76 CB750 super sport

brotus

brotus

Active Member
Finished up my GS400 project and decided i wanted something bigger. I always wanted a sohc honda and lurked on craigslist until i found a badass deal about 3 hours away. Needless to say i cruised out there real fast. It was owned by a doctor since the mid 90's and although it had 28K miles it ran and rode good. It hasn't been registered in 10 years and was in storage for a year. The owner brought it in because it wouldn't start and the shop replaced the RH handlebar controls (with the start/ kill switch) and fires right up now. Im not familiar with these bikes and there is a lot of things on it i don't recognize. Anybody that has any tip or tricks for these please chime in. I just plan on changing all the fluids and oil/filter and slowly restoring it.



Brought her home

 
So far the list for roadworthiness.

-Engine oil and filter. Any suggestions for a good oil to use? touchy subject, i know...
-air filter
-valve clearance check
-brake fluids
-replace burned out headlight
-clean/lubricate chain

also there is a small speaker under the headlight and when i try the turn signal it makes a tone/buzz.... i have never seen one of these before. is it a burned fuse indicator? i didn't check the fuses yet.
 
well after doing the oil/filters headlight chain and rebuilt the master cylinder, iv been cruising around on it. great commuter. love these engines they are so smooth
 
Also took the plunge and ordered a Vietnam see off eBay. The seller is very nice and asked for pictures of the stock seat pan to make sure it would fit. I was just going to put a new cover on the seat but the actual foam is all deteriorated so I figure I'll give them a try. Will post pictures when I get it
 
Had a problem today with the bike bogging down and eventually dying. It would run fine but occasionally anything more than half throttle would bog it down. I thought i was out of gas or had a fuel clog but the tank had gas and the inline filter was clear. Finall got home and checked if rust was coming out the petcock- nothing. I ended up removing the air box and the boots from the box to carbs were all shrunken and warped. The intake side of the carbs were coated in slimy brown petrified fuel gunk. Cleaned them and removed the filter. Filter looks fine but I ordered the carb boots from david silver spares. I also noticed that the crank breather wasn't hooked up to the air box so it may have been pulling air through that hole bypassing the filter.

On a side not I noticed that when the bike is nice and hot a small amount of smoke comes from the crank breather hose.... Is this normal? I figured some oil sludge might be in the breather tubes and when it gets hot it cooks the sludge? Ill pull the little filter/catcher and clean it out anyways.
 
Damn i just ordered a set from DSS... oh well they were only $8 each. I started the engine for a brief second with the air box off and it ran and revved normally- so i guess the problem was an airflow issue.
 
Forgot to mention- there was some black crud that drained out of the carbs when i removed the air box. Not sure if it was bits of deteriorated air boots or if it was some foreign material in the fuel i had just gotten. Maybe it had even come from the open crank breather hole in the air box. Anyway that was the culprit that clogged at least one and caused the bogging for anyone having similar issues.
 
Finally got the new seat installed

Installed the DIY fork boots

Still dealing with this gunk that now lives my carbs....

Because of this gas that i got from a dubious gas station
 
If your not sure about cleaning the carbs, it may be best to send them off, lots of places (or reach out here) will clean them, bench sync the slides and set the air screws to spec, you will still need to tune them after you get them installed.

Awesome Super Sport and a good choice for an upgrade... good luck with the project :o

P.S. That is rust and it looks like varnish in the bowls, you will want to clean the tank, do a search here we have some good results on tanks.
 
Awesome thread! Im gonna do the metal rescue on it. The tank looks rust free when you look in the filler hole, so I'm guessing there was some rust down in the bottom seam. Ill take a look in there with a boroscope before i put the metal rescue in.

I thought it was bad gas since i have clear fuel lines and the gas only got brown after this last fill up. I guess this gas maybe had more ethanol and dissolved some old tank sealer and sent it into the carbs?

Im going to clean the carbs in our ultrasonic in my shop at work, sync them up and hopefully be back on the road!
 
Hey, brotus. It sounds like you're dealing with the same issue I am- a degraded tank liner in a slightly-rusty tank. Before you pour a lot of expensive Metal Rescue in there, I'd suggest you make sure all the liner gunk is removed; the rust treatment won't be complete if some of the barrier is still present. Having a look with a borescope is a good plan. I picked up a cheap one on Amazon this week to use in my tank and it's invaluable. Be sure to check the lowest regions of the tank where liner liquid may have pooled when it was first applied. This seems to have been a problem with mine.
 
+1 for sure, was unaware of the liner, but you can buy a gallon of acetone and cook it out all together, just be mindful of the vapor, you will want to do the soak in a well ventilated area or best bet to just do it outside.
 
Thanks, That sounds like a good plan. I was gonna clean it out with either MEK or toulene (we have forced-air respirators at work) but acetone also sounds like a good idea.
 
I boroscoped the tank, looked like it was just a line of rust along the bottom seam. Cleaned the tank with soap and hot water, rinsing all the loose bits of rust out. I got a jug of metal rescue from home depot and let it sit in the tank for a day, came out nice and clean. Its all back together and runs good. I bench synched the carbs but I'm going to vacuum synch them tomorrow if I get a chance. I took it for a quick run down the street though, running pretty sweet as is!
 


The vietnam ebay seat is surprisingly comfortable and good build quality. I really like the way this bike came together.
 
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