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PLEASE Help - CB72 Carburetors

Fuel System: Gas (Petrol) tanks, Carburators
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G-Man
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Re: WOW! What a quick response!

Post by G-Man » Mon Dec 28, 2015 2:33 am

Good. LM will get you sorted, I'm sure.

G

ojwilliams1 wrote:Started working the problem over the phone with LOUD MOUSE this afternoon. G-man, LM confirms what you said. Should be able to fix with jets and settings. First we went over the things that I had already checked (float level, cable adjustments, etc.). Then he had me properly adjust the idle air screw and raise the needle setting. I'm to ride it tomorrow and let him know how it runs then he'll decide what to do next. Attached a couple of photos for grins.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

LOUD MOUSE
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Re: WOW! What a quick response!

Post by LOUD MOUSE » Mon Dec 28, 2015 4:18 am

We talked and worked on the carbs for over an hour.
He will fire it up Monday. ............................lm
G-Man wrote:Good. LM will get you sorted, I'm sure.

G

ojwilliams1 wrote:Started working the problem over the phone with LOUD MOUSE this afternoon. G-man, LM confirms what you said. Should be able to fix with jets and settings. First we went over the things that I had already checked (float level, cable adjustments, etc.). Then he had me properly adjust the idle air screw and raise the needle setting. I'm to ride it tomorrow and let him know how it runs then he'll decide what to do next. Attached a couple of photos for grins.

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ojwilliams1
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Operator Error - Carb Confusion

Post by ojwilliams1 » Tue Jan 12, 2016 11:06 am

Follow Up

Posting this so that those who see this in the future will know how things turned out and to thank Loud Mouse and G-Man for their help. First of all they were right! CL72 carbs work fine on a CB72; just need to change to the proper jets.

After troubleshooting over the phone with LM, I did a test ride and then called to tell him that little had improved. After a short discussion, he asked me to send him the carbs so he could look for the problem. While he had them he changed the #115 main jets to #100 (correct for CB72) and replaced several worm small parts. He then called and told me that he couldn’t find anything that would cause the symptoms I described. We then discussed a few other things to check and during the conversation he said something that suddenly made me realize what the real problem might be. I wasn’t sure at the time (it seemed so STUPID!) so I didn’t say anything then but as soon as I got the carbs back I put them on and took the bike out for a test ride. After she warmed up the bike ran great!

So what caused the original problem? OPERATOR ERROR! My first vintage bike was a ’74 Yamaha RD250 that I bought 5 years ago and ride frequently. You know how you choke a Mikuni carb on a ‘74 Yamaha? You push down to choke and up to release. This is opposite what you do on the CB72! I was trying to make the Honda run with the choke fully closed! No wonder she stopped. Anyway, I’m a little embarrassed but happy that there wasn’t a major problem. Live and learn. Even at 68! Thanks again guys.

OldScrambler
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Post by OldScrambler » Tue Jan 12, 2016 3:07 pm

Confession is very humbling........and SATISFYING.

I wanted to say something on your fist post, but was traveling without a keyboard.

LOUD MOUSE
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Posts: 7817
Joined: Mon Aug 15, 2005 8:23 am
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Re: Operator Error - Carb Confusion

Post by LOUD MOUSE » Tue Jan 12, 2016 4:50 pm

There is not always a simple way to cure bike problems on the phone or computer (phone contact is mush better) so at times I do need to "get my hands on something" if for no other reason than to eliminate it as the problem.
During a conversation I had with OJ he did say something about the carbs which I questioned but left alone.
?????????????????????
I could feel a Question In His Person which could have been/was the actual problem.
As he stated he found what was causing the problem and Is Man Enough To Get It out.
Thanks OJ.
Now go ride and have fun. ...............lm

ojwilliams1 wrote:Follow Up

Posting this so that those who see this in the future will know how things turned out and to thank Loud Mouse and G-Man for their help. First of all they were right! CL72 carbs work fine on a CB72; just need to change to the proper jets.

After troubleshooting over the phone with LM, I did a test ride and then called to tell him that little had improved. After a short discussion, he asked me to send him the carbs so he could look for the problem. While he had them he changed the #115 main jets to #100 (correct for CB72) and replaced several worm small parts. He then called and told me that he couldn’t find anything that would cause the symptoms I described. We then discussed a few other things to check and during the conversation he said something that suddenly made me realize what the real problem might be. I wasn’t sure at the time (it seemed so STUPID!) so I didn’t say anything then but as soon as I got the carbs back I put them on and took the bike out for a test ride. After she warmed up the bike ran great!

So what caused the original problem? OPERATOR ERROR! My first vintage bike was a ’74 Yamaha RD250 that I bought 5 years ago and ride frequently. You know how you choke a Mikuni carb on a ‘74 Yamaha? You push down to choke and up to release. This is opposite what you do on the CB72! I was trying to make the Honda run with the choke fully closed! No wonder she stopped. Anyway, I’m a little embarrassed but happy that there wasn’t a major problem. Live and learn. Even at 68! Thanks again guys.

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