Author Topic: Maine 78 cb750K Build - Time to get 'er back on the street!  (Read 23891 times)

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Offline toytuff

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Re: Maine 78 cb750K Build - Rideable! It's getting there!
« Reply #50 on: January 22, 2013, 05:17:54 PM »
"2 cool" right there!

tt

Offline Retro Rocket

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Re: Maine 78 cb750K Build - Rideable! It's getting there!
« Reply #51 on: January 22, 2013, 05:50:06 PM »
If you want the tank to stay rust free try this stuff...
Scroll down in the first link till you get to the car bodies in bare steel, have a read...
http://www.roadsters.com/gibbs/

http://www.getgibbs.com/

Nice to see someone build a racer replica and not label it a Cafe....... well done... ;)
« Last Edit: January 22, 2013, 05:52:01 PM by Retro Rocket »
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline wowbagger

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Re: Maine 78 cb750K Build - Rideable! It's getting there!
« Reply #52 on: January 23, 2013, 06:23:11 AM »
subscribed and nice to know there's a machine shop in town that knows Hondas.

Offline Blitzburgh207

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Re: Maine 78 cb750K Build - Rideable! It's getting there!
« Reply #53 on: January 23, 2013, 07:25:27 AM »
If you want the tank to stay rust free try this stuff...
Scroll down in the first link till you get to the car bodies in bare steel, have a read...
http://www.roadsters.com/gibbs/

http://www.getgibbs.com/

Nice to see someone build a racer replica and not label it a Cafe....... well done... ;)

Awesome!!! I wanted to keep that bare metal feel but you can practically watch the steel oxidize. I'm definitely trying that stuff!  Oh and thank you - I never liked the label "cafe" for some reason - feels overused. But I'm getting more used to it now that I've learned it's basically like saying "hot rod" right? I like the sounds of racer replica though  8)

@Stoli:  Yeah, this type of fairing just mounts to the headlight ears.  I used these style headlight ears mounted upside down to get the height I wanted.


As for the fender, It's actually from a k4 parts bike I bought.  My stock fender had perfect chrome and I didn't want to chop it up and the k4 fender was pretty pitted.  Since I wanted the finish to match the tank I sanded it down anyways. I cut the rolled edge off all the way around and shortened it to just before the holes for the braces.  The metal is very thin and lightweight so it really doesnt need any bracing.  It doesn't move at all that I've noticed - i just love the vintage look of the cr fenders. I wanted to buy the kit from M3 but $350 is a little steep for a fender  :-\ In the mean time I've looked for material to make struts out of but I'm having trouble finding anything...

Thanks for the compliments guys! And I'll be looking for some advice/opinions shortly - it's back to the drawing board again this off-season  ::)
1978 CB750 K8

Offline Stoli

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #54 on: January 23, 2013, 07:50:06 AM »

Has anyone tried that Gibbs stuff on highly polished steel? It makes sense that it works on sanded surfaces since it sounds like it "soaks in" to the small grooves on a brushed surface. Just curious if it works on a mirror finish surface and if it dulls the "chromed" look any...
My Project Threads:
Project #1 - http://forums.sohc4.net/index.php?topic=117106.0  First bike
Project #2 - http://forums.sohc4.net/index.php?topic=127364.0  Something different
Project #3 - http://forums.sohc4.net/index.php?topic=123831.0  Long and Low

Offline Stoli

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #55 on: January 23, 2013, 07:55:35 AM »
Blitz - Can you pass on any techniques/experiences on the process you used to build your seat pan and rear end. Looks like you used the Home Depot rigid insulation to build a male mold. Then what? Sanding, bondo, release agent, fiberglass???  Do's, Dont's ...

Thanks again for all the great feedback.
My Project Threads:
Project #1 - http://forums.sohc4.net/index.php?topic=117106.0  First bike
Project #2 - http://forums.sohc4.net/index.php?topic=127364.0  Something different
Project #3 - http://forums.sohc4.net/index.php?topic=123831.0  Long and Low

Offline Blitzburgh207

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #56 on: January 23, 2013, 08:34:58 AM »
Blitz - Can you pass on any techniques/experiences on the process you used to build your seat pan and rear end. Looks like you used the Home Depot rigid insulation to build a male mold. Then what? Sanding, bondo, release agent, fiberglass???  Do's, Dont's ...

Thanks again for all the great feedback.

Yeah, make a female mold lol.  This was my second attempt at fiberglass.  It went a little better than the first, but still a PITA.  I covered the insul. w/ tinfoil as smoothly as possible and taped the seams and used car wax as a releasing agent. I used woven cloth because my first attempt with the matt was an absolute disaster...really...probably the most frustrating thing I've ever done in my life.  Anyways my advice is don't use matt (although I think it may be stronger??)  unless you know what you're doing - and if you know what you're doing, don't listen to me.

