Topic: 71 cb750 rejuvenation etc .. Not calling it a restore

[Salman_z8]

After getting her home, and first thing coming off was the luggage rack and the strangely mounted turn signals. while destroying the tail light bracket

Everything slowly came off, engine out.
Read about the laying the frame on its side and lifting off of the engine here ... great tip.
this is how it sits, after i brought it through the car wash to get 44 years worth of grease and grime off, atleast to the point where handling it doesn't require washing your hands immediately after lol.

This was always a pain to put it on and off center stand ... so after cleaning someoff found out the center stand support beam was rotted on one end and shattered.
Always wanted a welder, got that as a birthday present.
Made some reinforcements and new raised stand stops after beating the collapsed beam back into shape.
Had my brother weld it all together since i couldnt yest atleast lol

unfortunately didn't take pics of the damaged frame, but i will post some of the repairs pre grinding and cleaning.
hopefully its good to enough to last another 40.

[Salman_z8]

I was told to bring this over from the intro section, so sorry for the repetition, or if its something that i wasnt supposed to do.

[Salman_z8]

Engines out.
Frame used to have a collapsed stand. Made some reinforcing brackets and had them welded in place.
(and practicing with my newly acquired welder, so next time i can do it myself)

[Salman_z8]

Now, i did ride it around 200kms before taking it all apart to find out what was needed.
I bought it as a runner, fired up everytime, no problems there.

Engine oil pan had leak, seems like someone tried to weld something in it. Havnt inspected the engine yet.
Checked compression before i pulled the engine out, 1,2,3,4 were 110, 120, 120, 100 ..
Didnt have a whole bunch of power, the most i got out of it was 100mph. Not sure if thats ok ...
O yea the engine has 38000 mi on it.

I do plan new bearings and at the least relapped valves, valve seals, and new piston rings if bores permit.
Engine doesnt  seem like has ever been worked on before.
However the biggest issue is tranny ... slippage in 3rd, 4th and even 5th.
I do plan to keep it stock, but what would be the best course for transmission repair ... Replacement with a used complete transmission .. forks, drum and gears off of ebay ? or is that not worth it ..
Are the transmission parts same in all K models till k6 ?
 i want to start collecting parts if ebay is the route, slowly .. but i will wait suggestions.

heres the list i have so far;
Powder coat frame, swinger and all other frame bits .. (everywhere there was factory black paint)
Everything originally zinc plated, replated
Forks rebuilt, rears new replacments
New swinger bushings
New rims, relacing with new or plated spokes ..and check wheel bearings
new electrical .. ( picked up a new harness from z1)
Need stock bars and controls
new turn signals all four .. ( aftermarket, but i will use my original lenses)
Engine overhaul .. and different sprockets .. plus new breather cover .. since the original broke while extracting a bolt
Transmission repair
Reworked guages ... new faces for sure
brake pads and shoes
and finally body .. hopefully enough money to buy a repainted set from yamiya

at least thats the plan.

Want to get rid of all the rusty bits, paint polish the engine ..
Hopefully can create something nice to own, thats a joy to ride.

[Stev-o]

"Slippage in 3rd, 4th and 5th" sounds like clutch to me, not tranny.  Did you try adjusting the cable?

I may have a spare breather for you, I'll check my storage. 

You want the stock bars? They are kind of high, super bats are more popular if not doing a proper restore.

[Salman_z8]

I should have said grinding, and it jumps out of gears .. Like rhe dogs have play and sits in between gears .. I am almost certain its the tranny. But we will find more out when i open it up.
If you have a breather in decent shape, i will take it. Something polishable.
And you are right the stock  handle bars are very big. The onesthwt were  on the bike were pretty low slung, i liked that but no pull back .. Almost flat. That bothered me. So yea something mid way and comfortable. With less than 100hp, it has to be comfortable lol.
I will post pics of the ones i pulled off.

