Carb cleaning

When I looked down into the airbox and saw that thin coating of grime along the intake trumpets I knew cleaning the carbs was a good plan.
I had already whilled the airbox off and cleaned all of that gunge off with degreaser leaving me a better view of the carbs themselves.

With the trottle held open you could see browny gold wax deposits on the needles that could only mean bad things through the rest of the carb. Mind you the bike ran fairly well so on the other hand it couldn't be that bad could it?

NSR World have a great walk through on breaking down the carb on the MC18-21 bikes. Althought eh cars on the MC28 are different they are pretty similar so this was a good reference to help if I got stuck later on when trying to put this all together.
So with the confidence inspired by a few reference photographs and the guidance from the website above, I cracked on with removing all the throttle cables, choke cable and various hoses. Two cross head screws held the clamps down on the intake manifold that dutifully released with he help of an extra long screwdriver (in this case not needed but if you ever plan to buy a straight four or longer buy one!) and the carbs popped off without a fight.

I had already cleaned the bench and spread some paper towel on it, so I placed the carb's on it and unscrewed the float bowls. I probably should have drained them first but there wasn't allot of fuel in there and the tissue did its job.

Next out came the float pins, freeing the floats and float needle. Both were in good condition and that went the same for the float bowl and the now visible
jets. A bit grubby but nothing catastrophic.

A large can of carb cleaner was just about to be my best friend as I depressed its trigger sending a high power spray of carb cleaning compound into the depths of the float chamber and back into my face. Some friend.
A soft bristled brush loosened and tough bits and another [more careful] spray got the float chamber sparkling.
Starting with the left carb, I removed each jet individually, cleaning it with carb cleaner and brushes. For the tougher bits like the blackened emulsion tubes, I had a harder brass brush that removed the dirt quickly without damaging the delicate jets. I finished off each one with a quick polish with Brasso to remove the last of the grime and when confronted with brass, I struggle not to Brasso it.
It is worth noting here with the image on the left, the differences with the MC21 carb image used for demo purposes on the NSR world website. Although the centre cluster of jets is the same, the float needle jet is offset left, the power jet hole is angled top centre corner (sided for each carb so top right of left carb) and the alloy screw is now a dome head also set at an angle closer to the centre jet cluster.

With the float chambers finished I buttoned them up, being sure to lube the rather dry seals (note to replace them in the not to distant future) and check the float needles were in their respective correctly.
Next off came the carb top plates. Inside is the the linkages from the throttle and slide tops. To remove the slides you have to remove all of the linkaging (from that I could see) and they weren't bad enough for me to go through the hassle of doing that so I simply disconnected and displaced them so I could get to the little plastic quarter turn cap that holds the needle in place on the slider. I popped this off and removed it with its spring and washer, followed by the needle itself. Sadly they were the stock fixed type and not adjustable. This was a pain as from what I had seen, no one sold jet kits for these bikes anymore so I was going to have to do this by trawling forums (the horror!) and the tidbits NSR World and co. gave out.
The needles were quick to clean and the sliders themselves also got a rub down, not that they really needed it. I cleaned the little shield on the main jet needle guide and the venturi before replacing the needle and replacing the top caps, polished of coarse.



As I was going I noted the all of the serial numbers of the jets. They were the same as those listed as the base settings on NSR World with the exception of the Needles but that was probably me reading the wrong number:
Carb 1:
MJ-140
SJ-38
Float-2.6
Needle-J8MA

Carb 2:
MJ-140
SJ-38
Float-2.6
Needle-J8LA