Shiny's 1980 CB750 F...happy with pods.

[TOOLS1]

Yea, I can just see the electricity dripping out of it.
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[shinyribs]

Alright, funny guy. You know what I'm talking about. You patronizing me bro??

[TOOLS1]

Watch it, you might irradiate your leg.




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[shinyribs]

Ahhh, my baby is back! Catch you guys later....

[shinyribs]

Im having to completely disregard any timing marks. I dont know why. If I try to time the bike to the T mark, which should my timing at idle, the bike won't run. The manual specifies 10* btdc at idle. I'm setting on about 30* .     No clue.


But she runs great! There's a little fueling stutter off idle at cruise, but I think I can tune that out with the I/m screws. She revs beautifully and quickly. Banging in to second gear at wot with a quick fan of the clutch gives pop-up wheelies. :). ( lil ones)

Two things about these carbs.

1- the throttle input ratio is way quicker than stock. A little dab will do ya

2- flat slides rattle a bit. I thought I had developed an exhaust leak or had an arcing plug, but finally realized it was just a carb clicking.

[shinyribs]

Made a carb support today. And I welded it with the torch just for some fun on a rainy day. I can't remember that last time I welded with oxy/acetylene and coat hanger. :)

[hambone]

wow,so glad this is working out...really enjoying this thread. I haven't had much time lately but wanted to check progress!! I really like your fabrication work especially  your carb support. they do vibrate a bit.im taking a long ride today to see my oldest daughter and cant wait! I simply love my Honda!this past month I picked up two more 750fs in fair condition and a 1978 cb 750k model.no idea when I can work on them but couldn't pass up the bargains .its a sickness! I may have to go to the food pantry this month!

[shinyribs]

Ha! Food pantry made me laugh.  Thanks man, and thanks for the help. Looking forward to getting this thing out and finely tuning it.

You are going to have to start coming around more and posting up all the bikes your working on.

[Truck]

Check these out.

http://www.ebay.com/itm/K-N-Carb-Air-Filters-Suzuki-GSX600-F-GSX750-GSXR1100-/141581592431?hash=item20f6eba76f&vxp=mtr 

[shinyribs]

Those are awesome. Those are also expensive! lol. Need to get some measurements and see if they have them in my size. Thanks for the link, Truck.

[Truck]

Yeah, but then again all the K&N filters are expensive. I'm thinking they might help a little with equalizing the airflow into the carbs, but I guess the only way to find out is to use them.

[shinyribs]

The listing claims they fit my carbs, but the dimensions are wrong. The flanges are 60mm I.D. , but my carbs ate only 50mm. Hmm...

[shinyribs]

Rainy weekend. Good time to sort out some odds and ends that's been annoying me.

First order was a new rear brake stay. The one that came with the bike was kinda interesting.


It hit the shock here.



And it rubbed the tire here.



So I made this. Laying on top of the old stay, with the attachment points lined up, you can see how uch tire clearance was gained.



And it clears the shock nicely now.


Next thing was my luggage rack. I wasn't completely satisfied with my original design. It worked fine, but it wasn't as easily removeable as I would have liked. Also, I wasn't overjoyed with how the upper shock mounts were done, so that got remedied at the same time.

Previously, the upper shock bushing was pretty much completely crushed when the hardware was tightened. Not cool. And the rear suspesion on this bike has always seemed overly stiff. Like it had too much sticktion. So I decided to sort out and shock mounts and the luggage rack with the same stone.





As you can see in this ^^^ pic, the lift plate bolts to the stock shock mount stud. It has an aluminum spacer to hold the lift plate out the correct amount. I removed that aluminum spacer and used that as an attachment point for my new luggage mounts.

Then I made the rest of the mounts.



Which fits like this.



And stick out about yay far to clear the paint well.



And once all together is barely noticeable when running without the rack.



Once that was all sorted out I had to fiddle around with bushings, bushing inner sleeves,etc until I got the upper shock bushing sorted out (no pics), but once set up correctly the sticktion issue did go away. I haven't ridden it yet,but the rear suspension cycles noticeable easier by hand now.

Powdr should be done tomorrow and ready to go back together soon.

[TOOLS1]

Nice looking brake stay. I am assuming that you have a solidly mounted caliper bracket with the caliper sliding on it, and not a floating caliper bracket. I had to make a new stay here recently for a bobbed CB 550 that has a Harley disc brake rear wheel. It had a floating caliper bracket that someone had installed a solid brake stay on, and it was binding the brake. I made a stay with hemi joints on the ends, and it cured the problem
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[shinyribs]

Yep, it's an F3 rear caliper. The stay connects to the caliper mounting bracket that comes off the axle, the caliper can float freely on the mounting bracket itself.

I saw something similar on a buddy's car once. Rear disc brakes on a 9'' Ford with no hoses. All hard lines. You can guess the rest.

