Topic: Terry's NEW Redneck CB750 rebuild. The "Swamp Rat". Too soon? Nah..........

[PeWe]

This will be a low cost build, right? Cheapest build ever...
Only replace the not working parts.

I fully understand such build

[Terry in Australia]

Thanks Per, yep, with 12 bikes and 4 current projects fighting for my few spare bucks, whatever I DON'T have to buy is a bonus! Plus I like to use whatever I can of the original parts, it's kind of a recycling deal. If you saw the "pissed off" thread, the "K2 Rear Wheel" I bought on Ebay turned out to be a Kawasaki KZ650/900/1000 item, (as per the pic showing the difference, below) so I've sent the seller an email, but so far, no reply.

Swamp Rat Monday 6 May 2019 6 by Terry Prendergast, on Flickr

Thanks to FB I've got a good rear fender on it's way and that guy has a back wheel for me too, and he knows his CB750 stuff, so hopefully all  this fcuking around won't slow the progress of this build. I really don't see how I can save this one?

Swamp Rat Monday 6 May 2019 5 by Terry Prendergast, on Flickr

Anyway, the engine top end rebuild is going fine. I came home from work last night and pulled the head out of the oven and went looking for other stuff.

Swamp Rat Monday 6 May 2019 by Terry Prendergast, on Flickr

As mentioned, I have probably the worlds largest collection of CB750 gaskets, so I pulled out a nice thick "Athena" one, and dropped it in place, along with new O rings around the two centre studs.

Swamp Rat Monday 6 May 2019 2 by Terry Prendergast, on Flickr

I sat the head in place, making sure not to drop the cam chain down the tunnel, and went looking for the head stud nuts and washers. On the weekend I found one of the head stud nuts on the trailer, so I put it somewhere so I wouldn't lose it, then I forgot where I put it, so I went thru my tub of cam towers and was lucky to find one nut.

Swamp Rat Monday 6 May 2019 7 by Terry Prendergast, on Flickr

Then I counted the head stud washers, and found 12. 12? There are 16 studs, right? I'm sure I remember each nut on top of the head had a washer, but don't remember the ones in the recesses near the spark plug holes having washers? Fcuk! OK, so I went looking for more washers. I found a care package that Eric had sent me some time ago, and found 4 washers. Woohoo! While I was in my garage, I looked at a couple of later model heads, and realised that the washers are set into recesses. Hmmnn, I never noticed that before, but then again, I've only rebuilt early engines, with the exception of my F2 many years ago, but I put a K6 top end on it. I went back and looked a lot closer at the swamp rat's head, and lo and behold, all but one washer was in place in their little recesses. I could also see where a previous "mechanic" had tightened the stud nut against the alloy casting with no washer, so I installed one of Eric's washers, and called it good.

Time to start torqueing. As previously mentioned, I torque CB750 heads to 20 foot pounds (or pounds feet, whatever.........) in 4 fP increments from 8 FP's to 20, then leave it overnight and then back it right off, and do it again the next day, and so far, 20 or so CB750 top end rebuilds later, no leaks. Well that's not entirely true, one bike I did for a customer had a warped head so it needed to be machined, but that's the only leaker that I've put together.

Tuesday torqueing 7 May 2019 by Terry Prendergast, on Flickr

I keep looking at this "Mystery" cam, can anyone identify it? I compared it to all my stock Honda cams, and none of them have this funny casting between the cam lobe and the tach gear? It's in really good condition as are the cam towers, so I'm guessing they were replaced not long before Gary parked it out in the weather? I wonder why? Interesting...........

Tuesday torqueing 7 May 2019 mystery cam 1 by Terry Prendergast, on Flickr



 

[PeWe]

Time that cam to verify lift and open/close at 1mm ( 0.004") lift. You might need an adjustable sprocket

[Terry in Australia]

Thanks Per, it wasn't on a slotted sprocket, so I've just shoved it back in and I'll see how it goes once it's all back together.

Speaking of which, the rain held off this afternoon, so while it was cold it was almost pleasant out in my driveway as the sun was slowly setting. I re-torqued the head. It always amazes me that I back the head nuts off no more than one full turn, then once again torque it down in stages, and by the time I've torqued it down to 12 foot pounds (or pounds feet, whatever...) I've turned those nuts at least 2 full turns! Between 12 and 20 (in 4 ft lbs increments) the nuts probably turn at least one more full turn.

