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I have a 1980 CB750K that no matter what I tried this summer I couldn't keep it running. I had it running great for about a week and then it just started acting up. I rode it the first time for about half an hour and it would start running lean, but every time I got on the throttle it would bog down for a second, then would run rich. It jumped the RPMs rediculously. It continued like this the 8 to 10 times I rode it. Each drive was less than an hour.
After driving it it wouldn't start unless I had the choke fully pulled and wouldn't stay running if I had it any less than pulled about half an inch. Right after it started up it would rev WAY too high and when I put the choke in it would die.
During the drives it was easy to keep the rpm at a decent level, until I came to a stop at a light or sign. It sputtered for a second then again would die. It took at least three ignition turns to get it to fire up.
After my last ride I haven't even been able to get it started.
I put new jets in it and rebuilt all four carbs thinking it would help since whoever did it last used what appeared to be some liquid that completely ate up and dissolved the rings and diaphrams. So at this point I can't work on it due to not having the time, nor the space to do so. It's parked for the winter and I put Stabil in the tank and ran what I could through the carbs before bleeding them and parking it.
I am sure there are multiple things that it could be. ANY advice would be helpful for when I try it again this spring.
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Administrator
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It sounds like a vacuum leak. Check the rubber boots between the carbs, and the head for leaks.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."
1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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Checked the boots on the carbs but not the head. It'll be first on the list for sure. Any other possibilities?
Connected by DROID on Verizon Wireless -----Original message----- From: "TOOLS1 [via Honda CB750'S]" < [hidden email]>
To: LODY < [hidden email]>
Sent: Tue, Dec 31, 2013 04:02:51 GMT+00:00
Subject: Re: 750 won't stay running
It sounds like a vacuum leak. Check the rubber boots between the carbs, and the head for leaks.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
1976 CB 750-A X 2
1977 CB 750-A X 2
1977 CB 750-K X 2
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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So, I was pulling parts from the 750 and saw a couple hoses disconnected. I reconnected them and was trying to fire it up with no success once again. It fired but wouldn't stay running. I randomly decided to check the coils and found out they are both cracked and the coil controlling the 2 & 3 spark plug was corroded to the point where the wire was falling apart inside the plastic. I ordered new parts already today and I'll see if I will be able to get it to stay running. Is there any other possibilities on what it could be if that doesn't work? Checked the boots on the carbs but not the head. It'll be first on the list for sure. Any other possibilities?
Connected by DROID on Verizon Wireless -----Original message----- From: "TOOLS1 [via Honda CB750'S]" < [hidden email]>
To: LODY < [hidden email]>
Sent: Tue, Dec 31, 2013 04:02:51 GMT+00:00
Subject: Re: 750 won't stay running
It sounds like a vacuum leak. Check the rubber boots between the carbs, and the head for leaks.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
1976 CB 750-A X 2
1977 CB 750-A X 2
1977 CB 750-K X 2
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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Changed the coils and found that the vacuum leak was indeed from where the boots connected to the head. They cracked further immediately when I removed them. I replaced them and have yet to throw the air box back on. I had thought about throwing on some air pods on and haven't decided if I want to run them on it yet. Everything I have read says it's a pain in the a$$ to get it tuned and running correctly. Any thoughts?
On Sunday, May 11, 2014 5:38 PM, Dan Lodermeier <[hidden email]> wrote:
So, I was pulling parts from the 750 and saw a couple hoses disconnected. I reconnected them and was trying to fire it up with no success once again. It fired but wouldn't stay running. I randomly decided to check the coils and found out they are both cracked and the coil controlling the 2 & 3 spark plug was corroded to the point where the wire was falling apart inside the plastic. I ordered new parts already today and I'll see if I will be able to get it to stay running. Is there any other possibilities on what it could be if that doesn't work? Checked the boots on the carbs but not the head. It'll be first on the list for sure. Any other possibilities?
Connected by DROID on Verizon Wireless -----Original message----- From: "TOOLS1 [via Honda CB750'S]" < [hidden email]>
To: LODY < [hidden email]>
Sent: Tue, Dec 31, 2013 04:02:51 GMT+00:00
Subject: Re: 750 won't stay running
It sounds like a vacuum leak. Check the rubber boots between the carbs, and the head for leaks.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
1976 CB 750-A X 2
1977 CB 750-A X 2
1977 CB 750-K X 2
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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No pods please. Lol. Fix the leak first and If you haven't, you should check your ignition timing. I think there's a post about checking your pulsar gap. I did that yesterday and my bike started and idle with little choke needed.
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I actually was given a set of pods yesterday and have yet to try them. I will likely put the stock box back on and get a new filter for that. I have also seen that putting CBR coils on it may make a difference as well. Is that a good Idea?
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I believe I do have the vacuum problem fixed though. I have plenty of suction through the carbs. I ran it a couple times with the box off and it did run pretty well, but with so little resistance it wasn't sucking as much gas into the system as needed. I covered the openings to give it resistance and it ran pretty decent, so I just gotta throw the box back on and hopefully THAT part is taken care of.
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I got it running pretty good. still revs high when i squeeze the clutch though. as i am sppeding up and when i'm slowing down. it's like the gas isn't disengaging right away.
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So... here's another development. I got an 82 bobber with a 750 on it. It came with pods installed on it. They weren't anything special and were unmarked as to a brand. I taped them 3/4 and it ran quite a bit better. However it didn't like to engage the clutch. I pulled the filters off and it went into the gears fine, but had almost nothing in the top end. It's a custom bike so a stock air box will be pretty much impossible to mount. I'm open to suggestions.
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Locked
