It was a dark and stormy night…..
Somewhere it was, but not here. It was rather warm, and the coolness of my subterranean shop was a blessing. It turned out that I would spend the better part of a weekend in there, wrestling the carburetors into the very tight, very new, KZ900 carb holder boots. Stock KZ400 boots are harder to find than Spanish treasure, so based on information on the KZ400 forums, with a little work, carb holders from it’s newer and larger brother would fit. And fit they did, but just barely.
The primary challenges, beyond having to modify the mounting holes on the carb holders (at $45 EACH that was not an easy decision in itself), was that the carb mouth I.D.’s were the same as the carb holder (boot) O.D. Obviously.. that is going to make for a tough install. If you have ever held one of these thick, hard, rubber boots, you’d understand the trepidation that kept this project on my ToDo list for 3 months!
Alas, I finally got motivated enough (gas prices and the fact the 3 week Washington Summer was upon us) to tackle the project last weekend. Here are some thoughts and photos. A quick thanks goes out to my 7 year old boy for taking the ‘action’ shots of dad working on the bike. You’re one in a million, kid!
Now, the size of the carbs is not the whole story. About 2 months prior, with a lot of soap, and pressing with most of my weight, I was able to force the carbs into the rubber boots. That’s where they remained for a long time. The concept being, to stretch them out into a static state that was larger than manufactured size, hopefully making the final install a little easier. And frankly, I think it helped out a lot!
What I tried to illustrate in photos, but clearly did not convey, is that even WHEN you get a single carb in the boot, the other carbs mouths is them 1/4″ off-center. The carbs are mounted to a thick aluminum flange. That flange forces the specific spacing of the carburetors. There is not play, no give, so the only thing that could possibly allow the successful installation of the carbs was REALLY forcing in one carb, then trying to pry it off center line while forcing in the other. All while holding up the carb set. If I’d had 4 hands it would likely have still been impossible.
Thinking about decades of home auto repair, I decided to use a not-often employed tactic of taking things further apart, to make it easier to put back together again. Often it’s an access issue, and although it looks like there is a lot of space, I was having one here.
I finally got the grand idea that if I dismounted the carbs from the mounting flange itself, it would be easier to manipulate than the entire carb set. So I set about unscrewing the carbs from the flange. In the end, it was what I needed to do, to get this project moving again.
Now, that was still a huge struggle to get the flange shoved into the boots, but I was able to get it done! Victory was at hand!!! Now, what remained was to tighten down the holder flange bolts. In what I was say was a stroke of genius, I had purchased round head Allen set bolts to replace the Philips head screws that, normally used. the heads are actually wider, and flatter, but the big bonus was being able to use an Allen key wrench to tighten them down. The brilliance comes in that I knew I might have try just this to get the carbs mounted, and these bolts were part of my plan.
I do not think I would have been able to do that with the Philips head, as the holes in the flange I used to access them were off-axis from the mounting bolts. Using a universal headed Allen tool, I was able to tighten down the bolts using the carb mounting holes in the flange.
Now of course, comes another challenge. The carb mounting bolts are THROUGH bolts from the BACK of the flange into the carbs. So, I would once again be working in the very confined space between the flange and the cylinder head.
Using a very neat tool I picked up at Harbor Freight for $3.00 (small right-angle multi-bit ratcheting wrench) combined with a #2 Phillips bit from another kit, I was able to get the screws that mount the carbs to the flange, tightened down. It took a little while for me to determine exactly what which of the bits were short enough to fit in there, but once that problem was solved, carb #1 was mounted!
As with most mechanical projects where some repetitive work is involved, the subsequent processes generally go much faster. And that was the case here. Viola.. CARB ARE INSTALLED!!!
In the last photo here, I think you can see (I can see it, but I know what I think I see) the degree of stretch required to get the carbs into the boots, and also the off center line mounting of the carbs in the holders themselves.
What remains to be tested:
More to follow!
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