OK, decided I had enough time to install the pucks, clean and install the cam towers, oil everything, then install the cam, rockers and rocker shafts, and bolt everything down. I think Per asked about stripped threads, helicoils etc, well the good news is that all the threads were good, all the original hardware was in place, so was nice not to have to mess around with helicoils and crap. I think I may have fcuked up the cam timing by one tooth, it was spot on until I poked my finger in the tensioner hole and put some pressure on the chain, and it moved the crank about one tooth on the chain. No biggie, I'll fix that tomorrow before I refit the tensioner, do the valve clearances and re-install the cam cover.

By the time it was all done it was getting dark, my back was killing me (I had an MRI two weeks ago and I've got all sorts of problems, so will probably need surgery later in the year) and I had to make a pizza.

Swamp Rat top end Wednesday 8 May 2019 by Terry Prendergast, on Flickr

Hopefully tomorrow will still be kind to me weather-wise, and I might even get some carbs, coils and a battery on it, and see if it'll run. Oh wait, maybe I better drop the pan, and clean the oil pump, put some fresh oil and a filter in it first. OK, maybe it won't be running tomorrow night, but hey, that's OK, less than two weeks ago the engine was seized with two pistons rusted into their cylinders, and now it's (almost) a runner again, I'm a happy camper!

Swamp Rat top end Wednesday 8 May 2019 1 by Terry Prendergast, on Flickr

Now I've only gotta worry about the crumbling fork legs (under the rotten headlight brackets, the fork legs are toast) the rotten wheels, the rotten tyres, etc etc. All in all, it's just pretty rotten. No biggie, lots of parts in the garage, so it shouldn't be too soon before I'm riding the ol' swamp rat. Sweet.............      

[Tintop]

Terry, given how rotten everything else is, have you had a poked at the lower frame rails?

[PeWe]

Quick build indeed. Yes, frame rotten too where it usually rust?

[Terry in Australia]

Thanks guys, yeah I've only given it a "cursory glance" so far, but it looks solid, but of course I won't know until I pull the engine and strip the frame and swingarm for paint.

So far the only frame damage I've spotted is someone has cut the airbox mount tabs off, but I'll make a couple and weld them back in. Not a biggie, all the other tabs appear to be in order, and you've probably noticed that someone has gone to the trouble of welding quite an intricate steering damper bracket onto the frame, which I'm in two minds to keep, or just chop off?

If the frame is rotten under the engine, I do have 4 other frames that I can chop bits out of, but I'm hoping that I won't have to, fingers crossed!

[PeWe]

You have parts for more CB750's, right?

[Terry in Australia]

Thanks Per, yes mate, I have lots of parts, probably enough to build several bikes, less lots of little parts.

Well sadly the battery in my iphone went flat when I was using the torch to check my cam timing and I couldn't take any pics tonight, but I've done the valve clearances, cleaned and re-installed the cam chain tensioner, found a much cleaner cam cover so installed a new gasket, fitted the nicer cam cover, removed the oil filter and cartridge, replaced the filter with a nice new Ebay filter, dumped the old oil out of the engine, and basically ran out of light, so tomorrow after work I'll drop the oil pan and pump and give both a clean, flush the pump and replace everything.

I've got a few oil tanks so over the weekend I'll find the best tank and hoses, give them a clean and hook them up, fill the oil tank with fresh oil, find some coils, plugs, a battery and some carbs, clean the points and see if I can't fire it up. Once it's up and running I want to hit it with my pressure washer to knock off as much of the crud as I can.

After sitting outside in the weather the corrosion on the alloy cases is really bad, so tonight I also experimented with some of Spotty's alloy wheel cleaner mixed with straight phosphoric acid, and it ate the furry white corrosion on the little cover that bolts onto the cam cover, leaving it corrosion free, but left a dark grey residue which I cleaned off with the wire wheel on my bench grinder. Just for fun I dropped that finned points cover in it, but was a little concerned that it would eat the cover as well as the corrosion, so I added a lot of water to slow the process somewhat. Hopefully it'll still be there when I get home tomorrow after work? We'll see......

