'71 CB350 with GSXR front end and other improvements

thanks for all the suggestions! i wired up lines straight from the battery to coils using a relay and started testing out my work with a multimeter. the power to the coils looked fine when turned on, but as soon as i added on anything else (like the lighting circuit), the voltage just plummeted to 5 volts.

I started removing stuff from the lighting circuit until i just had the lone LED bulb for the neutral indicator and was still seeing 5V. there was simply no way that my battery could not sustain 12V for lighting a LED bulb. The issue had to be something else.

I sat there for the longest time looking at everything.. and started thinking about what I had not already eliminated as an factor. Then I looked at the battery ground strap and where it connected to the frame. Then it dawned on me that I had just powder-coated the frame!

SILLY OLD ME HAD NOT REMOVED THE POWDERCOAT from where the ground strap connected to the frame. I pulled out the dremel and ground off the coating and reattached the strap.

BINGO. we have strong, solid juice!

I'm going to go off and drink myself into oblivion tonight. Sheesh!
 
Nice to see you got it going.

After you have a long ride, can you let me know what you think of the Avons? Thanks.
 
Still getting the VM30s tuned.. but on a separate topic, I ran across a recommendation for using posi-lock connectors and I was intrigued so I ordered a bag of them and was really quite impressed with what I got. Theyre screw together connectors that make it really easy to do wiring and they seem to be much much more secure than other type of connectors.

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http://www.youtube.com/watch?v=1VzjoQcM66o

I got the VM30s tuned to the point where the bike would idle properly and it was time to actually put the the drivetrain and tires to the test. It was a good first couple runs, just up and down the street. The bike didnt stall or die. It was belching a bit of smoke near the end (too rich?). The power delivery didnt seem 100% spot on - it would hesitate or bog down if opening up the throttle too fast from the closed position... but thats what tuning is for!
 
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i received a set of progressive rear struts and a headlight bracket last week. i fit them to the bike yesterday, and thats how she looks so far.

i'm planning on removing the exhaust pipes and having them de-chromed. i am still deciding on what finish i want tho. i'd like a naked steel look but i dont think they are stainless.. mabye a light gray ceramic powdercoat.. any ideas/suggestions?
 
This is a great build. Just picked up a 73 CB350. Found a tank in the same color gold on ebay last week. Guy had a sportster tank welded on top of the frame!
Lots of great work youve done with your bike. Lots of ideas floating in my head now!
 
Things been pretty quiet on this topic, but its only cuz life has been pretty busy!

Where I left things off - I was still attempting to "tune" the Mikuni VM30s, but it seemed like I could never get consistent running out of the engine, especially on the right cylinder. I was employing that little trick where you'd pull off one of the spark wires on a warmed up engine and if everything was running well, it would still run OK on a single cylinder. Pulling the spark wire on the right cylinder would result in the left cylinder running along just fine. But reversing the test, the left cylinder would just usually crash from idle and die.

I synched everything - ran compression tests, checked for spark and everything looked fine, so I was really starting to lose my mind. I decided to run one more test - I hooked up my digital timing light to the spark wire, but instead of doing timing, I set it to display the RPM read out instead. On the left side, the numbers were consistent and generally in sync with what I was seeing on the tachometer.

The revelation came when I switched to the right side spark wire. It would show numbers, then randomly, for a second here and there, it would just blink out, or drop to some low number like 200-300 rpm. I knew right there I was on to something. The spark was working, but not consistently.

I pulled off the gas tank and started examining wires. I replaced the spark wire, ran the test again. No improvement. I started looking at the whole ignition setup, and started to suspect that mabye it wasn't grounded as well as it should be. I rearranged some wires, and ran a dedicated ground wire from the ignition module/coils to a newly cleaned post on the frame.

Annnnnd.. success! No more mis-fires or skipping. Everything is firing cleanly and I am getting good feel on both sides of the engine. So now I can finally move ahead with fine-tuning the VM30s...

moral of story.. if you think your ground might be good enough. Its probably not good enough! I think one of the weak points regarding those old hondas is that they were designed to be assembled quickly, so the electrical harness had basically one ground point for almost everything (aside from the starter and battery). That leads to a lot of critical dependency on one point of failure, and probably a good deal of signal noise? I rebuilt the wiring harness so that it has three major sections, and each one of them has their own ground to frame. The forward part of the bike (running lights, horn, etc). Then the PAMCO/coils/ignition has its own ground (along with power directly from the battery via relay triggered by the kill switch). Then the rear running lights has its own ground in the rear. I think this setup will make for a generally more reliable and long running setup.
 
Good follow up editorial. Suck that you all of that fighting over a ground connectionbut it happens all of the time in dc systems.
 
I`m doing the same frontend on my 78 gs 400,but i`m haveing a bit of a struggle finding a 18" front wheel that does the trick.
Maybe i overlooked that info if there where any,so i`ll ask: What type of wheel are u using on this lovely build??
Cheers
Jorgen
 
The wheel was easily the most complex/expensive part of the build. I had Woody's Wheel Works custom drill a 40-hole 18" rim, and laced up the harley hub to it. The rear wheel, they were able to use a stock 36 hole rim for the drum hub. The rims are Excel, I believe.


Floegstad said:
I`m doing the same frontend on my 78 gs 400,but i`m haveing a bit of a struggle finding a 18" front wheel that does the trick.
Maybe i overlooked that info if there where any,so i`ll ask: What type of wheel are u using on this lovely build??
Cheers
Jorgen
 
@timmysf

What rim/tire combo are you running?

I'm going with this hub ->http://cognitomoto.com/collections/gsxr-conversion-parts/products/gsx-r-hub-bolt-on-conversion-laced-wheel and sticking with 17" rims.

With that said, I'm thinking about 17x3.5 rim both front and rear with a 120/70/17 in the front and a 150/70/17 in the rear.

I know I'll have to off-set the sprockets but do you think fitment will be ok with the above setup?

Also did you have any issues with caliper clearance in the front? A lot of people are lacing their front wheels with all spokes facing inward to make sure they have clearance but it still makes me nervous.
 
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