Topic: 1974 cb750

[Schnell]

Bought this a few days ago. As soon as the bike was on the trailer and I was beginning the process of strapping it down, a car stopped and the driver asked about the bike and told me about his Honda Shadow.

This is going to be an easy fix up I hope. Yesterday I removed, cleaned the carbs' jets, adjusted floats, and reinstalled them. Then, with an external battery hooked up, I was able to kickstart it to life. Today I replaced the fuel lines and reinstalled the stock airbox.

This evening I ordered tires for it and tomorrow I'll pick up a battery.

[Schnell]

It was a rainy day ...

[Gurp]

Great buy!!
Funny how one on a trailer brings people hoping you can fix theirs as well. It's made me a few bucks before and a few pals as well.

Sent from my LE2127 using Tapatalk

[newday777]

Congratulations on your new find! I hope this goes real well for you.
More pictures please!!

[RAFster122s]

Congrats on a nice find

[newday777]

I just did some night time reading of your trip on your 75. That was great reading through it and brought back memories of the trip I did in 2013 from NH to San Diego on my 08 goldwing I flew from San Diego to NH to buy. I took 10 weeks to get back, 9,000 miles. 3 weeks in NH to get the bike and found a pop-up camper for the trip while there setting up the bike and camper while visiting with family and friends, then a week taking back roads to Wisconsin to visit my youngest son and his family for 3 weeks. He worked on a small 850 acre vegetable farm in the middle of the state, we went up north to spend a weekend camping and fishing with the grandsons.
When I left there I headed north to Rt 2 to head west zig zapping around the countryside on the back roads, down through the farm lands and through the Black Hills traveling many of the same roads you did, just a year prior to your trip. I picked up the coast road to head south from southern Washington to San Diego. 
I  had sold my K6 in 1983 when I was starting my family and hadn't yet gotten another 750 until 2015, but in the late 70s I rode my K6 through many of the same areas you did, I rode it cross country 5 trips with my hound dog on the back. Lots of great memories.
Now I have a K5 in Planet Blue just like my K5 I had bought new. I'm back to living in NH and would love to be able to ride cross country on my 750 if my back would allow the trip.....
I also have some projects in the works, a couple K4s, a couple K6s and a K8. I'm semi retired but am still being a carpenter to fund my projects.

[BenelliSEI]

Nice find! That bike seems to be in very nice shape. Looks identical to one I found a few years ago. Actually the most original and cleanest bike I ever dragged home. Needed almost nothing. Good luck!

[Schnell]

I think that the original/previous owner attempted to resurrect this bike himself after its 30 year rest. He installed new fuel lines that were too big and leaked. He installed a new petcock and the rubber O-ring was not installed properly resulting in more gas leaks. He installed a new gas tank rubber and didn't mess that up.

So with a new battery, the carbs cleaned, and the gas leaks fixed, I was able to start it up and ride it around the neighbourhood block. It occasionally backfired quite loudly so a tuneup (valve gap, timing, and carb syncing) is still need but at least it runs!

I spoke with a mechanic today who has lots of motorcycle experience and owned a 1974 cb750 as his first road bike. He related that he has seen several ruined engines due to rubber bits from the oil hoses clogging up oil passages that feed the engine head, causing oil starvation and the resultant damage. Guess I'll replace those 50 year old hoses.

[RAFster122s]

More get destroyed by chunks of RTV where people don't know how to use gasket sealants or use stuff not as intended...
It breaks free a d clogs an oil passage and resulting oil starvation causes extensive catastrophic failure of cams, bearings and bushings and any other moving parts...

There is a fellow on FB whom had been mentioned a few times that does excellent hose rebuilds for the cb750.

[BenelliSEI]

“spoke with a mechanic today who has lots of motorcycle experience and owned a 1974 cb750 as his first road bike. He related that he has seen several ruined engines due to rubber bits from the oil hoses clogging up oil passages that feed the engine head, causing oil starvation and the resultant damage. Guess I'll replace those 50 year old hoses.”

Not sure that can actually happen. Supply oil goes from the tank, through the pump, directly to the oil filter before heading anywhere else. Overdone sealant is much more likely (see above).

Having said that, good idea to replace +50 year old hoses. I’m going to have a good look at the ones on my K1!

[MauiK3]

Good project!
Looks great.

[HondaMan]

I spoke with a mechanic today who has lots of motorcycle experience and owned a 1974 cb750 as his first road bike. He related that he has seen several ruined engines due to rubber bits from the oil hoses clogging up oil passages that feed the engine head, causing oil starvation and the resultant damage. Guess I'll replace those 50 year old hoses.