[Don R]

 I think that's the dreaded F2 cam. Mine has the ring around it like that.

[Terry in Australia]

I think that's the dreaded F2 cam. Mine has the ring around it like that.

G'Day Don, yeah, it could well be, I did an Ebay search for "CB750 F2 Cam Shaft" and saw 1 like mine, and about 10 that were different, but none of them had the thrust washer removed so I couldn't see if they had the same markings as mine has on the end?

Friday K2 fiddling 3 May 2019 5 by Terry Prendergast, on Flickr

Whilst I was consulting Doctor Google, I found this thread about Greggo having bought a cam with the same markings on the thrust washer end that the seller swore was a Yoshimura cam? Sounded like BS to me, but a couple of guys posted a magazine article that said Yoshimura were supplied blanks by Honda, re-profiled them, then sent them back to Honda for finishing, Honda then sent them back to Yoshimura who sold them under their brand. Greggo measured the lift and said it was very close to Yoshi's "Daytona" grind, and Mike Reick said it was similar to a Megacycle 125/65?

http://forums.sohc4.net/index.php/topic,99394.0.html

Personally, I was just happy that it was in such good condition, and anyway, if I wanna go really fast I'll ride one of my modern bikes, you know, the ones that also go around corners and stop...........

[754]

 Sochiro got it pretty much right in 69..
 Do I need to get to the End of the Game...faster... I don't think so..
 If I can still do 700 miles plus in a day on an old cb 750.. do I really need to go faster,  longer in a day?
 I will tell you the answer in another 12 years...

[PeWe]

Time the cam Terry and we will know which cam it can be

It is another feeling with more power passing cars really quick. That with my K6 that can brake rather well. Corners need som care... it is a CB750.  My K2 with stock engine is more like a scooter, heavy one and very relaxing to ride.
Good to not have a modern rocket. I'm too old and have too many years on a bike to die on one!

[MCRider]

Sochiro got it pretty much right in 69..
 Do I need to get to the End of the Game...faster... I don't think so..
 If I can still do 700 miles plus in a day on an old cb 750.. do I really need to go faster,  longer in a day?
 I will tell you the answer in another 12 years...

Then you'll be what? 90 years old?   

[754]

I will be 75, if I last that long..
 Due to our government or rather law enforcement  being able to seize your bike if caught at 24mph over the limit....
 Well that takes a lot of the fun out of it.
 So I will settle for more torque, not hp.. I cannot afford the tickets.
 I went at it hard a few decades, got my Ya Ya,s out long ago..

[PeWe]

Bigger bore for more torque then
Aim to 80 +.  Biker to 70 +. Trike after that....

[Jerry Rxman Griffin aka MuthaF'er]

Terry, a Yoshi cam will probably have an A or B on the end. My B is the Daytona

K = Kenny Harmon K grind?

[Terry in Australia]

Thanks guys, we all have differing opinions about our own personal preferences, but the good thing is that we are all passionate about motorcycles, and that's all that matters. As you all know I've had a lot of CB750's and I love them, I can pull them apart and rebuild them in my sleep, and there's nothing I love more than finding something like this old pile and turning it back into a rideable bike.

Franks comment about Soichiro getting it right in 1969 probably echoes what Triumph owners were saying about Edward Turner's getting it right with the Speed twin a generation earlier in 1935, or Ford owners lauding Henry Ford's efforts with the Model T a generation before that. It's a generational thing, my kids generation weren't around at the birth of the Japanese Superbike, so are probably more attracted to the Ducati 916 or Gixxer, or some other Icon from their era.

Just like we discovered back in our "Good old days", modern bikes are magnificent, they do everything better than the previous generations old bikes, and I get just as big a smile on my face riding my RC51 (now almost 20 years old anyway) as I do riding my K2. 700 miles in a day Frank? Jump on my 2001 Yamaha FJR1300 with it's comfy seat and big fairing, and you could ride 7000 miles in a week averaging 70 MPH and 50 MPG, and feel good at the end of each day's ride.