[Salman_z8]

these are the ones i pulled off, no internal wiring holes, and too flat .. if anyone wants to trade for something with some pull back .. pm me

[Salman_z8]

On my way home, picked up a new grinding disc.
cleaned up the center stand welding repair.
Even did some welding my myself .. for the first time proud moment lol

[Salman_z8]

took the front forks apart, and it was disgusting inside, not sure if you can make out in the pics, but it was like they were filled with some smoothie ..
circlips were rusted, pain to take out ..
Now heres the kicker, both the seals were different .. and there were two mismatched washers between the seals and the circlips .. one had a bevel, other was just a regular washer .. what gives ??

what seals do i need .. and which ones should i get ? oem ? can i still get them ?
should i get new circlips ? is there washers supposed to be in there and i am just looking at something wrong ?
i know i need new copper washers .. i didnt have a micrometer, but with a vernier it seems like the pistons are just about still good.

any suggestions ? i could probably just replace the drain bolt too ,, rather than wait to send every thing to get plated .. and new copper washers .. also the bottom tubes inside the fork bottoms, i dont see them in the manual ?

And also another question, how were the fork bottoms finished from factory ?
polished and clear on ? or painted .. 

[Salman_z8]

Closer inspection after disassembly revealed vice teeth marks on one of the inner fork tubes  .. Can someone tell me how far up the seal travel area is with stock springs on the tube.
I can put one roughly back together to see where it is, but if someone knows it would help. Somr idiot in the past probably didnt usr vice jaw covers.
There are deep, dented chrome pits. I would hate to have it all redone only to find out leaky seal.
I am sure there was water mixed in with the fork oil, so it must have gotten in somewhere. I hate it when PO's just destroy stuff due to improper repair techniques.

Everything i have taken apart so far either needs extensive repairs or replacement.
Now i am scared to pull the motor apart.

[Salman_z8]

Anyone has potential inner fork tube they want to part with ?
Dont really care for surface rust on the top part as i will be using headlight ears, but straight and anything lower than the bottom triple clean .. ?

[70CB750]

Following 

[edwardmorris]

Welcome.

Essential Reading: Download the factory manual and parts manual from these forums. Grab a copy of Mark Paris aka Hondaman's book for sure, you will need it.

Suspension: If you're seeing vice grip marks on the tubes on the lower ends, its possible that your fork lowers are dinged too. Tubes are cheap and easy to replace, I'd suggest closely inspecting the insides of the lowers. Good idea to replace all copper washers and prevent post assembly leaks.

Tranny: Slipping out of gear means you most likely have bent shift forks as well as worn out gear engageent dogs. You can either go for a low mileage replacement trans, or at least find a set of low mileage shifter forks and have the gears back cut by APE (not cheap).

Swingarm: Minimally change the bushings on the swingarm, but I'd recommend having it fully rebuilt by Hondaman/Mark Paris.

Replacement parts: Most are still available via Honda, and I don't think any aftermarket part can beat their quality. Yamiya repros are a close second.

All aluminum parts were either lightly polished, or clear coated right away after casting IINM.

There are members up in Canada, like evanphi and Frank/754 (many more). Get a hold of these guys and see if they can find you some used parts. Otherwise, Bill Benton is the go to guy for all things 750 including unobtanium. If all this fails, then resort to ebay. BUT, keep an eye on ebay for steal deals as well.

Marcel is your best source for all gauge work cb750faces.com, he's a member here, reach out to him.

PM me, I'll get you in touch with JT, my go to guy for all discounted NOS/OE and Yamiya parts without the hassle.

[Salman_z8]

thanks edward for the advice, thats why i came here

i do have a factory service manual, the funny thing was that for k0-k2 .. .the manual as well as the parts manual doesnt show the existence of a dampener rod lol which threw me off.
I think you are right i will get the hondamans manual too, good read from the sounds of it.
So as per your advice , went to the dealer today and got new fork seals, ( i would neve reuse a copper gasket even if my life depended on it, lol ) but yes, got new coppers, and the o-rings. the bottoms are fine, pistons are good.
i will actually do a rough install and reinspect if the vice marks will bother the seal or not, if yes then yea replacement tubes.
I am a total OEM kinda guy, if oems available that is.
I am almost certain that i will need new shift forks, now i will definitely change the gears too .. the questions is undercut or used tranny ..
Would you know why an engine that only produces 67HP at its best in stock form, is having transmission trouble at 38000 miles. PO's abuse perhaps ? or did they all ?
Which kind of asks the question, is there anything i can do while replacement to make sure it doesnt happen again if i stick with a good used tranny. or is undercut is my only choice ?
What about cycleX race tranmission ..
i will still change the forks, and possibly the drum too.

