Author Topic: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)  (Read 70291 times)

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Offline wohali

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Re: Bessie, my first rebuild: 78 CB750F3 (Back in the shop 2015-04-24)
« Reply #250 on: January 26, 2016, 12:24:06 PM »
Hi friends! I'm afraid I've been sick the last 1 1/2 years, unable to ride. It's been demoralizing; my desire to get in and fix whatever is wrong with the carbs has been low as a result. I expect Bessie's battery is dead by now, which is sad since I bought a really nice one last time, too.

I'm starting to feel better, and would welcome any advice on getting the carbs fixed up properly - either from anyone local willing to have a look, or anyone I might be able to mail them to for repair.

Offline grcamna2

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Re: Bessie, my first rebuild: 78 CB750F3 (Back in the shop 2015-04-24)
« Reply #251 on: January 26, 2016, 03:46:08 PM »
How're you doing Girl? I hope you feel better  :)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline h0tr0d18

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Re: Bessie, my first rebuild: 78 CB750F3 (Back in the shop 2015-04-24)
« Reply #252 on: January 26, 2016, 05:32:52 PM »
Get better and everything else will fall in to place!! I'm unfamiliar with these carbs but I've torn in to my fair share of carbs before, it's not rocket science, basic stuff but there are some tricks out there for sure.

Offline scottly

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Re: Bessie, my first rebuild: 78 CB750F3 (Back in the shop 2015-04-24)
« Reply #253 on: January 26, 2016, 07:02:38 PM »
Good to hear from you, Wo.
Don't fix it if it ain't broke!
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Offline wohali

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Re: Bessie, my first rebuild: 78 CB750F3 (Back in the shop 2015-04-24)
« Reply #254 on: May 11, 2016, 05:56:26 PM »
Finally, an update!

I have been feeling better health-wise and spent the last couple of evenings in the garage getting Bessie back up to speed.

This started with a replacement set of carbs for the bike off of eBay, since the old carbs were leaking and a local carb repair shop quoted me $400 to repair them. I was able to get the replacement set of carbs off of eBay for the same price, so I figure now I have a set of spare parts :) The new set had some issues, namely a leaking bowl, a missing bowl gasket and 120 nylon main jets (eew?). I swapped in the other carbs' 105 (metal) main jets and a bowl/gasket as well, did some bench leak tests, adjusted the float levels and confirmed the new carbs were liquid tight.

Also I learned finally how to put on/pull off the carbs on these bikes without fuss or muss - the trick is to drop the bottom half of the air box off before doing any work! SOOO much easier  :P

Today I managed to reassemble everything and was unable to get her to start up. After checking for fuel (lots in the cylinders, almost flooded), spark (plugs were fouled from my last run, so I cleaned them up a bit and put in an order for some new ones) and compression (yup, there's air coming out of the plug hole when I kick the starter, and I've previously done a compression test), a thought occurred to me. Pulled the spark advancer and yup, in my reassembly of it, I got the mark 180 degrees out of phase. (It was lined up with the "300" instead of the "TEC" label. The F3 service manual calls out the correct spark advancer orientation.)

Reassembled the spark advancer, put the tinder on the bike and gave her a few seconds on the starter...and Bessie came back to life !  ;D ;D ;D I am so so happy, I cannot begin to tell you guys. Oil pressure seemed to sit at about 70psi (I have a gauge on the RH side of the crank case) and, though she idled high and a bit roughly, she did idle.

After about a minute of running, I started to get some whitish-bluish smoke out of the tailpipe. It's enough to give some haze to the air, but not enough to create huge billowing clouds. This continued for about another 45s, and as I attempted to throttle her down to 1000rpm I saw falling oil pressure (to about 20psi), which I think is expected. I decided to call it a day and turned the engine off.

Now, Bessie's been sitting re-assembled for a couple of years now with assembly grease and motor oil sitting in all of the places it's supposed to be, on the valve stems and possibly in the cylinders as well. That said, should I be worried about some light coloured smoke right now? The volume seems less than after the last re-assembly and fire-up test a few years ago, when my bad boring job caused blow-by, but I've not taken her out on the road yet to see if she spews a lot like she used to. (Then again, even with the bad boring job, I was able to ride her 700 miles @ ~45mph, polluting the Ontario countryside...  :-\ )

What should I do next? My gut is to give her a once over for nut torque values and safety checks, then take her out on the road and have my phone handy should I stall out by the side of the road. But should I get her up to speed? How fast/how many RPMs/what gears? What should I be looking for when I do this? Not having been on any motorcycle for a few years now I feel out of practice, but I'm sure it'll come back...

Still....today was a qualified success! I am celebrating in my own way :D

Offline wohali

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #255 on: May 17, 2016, 08:42:24 PM »
Update again.

She's been started a half dozen times again since the smoke, and the smoke is gradually going away. I am getting some smoke on initial startup, but after warm-up and running for a while, the smoke is gone. So I'm not going to worry about it very much at this point.