[shinyribs]

I'll keep it simple so as not to bore you folks. But I had a slow return to idle that I just couldn't understand. Synch was spot on. Bikes seemed to be running well, but it still had a weeeee itty bitty sputter off idle. Also, I couldn't get a decent idle speed. It was idling too low , so I turned the idle knob up...still too low...little more, nothing...little more, still nothing....little more....2,000 rpm idle.  I gave it a little more timing ( still had a little dead spot at wot) and gave it some fuel at the idle mixture screws. Seems great now! I'm sitting at 3.25 turns from seated. Seems excessive? Maybe I should step up 1 size on pilots?

Pitiful audio quality. But it's a phone, what do you expect.  Revs nicely and has a dependable return to idle. Just needs a good road test before I can call it done.




Oh, and remember I mentioned seeing the ''boots'' pulsing at idle? (crazy fast idle from early on in the tuning)

[shinyribs]

Well, all is happy in DOHC Podville. Only other changes I've mad is opening up the idle mixture a tad. I'm at 3.25 turns from seated. I also bumped the timing up a few more degrees. Plugs look nice, no signs of detonation or preignition. Reliable return to idle and no flat spots. I was going a little warm in to a curve (3rd gear at about 45 mph) when I saw a dirt clod in the road. Jumped off the throttle ( too quickly), adjusted my line, jumped back on the throttle (too quickly) and got a little burp. Otherwise, very little pop on decel and revs out nicely. Even without the accel. pumps, these carbs have fantastic throttle response. Very crisp. And most of the cold natured attitude of the bike is gone completely. Very happy I learned about this swap. I'll be buying another rack of these for the 1100. No point in buying $700-800 worth of CR's whn these work perfectly well.

[Oilfield trash]

Man, seeing the last post is like reading the last page of a good book. Makes you sad there's not more. My first post here, but been a voyeur for a long while here and other sites. Hoosier daddy seems to be everywhere! Thanks for all the documenting. Looks great and sounds the same.

[shinyribs]

Welcome in bud. And thanks!

Im very happy with the Mikuni's for the most part, but the radiator hoses definitely leave a lot to be desired. Maybe I just happened to buy the cheapest piece of hose available, but I dont foresee this particular hose lasting very well. With under 500 miles on this setup it's far from done, so its still not what I'm comfortable to call a 100% cure. The bike runs great, but there's still room for improvement. I could happily ride the bike as-is from now on ( providing the hoses held out), but there's still a few quirks that only continued riding will expose.

- The hoses. Pulsing badly now. As much as 1/4" at idle. At freeway speeds #1 feels very deformed.

- The bike lacks the punchy-ness it once had. No bogs or hiccups, but it feels a little lazier when you're just tooling around.

- Fuel mileage suffered. I went from a typical 40-43 mpg (best of 47 iirc) to 30 mpg.

- The bike doesn't like parking lot situations. It feels jerky. I used to maneuver parking lots in 1st gear ,  engine just idling , and dragging the rear brake when needed. But I wonder if this isn't due to the pulsing hoses.

- The bike doesnt idle dead smooth anymore. I've checked the synch numerous times. It's not rough or horrible at all, but I can feel the engine when stopped in traffic. I didn't use to feel the engine idling at all. Again, I wonder if this is due to the pulsing hoses. When synching the carbs the gauge needles have more fluctuation then I've seen before. I really have to crank in the restrictors on the gauge hoses the get an accurate reading. I really think these pulsing hoses are just making it impossible to synch the carbs properly. Constantly changing intake volume, and all that.

I swear I'm not crazy and just chasing my tail, but I'm working on mounting some stock carbs back on here soon that I've modified per the Honda Racing manual I posted elsewhere.

Main reasons for this:

- Factory carb boot reliability.
- I'll get my closing cable back ( love those).
- Hoping getting the accel. pumps back will regain the lost punchyness.
- Fuel mileage!
- Ability to help others here that want to ditch the airbox without having to resort to mounting foreign carbs or spending a lot of time or money.

Plus, I just like to piddle. :) So stay tuned. I'm never finished. lol



Im happy with the setup.

[shinyribs]

^^^One word for all that.....poppycock.

If others have used that successfully I would LOVE to meet with them in person. For me, once the bike gets on the needle it goes nuts. Stuttering,stumbling....eventually dies. The article call for 102 mains ( I understand I don't have 1,000cc's). I have mains ranging from 068 to 140. I have stock needles and Dynojet needles. Every combination from 068's with stock needles (super lean) to 140's with Dynojet needles clipped as high as possible (super rich) produce the exact same results. I have no clue.

But if you look at the circuitry that you are modifying per that article you are converting the carb to a simple 2 circuit carb : idle circuit & main circuit w/needle. But, you eliminate the air bleed for the remaining main circuit. How can that main circuit ever function correctly with no air bleed to allow the emulsifier tubes to...emulsify?

Screw it. The Mikuni's ran fantastic, they just had low speed issues. But considering the pulsing hoses, and the fact that those hoses make the bike IMPOSSIBLE to synch, I'm going to Plan B on mounting the Mikuni's. I never remembered my clutch rattling so much before. But after mounting the stock CV's back on the bike, and being able to actually synch the carbs due to having proper boots, my ile was dead smooth and my clutch was again almost silent.

Yeah, I just need better hoses or boots for the Mikuni's and I think I'll be ok. So stay tuned,but teaser pic...