Author Topic: Cb750k1 refurbishment  (Read 12225 times)

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Offline 02z06dave

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Cb750k1 refurbishment
« on: March 09, 2018, 02:43:49 PM »
I picked up this late k1 about a month or so ago. Its a 9/71 build date, titled 1972. Its only got a bit over 8k miles and runs ok, has good compression. Im not intending a full restoration, just a freshen up and sell it on.

It looks like theres some oil seepage from the head gasket, so im going to pull the engine and replace gaskets, maybe rings, and paint/polish.

Ill also go through carbs, replace seals and bearings, etc. The paint is rough, especially on the tank, so all the body work is off to rj cycle for a repaint. All the chrome is pretty decent, just minor surface rust here and there, so im not getting anything rechromed.

My biggest decision is on the exhaust. All 4 pipes are solid. The left 2 are the correct 300s, the right has a 300 lower that is completely crushed and the upper is a 341. Id like to replace both right side pipes with correct 300s, but they may be expensive and hard to find. The other option is replace all 4 with repops and sell what ive got. I need to figure out what will be most cost effective.

Otherwise, the bike is mostly here and in decent shape, so im hoping for a pretty quick turnaround, 3-4 weeks. Im excited to be working on a cb750 again. Its been quite a while since ive had one to work on.

Offline DennyK

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Re: Cb750k1 refurbishment
« Reply #1 on: March 09, 2018, 03:03:51 PM »
Dave,
It looks like you found a real winner.  We have a bike from that same vintage, late '71 but with a '72 title, but it is a basket case.  Good luck with the exhaust decision.  I sold some parts to a Forum member dolamike from San Francisco for his project from that year.  His finished bike looks really great and he put together a nice looking 4 into 2 exhaust system.  Take a look for his posts, not sure the link below will work

http://forums.sohc4.net/index.php/topic,153185.125.html




 

Offline Stev-o

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Re: Cb750k1 refurbishment
« Reply #2 on: March 09, 2018, 04:51:55 PM »
Hey Dave...looks like a good start for a project. 

I also have a K1 project bike that I'll be doing later this year, wish mine looked as good as yours.  I'll need an exhaust and will prolly go re-pop 341's, I think they are around $1300.

Since you really only need two, it would be in your best interest to find two.  Have you checked with Cycleman in Toledo?

http://forums.sohc4.net/index.php/topic,170011.0.html

If you go the repop route, you could always sell the two good ones for at least $100 a pipe.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #3 on: March 09, 2018, 07:32:02 PM »
Hey Dave...looks like a good start for a project. 

I also have a K1 project bike that I'll be doing later this year, wish mine looked as good as yours.  I'll need an exhaust and will prolly go re-pop 341's, I think they are around $1300.

Since you really only need two, it would be in your best interest to find two.  Have you checked with Cycleman in Toledo?

http://forums.sohc4.net/index.php/topic,170011.0.html

If you go the repop route, you could always sell the two good ones for at least $100 a pipe.

Hopefully i can do better than 100 per pipe. The ones selling for around 100 are all rotted out. I would think good pipes would do better. I think im going to end up with the new set. There are a lot of pipes on ebay, but they all either have holes, are dented up, or both. Theres no sense in spending 100-200 on damaged rotted pipes that cant be restored

Offline SOHC4 Cafe Racer Fan

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Re: Cb750k1 refurbishment
« Reply #4 on: March 10, 2018, 02:08:22 PM »
You won't get your money back on reproduction exhausts. Try to find something better to replace the crushed one.
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Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #5 on: March 11, 2018, 05:35:05 AM »
I found a really nice lower right pipe yesterday, but the seller was unwilling to come off of the 500 plus shipping asking price. To me, thats just way too much for 1 used exhaust pipe with no baffle. Then this morning, i found both hm300 pipes for the right side 450 plus shipping for the pair. I had to jump on that. The upper looks good as is. The lower has surface rust, but it will clean up just fine. Im glad its going to have a proper original exhaust.

Offline Stev-o

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Re: Cb750k1 refurbishment
« Reply #6 on: March 11, 2018, 06:39:31 AM »
$500 for 1 pipe is crazy, glad you found both.   Although the chrome on these old exhaust is not the best, I've had very good results cleaning and polishing them up. 
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #7 on: March 11, 2018, 06:49:38 AM »
$500 for 1 pipe is crazy, glad you found both.   Although the chrome on these old exhaust is not the best, I've had very good results cleaning and polishing them up.

Yeah, i was kind of blown away, by the asking price and the unwillingness to negotiate. It also amazes me how many people want 200 for a pipe riddled with holes. The reproduction pipes look really good. If i needed a full set, id go that route in a second.

