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my 1980 CB750F starts up fine. however, as soon as i let off the start button, there's a very large grinding sound. only last a second or two and seems to be related to the starting process. happens regardless if the bike actually starts or doesn't start right way. i let off the button, it grinds.
Never diagnosed a problem with this bike before (just got it last year, but the problem just started recently) but assume it's an issue with the starter?
once it starts, it idles great, runs nicely. I just don't like the grinding sound. Any advice is appreciated.
thanks.
Tony.
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Administrator
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Can you record the sound, and post it here or somewhere else (YouTube, maybe)?
It will help determine where the noise is coming from.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
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excellent idea. will post as soon as i can. i travel for work so will be end of week. thanks for the idea. On May 11, 2015, at 6:22 AM, LukeM [via Honda CB750'S] < [hidden email]> wrote:
Can you record the sound, and post it here or somewhere else (YouTube, maybe)?
It will help determine where the noise is coming from.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
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NAML
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Administrator
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It might be the starter not wanting to disengage.
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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Administrator
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The bolts that hold the starter clutch together on the twin cams are famous for backing out. And the clutch itself can fail. If it's grinding I wouldn't crank on it anymore trying to diagnose it. It'd remove the starter cover and do a visual inspection.
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thanks shiny! what exactly am i looking for? loose bolts? is this something easily repaired or do you normally have to replace these when this happens? On May 11, 2015, at 10:56 PM, shinyribs [via Honda CB750'S] < [hidden email]> wrote:
The bolts that hold the starter clutch together on the twin cams are famous for backing out. And the clutch itself can fail. If it's grinding I wouldn't crank on it anymore trying to diagnose it. It'd remove the starter cover and do a visual inspection.
A free people ought not only be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government.~George Washington
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NAML
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Administrator
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It is in behind your timing plate. If you are careful you can probably fix it without disturbing your timing. Your ignition cover is the round one in front of your shifter. You won't lose a gasket, it's o-ringed. You'll see the ignition plate (pulse generators) up front. Your starter clutch is in behind that. Three bolts on it. If you remove them one at a time and put them back in with loctite ( solvent clean the bolt and the hole so the locktite will hold,brake cleaner works well for this) you may fix the problem. Of course, that is if you find they are loose. Otherwise, it may be the sprags inside the starter clutch that need replacing. Also and easy job, but you will have to take the second cover off that the ignition plate actually mounts to. It won't disturb your timing to do this, but you might lose that gasket in the process.
Clear as mud? I saw a good youtube video on this once. I'll post it if i can find it.
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Thanks! You Tube is a great resource. i appreciate your help. On May 14, 2015, at 7:40 PM, shinyribs [via Honda CB750'S] < [hidden email]> wrote:
It is in behind your timing plate. If you are careful you can probably fix it without disturbing your timing. Your ignition cover is the round one in front of your shifter. You won't lose a gasket, it's o-ringed. You'll see the ignition plate (pulse generators) up front. Your starter clutch is in behind that. Three bolts on it. If you remove them one at a time and put them back in with loctite ( solvent clean the bolt and the hole so the locktite will hold,brake cleaner works well for this) you may fix the problem. Of course, that is if you find they are loose. Otherwise, it may be the sprags inside the starter clutch that need replacing. Also and easy job, but you will have to take the second cover off that the ignition plate actually mounts to. It won't disturb your timing to do this, but you might lose that gasket in the process.
Clear as mud? I saw a good youtube video on this once. I'll post it if i can find it.
A free people ought not only be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government.~George Washington
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NAML
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Administrator
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You're welcome. Always happy to help.
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Administrator
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Sounds more like a metal sliding on metal type of squeal, rather than toothed gears grinding. Im guessing starter clutch.
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Administrator
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Sounds like his gerbil got caught in its exercise wheel, or the starter clutch is not releasing.
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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This post was updated on .
Hi Tjurek51,
Starter clutch or Starter motor. Mine does it too (as do many other DOHC's) occasionally, especially if it's been left unused for any length of time. I've not bothered fixing it. It's worth stripping, checking and cleaning the clutch components and lubricating the moving parts/shaft but NOT the rollers!
It could also be a dry shaft/bearing on the starter motor. When starting the engine, the motor spins fairly slowly but as soon as it fires, the clutch releases and the motor spins much faster. The noise usually occurs when you release the start button and the motor starts slowing down. A bit of lube should sort it.
Maz
'76 CB500T
'75 GL1000 'Wing
'79 CB750L
'90 FJ1200
'93 GS500E
In a little place called Bexley, Kent, UK (Just south of London!)
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Thanks!
From: "Maz [via Honda CB750'S]" < [hidden email]> Date: Monday, May 18, 2015 at 1:46 AM To: "Jurek, Tony (US - Minneapolis)" < [hidden email]> Subject: Re: Grinding noise when starting bike
Hi Tjurek51,
Starter clutch. Mine does it too (as do many other DOHC's) occasionally, especially if it's been left unused for any length of time. It's worth stripping, checking and cleaning the clutch components and lubricating the moving parts but NOT the rollers!
Maz
'76 CB500T
'75 GL1000 'Wing
'79 CB750L
'90 FJ1200
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NAML
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ok, silly question; took the plate off the starter clutch and there was some oil in there. is this normal or do i have bigger problems? most pictures i've seen show this area as pretty clean of oil.
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Rebuilt starter clutch, sound is still there, but not as intense. Any thoughts? On Tuesday, May 19, 2015, Jurek, Tony (US - Minneapolis) < [hidden email]> wrote: Thanks!
From: "Maz [via Honda CB750'S]" <<a href="javascript:_e(%7B%7D,'cvml','ml-node%2Bs456789n4056551h75@n3.nabble.com');" target="_blank">ml-node+s456789n4056551h75@...> Date: Monday, May 18, 2015 at 1:46 AM To: "Jurek, Tony (US - Minneapolis)" <<a href="javascript:_e(%7B%7D,'cvml','tjurek51@gmail.com');" target="_blank">tjurek51@...> Subject: Re: Grinding noise when starting bike
Hi Tjurek51,
Starter clutch. Mine does it too (as do many other DOHC's) occasionally, especially if it's been left unused for any length of time. It's worth stripping, checking and cleaning the clutch components and lubricating the moving parts but NOT the rollers!
Maz
'76 CB500T
'75 GL1000 'Wing
'79 CB750L
'90 FJ1200
To unsubscribe from Grinding noise when starting bike, click here.
NAML
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ok, just to close this out. rebuilt the starter clutch and the noise still remained. however, it was also a bit hard to start and maintain a low idle. So, synched up the carburetors and noticed the engine caught much faster and the noise went away. not sure if this makes sense, but seems to have solved my problem. also, bike now screams at 6K rpms (in a good way).
thanks all for the advice for this novice to follow.
now, time to plan for my real project: CB1000 Cafe Racer.
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Locked
