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Author Topic: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget  (Read 4264 times)

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Offline calj737

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #25 on: June 23, 2020, 02:09:49 pm »
Quote from: anotherCB on June 23, 2020, 01:01:39 pm
No, I haven't, just focused on getting it running first, but I am getting there eventually. There are a few things I need to address before I can go on a longer test ride.
I know that I can push the fork tubes through to get the bike lower in the front, not sure if that would make a difference, but what else is there I could do to adjust geometry? I am not very familiar with custom bikes so need to look into that.
Change the offset back to stock, closer to 50-55mm. GSXR is closer to 30-35mm.
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"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 anotherCB

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #26 on: June 23, 2020, 03:10:48 pm »
Yeah, but I have the Cognito Moto triple tree with the integrated Motogadget unit that I would have to give up.
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Offline SOHC4 Cafe Racer Fan

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #27 on: June 23, 2020, 06:32:32 pm »
Quote from: anotherCB on June 23, 2020, 01:01:39 pm
No, I haven't, just focused on getting it running first, but I am getting there eventually. There are a few things I need to address before I can go on a longer test ride.
I know that I can push the fork tubes through to get the bike lower in the front, not sure if that would make a difference, but what else is there I could do to adjust geometry? I am not very familiar with custom bikes so need to look into that.

You could alter the trail by using a different fork offset with the triple trees.  I believe you are using a Cognitomoto triple tree with the GSXR front.  In selecting the offset, however, did you mention to Devin at Cognitomoto that you would be running a longer swingarm?  If so, he may have already taken this into consideration.  If not, Devin may let you exchange it for a different offset if needed.  You should measure your fork offset, rake and trail and see how it compares to stock geometry.
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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
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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)

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 anotherCB

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #28 on: June 23, 2020, 07:31:41 pm »
You could alter the trail by using a different fork offset with the triple trees.  I believe you are using a Cognitomoto triple tree with the GSXR front.  In selecting the offset, however, did you mention to Devin at Cognitomoto that you would be running a longer swingarm?  If so, he may have already taken this into consideration.  If not, Devin may let you exchange it for a different offset if needed.  You should measure your fork offset, rake and trail and see how it compares to stock geometry.
[/quote]

I bought the bike as is, with forks and swingarm installed, not running with carbs apart. I know that the PO dealt quite a bit with the guys at Cognito Moto. My plan is to get it running right first, get the carbs adjusted and then look into the geometry. That is something I don't have much experience with, so should be a fun learning exercise! Thanks for pointing it out!
« Last Edit: June 23, 2020, 07:33:24 pm by anotherCB »
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Offline anotherCB

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #29 on: July 14, 2020, 07:43:36 pm »
Well, I guess I screwed up....

Bike was running really well, it just needed a carb sync and I wanted to double-check a few other things, one of those being cam chain tension. According to the Clymer cylinders 1-4 need to be at TDC + a few degress (whatever the book said). I didn't pay attention that there 2 different TDCs, one after the compression stroke and the other one after the exhaust stroke and from what I know now is that I think I had set the cam chain tensioner with the valves of Cyl 1 open. Long story short, I think the timing chain must have jumped over and I am afraid a valve hit a piston...Or what else could have happened?

I had thought about pulling the engine before this happened to strip off the ugly paint job, this makes the decision easier. Out it will go.

I will let y'all know what I find.
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Offline SOHC4 Cafe Racer Fan

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #30 on: July 15, 2020, 11:06:09 am »
That's a bummer. 
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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 anotherCB

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #31 on: July 15, 2020, 12:59:42 pm »
Quote from: SOHC4 Cafe Racer Fan on July 15, 2020, 11:06:09 am
That's a bummer.

Indeed. Only good thing, I wanted to pull the engine anyways to strip off the horrible paint job, but hopefully I don't have to spend to many $$$ for parts.
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1978 CB750K, 2016 R1200 GS/LC, 1973 R75/5

Offline anotherCB

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #32 on: July 17, 2020, 12:21:02 pm »
Collateral damage....I'll start another thread in the SOHC4 forum titled "K8 Engine Damage - cam shaft sprocket in pieces".
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Offline SOHC4 Cafe Racer Fan

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #33 on: July 17, 2020, 05:10:10 pm »
Quote from: anotherCB on July 17, 2020, 12:21:02 pm
Collateral damage....I'll start another thread in the SOHC4 forum titled "K8 Engine Damage - cam shaft sprocket in pieces".

Woof! You don't see that everyday.
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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 anotherCB

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #34 on: July 17, 2020, 06:23:13 pm »
At least now I am thinking the cam sprocket wasn't tightened down to the cam properly, doesn't make me feel that bad. Although I learned my lesson, I guess if you buy a bike "ran when parked" anything can happen!
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1978 CB750K, 2016 R1200 GS/LC, 1973 R75/5

Offline rickmoore24

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #35 on: July 17, 2020, 07:36:51 pm »
Man that sucks! You really cant trust it unless you put it together yourself, even then its sketchy. LOL Bummed for you man.  ;(
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1973 CB750 K3 (Hardtail 836cc)
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Offline PeWe

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #36 on: July 18, 2020, 11:06:09 am »
Quote from: calj737 on April 18, 2020, 03:55:26 am
Might want to replace that battery NEG cable and move it to a more suitable location. Grounding in that thin stamped area of the frame likely won’t get you the best results.
+3
Bad grounding in frame one reason of melted green wire to rectifier and sometimes more melted green wires in main harness. There are some posts about it.
I have also seen that many used rectifiers have melted green insulation or even connector housing where the pin sit on rectifier harness.

I have recently added extra ground wires to ensure good voltage with less drops.
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CB750 K2-75 Parts assembled to a stock K2

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
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline anotherCB

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Re: CB 750, one sided swingarm, Ducati rear wheel, GSX/R forks, Motogadget
« Reply #37 on: July 19, 2020, 04:17:24 pm »
For whoever is interested, I started a new thread with just the engine issues here:

http://forums.sohc4.net/index.php/topic,183590.0.html
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