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Discussion Starter · #1 ·
Just got the bike and some questions on the carbs. Pulled them and found one piston stuck, one with a hole in float and need cleaning. Main jets are 145 Low speed jet I believe says 38. Looked for carb kits but can't find one listed. Carbs are Keihin with
KK y 723A stamped on body. I posted on another site and I believe some of you might have responded to my compression issues. Bike has not been run for awhile and comp was 142, 144. I have carbs off and will try again to see if any difference. I can't find specs for compression on this engine but I believe it's 9-1.

Thanks,
Terry
 

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Terry -

Yeah, 9.0:1 is the compression ratio. I posted the "check yer' compression" page from the Honda manual over at the other place......

You're finally in the right place now.

450's don't like to be ignored, they get kind of bitchy after extended non-activity.
If I could post the manual for you, I would, but the file is WAY too large, and it's not available anywhere on-line that I know of. The Clymer manual is pretty worthless in this case.
Don't rush into anything - a 450 is not an engine you want to tear apart on a whim.....

Good luck.
 

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Discussion Starter · #4 ·
Thanks Bill. I started cleaning things. Got the lo speed jet cleaned and all the passages seem to be clear now and the piston moves smooth as glass. I ordered that 2.5 liter ultrasonic cleaner from Harbor freight plus a few other things to help me with the job at hand. I plan to pull the engine anyway as I am going to paint the frame and the engine too but first need to do a bit of cleaning up on it. Overall it looks good. I'm going to fog some oil in it and then recheck compression with the carbs off. As I was taking things apart I discovered it had new air cleaners and one of them someone had forgotten to remove the piece of tape around the filter! Not sure what this would have done but I'm sure it didn't help. One more question which you might answer. The part under the low speed jet (not sure what it's called;it's brass and has a screw driver slot in it) Should I try and remove it? I've seen these stuck and break trying to remove them. The passage is clear so should I leave it alone and just clean the jet?
 

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Discussion Starter · #6 ·
Yeah, Bill. That's what I'm referring to. I guess my next question is, am I better off to just tank clean the carb with the slow jet in place as all the passages seem to be open and then just button the whole thing up and screw a kit except maybe for a float bowl gasket?
Might not need anything else for it.
 

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Haoleman said:
Yeah, Bill. That's what I'm referring to. I guess my next question is, am I better off to just tank clean the carb with the slow jet in place as all the passages seem to be open and then just button the whole thing up and screw a kit except maybe for a float bowl gasket?
Might not need anything else for it.

No - take the slow jet out, I've never heard of anyone breaking it or anything. They do get stuck sometimes, but generally free up after a good "soak".
Be careful about what (if any) chemical you might use in the ultrasonic cleaner.
There are nylon parts around the choke and throttle shafts, as well as the big "button" on top of the vacuum cap dome. None of those parts respond well to temperature or chemicals..........

Whether or not you need a kit depends on the condition of the mixture screw, the jets, the fiber o-ring that goes under the vacuum dome (critical), etc.

A good air compressor is your best friend here - don't poke any wires or things like that into the jets or passages unless you absolutely have to.
 

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Discussion Starter · #8 ·
Thanks Bill. All the gaskets look good and wern't leaking when I took it apart. So far, a piece of nylon from a brush was all I needed to clear one of the jets. The cover of the low speed jet actually has a microscopic hole in it at the bottom. I actually had to use a 10 power magnifier to see it. It was clear. On the ultrasonic cleaner, it seems that most agree that simple green works great and won't screw anything up. If that's a good choice, I'll try that first. Other than the hole in the float (which I think I can solder up after removing the gas and drying it, it really isn't too bad so maybe just a cleaning will suffice
 

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You said "The cover of the low speed jet actually has a microscopic hole in it at the bottom. I actually had to use a 10 power magnifier to see it. It was clear...."
That "cover" is actually the "pilot" jet.......
 

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66Sprint said:
You said "The cover of the low speed jet actually has a microscopic hole in it at the bottom. I actually had to use a 10 power magnifier to see it. It was clear...."
That "cover" is actually the "pilot" jet.......
Steve -

You have no idea how painful this is for me, but I'll have to disagree with you.

This is actually the pilot jet for a 450 carb, generally included with a "carb kit" -



This is the "cap" I was talking about - you can see the small hole in the bottom that Terry mentioned.
But there is no hole in the top. It has "38" stamped on it, but no hole in the top.
It's a plug - all fuel in a 450 goes through the main jet first, then through the cross drill, then through the small holes in the side of the "plug/cap", out the bottom of it, and finally into the pilot jet itself.




This is the pilot "cap" in place-


With the cap removed, you can see (1) the hole that the actual pilot jet goes down into (it's way down in there, not visible in the photo)-
(2) the cross-drill channel, which is fed by the main jet
and (3) the little brass plug that they press in to close off the cross-drill.

So, all fuel in a 450 goes through the main jet first, then some goes through the cross-drill channel, into the holes drilled in the side of the "cap/plug", out the bottom hole in the "cap/plug", then finally into the pilot jet.


Now, I have no real way to measure that bottom hole in the "cap" - maybe it's appropriate to think of it a a 2-piece pilot jet ???? Howver, the "cap/plug" is never included in any carb kit I've ever seen......

I have a whole bunch of old guitar strings - maybe I can use them to approximate the bottom hole's diameter - I'll keep you posted......
 