Anyway, back to the swamp rat. My good mate Jona Oron in Israel (a member here) sent me a message last week asking me if I'd like some leftover CB750 parts, as he's sold his K8 and bought a Harley 883 from the US. He offered to just give me his parts (new braided brake line, stainless engine bolt kit, clutch lever, carb kits, fork seals etc) which I thought was very generous, and when he told me he was having problems with a Chinese knockoff Keihin carb on his Sporty, I offered to send him the old OEM carb off my XLH1200 which I replaced at only 3500 miles with a Mikuni HSR42 flat slide unit. Apart from the ridiculous postage price for a small 2 pound box, we both got something we need, for free. Sweet.

I bought a good(ish) rear fender from a guy on FB for $70 (including postage from Queensland) that I think will come up OK with a little panel beating and a dip in the phosphoric acid bath. I found a tail light bracket that looked pretty good, and a small tail light lens, hopefully I've got a tail light to go with it. I also found a left side switch block, a battery box complete with regulator/rectifier/starter solenoid, some blinkers, the top triple clamp that Don (Cafe Racer Fan) generously sent me a couple of years ago, the speedo and tach that I bought from Bill Benton, and lots of other bits, all in remarkably good condition, so it's getting there. I've gotta go thru some forks I spotted in a cluttered corner of my garage this morning, hopefully there's a good pair there.

I had to take the wife and mother in law out for lunch and some shopping (well, they shopped while I drank booze and played poker machines) today, but tomorrow, hopefully, I'll be able to drop the oil pan and pump, give them a good clean, hook up an oil tank and lines, a battery and some coils, and (fingers crossed) fire it up. Wish me luck!      

[PeWe]

Good luck Terry! I had a ride with my wife today on my K2 

She like that much more than my much louder and faster K6 (1005cc). "She is tired begging.... " Stock CB 750 with diffusers and wool feels much better for her.

About newer bikes, here a newer Honda and an old small K2!

[RAFster122s]

Good luck Terry! Hope it goes well.
David

[754]

Terry ,  first of all Kudos to you for getting yet abother 750 back on the road..
....sure I could get a newer bike and get to where I am going 3 hrs faster  ...fairing you bet , probably make it easier . (But here it could cost me my license or be impounded)
But when I get to where I go I am the guy that rode his old bike there   and I don't have to be one of the  guys on a modern bike telling tales about the cb 750 I don't have there. .
 I had a more modern bike 30 plus years ago, the R 100 RT  that came with the kicker you claim the factory never made..
 Yeah it was great for miles, unfortunately the mechanical issues  (there were many) made me part with it. 

Just read in Friday paper..
 5 bikes riding at 80 mph in a 50 zone, bikes impounded for a week, 385.00 fine each tow fees,  impound fees..
Yeah I don't need to ride faster... can't afford it..

[Terry in Australia]

Thanks Guys, I'm looking forward to getting outside shortly and making a start, while watching a youtube vid of a guy firing up an old K0 he found leaning up against a house. I've gotta say, his K0 is in much better shape.......... My phone battery is fully charged, so hopefully I'll remember to take some pics!

[PeWe]

Hopefully not much smoke nor bad sound from inside......

[Terry in Australia]

Well what a day I had Sunday. Woke up early, cooked me some vittles (I've no idea what "Vittles" are, but I know that a "Vittler" is an old term for a military person who sources food, so I'm guessing that "Vittles" are food) before my big day in the driveway began.

Terry's brekky 4 May 2019 by Terry Prendergast, on Flickr

Okay, protein in, coffee swallowed, and out to the driveway, and the ol' Swamp Rat. Being the careful motorcycle technician that I like to think I am (but know I'm not) I decided to drop the ol' sump pan just in case there was a little bit of sludge to remove. There was, lots...........

Swamp Rat Sunday 12 May 2019 5 by Terry Prendergast, on Flickr

Of course, there was a little sludge build up on the pump as well...........

Swamp Rat Sunday 12 May 2019 4 by Terry Prendergast, on Flickr

Did I say a little? That's like saying I like to drink a little bit. Anyway, I started to clean out all the sludge, and found this. Bugger.

Swamp Rat Sunday 12 May 2019 6 by Terry Prendergast, on Flickr

Swamp Rat Sunday 12 May 2019 9b by Terry Prendergast, on Flickr

OK, so I went looking for a better sump pan. I found this one, but sadly the thread for the sump plug was stripped, and I didn't have a 12mm coarse thread helicoil kit, so I had to think of an alternative plan.

