Author Topic: First serious build ever - CB750 K7 Café  (Read 23710 times)

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Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #25 on: May 31, 2016, 02:22:01 pm »
Did you perhaps install the floats upside down???
When I bought it the PO had mounted one upside down, actually. But that's fixed now!

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #26 on: June 03, 2016, 02:38:53 am »
Must say that I'm damned impressed by today's global shipping. Got brakes from China, ordered Monday, received them today.



Don't have too high hopes (Chinese brakes, hmm...) but going to use them just so I can test the front fork. If I like it, I'll build a Brembo system in the front, or maybe AP.

Offline calj737

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Re: First serious build ever - CB750 K7 Café
« Reply #27 on: June 03, 2016, 04:29:49 am »
Pretty sporty looking there  :)
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #28 on: June 03, 2016, 05:27:01 am »
Pretty sporty looking there  :)
They were the cheapest :D Understandable so, as there's A LOT of material taken out. Retarded grooves, from a performance standpoint, unless every gram is of utmost importance.

Anyway, just waiting for the calipers now so I can get going!

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #29 on: June 06, 2016, 01:44:27 am »
Woot woot, a successful day of wrenching!

Alright, so my goal for the day was to set all the floats to spec since I knew I had been messing with one. It ended up being the only one that wasn't to spec, all of the other ones were a couple of millimeters off. I set them as close as I could anyway.

But, on the way of demounting the carbs I found what I believe to be the reason for my issues;



Bear in mind that I have only ridden this bike for perhaps an hour, tops. And it has already collected this much crap in the filter. Obviously the carbs needed a thorough cleaning, which I did.







I also removed the seals for the first time to inspect them, and the PO had used some kind of adhesive which OBVIOUSLY did not like gasoline (I can't understand why he did it, since you can push the seal to fit...).



It's hard to see, but there definitely was some silicone-like crap under all the seals. I can only assume that some of it has gotten dissolved and mixed with the gasoline. I removed all the gunk, without any problem following.



I've never had a more pleasant spot to work on before, I brough the carbs with me and sat in the garage, rather than the basement.

It make a BIG difference of cleaning the carbs (again). Before I really had to rev it when taking off so it wouldn't die, now I could probably have taken off without giving it any throttle at all. It pulled A LOT more in the lower register, and had no "flat spots" throughout the rev curve. Don't know how high I revved it though, as I haven't got a tacho and couldn't hear the engine due to a really crappy helmet (a new one is going to be purchased shortly).

https://vid.me/vymB

Here's a video of it idling when hot. A lot better throttle response now as well.

Another thing I noticed now was that it was A LOT harder to start without using the choke (which I obviously didn't connect as it wasn't needed before...). Before it has always started within a second, now it probably took me five or six tries within half a minute to get it going. This makes me assume that it was REALLY rich before, which could explain the fluid in the right hand exhaust. I've got some new spark plugs that I'll install next time I'll take it out to check. I really need to hook up the choke cable though. I don't want it on the steering head, so I'll most likely relocate it, perhaps near the seat lock / oil reservoir. Don't have a choke cable though, so I'll have to look into lengths etc.

There are also some minor adjustments that I need to do, for example there has grown some more slack in the drive chain. Which I find really odd, chains shouldn't really stretch like this should they? It might mean that I didn't tighten the axle enough, but I torqued it to spec... There's also a little bit too much tension in the throttle so it doesn't return all the way as snappy as I would want, I need to help it the last millimeter or so.

Anyway, really happy with this session! The carps are all set to try out Carpy's exhaust once it arrives!

Also, complimentary picture of a chain saw bear I carved when I was younger. It's holding up to the weathers well! :D


Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #30 on: June 12, 2016, 09:14:58 am »
This god damned carb... Or actually, the carb isn't the issue. The tank is.

So I cleaned it, it ran like butter, went out there today again and took it on a ride. Went great, up until where it started losing power, and you could actually feel a "kick" when the power came back. And it got worse and worse. Before I got home the overflow had started leaking again. Checked the fuel filter, and sure enough, there was a bunch of crap.

Obviously I haven't gotten all the gunk out from the tank. I COULD clean it thoroughly (electrolysis or acid) but what's the point? I'm not going to use this tank anyway...