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Bill ...I'm not argueing... Just stating what Honda calls it....
The Honda manual calls part# 4 on page 44 in the 450 K0 manual, the pilot jet....(referring to the drawing on page 45 of 134)
Part number is 99104-03804 (for the #38 jet)..... It has a specific sized metering hole and therefore IS a "jet" ....
I agree that it "accesses" its fuel supply through the main, but that is irrelevant to its "metering" function....
What you call a pilot jet, Honda calls the "slow" jet......(again, it's a 38, so your two-stage pilot is a great explaination.......
We are probably just discussing a difference in terminology/definition...... Ain't semantics great!?!... :lol:
See, we're BOTH right!....LMAO! .... Steve
 

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66Sprint said:
Bill ...I'm not argueing... Just stating what Honda calls it....
The Honda manual calls part# 4 on page 44 in the 450 K0 manual, the pilot jet....(referring to the drawing on page 45 of 134)
Part number is 99104-03804 (for the #38 jet)..... It has a specific sized metering hole and therefore IS a "jet" ....
I agree that it "accesses" its fuel supply through the main, but that is irrelevant to its "metering" function....
What you call a pilot jet, Honda calls the "slow" jet......(again, it's a 38, so your two-stage pilot is a great explaination.......
We are probably just discussing a difference in terminology/definition...... Ain't semantics great!?!... :lol:
See, we're BOTH right!....LMAO! .... Steve

I'll have to concede this to you, Steve.
First, I have to preface that with the probably incredible (and definitely humiliating) confession that, up until a few minutes ago I never actually looked at a drawing or fiche of the 450 carb.
But you're right - Honda calls the "plug/cap" the pilot jet, and the other buried one the slow jet.
The carb is just so brutally simple that neither myself or any of my contemporaries really considered that thing to be a jet.

An object lesson to everyone (and especially me) of the perils of over-familiarity. And I'm definitely guilty of that - I know every piece and bit of a 450 like the back of my hand. When I tear one down, I never separate or bag anything, I just throw it all into one big box and have no problem at all putting it all back together with great speed and accuracy. Now that's being over-familiar......

I can't help wondering, though, why the "pilot" is never included in a rebuild kit, just the "slow" jet?? I never recall seeing it included, not even back in The Day.

Well, at least I had the function right......I'll just slink away now.
 

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I'll have to concede this to you, Steve.
First, I have to preface that with the probably incredible (and definitely humiliating) confession that, up until a few minutes ago I never actually looked at a drawing or fiche of the 450 carb.
But you're right - Honda calls the "plug/cap" the pilot jet, and the other buried one the slow jet.
The carb is just so brutally simple that neither myself or any of my contemporaries really considered that thing to be a jet.

An object lesson to everyone (and especially me) of the perils of over-familiarity. And I'm definitely guilty of that - I know every piece and bit of a 450 like the back of my hand. When I tear one down, I never separate or bag anything, I just throw it all into one big box and have no problem at all putting it all back together with great speed and accuracy. Now that's being over-familiar......

I can't help wondering, though, why the "pilot" is never included in a rebuild kit, just the "slow" jet?? I never recall seeing it included, not even back in The Day.

Well, at least I had the function right......I'll just slink away now
Forgive me Oracle for i have sinned.....:twisted:

Ok for you sins, that's three days in the garage WITHOUT the heater, and one chapter of the CB450 Carburetor manual read out loud :lol: :lol:

Rod from OZ :cool:
 

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Discussion Starter · #14 ·
Did I open a can of worms or what? It's good that I didn't do my usual "Oh, I'll just take my 1/4 inch drill and ream it a bit!"
Now that I am getting into the thick of it, can someone recommend a good tear down manual either online or in print and where to find it?
Don't know if I mentioned it but back when I was a kid in the early 70's I was a Honda mechanic. Spent the rest of my working life as an appliance servicer until we bought this inn 4 years ago. I have a need to get dirty!

Terry
 

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Discussion Starter · #15 ·
Well, soaked the carbs in simple green and came back to a pile of mush! The carbs turned into some sort of pot metal sulfate. Naaah! Just keeping everyone awake. Man, I can't believe what a good job it does as a carb cleaner.

I bought some stripper at Menards called Zinsser Strip Fast Power Stripper. Says it will strip 5 layers at a time including epoxy and polyurethane. Sorry Zinsser, That's a bunch of BS. It has no nasty odor so therefore it doesn't work. Not even a little bit. I am trying to strip the clear coat off the carb piston covers or whatever you call them (the big shiny thingys) and then the side covers and all else on the engine that will require paint removal to polish. Should I just go to an auto paint store and buy some of the good stinky stuff?
 

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When cleaning the "clear-coat" off the carb bells, be sure NOT to get any on the white plastic center button.....
 

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Discussion Starter · #18 ·
Well, I found an old can of stinky stripper and it worked somewhat but I need to get some real nasty stuff. While cleaning the carbs I found that someone drilled a 3/32 hole in the bottom of the float bowl. Why??? I guess it was fixed with JB weld. Polishing it exposed the hole. If anyone has a spare carb for parts they would be willing to part with, please let me know. All the rest looks good and I got them cleaned up nicely
 

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I probably have an extra bowl, but it will be dirty and need cleaning and polishing,
but the price will be small.......
Need a shipping address e-mailed to me at [email protected] :D Steve
 

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Aircraft stipper from Autozone works very well, and also burns skin like a mother*^#@!!! It stripped all of my parts easily..


GB :mrgreen:
 
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