But engine will be after the chasis is in good order. but will collect parts in the meantime.

Heres what i did today after work;  Not bad for 44 yr old bottoms .. what you guys think ..
Its not show quality, but then i didnt want show quality. i did deliberately not smooth out the casting grain. Just to keep it special lol. Is there any chance my forks could be sandcast forks ... the bottoms castings are all wavy and ripply .. if that even makes sense.

 

[Salman_z8]

now i gotta find the seal back up washers .. to go between the circlip and the seals.
Honda doesnt have it available anymore, also could find the circlip too .. mines rusted badly,
I guess i will have to  wirewheel and paint then. calliper paint should work.

[edwardmorris]

thanks edward for the advice, thats why i came here

i do have a factory service manual, the funny thing was that for k0-k2 .. .the manual as well as the parts manual doesnt show the existence of a dampener rod lol which threw me off.
I think you are right i will get the hondamans manual too, good read from the sounds of it.
So as per your advice , went to the dealer today and got new fork seals, ( i would neve reuse a copper gasket even if my life depended on it, lol ) but yes, got new coppers, and the o-rings. the bottoms are fine, pistons are good.
i will actually do a rough install and reinspect if the vice marks will bother the seal or not, if yes then yea replacement tubes.
I am a total OEM kinda guy, if oems available that is.
I am almost certain that i will need new shift forks, now i will definitely change the gears too .. the questions is undercut or used tranny ..
Would you know why an engine that only produces 67HP at its best in stock form, is having transmission trouble at 38000 miles. PO's abuse perhaps ? or did they all ?
Which kind of asks the question, is there anything i can do while replacement to make sure it doesnt happen again if i stick with a good used tranny. or is undercut is my only choice ?
What about cycleX race tranmission ..
i will still change the forks, and possibly the drum too.

But engine will be after the chasis is in good order. but will collect parts in the meantime.

Heres what i did today after work;  Not bad for 44 yr old bottoms .. what you guys think ..
Its not show quality, but then i didnt want show quality. i did deliberately not smooth out the casting grain. Just to keep it special lol. Is there any chance my forks could be sandcast forks ... the bottoms castings are all wavy and ripply .. if that even makes sense.

You're more than welcome. As you'll see, folks on these forums are arguably the best community. We love projects and gladly help out those who wish to save these beauties and keep them on the road. Heck, most here even help those who wish to chop/cafe/destroy them whilst getting them back on the road 

The K0-K2 manual is correct, and Mark's book will fill you in on some of the finer details and "inside knowledge".

For missing fork bits, if you didn't have any luck with members up there, PM Bill Benton, he should have what you need in good condition. Don't wirewheel and paint, get a good condition used set of circlips and have them zinced. I rezinced mine and they came out good as new. Check the fork tubes to see if they're bent as well.

OE stuff is around, and hard to find bits are usually available via JT.

Mark's book goes in extensive detail on how to inspect every single part for wear and reusability. Bent fork will usually be visible directly but there are proper ways to measure them. I didn't want to take a chance with mine so I went with a set of almost new shift forks from Bill (both bikes). 38K isn't too much for these bikes but yes, abusive riding and power shifting will destroy the forks and dogs. There isn't much to do after you find a good used tranny except use a good quality engine oil and ride it properly. These bikes run flawlessly. Stick with a forum member like Bill for a used tranny as he's a highly experienced Honda tech and will inspect everything before offering to sell. You may land a good deal on ebay with nice looking gears but you won't know for sure if the shafts are bent or such until you check them yourself. No idea about CycleX, never used anything of theirs except for the MLS head gasket. Back cut trans may not be necessary for street riding. Heck, I was actually advised against it for street use. As for the shift drum, it might be ok, you'll have to follow the inspection steps in Mark's book to determine that. I replaced mine with a later year 750 as they improved a bit and finding neutral is a little easier.

Engine after chassis is good plan, don't get into the engine without reading through the teardown section of Mark's book. Some critical noob gotchas to look out for. Have you removed the triple trees? Definitely remove the old ball bearings and install new tapered steering stem bearings. All Balls makes a good set for the 750s, this is a no-brainer upgrade. Careful with the VIN tag when you get it to PC. While there are now ways to get a replacement, I'd suggest do all you can to keep the original safe and reuse it.