If you use the cloth, take the time to cut your layers out ahead of time and know how they're going to fit your mold.  I even numbered mine with a marker so they wouldn't get messed up. I made the mistake of only cutting out I think 4 layers ahead of time and it wasn't enough.  ...I would guess a minimum of 6?  Because I ran out of pre-cut stuff I let it cure and added a few more layers later.  That was my second mistake: Do it in one shot.  A mechanical bond is nowhere near as strong as the chemical bond.  Oh yeah - and buy the little rollers that get the air out, they are invaluable.  You should be able to see through the fiberglass to the mold when you're doing it.

Third, I recommend making a female mold because I spent a ridiculous amount of time w/ a sander and bondo.  Fiberglass is really hard and the dust is nasty.  Next time around I'm going to make a female mold because I think the extra time to make the extra will be made up with the final paint prep and just overall quality.

Also, make sure your design is solid.  Meaning know how you're going to mount the seat, lights, etc.  ...I didn't think about mounts, etc. and it didn't quite come out how I wanted... But now I have a welder MUAHAHAHAHA

p.s. don't mix too much epoxy at one time.  You won't have enough time to use it all.   ;)
1978 CB750 K8

Offline Stoli

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #57 on: January 23, 2013, 03:22:58 PM »
Yo Blitz - Cold enough for you up here in the northern provinces today?

I read your post about your 2mm needle shims and 135 mains prior to teardown. Is that still working for you after the rebuild? Any areas in the throttle range that are giving you trouble?
My Project Threads:
Project #1 - http://forums.sohc4.net/index.php?topic=117106.0  First bike
Project #2 - http://forums.sohc4.net/index.php?topic=127364.0  Something different
Project #3 - http://forums.sohc4.net/index.php?topic=123831.0  Long and Low

Offline Blitzburgh207

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #58 on: January 23, 2013, 06:57:43 PM »
Hell I hope so! I thought my eyes were going to freeze today.  Cold enough that I was able to convince my gf to move my motor into the spare bedroom! lol.



BTW the current tuning feels right and sounds right but I think it's a little rich....not sure where.  It is close though. I think I want to get it dyno'd before I get it on the road to have it really fine tuned.
1978 CB750 K8

Offline Stoli

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #59 on: January 24, 2013, 09:08:14 AM »
OK, let's talk about rearsets. I've been researching them for months and the only decision I have made is that I will need a pair and they should be fully adjustable. I don't think my bike will be very comfortable to ride even with rearsets (I'm 6' 4" with a 36" inseam and bad knees) but I'm pretty sure it will be impossible to ride with the stock pegs and clubman bars. Some say the pegs should fold up for safety reasons in case they drag in a turn but based on the position of most, it looks like you'd have to be almost tipped over to drag them. What kind do you have and is that mount something you fabricated yourself? How close do you get to the right peg when you kickstart the bike? There are some decent pics of your right set (rear brake), any of the shifter?
My Project Threads:
Project #1 - http://forums.sohc4.net/index.php?topic=117106.0  First bike
Project #2 - http://forums.sohc4.net/index.php?topic=127364.0  Something different
Project #3 - http://forums.sohc4.net/index.php?topic=123831.0  Long and Low

Offline Blitzburgh207

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #60 on: January 24, 2013, 04:35:41 PM »
You would be surprised. I think my rearsets and clip-ons are more comfortable than the stock pegs and drag bars that came on my bike.  As for the mounts, I made them out of 1/4" aluminum which wasn't quite enough because they flex a little. I'm planning on cutting the passenger pegs off and welding on new brackets.  The kick start does clear the foot peg when it's folded but it hits the brake lever.  The linkage has a quick release pin...I guess I just got used to dropping the lever down to kick start it.  I'd like to bend the kick start so it clears but mounting the rearsets back an inch or so may solve my problem, we'll see. As far as scraping while turning - I haven't had that problem but I'm not sure how close they actually come.
1978 CB750 K8

Offline liPPy

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #61 on: January 31, 2013, 07:36:47 AM »
Hey there Bb - I'm liking the rearsets. Any chance you could post up some pictures of both sides so I can get an idea of how you made the mounting plates?

I'm getting ready to do the same with my 78k.

Thanks! liPPy.

Offline Blitzburgh207

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #62 on: January 31, 2013, 10:53:07 AM »
I'll try to get a decent picture at some point.  What I did find thought is that we (K7 and K8) have a smaller..uh.. brake spindle? (Idk what it's called) than the earlier K models because the arm that came w/ the K0-K6 kit did not fit.  I still need to count the splines and call fast from the past to see if he's got anything that will fit...  What I ended up doing in the meantime was rigging up a K4 kickstarter base (same number of splines) for the brake linkage.  It was pretty ugly so I don't really want to post pics haha.  You can see it above.

