Topic: Reviving a '73 750

[gpzkat]

Picked up a '73, complete but tired, needs full going through.  Top end off due to leaks at base and head gasket. It all looks very good inside, journals, cams, bores etc are in fine shape and will get the proper attention.  Many new parts on the way.  Returning to stock as much as possible, but alas, the pipes will not be 4/4 stockers unless I win the lottery, so the 4/2 slip ons will have to do.  Had a lovely '76 back in the 90s, fond memories.  Hoping to be able to go with the orange flake, that'll likely be the toughest thing but I have some local resources that have done great work for reasonable rates with me supplying the paint.  If there's any interest I'll document the build.    Just finished a GS1100E with Mr. Turbo, and interesting Bonneville history and needed something new to skin my knuckles on.

[SOHC4 Cafe Racer Fan]

Go for it (as in document it)!!

[gpzkat]

OK! 

Fairly surprised how the pipes are turning out, did 2 tonight - still have to buff on the wheel, but what I thought was bad rust was mainly baked on oil and road tar, so these will be presentable at least, along with the new MAC 4/2 slipons that arrived today.  Pic shows two done, the worst ones first so I'm relieved at them being usable - but one is mashed at the aft end so I have to figure out a fix.  The outsides are better than the insides, so that's good too.

I will take several parts (carbs, hubs, etc) to my friend's on Saturday to use his blast cabinet and give them the soda treatment.  Also my neighbor runs a powder coating shop and does great work, so frame, swingarm stands, head stock etc will get done soon.

New repro seat, fork tubes, Avon tires, front rim, spokes, rings, seals, gaskets, bars, mirrors, carb kits, etc all on the way.  I am funding from a couple free Goldwings I got and sold fast for $1300 so that's about my budget (plus the $700 for the bike). Already chewed through about $750 but have most of what I need, mechanically.

My friend who has a '74 gave me a rear rim as he's going to a 4", it's not bad, can see a bit in pic below.
I have a new 15L ultrasonic cleaner and am using a coffee can plunged into it, works great - either dollar store degreaser or sometimes gasoline.

Front bearing retainer is really mangled, will either sort that out or leave it be, the bearings seem OK, should be able to tape over it and soda blast the hub hopefully.







This is the level I'm working toward...have to show off...

[Stev-o]

Subscribed for the K3 project. Nice Suzi!  You have a Duc too?!

[MauiK3]

cut the bearing retainer out.

[754]

Looks like maybe a 77 or 78 K front hub, it will work. Should be finned one..

[gpzkat]

Stev-O - yeah 2013 Multistrada, great bike and I love it but have 3 bikes now so it may go.

754 - it's finned radially inside between spokes if that's what you mean.   -Edit: missed that you mentioned front, OK thanks for info.

[gpzkat]

Bead and soda blasted today.  Happy with results.  Also have a loaner buffing wheel stand.  The seat and front tire (Avon) arrived.  Seat is the repro, seems quite good, got from 4 into 1.

Head and barrels will get vapor treatment so I did a light job on them.

[Stev-o]

Blasted parts and seat look good!  I love vapor blasting, did my entire H2 motor.

[MauiK3]

Settle in for some long polishing sessions!!

[mrbreeze]

A couple of tips....make sure you use OEM cam pucks. Aftermarket pucks have been known to not be as thick as OEM and may leak. Look for a post called Brandon's leak free top end. Lot's of good info there. Get time serts for the cam tower bolt threads. The threads are known to easily strip out and will cause problems. Get a new OEM tensioner. I just read about a member that used an aftermarket part and it failed.

[gpzkat]

I just finished my GS1100E, all by hand and a bench grinder with mops, but now have a freestanding polisher with Tripoli and white rouge so that helps.  I'm pretty efficient, wet sanding then buff.  The GS was a chore because the turbo, the collector, and the connector were all badly tarnished stainless.  Lots of elbow grease and hard to reach nooks.

Settle in for some long polishing sessions!!

[gpzkat]

Thanks - starting to add up the $.  The tensioner sure seems fine (how can I tell if shot?), there is no discernible wear and the unit functions.   Also the cam chain should be replaced as a matter of course, I guess.  Thing is I've had and heard of CB750s with 2 or 3x the 30K mileage this has, and this one is really well maintained and was a commuter, not a beat on bike that burned oil.   Really pristine inside. The only reason it's apart is the base and head gasket leaks.  But new is always best, with OEM or high quality replacements.  My '76 never had any leaks, must've been a unicorn.

I am looking at the guides/seats and wear items in the top end and measuring, nothing out of whack.  The valves dropped right out and only had light carbon deposits which dissolved in my ultrasonic cleaner, for the most part - a couple stubborn spots on exhausts, but zero on intakes.  The valve seats are really clean, and I'm wondering if a 3 angle grind is necessary or just lap them, leave the guides in and check it out?   I got a high quality gasket set, will check out the pucks but yeah they are aftermarket.

Cam tower threads, hmm, torque to spec (clean well first) and still strip?  Jeez this is a Honda, I thought they were invincible!

I have to watch out being a cheap a$$, I was broke for so long in my life that it stuck in me to be, uh 'frugal'. But false economy etc...

A couple of tips....make sure you use OEM cam pucks. Aftermarket pucks have been known to not be as thick as OEM and may leak. Look for a post called Brandon's leak free top end. Lot's of good info there. Get time serts for the cam tower bolt threads. The threads are known to easily strip out and will cause problems. Get a new OEM tensioner. I just read about a member that used an aftermarket part and it failed.