So, I've decided that I deem this bike road worthy, and in extension also worthy of a rebuild. So I'm going to start the rebuild now, and assume that the gunk is all my worries in the world (which most likely isn't true...).

This is the plan;

Step one is getting the CBR1000F front end on, including a custom triple. I'm currently waiting for the calipers, after that I have all parts. Oh, and the wide tyre I have test fitted at the moment? Too wide. Doesn't clear the fork tubes. So I can't use it for mock-up.
Step two is getting the bare frame, detabbing, welding reinforcement triangulations.
Step three is getting a new tank and seat, and modifying the frame accordingly.
Step four is redoing all the electrics.
Step four point five (as in, haven't decided yet) is painting the engine.
Step five is too far ahead to plan at the moment.

Offline calj737

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Re: First serious build ever - CB750 K7 Café
« Reply #31 on: June 12, 2016, 12:34:24 pm »
An overnight soak with Distilled White Vinegar will remove the rust from that tank. Fill it to the top to insure you reach the underside, then rinse and neutralize. Fill with gas, and ride! By the time you wake tomorrow, you could be riding  ;)

I get that you're about to rebuild the bike, but why not enjoy a few weeks of riding before tearing down now?
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #32 on: June 14, 2016, 02:23:45 am »
Look what arrived today... :-*



Unfortunately I'm afraid that the fitment is a bit off, I'll see if I'm correct when I finish work!

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #33 on: June 14, 2016, 02:16:42 pm »
https://vid.me/iIFc

Alright, this exhaust is #$%*ing insane!!! It's damned loud!

Offline SOHC4 Cafe Racer Fan

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Re: First serious build ever - CB750 K7 Café
« Reply #34 on: June 14, 2016, 03:29:48 pm »
Yes, sounds like its straight through with no baffle.  That'll wake up the bears!
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"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)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline 70CB750

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Re: First serious build ever - CB750 K7 Café
« Reply #35 on: June 15, 2016, 05:48:25 am »
Following.

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #36 on: June 15, 2016, 11:14:07 am »
Alright, time for a bit longer post.

First of all, the fitment issues I was worried about wasn't much of an issue. It wasn't an absolutely perfect fit, but I didn't have to tug much either. I could easily bend the pipes enough with my fingers, not really a big force required.

Anyway!



I had to stop and take a picture without any headers mounted. The headers are EXTREMLY gorgeous on this bike.



As I said before, it wasn't much of an issue to get the new header on. It was perhaps a couple of millimeters off, at max. The fitment below though - wow. #$%*ing ACE. It couldn't have been better!





It's really hard to get a proper picture, but it isn't many millimeters below and it follows the lines beautifully.

However, when I were to remove the center stand I noticed something that I barely could believe my eyes when I saw...



The chain was actually riding ON TOP OF THE CENTER STAND! What the heck!? How could I have missed this? I have never had it on the side stand before, just used the center stand. The chain had grinded the center stand down. Not by much, but a little. I checked the entire length of the chain, and I could actually not see any wear at all. Nevertheless, I want a new chain.

To end, have you guys ever seen a more complicated choke assembly?  ;D



EDIT: I'll add the videoclip if people miss it. https://vid.me/iIFc here's the video of the Carpy CB750 Yoshi exhaust. Same as above.
« Last Edit: June 15, 2016, 11:32:46 am by cb750tr »

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #37 on: June 15, 2016, 11:14:39 am »
Following.
Cheers! Welcome and thank you :)

Hopefully it will get a bit more interesting to follow once I actually start the rebuild...

Offline calj737

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Re: First serious build ever - CB750 K7 Café
« Reply #38 on: June 15, 2016, 12:07:49 pm »
That a Carpy exhaust?
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #39 on: June 15, 2016, 01:14:23 pm »

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #40 on: June 16, 2016, 10:23:57 am »
Got my CBR1000F calipers today. Getting a custom banjo made tomorrow, and will start fabricating custom brackets for them.

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #41 on: June 17, 2016, 09:39:28 am »
Alright, first of all - magnesium brackets, cool as heck.