As far as the mounts - I basically just copied the idea from the left side mount for the F1 models where it bolts onto the motor mount and is uses that little tab/peg to keep from rotating like the stock pegs.



Worked for me but I think I read somewhere that Mr. Riek did not feel that it was stable enough.
1978 CB750 K8

Offline Blitzburgh207

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Re: Maine 78 cb750K Build - It's cold out again...Time to wrench
« Reply #63 on: February 24, 2013, 01:06:38 PM »
Well I've solved my transmission woes and now I'm onto the burning oil.  I pulled the top end this afternoon and I wanted to post some pictures so you guys can help me diagnose this.

Whenever riding with friends, they would tell me that there would be a puff of smoke out my exhaust when I really cranked on it.  Otherwise no sustained smoking, sometimes a puff at startup. I figured maybe I damaged a valve guide seal on assembly.  There is definitely some oil on the exhaust side around the valve stems, but I can't tell if it's from the seals, or if the machine shop effed up my head when they installed the new guides.  Check it out: (btw the white fibers are from paper towels I stuffed in there for transport)

#1


#2


#3


#4


Heres the chambers:

#1


#2


#3


#4


Sorry for the long shots down the cylinders....I'm having a lot of trouble separating the head from the jugs  :-[

And here's the pistons (1-4 left to right):


#2 piston looks to be burning oil like a mofo...do I have a ring upside down? How can I tell?

Thanks in advance for your help!!!
1978 CB750 K8

Offline Vinhead1957

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #64 on: February 24, 2013, 04:20:40 PM »
That is definitely the problem ....  Valve seals.  Now why.  My softail had that problem and what Harley had done in 2005 was to go with thinner valve stems and did not change the seal for that year model. Surprise surprise they updated the seals in the parts dept but hid behind the lie to avoid a recall.  1 quart per 1000 miles oil usage and when I booted it my follows also remarked something coming out the exhaust.   Take the head back and show and tell.  They may give you some credit towards the fix.  Did you have new valves installed?  Everything should have been measured to avoid this.

Offline Vinhead1957

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #65 on: February 24, 2013, 04:30:01 PM »
I gotta ask how are you driving that in ME when I just cleared the driveway of more snow?

Offline wowbagger

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #66 on: February 24, 2013, 05:31:55 PM »
I gotta ask how are you driving that in ME when I just cleared the driveway of more snow?

Excellent question.

Offline Blitzburgh207

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #67 on: February 25, 2013, 10:11:39 AM »
Thanks for the suggestion Vinhead - I'll be bringing it to the machine shop if I find that the head was damaged during guide replacement.   I may have to bring it there anyways to throw in the hot tank to separate the head from the jugs!! Maybe I sealed them a little TOO well  ::)

p.s I haven't ridden it since Nov when my tranny #$%* the bed.... after fixing that issue I'm just now getting around to pulling the top end off and having a look.  ....I only ride my snow plow in the winter  ;D

1978 CB750 K8

Offline Vinhead1957

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #68 on: February 25, 2013, 12:28:57 PM »
I rode mine this morning in OOB. What a beautiful morning! The snowblower I mean

Offline metalhead0283

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #69 on: February 25, 2013, 02:49:21 PM »
nice to see few guys from maine on here
77 xs650  81 xs650  76 cb550f  2010 triumph street triple

Offline wowbagger

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Offline Vinhead1957

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #71 on: February 26, 2013, 05:57:48 AM »
Those guys are nuts!  Living life though and beating the house bound blues.

Offline SOHC4 Cafe Racer Fan

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #72 on: February 26, 2013, 06:39:15 PM »
Shoot. I complain when it's cold in Southen Cal.  :o
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"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

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Offline Blitzburgh207

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #73 on: February 26, 2013, 07:30:33 PM »
Those guys are nuts!  Living life though and beating the house bound blues.


Nah they have 2-wheel drive, they're fine.  ;) That same weekend of the record snow a friend of mine posted a picture on Facebook of a couple on a bike w skis strapped to the back on their way to sugarloaf! Last year there was a teacher at my school (umaine) that rode all winter on an old military bike w huge studs on the tires...haven't seen it this winter though.
1978 CB750 K8

Offline wowbagger

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Re: Maine 78 cb750K Build - Help me diagnose why I'm burning oil please!!
« Reply #74 on: February 27, 2013, 05:59:18 AM »
No point living in Maine if you can't enjoy the snow.

Anyway, back to the bike. Did you ever get the burning oil issue sorted out?