[mrbreeze]

Yeah I'm basically a cheap a$$ myself but after reading some horror stories here I wonder if it may be cheaper in the long run to buy the best quality parts on the first go round. The stuff I listed is just info I got from others that had problems and tried to prevent from happening to others. Some people are are more anal than others so you gotta sort out what feels right to you.

[Stev-o]

...it may be cheaper in the long run to buy the best quality parts on the first go round.

The bottom line is the cheapchinacrap is just not as good as the OEM Honda parts.
So dont use them to save a few bucks.

[mrbreeze]

...it may be cheaper in the long run to buy the best quality parts on the first go round.

The bottom line is the cheapchinacrap is just not as good as the OEM Honda parts.
So dont use them to save a few bucks.

Especially when you have to burn your time and a new gasket set to go back inside. That's not to mention if it causes other parts to fail.

[754]

A good triple cut valve job is better than factory, and can only help.
 Show us the can tensioner and rollers, and we can advise..

[gpzkat]

You guys are great, I really appreciate you taking the time to respond.

Here's the tensioner and rollers and also the valves/pistons and a representative combustion chamber - all are in this condition, I see some scuffing on the piston and also on the exhaust valve seat but doesn't seem that bad.

[gpzkat]

You guys are great, I really appreciate you taking the time to respond.

Here's the tensioner and rollers and also the valves/pistons and a representative combustion chamber - all are in this condition, I see some scuffing on the piston and also on the exhaust valve seat but doesn't seem that bad.

I got quoted $200 to vapor blast the head and sleeves. Hmm...

[mrbreeze]

That is a great picture of the tensioner and guides. You gotta realize those parts have been inside that engine for quite a few years. Then you gotta ask yourself just how far can I push it till those parts fail. Think about the damage that will occur when they fail. If I had my cylinders off sitting on the bench right now it would be a no brainer to p Thatut new parts in. And after reading about a guy who cheaped out and bought an aftermarket tensioner that he had to go right back in and change I'd make sure my new one was made by Honda that lasted 40 plus years.That's just me though......

[gpzkat]

Yeah hard plastic/rubber through many heat cycles ages and gets brittle, no?  Hate it to chunk out on me.  I will get the good stuff.  Just the roller assembly and long guide right? I'll do some research and see what price I can find.

That is a great picture of the tensioner and guides. You gotta realize those parts have been inside that engine for quite a few years. Then you gotta ask yourself just how far can I push it till those parts fail. Think about the damage that will occur when they fail. If I had my cylinders off sitting on the bench right now it would be a no brainer to p Thatut new parts in. And after reading about a guy who cheaped out and bought an aftermarket tensioner that he had to go right back in and change I'd make sure my new one was made by Honda that lasted 40 plus years.That's just me though......

[754]

I tossed a roller way way worse that that yesterday  , and saved one that looked like yours ..try this.. grab with thumb and first finger  on two sides, about 3/4 inch apart.. mine was still flexible, so I put that in the use again pile. If it was hard as a riock and stiff, I would have to think about it...
 The grey on the pistons, not sure if its from sitting or moisture, were the bores  rusty.
 Your chamber looks real clean, don't know about rest of head.. but I think 200 be too much in my mind for a head and barrels for cleaning..

[mrbreeze]

Yeah hard plastic/rubber through many heat cycles ages and gets brittle, no?  Hate it to chunk out on me.  I will get the good stuff.  Just the roller assembly and long guide right? I'll do some research and see what price I can find.

That is a great picture of the tensioner and guides. You gotta realize those parts have been inside that engine for quite a few years. Then you gotta ask yourself just how far can I push it till those parts fail. Think about the damage that will occur when they fail. If I had my cylinders off sitting on the bench right now it would be a no brainer to p Thatut new parts in. And after reading about a guy who cheaped out and bought an aftermarket tensioner that he had to go right back in and change I'd make sure my new one was made by Honda that lasted 40 plus years.That's just me though......

I don't think Honda realized these bikes would still be popular 50 years later.

[gpzkat]

OK will check.  The bike had been sitting outside covered in the Socal dry climate. Bores were fine, came off easiest I've ever done.   Maybe the ultrasonic discolored the pistons, dunno.  I soda blasted them lightly and still darker in areas. I can clean them up.  Rest of the head is really good, no scoring or anything suspect.  I see some little dings in the valve seats that lapping should cure - I think.  I dunno, I'll stew on the 3 angle grind a bit as I have plenty of other stuff to do.

Yeah I was thinking 100 since they are already bead blasted and clean. But labor's expensive here. On the GS1100E it was painted, so some VHT brought it back to a nice look. I don't think anything except the top of the CB engine case was painted, but haven't researched yet, just judging by what I see.  I just read that bead blasting alone will 'open up the pores' but who knows.  I bet I can live with it, give it the old elbow grease final clean.

I tossed a roller way way worse that that yesterday  , and saved one that looked like yours ..try this.. grab with thumb and first finger  on two sides, about 3/4 inch apart.. mine was still flexible, so I put that in the use again pile. If it was hard as a riock and stiff, I would have to think about it...
 The grey on the pistons, not sure if its from sitting or moisture, were the bores  rusty.
 Your chamber looks real clean, don't know about rest of head.. but I think 200 be too much in my mind for a head and barrels for cleaning..

[Stev-o]

Yeah hard plastic/rubber through many heat cycles ages and gets brittle, no?  Hate it to chunk out on me.  I will get the good stuff.  Just the roller assembly and long guide right? I'll do some research and see what price I can find.

That's just me though......

I don't think Honda realized these bikes would still be popular 50 years later.

Nor did they want them to be!  I'm sure they would prefer us to buy a new bike after riding one for 3 years or so.