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Let's see your CB750

my old bike and my buddy's bike

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The pegs and grips were all turned by the builder when he did the scooter. He got cancer and that was that. Sold the bike for bills.
 
Thanks man. I gotta date the engine and either fix the floats on the carbs or put it back to original. But the guy did such a nice job I really am reluctant to change anything.
 
'74 K4

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Hi Folks!
New here, but have learned a ton of stuff from all of you who have taken the time to post tips. Thank you all!!!

This is my project that I started at the end of March this year. It wasn't nearly as bad as some I've seen, having been garaged for most of the time. Very dirty though, and was totally neglected for 25+ years (possibly longer), but had only 10,300 on the odometer. Tank, side covers, and seat were nearly perfect, and most of the chrome is decent after a little cleaning and polishing. The crash bar, sissy bar and luggage rack are history, but because it's in good shape, I decided to leave it mostly stock. She's now got new tires, chain, modular coils & wires, plugs, filters, carb kits, battery and fluids. Used the methyl salicilate (wintergreen oil) and ethanol trick to soften the petrified rubber parts. Worked like a charm. Ultrasonic cleaner spiffed up the laughably goobered carbs nicely.

She fired right up after the long sleep and everything works just like it did when Lynard Skynard was recording Sweet Home Alabama! Running really well too, but I still need to vacuum balance the carbs, check timing, and will likely replace the original pipes with a 4 into 1. They actually look pretty good, but are sort of swiss cheesy from rust. It's been a fun first project, but I need to be careful that my '78 Triumph Bonneville that I've had since new, doesn't get too jealous of the new girl. :)

I love looking at all of your great projects. You guys are awesome! I might need to try something a little more custom next time, now that I've got my feet wet.20180521_080437.jpg033118.jpg
 
My 79 CB750k 10th Anniversary Edition

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black tracker handlebars
black Mac 4 to 1 pipes
chopped fenders
lower profile signal lights
and other than a few parts stripped, thats about it. Though, im hoping to arrive at this styling by the time im done..

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So im looking to get it safetied. Looks like I just need to put my chain guard back on and put on DOT approved signals. POSSIBLY fenders, depending on how strict the guy is. If its just the signals.. where should I go to get the cheapest DOT approved signals?

BTW.. this is my first post here in this forum. Yay!

My previous bike was a bit of a rat rodded 79 CM400T. Fun, but small and a little too chopped up for my liking. My nearly stock, but tastefully modified cb750... im diggin it!! #waymorepower #idontthinkhashtagsworkhere

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A bit about me...

Name: Doug
Location: Winnipeg MB, Canada
Occupation: Contractor / Graphic designer (self employed)
Hobbies: guitar/bikes/building things/tinkering
Background: Mechanics, I.T.
 
Hello everyone. Just got a hold of a family 79 750k. I need to baseline it. Starts instantly, but surges and leaks gas from the carbs. Here she blows! Throttle sticks and the front brakes don't hold her still even when walking. I have a bit of work ahead of me.
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Thats a beauty 750K. The work ahead you mention is pretty minimal stuff really.

Gas leaking from the carbs. A lot of these bikes, if the fuel petcock is left "on" (up position), they will leak out overnight a bit. So make sure when you're parking it, even if just for a couple hours, turn your petcock to the horizontal position, "off". If they still leak, you probably have to replace your petcock valve since that would mean fuel is still getting through. If it leaks while its running, take the carbs off and make sure the floats and tiny little mechanisms that maintain your fuel level in the bowls are working properly. They're likely stuck if it leaks while running, meaning the level control inside isn't working right and letting too much fuel into the bowl, creating an overflow situation so they leak out.

RPM Surging: If your throttle sticks and this is why your engine is revving, try lubricating your throttle cable. Take the throttle assembly apart and spray in some silicone lubricant spray into both throttle cables. Make sure the lever components etc and the springs are functioning properly on the carb as well. Also, make sure that you have about 1/4" of rotational play when your throttle is a its bottom position (not engaged). This play ensures that you dont risk opening your throttle on the carbs without intentionally twisting the grips.

If your engine rpm surges after start but your throttle isn not being twisted and your throttle play is set right, or after your rev it once quickly but the rpms stay up and it takes time for the rpm's to come down, you likely have a leak in one or more of your carb boots to the intake on your engine. Take some Ether and systematically spray your carb boots that feed to the engine on top and bottom. if you hear the engine spike again in rpm, you know which boot(s) is leaking. These boots are rubber and when rubber gets old it gets rock hard and can crack. If air is getting in past the carbs, that means its leaning out the air/fuel mixture, getting more oxygen and therefore revving up. You can find rubber boots online pretty easily. try www.cb750supply.com.

Brakes: If your brakes aren't holding even with very little pad left on the shoes, that likely means you have air bubbles in your brakes hydraulic fluid lines. Check your master cylinder first to make sure you have brake fluid in there above the "low" level. If you dont, then you're sucking in air into your brake lines and that will cause a very spongy brake response, or no brake response. Check youtube for a quick "how to" on bleeding brakes. If your brake lines are bled properly already and you have fluid in the master cylinder, you should get friction in the brakes enough to stop it when walking it even with next to no brake pad left.

Again, if thats all you have to get the bike operating properly, you're in good shape.

Listen for any ticking or rattling sounds in the engine its self. Specifically, listed at the top of the engine. If you hear ticking sounds that follow the rpm of the engine, you likely need to set your valve lash (space between cams and rockers). If you hear a rattling sound that gets more intense when revving up you likely need to adjust your timing chain tensioner. If you have a really bad engine vibration, you may need to adjust your balancer chain. Find a good tutorial on youtube for any one of these if you hear/feel any of this and get yourself a good set of feeler gauges. @hackaweek on youtube has an excellent cb750 build that includes all this if you want an excellent documented run down of a cb750.

Good luck!
 
There are no rocker arms to check, clearance is between the cam and the shim and lifter cup. The valves get tight in these motors, hardly ever see them loose. There is no balancer in these motors...

Once you get to working on this bike please start a post in appropriate forum section so we can help with questions etc.
 
Thanks folks. I'm going to start tearing down this weekend. That write-up is very helpful. My biggest problem is the fact that the bike isn't charging and has to be thrown on the tender to get run time. Experience with a previous Honda led me down the burned connector path with success. I'll start a build/problem thread to try and get help and work through the issues.

This bike is so freaking comfortable. How the hell did they have so many features in 79?

 
{Got my 74 yesterday}(https://www.reddit.com/r/motorcycles/comments/92sv9i/picked_up_74_cb750_yesterday_couldnt_be_happier/?utm_source=reddit-android)
 
G'day guys,

just got my first Honda this week.....and I'm still trying to work out exactly what year model it is. Frame number is RC01-1000770, and engine is RC04-2219544

Bought it from a guy at work who wasn't doing anything with her, and I needed a new hobby, after getting out of old cars (which I've had my whole life). I've got 2 other bikes - an 01 Suzuki GSX1400 and an old 1984 Yamaha Virago XV1000. The Honda looks like it will be fun though. I've just started pulling bits off, and the carbies are on the bench as we speak.
Not used to old Hondas, and it's really hard looking for bits when you're not sure what it's meant to have. The damn headlight looked wrong, and when I removed it, she had a Yamaha bucket.....go figure. Anyway.....here's some pics. The whole album so far is here - http://s216.photobucket.com/user/71beeman/library/Honda cb750

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