I went to time the bike and it appeared that she was always advanced. So I decided to take the advancer apart and re-lube it, and while I was at it shorten up the springs by a half turn like Hondaman recommends in his book. After reassembly and re-timing, I've got her advancing to full around 2600-2700 rpm per the dash tach (which is uncalibrated but probably OK, I don't own a dwell tach). This has eliminated most of the backfiring as well, though I still get some when I first start the bike up from cold.

Other than an embarrassing stall out when I forgot to re-open the fuel petcock ::) the bike started to run better. I'm still unable to get a reliable idle lower than about 1500RPM, so at some point I'm going to have to investigate why that is. Suggestions welcome on how to get a better slow idle - note the carbs are recently rebuilt and were clean when installed.

I've also had her in all 5 gears, at RPMs up to about 6000. Oil pressure per the gauge doesn't hit higher than about ~40psi at ~5k RPM, and typically at idle the pressure is around 6-15psi. I don't know if these are good numbers or not, so I'm going to scour the forum to see if anyone had published any reference numbers. The pressure gets better when the engine is hot than cold, but I'm still a bit nervous as I thought pressure was supposed to be a bit higher than this. Given I'm planning some touring this summer (a ride to Ohio and back) I want to be extra sure things are in good shape.

Next up: some more puttering around the city so I get a good 50mi on her before I take her on the highway. I want those rings "set."
« Last Edit: May 17, 2016, 08:47:44 PM by wohali »

Offline wohali

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~
« Reply #256 on: June 19, 2016, 10:15:31 PM »
More news:

I've installed a new OEM oil pressure sender as i wasn't trusting the oil pressure gauge. It works great. On today's ride, at highway speeds the gauge stayed between 45-60psi, settling down towards 45psi as the oil heated up, though at idle speeds I was seeing the gauge reflect ~10psi. The oil light didn't light up, though, so I think it's reading a bit low overall. I'm fairly well convinced at this point that the oil pressure is good.

Rode for about 1.5h today, for a total of 75 miles, most of that at highway speeds (50-65 mph). She rode completely perfectly. I have no worries that my big summer trip (~1000 mi) will go down just fine.

Things left to do to the bike:
  • Repaint the gas tank and new side panels
  • Tighten a few loose bolts here and there, reaim the headlight
  • Another oil change

Thanks for staying with my build thread everyone! She's almost done at this point. Once the cosmetic work is done I might submit her for the monthly build. :)

Offline grcamna2

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #257 on: June 19, 2016, 10:42:43 PM »
I imagine you're feeling a bit better plus getting the CB750 running strong and clean now Wohali  :) Good to hear some news about how it's all working for you. Have a nice week upcoming.
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline madmtnmotors

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #258 on: June 20, 2016, 04:42:54 AM »
I'm still unable to get a reliable idle lower than about 1500RPM, so at some point I'm going to have to investigate why that is. Suggestions welcome on how to get a better slow idle - note the carbs are recently rebuilt and were clean when installed.

You will be amazed at what a good vacuum sync of the carbs will do to smooth out the idle. I can get a smooth idle out of mine all the way down to 950 rpm.
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
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Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

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Offline 70CB750

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Re: ~
« Reply #259 on: June 20, 2016, 04:47:06 AM »
I have no worries that my big summer trip (~1000 mi) will go down just fine.



Where are you headed?

Offline wohali

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Re: ~
« Reply #260 on: June 24, 2016, 11:22:51 AM »
I have no worries that my big summer trip (~1000 mi) will go down just fine.
Where are you headed?

Toronto -> Sandusky, Ohio (Cedar Point, group of friends meeting up there for a weekend) -> Chicago -> back home. The Chicago part of the trip is still up in the air, I'm not sure I'm physically capable of such a long ride in full leathers in the heat, but we'll see :)

And thanks for the reminder to vacuum sync the carbs, that's a great idea. They've only been bench synced at this point. I have 2 pressure gauges, not 4, but hopefully I can get a good reading on them. If not maybe the local motorcycle shop is able to rent me a pressure gauge set for the weekend.

Offline grcamna2

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Re: ~
« Reply #261 on: June 24, 2016, 11:25:56 AM »
I have no worries that my big summer trip (~1000 mi) will go down just fine.
Where are you headed?

Toronto -> Sandusky, Ohio (Cedar Point, group of friends meeting up there for a weekend) -> Chicago -> back home. The Chicago part of the trip is still up in the air, I'm not sure I'm physically capable of such a long ride in full leathers in the heat, but we'll see :)

And thanks for the reminder to vacuum sync the carbs, that's a great idea. They've only been bench synced at this point. I have 2 pressure gauges, not 4, but hopefully I can get a good reading on them. If not maybe the local motorcycle shop is able to rent me a pressure gauge set for the weekend.

