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Author Topic: 71 cb750 new engine build  (Read 18208 times)

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Offline turboguzzi

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Re: 71 cb750 new engine build
« Reply #50 on: October 19, 2011, 11:00:08 PM »
that's why i suggested doing it on a dyno.... ;)
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #51 on: October 22, 2011, 09:34:56 AM »
Quote from: MRieck on September 30, 2011, 07:21:40 PM
Quote from: orkid1989 on September 30, 2011, 07:07:43 PM
slight problem. when i try to use the electric starter on the bike it will start to turn over the motor then it will just start spinning without the motor turning over. stripped gear maybe? what would happen if the starter clutch goes out?
The rotor mounting bolt is not tight enough.
cranked the mounting bolt down with my impact and it still has the same problem. im thinking that the gear on the starter is stripped. any ideas?
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Offline wrenchmuch

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Re: 71 cb750 new engine build
« Reply #52 on: October 22, 2011, 02:22:33 PM »
The gear is under the alternator cover but its very unlikely to be the problem . Does it sound like a bunch of ball bearings in a blender when you hit the start button ? Could be the starter clutch . Need to pull the rotor off to get at it .
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #53 on: October 22, 2011, 02:43:31 PM »
Quote from: wrenchmuch on October 22, 2011, 02:22:33 PM
The gear is under the alternator cover but its very unlikely to be the problem . Does it sound like a bunch of ball bearings in a blender when you hit the start button ? Could be the starter clutch . Need to pull the rotor off to get at it .
Sort of. If it is the starter clutch how would I go about fixing it? The motor will turn over a few times then stops and I hear the spinning. Then I let off the button and as the starter motor winds down it feels like it grabs all of a sudden.
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Offline MRieck

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Re: 71 cb750 new engine build
« Reply #54 on: October 22, 2011, 04:36:36 PM »
Quote from: orkid1989 on October 22, 2011, 02:43:31 PM
Quote from: wrenchmuch on October 22, 2011, 02:22:33 PM
The gear is under the alternator cover but its very unlikely to be the problem . Does it sound like a bunch of ball bearings in a blender when you hit the start button ? Could be the starter clutch . Need to pull the rotor off to get at it .
Sort of. If it is the starter clutch how would I go about fixing it? The motor will turn over a few times then stops and I hear the spinning. Then I let off the button and as the starter motor winds down it feels like it grabs all of a sudden.
Take it about and see what is going on.
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #55 on: October 22, 2011, 05:12:08 PM »
Quote from: MRieck on October 22, 2011, 04:36:36 PM
Quote from: orkid1989 on October 22, 2011, 02:43:31 PM
Quote from: wrenchmuch on October 22, 2011, 02:22:33 PM
The gear is under the alternator cover but its very unlikely to be the problem . Does it sound like a bunch of ball bearings in a blender when you hit the start button ? Could be the starter clutch . Need to pull the rotor off to get at it .
Sort of. If it is the starter clutch how would I go about fixing it? The motor will turn over a few times then stops and I hear the spinning. Then I let off the button and as the starter motor winds down it feels like it grabs all of a sudden.
Take it about and see what is going on.
I plan on it. Just want to know what I am looking for
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #56 on: October 23, 2011, 07:38:31 AM »
found a link.
Honda CX engine CX650 starting.
this sounds almost exactly like what it does. like the description "ball bearings in a blender"
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #57 on: October 23, 2011, 08:08:45 AM »
im guessing that it is the starter clutch. in that case i was wondering if this starter clutch kit will work?
=electrical]http://www.partsnmore.com/parts/honda/cb750k/?filters[category]=electrical
Starter Clutch Repair Kit
#24-5001 | Honda CB750K (1976-1978)
Starter Clutch Repair Kit $28

i looked up the diagrams and from what i found both the k1 and k7 use that same starter clutch so i am guessing it will work
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Offline wrenchmuch

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Re: 71 cb750 new engine build
« Reply #58 on: October 25, 2011, 06:37:35 AM »
I checked part numbers between K6 and K1 models and the numbers are the same . The kit will work in a K1 . If you don't have a rotor puller you might think of ordering one at the same time . Check the starter gear where the rollers contact the gear for chatter marks . I don't know what best way of removing the marks is . Maybe have the shoulder turned down by a machinist ? I'm building an engine right now and this is one of the things I have yet to address . There is also a seal in that gear (Honda P.N. 91215-300-003  Measures 25x33x4 MM ). I don't know if the P.N. is still current .
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #59 on: October 25, 2011, 06:53:16 AM »
Cool. Thanks for the info
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Offline 750cafe

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Re: 71 cb750 new engine build
« Reply #60 on: October 25, 2011, 07:29:54 AM »
Quote from: orkid1989 on April 24, 2011, 07:00:18 PM
i mostly just want to outrun my friends 1200xr sportster. any advice would be greatly appreciated

Your stock bike should have been able to do that without breaking a sweat.
A CB500 can do that with ease!
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #61 on: October 25, 2011, 07:47:52 AM »
Quote from: 750cafe on October 25, 2011, 07:29:54 AM
Quote from: orkid1989 on April 24, 2011, 07:00:18 PM
i mostly just want to outrun my friends 1200xr sportster. any advice would be greatly appreciated

Your stock bike should have been able to do that without breaking a sweat.
A CB500 can do that with ease!
possibly except for the fact that my bike was running on roughly 80psi compression and couldnt exceed 60mph without a hill
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #62 on: October 30, 2011, 06:03:33 AM »

got the gauge mounted on the bike. also think the starter is going out. after the bike warms up i turn it off and try to restart it and the starter has a very high amp draw. all the lights on the bike get very dim and the battery says 12v. so for now i unplugged it and removes the reduction gear. synced up the carbs and started tuning them and found that i need to drop the needle and increase the main jet size. im loving this new gauge :)
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #63 on: November 02, 2011, 05:32:19 PM »
just finished installing the front brake master cylinder and rebuilding the starter clutch. runs like a champ now.
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #64 on: November 07, 2011, 02:56:45 PM »
before and after (well still working on it)
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Offline 750cafe

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Re: 71 cb750 new engine build
« Reply #65 on: November 10, 2011, 11:22:24 AM »
It looks much more user friendly now.   ;)

Eric
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Offline orkid1989

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Re: 71 cb750 new engine build
« Reply #66 on: November 10, 2011, 07:12:19 PM »
Quote from: 750cafe on November 10, 2011, 11:22:24 AM
It looks much more user friendly now.   ;)

Eric
thanks. its still a work in progress but i think i am getting somewhere. now that im almost done on the performance side i will start focusing on the more visual side of the build. should be fully restored before next season
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