Like BenelliSEI said: not even possible. The oil from the hose goes thru the pump, then to the oil filter, from there to the engine.
I've met quite a few old bike wrenches who talk like that. Their experience is usually inversely proportional to their claims.

[Schnell]

Thank you for your reply HondaMan! Makes me feel better.

Don't know if you remember installing one of your hybrid electronic ignition systems of a Canadian traveller's 1975 Planet Blue cb750  in Colorado Springs, almost exactly 9 years ago?

[Schnell]

I have to remove the exhaust system because of rust holes in the mufflers. Problem is, the slip on mufflers will not slip off the headers, and the headers will not let go of the engine exhaust spigots. So I attacked the screws holding the spigots to the engine. My little electric impact gun got 4 of the 8 screws out. 2 screws simply would not budge, and the Philips heads of the 2 other screws became mangled.

Luckily I have a mechanic buddy with a shop who will help out.

[BenelliSEI]

Heat the end of the pipe with a propane torch, then start twisting and pulling…..

[newday777]

As John says, heat the header so it expands from the spigot, tap with a hammer on the header and twist the header back and forth to loosen it's rusty grip as you apply forward pull.

[Gurp]

VESSEL MEGADORA IMPACTA (+2x150(6") J) https://a.co/d/feZhMLc

Get some vessel screwdrivers and the impacta. It's a life saver!

[Schnell]

Total work time less than 10 minutes at my mechanic buddy's shop with proper air tool and all good.

Earlier today was good too. New tires, air filter, and oil filter arrived.

Now I'd appreciate recommendations for a new exhaust system. Not buying expensive 4into4 exhaust.

[HondaMan]

Thank you for your reply HondaMan! Makes me feel better.

Don't know if you remember installing one of your hybrid electronic ignition systems of a Canadian traveller's 1975 Planet Blue cb750  in Colorado Springs, almost exactly 9 years ago?

I do, but it was in Commerce City (which is a little east and north of Denver)! Didn't you then ride thru the snow to get to the West Coast afterward?

[newday777]

Delkevic is a decent 4into1 system and about the lowest cost exhaust to fit

https://www.ebay.com/itm/182474158298

[BenelliSEI]

Delkevic is a decent 4into1 system and about the lowest cost exhaust to fit

https://www.ebay.com/itm/182474158298

+1 to this suggestion. Nice product at great prices.

[Kelly E]

Delkevic is a decent 4into1 system and about the lowest cost exhaust to fit

https://www.ebay.com/itm/182474158298

+1 to this suggestion. Nice product at great prices.

Yep, we have 3 Delkevik exhaust systems and are happy with all of them.

[Schnell]

Thank you for your reply HondaMan! Makes me feel better.

Don't know if you remember installing one of your hybrid electronic ignition systems of a Canadian traveller's 1975 Planet Blue cb750  in Colorado Springs, almost exactly 9 years ago?

I do, but it was in Commerce City (which is a little east and north of Denver)! Didn't you then ride thru the snow to get to the West Coast afterward?

No snow on the mountain pass I took. I got to the coast near Stockton.

[HondaMan]

Thank you for your reply HondaMan! Makes me feel better.

Don't know if you remember installing one of your hybrid electronic ignition systems of a Canadian traveller's 1975 Planet Blue cb750  in Colorado Springs, almost exactly 9 years ago?

I do, but it was in Commerce City (which is a little east and north of Denver)! Didn't you then ride thru the snow to get to the West Coast afterward?

No snow on the mountain pass I took. I got to the coast near Stockton.

Ah, OK: I'm thinking of someone else, then. He came thru here from Michigan (or maybe Minnesota) where he bought the bike, enroute back to his home in CA. Then he sent me the engine for a full rebuild a few months later, when I discovered the famous, "Hey, there's no oil jets in this head!" engine.

[Schnell]

A few days ago I tried mounting new tires using a big screwdriver and a pair of BMW tire irons that are too short. Success with the front wheel but the rear wheel was more difficult. Ended up jabbing my hand when the screwdriver slipped. Lesson learned: Use the proper tool for the job. A couple of days later after letting my hand rest and heal a bit, I bought the proper tools and yesterday finished the job.

Today I adjusted the cam chain tension, gapped the points, and did static timing on it. Tomorrow I'll adjust the valves.

The bike came with a 4into2 exhaust system which I like, but one of the mufflers had a couple of rust holes which I "fixed" with JB Weld. I learned after, that this would not last or pass a safety check. I don't know a welder which is what would be needed for a proper fix. So I'm looking for a new exhaust system. I was willing to spend twice the price of a new 4into1 system for a David Silver Spares 4into4 but was quoted $1700us shipped to me in Canada. That's just too much for me.

Any recommendations for exhaust?