Topic: I'm Back - '78 750K Restoration Has Begun

[Stretch]

Hey guys, been a while. When I was last here my FNL was debating on whether or not to sell me his 78 750K. In the time that has passed he's developed Parkensens and has decided to let me have his pride and joy.

This bike has sat since 2008, most of it in an out building. Last year I was able to convince him to let me bring it to my shop where it could be stored safely in a dry place to try to halt the rust that was beginning. It doesn't look too bad but it was getting to the point that I told him that he really needed to sell it or let me store it for him.

I do have experience bringing dormant bikes back to life but not much experience with this particular bike. What I'm wondering is, after carbs, brakes and unfortunately, tires, what should be the next area to work on? I'll need a complete carb rebuild kit so who is the carb guru here? Tires? blah, blah, blah....

The biggest expense will be exhaust. He didn't think it was loud enough so he gutted the mufflers and now they are just rusted shells hanging on the end of rusted pipes. I will put the 4 mufflers back on it.

What else do I need to be thinking about?

I'll post some pictures as soon as I can take some. Its burred behind several other bikes so it may take some time to get some current one.

[NobleHops]

Unweight the front end and turn it side to side and see if you feel it centering. If so then it's time for steering head bearings. It's likely.

Brake lines are probably junk.

Chain and sprockets.

There are a few seals that seem to dry up and leak, the tachometer, shifter shaft, and kickstart. All easy to replace.

Do the 3000 mile tuneup.

Clean all the electrical junctions - a small caliber gun cleaning kit (Walmart) has small bore brushes that are perfect for the bullet connectors along with a can of Deoxit.

That's all a good start.

N.

[Stretch]

I debated what to do with this bike. It has rust, not bad, but rust everywhere. My FIL though it was too quiet so he gutted the mufflers so I wasn't sure how far to go. After spending several hours thinking about it, I think I'm going to clean it up, get it running and show it to him. It would be sorta like a last hurrah for him and his pride and joy.

So, where can I find a carb rebuild kit. I know they have never been off the bike so I bet the o rings are probably dry/junk.

What is the recommended oil (without starting an oil war)?

Is it normal for the top head gasket to be seeping a little?

Since I have very little experience with points/roters, what should I expect?

[NobleHops]

Gasket and seal kits are plentiful, reuse your existing brass.

Motorcycle specific oil, I personally prefer golden spectro 20w50

Yes, common, you might get lucky and cure it by retorqueing the head and then replacing the rubber pucks under the valve cover. On a 750 that means removing the engine from the frame.

[Stretch]

I'm looking at exhaust for this bike. What is the differences between the exhaust setup between a 750K and 750F other than the F exhaust is about 1/2 the price???

[Stretch]

I rebuilt the carbs yesterday. Maybe it was because it was the first time working on these carbs but what a PIA. Man these things are dense! The probably weigh twice what the 4 for a V4 weigh. For those that say a set of V4 carbs are a difficult, not so. These were every bit as much work to rebuild as the v4s but I will admit, they are easier to get mounted. It also made me realize how advanced the V4 is compared to its predecessor.

I was able to find a set of used exhaust relatively cheap. They aren't perfect but this bike isn't by any means perfect either. They're much easier to put on than the magna/sabre exhaust.

It seems like anyone with just a little electrical experience would know that it takes more than one wire to make turn signals work. Pigtail connectors everywhere!!!!!!!

I can tell that the front brake is not returning like it should so its probably time for a rebuild and I'll clean out the rear drum while I'm at it.

I thought his bike was a very nice bike the last time I saw it 5 years ago. Time has definitely not been good to her. Now I'm catching up on 40 years of neglect.

The work continues...

[Stretch]

OK, I'm stumped...

There are two, what I think are ground wire connections (green wires) that I don't know where they go.
1. It comes out of the loom at the coils. It comes out of a connector with a yellow wire, runs about a foot down the left side to about the carbs and ends with a blade connector,
2. It comes out of the loom behind the left side cover, the wire is about 2 inches long and has a 90* blade connector

In the meantime, I've removed the exhaust, acid washed the exhaust collars and cleaned the mounting brackets and up behind where the mufflers will be mounted. Cleaned up the front disc brake caliper and installed a new bleeder valve. I'll flush the system tomorrow when I get the right brake fluid. Rewired the rear turn signals. Rebuilt the carbs.

Still need to get an oil filter element. I'm going to change the fork oil, I run 15w fork oil in my other bikes. Will this work in this one and how much oil do the forks hold and do both sides use the same amount?

Can someone tell me where I can download a manual for this bike?

Fark'n rust everywhere. It is a shame because this bike could have been something really special if I had gotten it years ago when I tried to buy it. Oh well, the cleaning goes on....

[CycleRanger]

OK, I'm stumped...

Can someone tell me where I can download a manual for this bike?

You can get the shop manual here:
http://www.honda4fun.com/materiale-documentazione-tecnica/shop-manual
The parts list is also available from the same site.

Don't worry, the manuals are in english.

[mt-ac]

This should be a good thread for me to follow in the interest of getting my 77' 750K up and running.  Thank you for posting the link for the shop manual is a great help as it goes beyond my Clymer manual from 1982.  The link shows a different carb than my Keihin PD41A's.

[Stretch]

Just an update:

Carbs are done, front brake clean and flush done, turn signals fixed, rust has been removed off the chrome but the frame will have to wait for someone other than me to strip it down for a repaint. Since this bike will sit for a while after he sees it. I'm going to forgo the tires and a battery for now, exhaust is on, chain has been cleaned and lubed and new plugs in.

Next step it oil and filter change then fuel. The battery has been borrowed from another bike. Hopefully I'll report back that it is breathing on its own later today.

[Stretch]

Well, here it is. I've been working on this for about a couple months and I just had to get it out and take it for a ride today. Its still a work in progress but from a distance it looks pretty good.

My Father in Law can't ride anymore and this was his Christmas present to me this year, the title to this. I tried to buy it from him about 6 years ago and he wasn't ready to let it go. He bought it new back in 78 and had kept it in an outbuilding its entire life. It hadn't been ridden for about 10 years so all the usual stuff had to be gone over.

Anyway, here it is...

[Marks78]

Looks good Magnaman! I too am in the (very long, slow) process of bringing a CB750K8 back to life. Your's was in better shape to begin with than mine but I hope to someday achieve equally satisfying results. Thanks for sharing a job well done. 

[Stev-o]

Looks real clean...nice job

[nbcam]

Nice bike, looks good

[Stretch]

The bike is a work in progress. I didn't strip it down because of the time frame to get it running again. It runs good but the air fuel mixture on the #1 carb isn't working correctly. Maybe this winter I'll take the carbs back off and try to clean that one again. I have too many projects going right now.

It runs good, idles good but has a hesitation if I nail the throttle off idle. When the rpms are above idle it runs and accelerates good. One exhaust pipe has a hole rusted in it so I'll stuff it with JB Weld in hopes to cut down on the noise. There's still one side of the frame that I'm going to clean up and paint then it will be an even better looking bike at 10'.

The aluminum on the valve cover has some oxidation that is just going to have to be that way because I'm not a fan of polished aluminum on these things. The engine could stand to be repainted, IF I ever take it out. The swing arm needs to be cleaned up and painted, IF I ever take it off. The rear spokes need to be replaced when I ever replace the tire.

Its just the little things that make a bike really stand out and as this one is its something to be proud of. My FNL keeps asking me if I'm going to ride it. Maybe just to bike shows.

My impressions of this bike:

• It runs well but it isn't a V65,
• It seems like a much heaver bike when trying to stop. While a front disc brake is an improvement over the drum, it could stand another piston or a disc on the other side,
• The seat is quite comfortable and the foot position is very neutral, I think this could be a good bike for a long ride,
• The throttle spring is really heavy. Fortunately my FNL, being the crafty devil he was, made a throttle lock that works pretty well.

I can see why this bike was so popular. Comparing it to what was out there at the time, its no wonder it sold so well. With a faring I think it could be a great distance machine. I have the one that was purchased with the bike when new, I just haven't put it back on yet. Its just a shame the reproduction exhaust for these things is so damn expensive.

With 4 bikes running and three to go, it looks like this one may go back into hibernation for awhile.

Can someone tell me the mpgs to expect and the fuel capacity? I do a trip to NC each spring and this might be a good candidate next year.

[Stretch]

I piddled a little this week and though she could use some detail work. The flat black paint was flaking so I thought I'd give them a touch up. Instead of using flat black I went with a gloss black. I think they came out terrific! With a black tank, the letters stand out without the faded flat between them. What do you guys think?