New guy with project bike

[matt365]

Actually, I'm running 120/90/r18 Bridgestone Spitfires on the stock rear rim. I was told that I could go one size thicker at 130's.

Nice

Hey Noel, what hubs from what year are you running to have spoked rims with a rear disc? I would like to go to spoked rims rather than the mag if I can. Those mag rims are rediculously heavy.

The rear is a 2.15'', and The stock size for that rim is 110/90/18, but I don't want to stress out the rear tire by putting on a 130 - Will it deform the tire at all?

 

[coolatula]

Yeah those sidecovers are notorious for cracking. They were likely well on their way before you touched them. You have to be very very careful when putting them on or taking them off the bike.

Invest in some new rubber grommets for the mounts. Soft rubber helps, and they're cheap. You should be able to order them directly from a Honda motorcycle dealer (if you can find one).

Or just run pod filters cut away then file smooth the cover mounting tabs and do away with the covers entirely. This gives most bikes a look of being lighter even if it doesn't really take much weight off.

 

[matt365]

Or just run pod filters cut away then file smooth the cover mounting tabs and do away with the covers entirely. This gives most bikes a look of being lighter even if it doesn't really take much weight off.

I thought of that. I have pod filters for it now, but I would like to cover up those ugly electrics on the left side.

I was told by my buddy that I got the bike through that you can't jet these older slide barrell carbs. I was told it has an issue where it won't maintain a stable idle after 5000 rpm. Since it is running pod filters and a full exhaust I figured it might have a jetting issue.

Any best guesses on that?

 

[coolatula]

I thought of that. I have pod filters for it now, but I would like to cover up those ugly electrics on the left side.

I was told by my buddy that I got the bike through that you can't jet these older slide barrell carbs. I was told it has an issue where it won't maintain a stable idle after 5000 rpm. Since it is running pod filters and a full exhaust I figured it might have a jetting issue.

Any best guesses on that?

Never heard of that about the carbs. on Honda 750F?
The CB750/Honda boards could answer that or a shop that works on vintage Hondas.
The idle circuit/pilots should be totally different after you rev past them and start running on the main jets. The float levels have an effect also on how rich/lean you run. It all has to work in unison with your new set-up/parts to have the best tune. My floats were way off(rich) on my old FZR1000 and after set properly to my jets/exhaust it revved/pulled quicker and cleaner.

Aftermarket exhaust was a VERY popular upgrade on the F models. In fact I bet I used to see about as many WITH aftermarket pipes as with stock exhaust so,if they weren't able to tune them correctly I doubt there would have been that many running around.


Here's some jet kits for a CB 750/900F:
http://www.ridegear.com/rg/item/F-34018/Dyno-Jet/Jet-Kit-Honda-CB750-900C-F-80-82.html?mv_pc=GBProducts


Here's a CB website that discusses "F" models: http://www.cb1100f.net/

Jetting question asked on the website:
http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&p=146688

http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=37242&highlight=jetting

 

[matt365]

Never heard of that about the carbs. on Honda 750F?
Here's some jet kits for a CB 750/900F:
http://www.ridegear.com/rg/item/F-34018/Dyno-Jet/Jet-Kit-Honda-CB750-900C-F-80-82.html?mv_pc=GBProducts

Thanks for the links.

One difference about the jetting on the earlier CB750s and the '80 models were the slide barrell carbs on the older bikes. I'm going to see what other carbs would work with it, and if I can jet the existing carbs. Since slide barrell needs the fuel sucked into the engine, I couldn't get her fired up before I stored her for the winter. I'm betting if I had her in a heated garage, and cleaned up the plugs she would fire right up though. My buddy took it for a spin in the middle of the summer, and then it has sat since.

Man, this introduction thread has kinda ballooned into a bunch of technical questions

Leon might want to move this post ;D

 

[locOleoN]

Nice
Hey Noel, what hubs from what year are you running to have spoked rims with a rear disc? I would like to go to spoked rims rather than the mag if I can. Those mag rims are rediculously heavy.
The rear is a 2.15'', and The stock size for that rim is 110/90/18, but I don't want to stress out the rear tire by putting on a 130 - Will it deform the tire at all?

Hey Matt,
Im just running the stock 75-76 cb750f rims on the back & front.
Better yet, if you are planning to hunt down a set of spoked rims with front & rear with disks, try to get your hands on a 74-76 Honda gl1100 goldwing. They are the exact rim as the 75-76 cb750f but they are aluminum w/ high collars... Its much lighter and sexier...

I was planning to eventually find a goldwing set and just swap it in.

Cheers

 

[matt365]

I thought the CB750F only came with a drum brake in the rear?

 

[locOleoN]

I thought the CB750F only came with a drum brake in the rear?

Nope actually, the cb750 K models from 69-78 were all drum rear brakes. The cb750 F models "supersport" models from 1975-78 were all disk brakes. The cb750 F models from 77-78 all had the aluminum comstar rims, whereby the years 75-76 cb750f models had the spoke rims.
I think you may be confusing the K model & the F model of the cb750

the 1975 & 76 F model "super-sport" used the honda goldwing gl1100 rear brake calipers & rotors, except the rims were chromed steel, not aluminium rims w. spokes, so the 74/75 gl1100 rear rims can be swapped over with no mods including the brake rotor.

A lot of people just pull the back & front rims from that year goldwing and slap them on to the 75/76 cb750f, so that it has the high collar aluminum rims w/ spokes.

Just keep in mind that since the 75&76 cb750f have a different front brake set up than the 77/78 models, (75/76 use a front brake caliper mount in front of the forks, where as the 77/78 front brake calipers are mounted behind the fork, directly on the forks), if you pull a gl1100 front rim, it wont fit on the 77/78 model cb750f that you have...

feel free to call me if you have any questions: 416 597-3999

 

[TonUpSoldier]

Thanks for the links.

One difference about the jetting on the earlier CB750s and the '80 models were the slide barrell carbs on the older bikes. I'm going to see what other carbs would work with it, and if I can jet the existing carbs. Since slide barrell needs the fuel sucked into the engine, I couldn't get her fired up before I stored her for the winter. I'm betting if I had her in a heated garage, and cleaned up the plugs she would fire right up though. My buddy took it for a spin in the middle of the summer, and then it has sat since.

Man, this introduction thread has kinda ballooned into a bunch of technical questions

Leon might want to move this post ;D

You should still be able to re-jet..on Mikuni CVs you often have to drill a bigger hole in the slides to assist in the vaccum pull on them...check into Dynajet kits..they may have just the thing for you and will tell you how to do it based on your pipe/pod set up and type of carb..

 

[Kuyarico]

Welcome and congrats on the F! I love mine. It's a 76 with comstars. I also have the superbike bars and I love them. I rocked some adjustable clubmans for a while and went back to the superbike bars. Anyway, let me know if you have any questions. I learned a bunch about carb tuning these things.
Not exactly a cafe, but I've got one of those too