I hope you enjoy your journey wohali  :)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline wohali

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #262 on: July 25, 2016, 08:19:49 PM »
Just back from the 700+ mi trip. Other than a couple of rough starts, she ran fine. Things I learned:

  • I get about 42 MPG at highway speeds (~speed limit)
  • Average oil pressure at highway speeds is about 45-48 psi

I really need to get the tank repainted (where I has some body fill done for a dent, the paint has bubbled off), replace the exhaust header with one that still has some chrome on it, and sync the carbs. Other than that I am very happy with Bessie's performance.

Offline grcamna2

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #263 on: July 25, 2016, 08:21:45 PM »
Very nice wohali  :)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline kap384@telus.net

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #264 on: July 26, 2016, 09:27:11 AM »
Great to hear!
1965 Honda CB450K0
1972 Honda CT70K1
1975 Honda MR50
1975 Honda CB400F Supersport
1977 Honda CB750F2 Supersport
1978 Honda XL100
1979 Honda CBX Supersport
1982 Honda VF750S Sabre - Adventure Bike modified
1983 Honda CX650T
1995 Honda VFR750
2016 Honda CRF1000L Africa Twin
2015 KTM 200 XC-W
1963 Suzuki T10
My 1977 CB750F restoration - http://forums.sohc4.net/index.php?topic=66779.0
My 1975 CB400F restoration -
http://forums.sohc4.net/index.php?topic=145196.msg1651779#msg1651779
'More Stock Than Not' thread - http://forums.sohc4.net/index.php?topic=90807.500
My CT70 Resurrection - http://forums.sohc4.net/index.php?topic=145221.0
Best Motorcycle Tool Ever - https://www.engduro.com

Offline wohali

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Re: Bessie, my first rebuild: 78 CB750F3 - now a fond memory
« Reply #265 on: April 21, 2023, 09:45:30 AM »
And just like that, she's gone.

My last attempt to ride her (in 2019 for another cross-country) ended 1000 miles later in serious hip and knee pain for days.

I parked Bessie at the end of 2019 and then the pandemic happened. The battery died, even being on a tender, and with bike insurance being sky-high in Ontario, I decided enough is enough this year. A lovely gentleman who knows and appreciates CBs just walked away with her for a very fair price.  :'(

Maybe another CB is in my future, maybe not, but I will always treasure the memories we made together, and especially the help of all the great people here in helping get her back on the road.

Thanks again for being such an awesome community.

Offline newday777

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #266 on: April 21, 2023, 10:44:04 AM »
Howdy
Any pictures of your bike leaving or finished pictures? I wasn't around to see it while you were doing it and some other of the pictures aren't showing in the older posts now.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline wohali

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #267 on: April 23, 2023, 09:34:54 AM »
I was too overwhelmed to take a picture of it leaving, but here's the best picture I have of it finished from 2011, and a picture from a few months later for the SOHC4 2011 World Rally.



« Last Edit: April 23, 2023, 09:40:15 AM by wohali »

Offline BenelliSEI

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #268 on: April 23, 2023, 04:59:18 PM »
Congrats on selling to someone that appreciates your efforts. Still in Toronto? We moved from Bathurst and St. Clair Ave., out to our farm, just north of Mosport, several years ago. If you ever need a cb750 fix, come by the shop. I’m sure we could find you one for an afternoon! John D.

Offline wohali

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #269 on: April 23, 2023, 05:52:18 PM »
That's really lovely, thanks! Though, if I get back on a CB750, I'm going to want to keep it...  ;D ;D ;D

Offline BenelliSEI

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #270 on: April 24, 2023, 05:12:06 AM »
That's really lovely, thanks! Though, if I get back on a CB750, I'm going to want to keep it...  ;D ;D ;D

No problem! That can be arranged too. I always have a few extra. Have a great week, J.

Offline Stev-o

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #271 on: April 24, 2023, 08:35:47 AM »
And just like that, she's gone

Maybe another CB is in my future, maybe not, but I will always treasure the memories we made together, and especially the help of all the great people here in helping get her back on the road.

Thanks again for being such an awesome community.

Thanks for coming back with the update, we wish the best for you!   

The bike was a part of your life for 12+ years, most never have one that long. 

Maybe a classic car would suit you better at this point?  Good luck!

'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Kevin D

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Re: Bessie, my first rebuild: 78 CB750F3 (Back on the road 2016-05-12)
« Reply #272 on: April 24, 2023, 05:25:56 PM »
Nice to hear from you wohali. Thanks for bringing Godzilla across the border. I had to dig for a while to find this, 12 years ago. Think I see Bessie just beyond the banner, and you dead center in the roster.

http://forums.sohc4.net/index.php/topic,91614.msg1038186.html#msg1038186
71 CB750 K1
104,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
————————————————-
Former Honda parts kid/counter kid/do all
—————————————————————-
Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration