Author Topic: (cb750K1) Yolanda was dying, then died, now wont start (got it running!)  (Read 7982 times)

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Offline ekpent

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Re: (cb750K1) Yolanda was dying, then died, now wont start :(
« Reply #50 on: May 22, 2013, 07:54:21 PM »
Can we all see a picture someday of your large right leg compared to your normal size left after all that kicking  ;D   unless your using both  ;)   They will start easier than that when all is dialed in.

Offline cheftuskey121

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Re: (cb750K1) Yolanda was dying, then died, now wont start :(
« Reply #51 on: May 22, 2013, 08:39:51 PM »
Can we all see a picture someday of your large right leg compared to your normal size left after all that kicking  ;D   unless your using both  ;)   They will start easier than that when all is dialed in.

nah only my right leg. being short requires my leg to come way up to kick too. one benefit of being short and stocky is very strong legs. I could out-leg-press anyone in high school including the football players. still waiting for it to come in handy if I ever need to punt someone ;)

well I got in from work late, and don't have much motivation to get in the garage. I am off tomorrow so off to bed and up early for a hopeful day or troubleshooting, and getting that stator cover off to fix that leak and get my starter motor out to replace the brushes. hopefully tomorrow evening I will have a leak free bike that I don't have to kick as much. about to order an oem points plate/condensers etc, no use in using the old crud. thinking about a new oem coil assembly as well, for overkills sake. need to pick up a spark advancer as well since I filed that small pin/tab on the advancer shaft off for my pamco. have to check what number is on it.
« Last Edit: May 22, 2013, 08:45:08 PM by cheftuskey121 »

Offline bjbuchanan

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Re: (cb750K1) Yolanda was dying, then died, now wont start :(
« Reply #52 on: May 22, 2013, 10:02:16 PM »
IIRC, if you wanna pull the stator cover you gotta pull the tranny shifter cover which has its own gasket as well. In either case lean the bike over to the right propped up to limit oil loss and mess

How well have you checked a reliable flow of gas to the carbs? Sometimes it is the easy stuff.. Like is your gas cap venting?

I know one ghetto redneck way to see if you are getting fuel flow is to take the drain screw off and turn the petcock on and see if fuel flows. Not exactly scientific but you should get some nice flow out of that drain hole
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline Tews19

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Re: (cb750K1) Yolanda was dying, then died, now wont start :(
« Reply #53 on: May 22, 2013, 10:04:47 PM »
If you got new coils why change? I would go with dyna coils if I were changing out. Had them on my 550F. I could an immediate change.
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline cheftuskey121

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Re: (cb750K1) Yolanda was dying, then died, now wont start :(
« Reply #54 on: May 23, 2013, 09:15:06 AM »
ok so who was it that suggested the killswitch wire in the bucket? I owe them a beer! bike will stay running now and not stutter or die. I pulled the headlight out and noticed my headlight would dim slightly if I wiggled the nest. I narrowed it down to a loose fitting killswitch (black/white) cable. soldered that badboy up, put the headlight back in and it fired up immediately. rode it for 10 minutes with no issues. going to pull the spark plugs to see how they look now. I also want to let the bike cool completely and see how many kicks it takes me from cold.

so now onto the 8 other things I have to do including the 3000 mile tune up. small victory! thanks for all of the suggestions and help.

Offline Vinhead1957

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You owe brandEn a beer

Offline 70CB750

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Excellent!

I read somewhere that 90% of carburetor problems are electrical  ;D
Prokop
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I love it when parts come together.

Dorothy - my CB750
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Offline cheftuskey121

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Excellent!

I read somewhere that 90% of carburetor problems are electrical  ;D

this is gold

Offline brandEn

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haha, sweet. Glad ya got it working.

Offline cheftuskey121

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ok so now I have let the engine cool down completely twice and it it started after four kicks the first time. I let it cool down again and it fired up immediately. feeling much better!

now I am about to take off the airbox, carbs, cam tensioner, and get into the starter. guess the shifter and stator covers are coming off too. I ordered an offset 10mm wrench to help me with the valves so I can't get that just yet, and I am about to order a morgan carb tune so I can balance those as well.

I pulled my plugs and they look just a little lean. not wet, and slightly white. not tan or black though. I did not do a plug chop at speed though. what is a proper length of time holding any given throttle to do a plug chop?

Offline Tews19

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Justin save the money on the Morgan carbtune. Great tool but with the 750s a bench sync has done the job. If you had a 550 then I would say get it.
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline cheftuskey121

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is it really not that worth it? I did a decent bench sync and clearly its running but cant it always be a little better? I've nothing but good things about the carb-tune. are the 550s really that different?

Offline Tews19

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With carb sync tool you get 2 short brass fittings and 2 long. For the 550 you use the 2 long for the inner carbs hard to get at and the 2 short on the outside. Opposite for the 750. They were a #$%* to sync. I gave up on the 750. Benched sync'd and it runs great.