[Salman_z8]

Excellent advice again edward. Respect.
I was also skeptical on that tag thing.
Yes triples apart, heck everythings apart.
Tubes arent bent, it seems like they will be fine afterall.
Zinc plating it is then, since i dont want to buy a chinese snap ring, Like to avoid as much as i can.
http://www.ebay.ca/ulk/itm/301779481556
http://www.ebay.ca/ulk/itm/361416545506

Really interested in these, these should fit right ? Anyone.
The donor bike had 20,000 miles, and the seller says they look excellent. Even pics look good.
Hows the pricing ? Is it ok ? I have no idea.
I can take a chance with these one.

Also, heres some cleaning i did of the gaitors.
Took longer than polishing the bottoms for soaking and really hetting in there to get decades worth of grime off.

[Salman_z8]

How do i get a hold of bill benton ?

[edwardmorris]

How do i get a hold of bill benton ?

Send him a PM. His forum handle is Bill/Benton Racing. Also, check with Frank first as he's in CA and may have spares. Might save you on shipping. Frank's forum handle is 754. As I said earlier with ebay, no way of telling until you have it in your hands and you do the inspection (although that's not to say you find a good one).

[Salman_z8]

Ok, so i guess i got sucked into buying a transmission.
13000 miles, no issues .. But heres the kicker .. The sellers parting two bikes .. A cb750k3 with 17000 miles
And a 76 cb750f with 13000 miles. I can pick the forks, shaft, drum and complete tranmission from either .. Both are pretty much as decent as i cant find in a used collection. I was going for the lower mileage 76 ..
Any reason i shouldnt and go for the k3 instead ?

Kind of a gamble, but if it turns out as good as the seller says, atleast tranmission should be wll set.

[jerry h]

Hi,

Thanks for posting - it's great to see another one getting cleaned up and back on the road.

I did the same thing with my gators... they looked good, so I cleaned them up and re used them when I did  my front end.  Less than a year later, one split in two, had to rip the whole front end apart again to change the darn rubber gator.  Buy a new set now from Honda while you have it all apart. 

Take care,
jerry

[Salman_z8]

I was really hoping to have everything ready to be dropped off at the pc'ers before i left, but didnt happen.
I will be away till first week of december, so wikk continue when i am back.

[754]

I will look for a fork tube, will take a few days..
 Your lower fork legs are K1 or K2, sandcast and KO are different near the seal area.
 The transmissions you bought have wider output bearings, you might be able to use them , or use the old style setup. Later f models had different gears turning the output shaft, i am not sure what the 75 f used.

[Salman_z8]

Thanks frank.
Should i get the k3 transmission then instead if you think there might be differences in fitment with a transmission from a 76f.
The seller confirmed me that it would fit !?!?
Confused. It wont be shipped till nov 25, as i will be away .. So i can switch .. Any suggestions ?

[Salman_z8]

Time to bring this project back to life .. I was away for almost couple months .. Wow that was long.
So have a few updates;

Front forks are fully back together and ready to go back on the frame ( not happening soon lol )

Frame, swinger and all bits came back from the powder coaters just now, they look super good. But they may have not masked during sandblasting, and i might need some new races now .. May be .. Its all still wrapped up in saran wrap.
It looked so beautiful, i didnt even dare peel lol.

I have acquired an engine stand, now will make adapters to fit the sohc motor.

Gauges are apart, will be ordering new faces, jewels and just to feed into my OCD'ness, new trim rings as well.
All 4 bulb shields however had snapped off, so gotta repair those.
Then bondo the outside covers, and paint everything.
I have sourced a zinc plater, so that should take care of zincing needs.

Now i need a good and cheap chromer. Yeah .. I am poor

O'yea .. Spent massive amount if time cleaning and polishing the pipes.
I have the HM300's, without the warning stamp in the insides OEM ??
Turned out good .. I would love to get new ones but .. Too much $$$$
Anyone has a lower left HM300 kicking around .. In decent shape ??

i will have parts that will be left over, oem parts if anyones wants .. Would be nice to get some funding ..
Will post pics later as well.