With classes out yesterday (I'm a teach) I've decided to get to the root of my full-throttle problem. Symptoms? Running lean in hot weather in top gear between 5-6k.

Bike is 18 years old, so I figure it needs a little help. I looked into the tank and saw what I thought was a bit of the old red stuff. A further look into the tank reveals that it's pretty clean, with perhaps a tot of rust near the seams (where they always rust).

I spent the last 4 hours removing plastics, taking the tank off (I've never done this on a bike, and it was not all that fun), and taking off the very complicated intake system. I am now down to loosening the screws on the carb boots (the manual refers to them as the "insulators") and cannot see any but the left-most screw. I see #2's if I really get the flashlight in there but see no way to access it. Any tips or hints as to how I can find these bad boys?

I pulled off the fuel filter and emptied it into a gas can. I wanted to tap it on the table-top to see if any debris would come out, and was surprised to see it producing rust...

Wads of rust. More, and more, and MORE - it was like that weird hard zit you get that you just touch and it shoots pus, then 10x as much crap comes flying out of it than you ever imagined could fit in there.

The pile of rusty dirt was close to a tablespoon! No wonder why I was running lean!

 

So I had a re-look, and determined that I was trying to reach the head-side of the boot (insulators) and that the proper screws were on the undersides. They were still amazingly hard to see, but I got to them (I thought) and loosened the screws.

The carbs were still stubbornly stuck, and I tried to see if I properly unscrewed all the hose screws. Flummoxed, I broke out a monstrously-large pry bar (can you tell where this is going?) and pried upward.

I'll bet you can guess what happened next.

I fortunately was prying up on a coolant line connection to the carbs, which promptly broke.

Don't do things with pry bars out of desperation, people. Getting back under my carbs (after the temper tantrum carefully enacted in an enclosed garage, so my neighbors could not tell how catastrophically stupid and violent I am) I discovered that I had somehow forgotten to loosen the boot on Carb #2 and that #3 and #4 were loose, but not loose enough to do the trick.

The carbs came off easily after that and encouragement from my wife's hairdryer, which I used to loosen the rubber. The garage is about 25 degrees F out there and rubber isn't particularly cooperative at low temps. I inspected the broken part; it's that Y-shaped rotating part between the carbs. It's not a big deal, and I am told that the carbs don't need coolant running between them in the first place as it's there to prevent icing, and I don't live or ride in any conditions that may cause such problems.

Now the carbs are off. I have a decision to make - do I have them professionally rebuilt, or should I do it myself? It will cost $300 for the local guy to do it with new carb kits.

 

I would rebuild them myself. The hardest part was getting the carbs off. Do you have stock exhaust and air filter. Might want to look into rejetting since you got the carbs off now.

 

So I took the #1 carb off and pulled the needles - it's not overly lacquered, and the passages seemed clean (except the idle jet, which is still a little clogged; all the parts are soaking in kerosene overnight, including the carb body).

Kerosene IS the right stuff, right? It wasn't super-effective, but combined with scrubbing from a toothbrush the lacquer came off the bowl and floats.

Oh, and from the lack of buggering of screws I can only assume this is the first time in 17 years the carbs have been taken down. Should I do the pilot screws? I'm thinking "probably." I gotta find somebody with a .22 shell so I can make the D-screw. I'm not particularly eager to dremel them but I certainly can do it.

 

Now I have to decide what to do about the tank.

The rust in the fuel system did not materialize from thin air. It came from my tank, which seems to be rusting slightly in the seams. There is a tiny bunch of insubstantial rust right beneath the filler cap; the remainder of the tank looks pretty great.

I am weighing the option of shipping it off to California for a guy to work on it using an electrolytic method which does not harm the outside paint. All up with return shipping I expect to see $350. I could just fill the tank with BBs or fasteners and go at it with liquids and other stuff for a couple of days, then Red Kote it - or leave it uncoated.

Since I've found no rust in the float bowl on #1, I can't really say that the fuel filter didn't do it's job. Lacquering of the fuel was much lower than the bikes I've seen on the internet - mine is in very good shape. I may just slap a new fuel filter on there and go to town; fuel filters are cheaper than shipping tanks to California.

 

We have an old jaguar fuel tank coated at a rad shop. Wasn't close to that expensive. They were able to knock off a good portion of the rust and they coated it with an epoxy. I'd check local rad shops before spending those bucks sending it away.

Kerosene is fine for cleaning. You can use whatever, as long as you don't go overboard on soaking the rubber bits. I boiled the carbs from my old kwak in lemon juice on the bbq for an hour. Removed all the crap and they smelt lemon fresh afterwards.

 

More decisions: Should I bypass the carbs for the coolant? I seem to recollect during my flying days that carbureted motors in aircraft need carb heat during humid conditions, but it takes away power. Are we voluntarily killing our power because Honda just wants to avoid lawsuits for iced-up and stuck carbs in Jolly Old England, where riders ride in 80% humidity at 40 degrees F?

 

I have cleaned out the carbs and re-assembled them individually. This went quite smoothly considering I used the resource here and in the shop manual.

I also took this opportunity to clear out the coolant and flush the system, and to clean the after-part of the engine and running gear, and the hoses and wires. I bathed all the plastics and rubber in silicon spray and everything is looking like new.

I am awaiting the joint set and the o-ring/gaskets from both Honda and an aftermarket O-ring company on the internet - I just ordered them to compare them to the stock Honda stuff to ensure that people not wanting to pay the ridiculous 10,000% mark up on .03 cent O-rings have at least another option if they want to save like $50. I will report here how feasible they are as replacements and give pricing and vendor information.

Us old-school CBR people have to figure out how we're going to repair these long-lasting bikes into their (and our, LOL) old age.

 

Hey bud, in no way would I send my tank off for that procedure. Not only is it going to take a few, but the cost is astronomically high for something you can do yourself for 15 bucks. Vinegar works absolutely perfect for this. I as well as many other people can vouch for it. Not sure if you have done it before or not but there really is no BS with the technique. It flat out works. My tank was completely rusted from top to bottom and really thick up top. Vinegar made it look like new.

 

So should I go out and buy 4 gallons of cheap vinegar? Acetic acid is effective on rust, but it's not too strong. Frankly, my rust isn't all that severe, either.