Dont get me wrong morgan is a great tool. IMO it really isnt needed for the sync of 750 carbs 
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline bjbuchanan

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I like to sync stuff using manometer or guages, I have a mean perfectionist streak I try to ignore with most things but work like that brings it out. Valve lash and sync I gotta nail or it bothers the hell out of me

I would set your airscrews to stock position and ride just a little and then let it idle for a min or two and kill it. You gotta ride a little to get the old coloring and crap off, unless you run fresh plugs or clean them up real good. I say let it idle for a min or two so you get a real true coloring to indicate. It isn't like a WOT plug chop or something like that where you gotta worry about running outta road or finding a convenient pullover spot. Given the fact you haven't modified the bike up much stock positions are probably gonna work for you so start there

The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline cheftuskey121

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thanks. I like to be a perfectionist too. sometimes it is literally counterproductive especially when I am trying something new that I have no confidence in. I end up walking away instead of doing the work. after a 45 minute ride around the neighborhood (thankfully its large with a lot of stops and turns for me to practice on!) I check my plugs. they are a light tan. they are not black or sooty or wet. they are not white either. light tan. getting closer! I think the gas I am smelling in my oil got in there one time but I don't think I am continuing to leak gas in the engine.

should I run some seafoam through the oil and then change? or is it still too early. I think maybe I've put 30 miles on the bike. still not registered....not going out of the neighborhood.

Offline Vinhead1957

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Save the money and get it Legal!

Offline Stev-o

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Great news.  I wouldnt bother with the seafoam
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline bjbuchanan

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Yeah screw the seafoam for now just enjoy that sucker
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline RAFster122s

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Seafoam in the gas helps keep the carbs clean for the CV carbs on my CX500 and most on the CX GL forum recommend it. Seems to help keep the ethanol fuel a little more stable as well. Quit using Stabil and switched to Seafoam.
David- back in the desert SW!

Offline DJ_AX

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Save the money and get it Legal!

That's where the real fun begins :)
~ Vincent . . . '75 CB750 K5 . . . '97 BMW r1100rt . . . had; '75 CB550 K1 (sold) . . .  '73 CB350G (gifted) HELL YEAH!
Disclaimer: I could be wrong. :)

Offline bjbuchanan

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I like to use some seafoam occasionally when the mood strikes me but for the most part I just ride it often
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline EnvinoVeritas

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About those airscrews.....I had a rough time with mine until I figured out the best way for ME to do it. I tried using the instructions in the service manual,  but I just didnt have much luck there. I would adjust the screws and wait and just not get much difference. I attribute that to not using a digital tach since I didn't have one. I don't think the one on the bike is accurate enough to see 50 rpm changes.
   With that, here's what worked for me. I set the screws out one turn, on my bike that is way rich.  Then I grabbed a long skinny screwdriver and hit the road. I found an empty road that I could cruise at 35-40 mph without being bothered, and pull over frequently. I cruise at 35-40, in 5th, very light steady state throttle, and noted the behavior of the motor. An overly rich airscrew will burble and miss and be very annoying to ride at that throttle setting. It will have okay throttle response though, it wont die when you open it up briskly. Stop, adjust them all out 1/4 turn. Ride, and note. After a few stops and adjusts the burbling will go away, little by little. When it starts to cruise smoothly, make sure you briskly open the throttle and see what it does. When you start getting too lean, it will start hesitating or bogging on brisk throttle opening. You will likely never be able to whack it wide open without killing it (no accelerator pump) but you should be able to open it briskly.
    A couple of caveats that I learned. It will be harder to start cold the leaner you go on the airscrew, you will need more choke for longer. When my bike was way to rich, I hardly needed any choke at all.  Throttle response will suffer if you go too lean, as will idle quality.   The setting I ended up settling on was a compromise between cold starting ease, idle quality, and burbling at very light throttle settings. I have a good idle and it starts well enough cold, but still has an ever so slight burble.
    Dont know if you need this info, but it seems like you might be messing with those airscrews soon.....

Offline EnvinoVeritas

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oh and every so often while adjusting one should rip through the gears like a wildman. A) its fun B) all that burbling around in a rich condition could foul your plugs and foul your adjustments. Burn those babies off every few minutes. A good time will be had by all.

Offline cheftuskey121

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very good observations and advice! thanks so much, this will be very helpful. I am still a tad lean. still takes a few kicks to start and there is the ever slightest hesitation if I try to goose it. I can clearly on the plugs they are a light tan. very close though. these are air screws because they are in between the carbs and airbox, so loosening them leans it out yes? I am one turn out and slightly lean. that does not seem stock but it is what it is. if I have to screw them in just a tad to get the mixture right then that's what I have to do I suppose. thanks again

Offline EnvinoVeritas

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Yeah in is rich, out is lean :)