Anyway, after I examined the calipers closer I figured drilling SHOULD be easier and better than making a custom banjo. I didn't know exactly where the fluid canal went, but I just figured that it would be odd if it wasn't center to center on the outer pistons. So pretty much just crossed my fingers and went for it.



Excellent condition, they haven't traveled far.



Took a total of four screws to disassemble the caliper enough. Go go racing inspired bikes!



So, here's my plan. The fluid canal SHOULD be, if this follows logic, right at the bottom line.



Success! I hit it absolutely PERFECTLY dead center. Didn't take more than twenty minutes for the whole procedure. Woot woot!

Now, the thing is, I would want a RCS 19 master brake cylinder. It is probably too big for this though. But I want one. :(

Haven't quite decided what to do.


« Last Edit: June 17, 2016, 09:41:16 am by cb750tr »

Offline SOHC4 Cafe Racer Fan

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Re: First serious build ever - CB750 K7 Café
« Reply #42 on: June 17, 2016, 09:47:19 am »
The 19RCS is overkill.  I have one, and it is pure bike porn, but not needed for this application.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"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)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #43 on: June 17, 2016, 10:39:01 am »
The 19RCS is overkill.  I have one, and it is pure bike porn, but not needed for this application.
What does needed REALLY mean... :D

Offline SOHC4 Cafe Racer Fan

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Re: First serious build ever - CB750 K7 Café
« Reply #44 on: June 17, 2016, 11:34:57 am »
I had the Brembo 19RCS on my RC51 (which already has pretty amazing brakes stock) and with Goodrich lines, I could easily brake with one finger.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"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)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #45 on: June 27, 2016, 10:48:31 am »
I haven't had time to work anything on my bike, but I did make a "lift" for it. Since the engine pokes out below the frame I couldn't just raise it "normally", so I made a quick cradle and two chassis stands for it. Works like a charm.




Offline Andy K

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Re: First serious build ever - CB750 K7 Café
« Reply #46 on: July 03, 2016, 11:12:10 pm »
ex bikes:
Honda CBR 1100XX '98
Suzuki VL1500 Intruder LC '98
Suzuki GSX1300R Hayabusa '03

this is my version of Honda CB750 '77:
http://caferacer77.blogspot.fi/2015/10/tasta-lahdettiin.html?m=0

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #47 on: July 06, 2016, 01:01:48 pm »
this is my version of K7: http://caferacer77.blogspot.fi/2015/10/tasta-lahdettiin.html?m=0
Cheers, a fellow K7! That seat looks really hard to drive any longer moments on... :D

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #48 on: July 16, 2016, 02:17:15 pm »
Finally got some more work done.

This was my only week of vacation this summer, so I planned to get loads done on the bike. But as it always is, there are always other things that get planned, etc etc.

But, today I made some progress. Got the old fork off, and got the new one on.





Was a closer fit that I would have thought. The steering stem seems to fit bolt on, and I think the bearings won't be as hard to solve as I had previously thought. Will obviously have to manufacture a top triple, but it's an extremely simple task if I can only get my hands on some accurate measurements.





This is as close as I got it with just my hand tightening. I didn't have a c-spanner of the correct dimension, so I didn't want to damage the lock nut with something improvised as I couldn't really get much done anyway. Thinking of manufacturing a lower triple as well, both so it will look unified (if that's the correct English term, I don't know) and so I can use the stock steering stop. But before I can do that I need to get the tank, and that is a LONG time away I'm afraid so... Meh. Don't really know what the plan is. I need to get the top triple manufactured so I can make sure everything works (might have to come up with some solution with the lower bearing to keep dirt from getting in as well). If I recall correctly I have some tapered bearings for the CBR1000F, I need to test these out and see how close they come.

Anyway, some good progress! I think this front end with 17" rim will look A LOT better than stock! And the forks are in the ballpark when it comes to rake and trail, I believe.

Offline cb750tr

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Re: First serious build ever - CB750 K7 Café
« Reply #49 on: July 16, 2016, 02:18:38 pm »
Oh, and my Carpy exhaust is currently getting a thermal aluminium coating that should last quite a while. Really curious to see the end result of this!