Swamp Rat Sunday 12 May 2019 8 by Terry Prendergast, on Flickr

Good old JB Weld. Of course, I needed it right away, so I first cleaned the damaged area on the outside, then splooged some in, so there was a nice deep puddle of the magic gloop.

Swamp Rat Sunday 12 May 2019 9c by Terry Prendergast, on Flickr

Anyway, so as not to bore your pants off I won't post a pic of me cleaning and reinstalling the oil pump and sump pan, but I did, and then it was time to find an oil tank and hoses. I was a bit worried that being a 1975 engine it would have the big engine breather tube at the back of the gearbox, but in fact it had the small one, so I just used one of the early oil tanks I have hanging in the garage, and a pair of good hoses that still had the alloy crush washers in them. The bottom hose fitting on the oil tank has been brazed back on, (maybe after a crash) but it was clean inside, and I blew the hoses out, and called it good. 

Swamp Rat Sunday 12 May 2019 9d by Terry Prendergast, on Flickr

Swamp Rat Sunday 12 May 2019 9e by Terry Prendergast, on Flickr

OK, so what next? I know, some carbs! I didn't have any nice soft carb rubbers so I found four rock hard old #$%*ty ones, and dropped them into my "shed Kettle" and boiled the sh1t out of them until they were soft enough to fit to the head, then using Steve-O's "Fence Paling" method, levered the carbs into place.

Swamp Rat Sunday 12 May 2019 9g by Terry Prendergast, on Flickr

Sadly I broke my special tool in the process, so I'm gonna have to "borrow" another one from one of my neighbours fence thee next time I do this.

Swamp Rat Sunday 12 May 2019 9f by Terry Prendergast, on Flickr

OK, so I had an oil tank full of nice fresh oil, some carbs, an ignition with cleaned points, so what else did I need for smoke and fire? I know, coils and plug leads! Some d1ckhead (me) had cut the signal wires offa every old Honda coil in my garage to connect to Dyna coils from previous builds, so I had to chop a blue and yellow wire off an old wiring harness to fix them.

Swamp Rat Sunday 12 May 2019 9h by Terry Prendergast, on Flickr

I installed four crappy old plugs that I cleaned up a bit on my wire wheel, bolted in the coils, and by that time it was getting dark, so I called it good and gave it away for the day.

Swamp Rat Monday 13 May 2019 3 by Terry Prendergast, on Flickr

Last night, I had a little time after work, so I hooked up my little temporary fuel tank and an old car battery.

Swamp Rat Monday 13 May 2019 4 by Terry Prendergast, on Flickr

Swamp Rat Monday 13 May 2019 by Terry Prendergast, on Flickr

I cranked the engine by connecting the battery directly to the starter motor to check if I had spark and circulate some oil, and confirmed that I had spark. I filled the carbs with fuel, and fuel pissed out of two of them, and no amount of tapping the float bowls would stop the flow, so I dumped the fuel back into my can, and gave it a few kicks, as the battery had died again. I got a few pops, but nothing like a start, so gave it away for the night.

Tonight I had a closer look at the carbs, and realised that I'd missed something critical.

Swamp Rat Missing vacuum screws by Terry Prendergast, on Flickr

Yep, that'll do it. I raided another set of carbs, stole the screws, installed them, and kicked it in the guts, and guess what? It runs! Life is good!

Not only did it run, it ran on all 4 cylinders, and blew no smoke! I checked the oil tank and the level had dropped by approx 1 litre, so that told me (without having an oil pressure gauge to hook up) that the oil was circulating, but just to be safe, I shut it down. Anyhoo, 16 days ago I bought this thing for $500 ($350 USD) with a rusty seized engine, and now it has a sweet running engine.

Next step is to pull it out (the engine, you sicko's.........) strip off all the rotten rusty parts, send the frame out for blasting, paint it, and start putting it back together into some semblance of a motorcycle. I want to be riding this bike by the end of June, so I can crack on with my big Kawasaki's and my RC51. Wish me luck, I feel like this guy here looks right now!

Leo Monday 13 May 2019 by Terry Prendergast, on Flickr

   



 





 

[MoMo]

Good job, also good to see that you're able to eat without complications...Larryy