advance for your help.
Best Regards,
Raúl

Sorry, but I cannot put the photos because I don´t know how to do it. This is very complicated. There is not an easy way?

[extonyg]

hello your english is ok better than some peoples on here haha, from what you say about the spark plugs its sounds as if its running too rich (too much fuel) maybe try turning the mixture screws on the carburettors in half a turn and see if this makes it any better. i would says its down to carburettor set up rather than electrical.does it have an aftermarket exhaust not a standard one?

[RedexRobB]

how to put up pictures : viewtopic.php?f=43&t=1184

If the plug is black and sooty then it does sound like a problem with the fueling to me. Has anything been changed on the carburettors? It may be more than just the air/fuel mixture tho, it could be jet sizes aswell.

[rekako]

Hi everybody,

First of all, thanks a lot for your soon answer.

We have tried to attach the pictures of spark plugs, but they exceed of capacity permitted. We´ll continue trying. Because I think the photos will show the problem better.

My little knowledge are focused to two stroke engines. The carburettors are much simplier.

EXTONYG: Where are the mixture screws? The exhaust isn´t the original one but I think it is similar to the original.

REDEXROBB: The person who repaired the carburettors told me that they were in original size, but I would have to open them to see it.

Thanks again for your interest.

Best Regards,
Raúl :smt013

[RedexRobB]

use 'Paint' in windows to shrink the picture, or use a photo hosting website.

The air mixture screws are underneath the carbs in a small, tube like, hole. What they should be set at appears to be dependant on the model, but you can use a tuning kit that allows you to look inside the combustion chamber while the engine runs which gets them perfect.

[rekako]

Hi everyone,

I enclose hereabove the site where see the photos of my spark plugs. Maybe seeing them you could guess which is the problem.

http://picasaweb.google.es/rekako26/AlbumSinTitulo#

Thanks for your collaboration.

Best Regards,
Raúl

[rekako]

use 'Paint' in windows to shrink the picture, or use a photo hosting website.

The air mixture screws are underneath the carbs in a small, tube like, hole. What they should be set at appears to be dependant on the model, but you can use a tuning kit that allows you to look inside the combustion chamber while the engine runs which gets them perfect.

Hi RedexRobB,

I unknow totally the tuning kit that allows to look inside the combustion chamber and I suppose it won´t be cheap. I have never seen it.

I have shown the photos of spark plugs in the main message. I insist they only had 4.97 miles, it is very strange.

Thanks for your interest,

Best Regards,
Raúl

[extonyg]

ye they are very sooted up definatly running to rich, does the bike have any air leaks around the carbs?do the revs hang on?as this could be part of the problem, if not i would be checking all the carb settings needle height (if there adjustable standard arent i believe), jet size etc

[RedexRobB]

yeah almost certainly running rich, in which case you need to look at your fueling. Could be a case of simply altering the mixture screws or get a bit more involved and changing jets. If you want to get it perfect your best bet is to take it to a Dyno where they can monitor the fuel/air ratio.

The tool i am talking about is this

http://www.gunson.co.uk/tools.aspx?cat=673

[rekako]

Hi everyone,

Excuse me for my delay in giving you a response. My job and family require my attention these days.
As you indicate, it seems to be a problem of mixture air/fuel. As soon as I could, I will open the carburetors to have a look at the jet size or components size. On the other hand, I think the needle height is not adjustable.
Besides, it shouldn´t have any air leaks around the carbs because carburetor holders are completely new.

We will inform you as soon as I get new results. Thanks for your help.

Best Regards,
Raúl

[extonyg]

ye the needles might not be i dont think standard ones are.ye just make sure the clamps around the inlet rubbers for the carbs are done up nice and tight and also that the airbox is sitting down flush on the carbs as my airbox was 'warped' causing and air leak.let us know when you have stripped the carbs down.

[noelb]

blocked air filter?

[rekako]

Hi Noelb,

It shouldn´t. The box of air filter and air filter are completely new and cleaned. All the system is revised and it is cleaned.

Thanks,
Raúl