Offline MauiK3

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Re: Cb750k1 refurbishment
« Reply #8 on: March 11, 2018, 10:18:00 AM »
Why get 341's when you can get no-number repop's? Yes they are a little louder but there is less to rot inside and they are likely lighter.
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Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #9 on: March 11, 2018, 10:21:43 AM »
Why get 341's when you can get no-number repop's? Yes they are a little louder but there is less to rot inside and they are likely lighter.

I didnt get 341s, i got 300s

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #10 on: March 29, 2018, 01:47:35 PM »
I finally got the bike torn down. I need to get going on the engine, but im procrastinating a bit. Today i thought id give polishing a try. Ive never really done it, but i want this bike to look good, so i bought a bench buffer and some polishing compounds and went to it. I was able to get one fork broke down, polished and back together with a new seal. Its by no means perfect, but i ran out of patience and i think it looks good enough. It was pretty damaged in one area and required some sanding to smooth it out.

Offline Stev-o

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Re: Cb750k1 refurbishment
« Reply #11 on: March 29, 2018, 03:18:23 PM »
Looks good Dave. I too get impatient with polishing...
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #12 on: March 29, 2018, 03:22:16 PM »
Looks good Dave. I too get impatient with polishing...

Yeah, it really sucks. But, i need to keep costs down where i can so i can make money on it.

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #13 on: April 13, 2018, 02:51:17 PM »
Today, i got the frame painted and some other little parts. Im pretty happy with how it all came out. I was intending to do the gaskets on the engine and maybe get it painted too, but i ran into some issues. Cylinder #1 had a lot of rust and crud, upon removing the cylinders, i could see that the rings were stuck to the piston too. It looks rather worn. Im going to try honing the cylinders and measure to see if i can just get new rings and be done with it, but i fear its going to need bored. The cost doesnt bother me as much as the time. The machine i usually use is super slow and i dont have 2 months to spend waiting around. Does anyone know a shop thats a bit quicker, like maybe a few weeks?

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #14 on: April 16, 2018, 03:25:46 PM »
I emailed cycle x and they have pretty fast turnaround time. I was told no more than 3 days from when they get the part. So im getting their 2nd over pistons and theyre boring the cylinders. Ill be cleaning up the head and installing to valve seals myself and maybe lapping the valves. They arent leaking right now, so i probably dont need to. Since im at a little stand still until i get the cylinders and pistons, i did some polishing today. Got the sprocket cover done. It came out well. Im trying to get one thing polished or painted each time i work on it.

Offline Stev-o

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Re: Cb750k1 refurbishment
« Reply #15 on: April 16, 2018, 04:12:00 PM »
Just curious Dave, how much do they charge to bore?   [my guy is $50/hole]

Sprocket cover looks great!  Want to do mine...ha?!
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #16 on: April 16, 2018, 04:15:05 PM »
Just curious Dave, how much do they charge to bore?   [my guy is $50/hole]

Sprocket cover looks great!  Want to do mine...ha?!

They have pricing on their website. I chose the budget option which is $150. I was thinking about taking on some polishing work for extra money. Id happily do yours

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #17 on: April 24, 2018, 01:49:02 PM »
Got word from cyclex that theyre done with my cylinders and sending them back with new pistons. I got busy and got some more polishing done. Hopefully i can have the engine back together by early next week and get going on reassembly.

Offline calj737

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Re: Cb750k1 refurbishment
« Reply #18 on: April 26, 2018, 05:53:52 AM »
It would be very wise to have the head mating surface milled flat (hoping CycleX did the block too). Best prevention against leaking gaskets.
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Offline Tews19

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Re: Cb750k1 refurbishment
« Reply #19 on: April 30, 2018, 09:05:16 AM »
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Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #20 on: May 03, 2018, 04:51:26 AM »
Got most of the body parts back from paint. Just waiting on the tank now. The color is a little lighter than i was expecting. Its supposed to be candy gold. I never saw the color new because i wasnt alive yet, maybe this is what it looked like then. Either way, im satisfied with it.

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #21 on: May 03, 2018, 05:21:00 AM »



Offline PeWe

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Re: Cb750k1 refurbishment
« Reply #22 on: May 03, 2018, 01:47:28 PM »
It look really good. The Honda badges and diamond will make more depth to the paint. Use Honda original diamonds if you can choose. The small detail with HM visible. Honda does not cost that much more than replicas without HM.
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Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
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http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
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http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #23 on: May 03, 2018, 02:14:15 PM »
Yep, ive got a set ready to go on

Offline 02z06dave

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Re: Cb750k1 refurbishment
« Reply #24 on: May 03, 2018, 02:15:32 PM »
I accidentally picked up a nice set of k0 tank badges instead of k1. Does any have any k1 badges theyd like to trade me