Author Topic: K0 750 won't idle......and my mechanic has had the damn bike for 6 weeks!  (Read 2956 times)

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Offline zoo mob

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I've got way too many projects right now, and my K0 had been sitting with the carbs in pieces since last fall, so I decided to take it to a local old timer to get it back on the road. Pretty much just needed to have the carbs put back together and tuned etc. Said it would be two weeks and its been six, he says it runs etc. but he's having a hard time getting it to idle. I'm really fed-up and want ot get the thing back. What the hell could be the problem with not getting a good idle? Could it be as simple as adjusting the cables? I'm close to just going up there and getting it and finishing it myself. Thoughts?
Andrew
 1970 750 K0
 1980 BMW R100T
 1980 GS1100E
 1993 XR650L
Always looking for more

Offline Hasenkopf

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thought =  should have done it yourself, sorry dude.
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Offline Johnie

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I hope he knows he has to sync the slow idle by the large screws on the side of each carb. Then do another sync at around 3,000 RPM by adjusting the cable tops. If the cables are set to high to start, he will not be able to get a low idle. Believe me, these KO carbs can be a real bear to dial in...
« Last Edit: June 02, 2010, 08:57:00 PM by Johnie »
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline Spanner 1

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Posts= 390 I can reply...respect but lay it back on your 'mechanic'...
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline zoo mob

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I figured I was opening myself up for some criticism on this. I don't really get what that last response was, but yes, perhaps I should call him "the dude who has had my K0 for too damn long as opposed to "my mechanic" since he's not exactly on retainer or anything. Yeah, should have done it myself for sure, but the fact that I had a ton going on and that this guy has pretty much any SOHC4 part you'd ever need, that he sold me a different K0 minus motor and carbs for $100, and claims to have worked on these bikes since they were new made me think he knew WTF he was doing.

Johnie, thanks for the tip, I'll try to diplomatically forward it on to him. I just want to ride the damn thing.
« Last Edit: June 03, 2010, 07:09:02 AM by zoo mob »
Andrew
 1970 750 K0
 1980 BMW R100T
 1980 GS1100E
 1993 XR650L
Always looking for more

Offline fastbroshi

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I hope he knows he has to sync the slow idle by the large screws on the side of each carb. Then do another sync at around 3,000 RPM by adjusting the cable tops. If the cables are set to high to start, he will not be able to get a low idle. Believe me, these KO carbs can be a real bear to dial in...

  On that note, I don't think I've seen any posts on how to do this.
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co425

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If it's smoking bad the slides are in backwards. The lip on the slide goes to the rear. If so the idle screw will do nothing.   

Offline Johnie

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If it's smoking bad the slides are in backwards. The lip on the slide goes to the rear. If so the idle screw will do nothing.   

It has been a couple years since I had my slides out, but I thought there was a cut-out on the side of the slide which will keep you from being able to bottom it out if you had it in backwards.
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

co425

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The will botom out in backward and swapped left to right or visa versa. 

Offline Stev-o

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I'm thinkin' you should have picked it up three weeks ago!
Go pay him a visit and check the bike out, if he can't get it to idle, he clearly is not the guy for you.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Johnie

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The will botom out in backward and swapped left to right or visa versa. 

Good refresher lesson. Thanks...
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline 754

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 If he worked on them for years, but cant do the carbs, he probably wont learn in another 2 weeks..






 get it home......before he sells it to someone for 200.00... :o
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline MickeyX

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If he worked on them for years, but cant do the carbs, he probably wont learn in another 2 weeks..






 get it home......before he sells it to someone for 200.00... :o


I was just thinking that very same thing.  ;D
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Offline zoo mob

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Can someone explain the slow idle sync a little more thoroughly to me? I've been talking to the guy with my bike, trying to get this worked out. There's no worries with not getting it back, more of a matter of when. He said he'd throw some K1 carbs on it and sync them, swap out the jets etc. and let me keep them. I may do that for now just to avoid having to re-tune these things, my bike is not exactly show quality right now.
Andrew
 1970 750 K0
 1980 BMW R100T
 1980 GS1100E
 1993 XR650L
Always looking for more

Offline Johnie

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If he throws on some K1 carbs for you fine, but tell him you want to keep the KO carbs. Those are pretty valuable. More so than the K1 carbs. He will also have to change the throttle linkage for you. If you want to talk about the slow idle on the KO carbs shoot me a PM. I would not mind if you give me a call. It would be easier to explain than try to type this all out here.
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline zoo mob

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Cool, I'm definitely keeping my K0 carbs. Now that I think about it, he said they were coming off a '72 which is a K2, as long as they're jetted right and of course the throttle cable is replaced, should be goo to go correct? I'll get in touch whenever I decide to put the other carbs back on. Thanks.
Andrew
 1970 750 K0
 1980 BMW R100T
 1980 GS1100E
 1993 XR650L
Always looking for more

Offline Duke McDukiedook

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K1 and above is a two cable system, so along with having to change the throttle linkage, you would have to get a K1 or newer right handlebar two cable control. Your costs with this guy keep slowly creeping up.
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Offline Johnie

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Cool, I'm definitely keeping my K0 carbs. Now that I think about it, he said they were coming off a '72 which is a K2, as long as they're jetted right and of course the throttle cable is replaced, should be goo to go correct? I'll get in touch whenever I decide to put the other carbs back on. Thanks.

What exhaust are you running there? That will have something to do with the jetting too. The KO and K2 jets are different.
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline zoo mob

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HM300s
Andrew
 1970 750 K0
 1980 BMW R100T
 1980 GS1100E
 1993 XR650L
Always looking for more

Offline Johnie

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The HM300's with stock air box run the 120's. The K2's with the HM341's are the 110's 0r 105's depending on the carb number. Check these specs out for exactly what jetting you would need assuming you have stock air box on there.
http://www.motorcycleproject.com/motorcycle/text/specs.html
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline zoo mob

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Stock K1-K6 airbox and I think it has an emgo filter which I've heard are tad more restrictive, we'll see.
Andrew
 1970 750 K0
 1980 BMW R100T
 1980 GS1100E
 1993 XR650L
Always looking for more

Offline 754

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 Hundreds of folks have run K2 carbs with one cable.. hope your kill switch works..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline zoo mob

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Well the bike is still not here, so I can't look to confirm this, but is the problem that the K2 carbs have the push/pull cables, and the KO throttle only has a spot for one cable? Also, assuming the one cable broke, wouldn't the the carbs spring back shut? What's the danger here?
Andrew
 1970 750 K0
 1980 BMW R100T
 1980 GS1100E
 1993 XR650L
Always looking for more

Offline crousos

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You probably checked this already but I had the same not idling problem with a 1973 350F even after a had the carbs cleaned and tuned and it turn out it was the points.


Constantin

Offline 754

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 I'd say if you are willing to ride a single cable K0, you wont be any worse off with a K2 setup with only one cable..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way