Topic: 1976 CB750F - first bike, first build - mild cafe

[riffman12]

to clarify my brake light issue:

Here's a couple shots to show how little clearance I have under my seat:





I ordered this light off amazon on a bit of a gamble. It's meant to go under a harley fender...and it mounts with sticky tape, but I get the feeling it's going to kiss the tireif the shocks compress all the way:

http://amzn.com/B019VTK2YY


Does anyone else have ideas?

I'm even open to putting something on top of the seat, I'm just worried it will ruin the nice line.

[seanbarney41]

I used to run turn signals with red lenses and dual filament wired into the tail light and brake light...but then no rear turn signals,  although I think something could be done about this with a trailer light controller.

[riffman12]

I used to run turn signals with red lenses and dual filament wired into the tail light and brake light...but then no rear turn signals,  although I think something could be done about this with a trailer light controller.

I think I might get hassled a little too much by the CA police if I do that. I'd also like the brake light to be plenty visible.

I received that light from Amaaon, and it doesn't fit  The curv is too wide compared to the one on my seat so there's a big gap.

Time to try something else...

[SOHC4 Cafe Racer Fan]

Did you look into the LED strip?

[riffman12]

Did you look into the LED strip?

Yep that's what I wanted to do, but I don't have a vertical surface to stick it on. It would be aiming at the sky if I stick it on my seat. 

[Roach Carver]

I have seen that seat on other bikes but it seems like the rear came out a different/less steep angle with more clearance between the tire and the sheet metal.

[Roach Carver]

this is a forum members bike. its different but definitely provides more clearance

[SOHC4 Cafe Racer Fan]

That's Dave Hiller's (aka Doctor D) bike.  I have a similar seat on my 750.




I was thinking something along the lines of welding in a curved slender bar to follow the curve of your seat edge and then mount the LED strip to it.

[riffman12]

I have seen that seat on other bikes but it seems like the rear came out a different/less steep angle with more clearance between the tire and the sheet metal.

I think the difference is that I shortened my seat. I knew from the beginning that I wanted the seat to end roughly over my rear axle. It was a little long when I bought it.

That other seat is pretty, but different shape than mine.

I bought this thing as a gamble: http://amzn.com/B002GTOE82

It looks like if I take that light off the plate bracket, it might fit under my seat with some kind of adhesive. If not, then I'll look into welding some sort of mount, or a surface to mount the LED strip.

Thanks for the help guys. Chain is on,waiting on brake lines still. Then it's just paint until this thing is riding. 

[riffman12]

OK it's been a little while here. Been waiting on some parts as well as figuring out a tail light.

I'm rebuilding rear MC this weekend as I finally found a rebuild kit. Also going to fill and bleed my front brakes.

Next week is paint, then on to tuning.

I think I'm going to go ahead and replace my 4 spark plug caps as they're cheap and the ones I have look original. Just as clarification, is this what I want?

2 of these: http://4into1.com/ngk-spark-plug-resistor-cover-120-degree-vd05f/

2 of these: http://4into1.com/ngk-spark-plug-resistor-cover-straight-sd05f/

right?

[Roach Carver]

Yes

[riffman12]

cool thanks. Ordered them.

Next issue: I finally got my tail light mounted but I'm a little worried that my tire will hit the light under full compression. Here's how it looks:



I'm mentally blanking on this...does anyone have a good way to measure how much the wheel will move upward under full shock compression? The swingarm hinge and the fact the shocks don't go straight up and down are confusing me.

I posted the pic before, but you can see here why I'm having clearance issues; the seat is pretty far forward:




Any ideas on how to make sure my tire won't hit? Am I making this more complicated than it needs to be?

[budman]

Any ideas on how to make sure my tire won't hit?

Become really proficient at dodging potholes?

[riffman12]

Become really proficient at dodging potholes?

haha perfect. Not so easily done in the bay area...

here's a couple similar pictures with it off the center stand (aka milk crate). So this is at normal rest:

[budman]

I'm kind of in the same boat.  I heavily modified the rear section of my CB750 and lost some clearance.  I see a lot of brats with low seats and I've wondered if they have problems with the tire hitting the frame.  There are shock extenders that you can buy but they look kind of odd to me.  You end up having to rotate the clevis 90 degrees.  Longer shocks maybe?  Until I get my bike running and rideable I'm not going to worry about it just yet.  I live in Houston.  I currently ride a rigid and I've become really good at dodging potholes.

[seanbarney41]

Take the springs off the shocks, put the shocks back on the bike, and compress the shock to the bumpstops is the correct way to check clearance.  You may be able to space or obtain a slightly larger bumpstop.  Longer shocks will decrease rake and trail which is sometimes ok but you gotta do the math...or be prepared to find out the hard way

[riffman12]

OK been a while since an update. I've been back and fourth with brake lines, tail lights etc. so this is where I'm at. If anyone sees anything that looks wrong, please let me know!

bobbed front fender and front brakes all finished:




Rear brakes all finished:




chain, turn signals, and side plate mount installed:




waiting for my blade fuse holder from HondaMan then it's time for tuning. While waiting for that, I noticed this. Anyone know why I would have one green wire dangling here?




Also installed new NGK plug caps so the bike is all ready to run as soon as I have the fuse box in. If anyone has a good tuning guide that would be great! Not really sure what to do with the air screws with the K&N filter and carpy exaust.

[SOHC4 Cafe Racer Fan]

You might want to move your license plate holder to the right side of the bike.  Otherwise, you might clip your leg when you are pushing the bike around (dismounted). Ask me how I know.

[riffman12]

haha good tip, I'll try that out. My only worry is that my exhaust will blast the back of my plate then 

[SOHC4 Cafe Racer Fan]

Good point.  I've learned to live with mine on the left, and I use a similar pipe, too.

[Jerry Rxman Griffin aka MuthaF'er]

The extra green is just a spare ground. We'd all probably like to know what Honda initially had in mind.

Good job on the fender.   

[riffman12]

update:

I had a little tab welded up for my LED tail light. It's angled just enough that the light will be more visible than if it were on top of my seat. It doesn't look pretty right now, but I think once painted all will be OK:




and with the light mocked up:




what do you guys think?

Also got my HondaMan fuse block in the mail, installed that. So the plan is tuning tomorrow, test ride and more tuning on Sunday. Then if all goes well, the seat and side covers will be off to paint next week 

[riffman12]

Anyone have a quick guide on carb syncing with gauges?

I know the top adjusters are the major thing you change, but im pretty sure mine are close. From that point do i just fiddle with mixture screws?

[Jerry Rxman Griffin aka MuthaF'er]

Get all 4 flowing as close as possible. Get your jetting as close as possible including the screws. Take it to the dyno.

[riffman12]

OK cool. Got it running much better today. Once warm it starts on the first kick. Sync gauges are all very close together. I'm aiming to do a little test ride tomorrow to do some higher throttle tests.

This is after idling / gauge syncing / little revs here and there:




Specs:

1976 CB750F
Carpy 4 into 1 exhaust (with baffle)
stock airbox with K&N filter
115 main jets (105 is stock)
stock 42 pilots
stock needle position
air screws were 3/4 turn out (1 turn out is stock)


I'm pretty new to carb tuning. How does this look for idle readings?