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

[Terry in Australia]

Thanks guys, I'm a big fan of the Stephen King movie, "Christine", and as I was riding along yesterday enjoying life, I thought back to all of my injuries this year.

I crushed a finger, dropped a brake assembly on my foot smashing my big toe, broke the toe beside it running up the steps to intercept the guy delivering the battery for it, and of course, the clutch plate in the face a couple of weeks ago. I was just thinking how the old swamp rat had some "Christine" qualities of it's own, and even though I'm not big on giving bikes peoples names, I was just thinking that like that old red Plymouth Fury, the Swamp Rat might be renamed Christine.

I hadn't discussed any of this with the wife, but ironically, she mused that maybe the bike could rebuild itself, just like Christine? That was a jaw dropping moment for me.........

Anyway, new day, new idea. I'm thinking that the bottom end of the engine and gearbox should be fine, as the 3.5 litres of oil was sitting in the crankcases when this happened. I'll drop the oil, pump and filter, then pop the cam cover off and if theres no metal in the oil, inspect the cam and rockers (which I'm presuming are destroyed) and put my new borescope down the spark plug holes and have a look at each cylinder for damage. If the bores are good, I might replace the pump, cam, cam towers and rockers, and see if it'll run. If it sounds ok, job done and back for another ride, if not, plan B. Christine, dont fail me now......

[web]

Either that or your "too soon" subtitle came true, ie trying to do things too quickly...

[Terry in Australia]

Ha ha, quite possibly, I'll be 60 in March and have enough projects to last the rest of my life, so time is of the essence!

[Terry in Australia]

The sun is out and the weather is warm, so it's autopsy day for the Swamp Rat. I'll drop the oil and filter first, then the pan and pump, and see where I go from what I see in the pan. I hope it's not total carnage...........

[jaytee-nz]

Or "Total Cornedge" as Tony Greig would say !

[Terry in Australia]

Ha ha, well I had a little time today and I know that the weather is supposed to turn back to winter on the weekend, so I took a peek at the oil.

27 Nov 2019 Swamp Rat autopsy. by Terry Prendergast, on Flickr

It didn't look too bad, but I dropped the exhaust, the filter and the oil pan, and looking at the pump's screen, it didn't look good.

27 Nov 2019 Swamp Rat autopsy.  1 by Terry Prendergast, on Flickr

I dropped the pump, expecting it to be seized, but it was fine, apart from the fact that most of the screen was blocked with metal, and maybe old sealant?

27 Nov 2019 Swamp Rat autopsy.  2 by Terry Prendergast, on Flickr

Anyway, I could have done a top end strip, but decided that with the limited time I had, I'd be better off hauling the engine out in anticipation of slotting another engine back in.

27 Nov 2019 Swamp Rat autopsy.  3 by Terry Prendergast, on Flickr

So if it's not raining tomorrow after work, I'll haul the engine out of the bitsa and install it in the swamp rat:

27 Nov 2019 Swamp Rat autopsy.  4 by Terry Prendergast, on Flickr

Then I'll put this engine back into the bitsa. It's the one I originally put in the bitsa, but couldn't register the bike with it because the arsehat previous owner still has that engine number listed against the registration for a bike in Canberra. The engine was a good one, although it had had some welding on the cases that weeped a little oil, but eventually I'll swap the guts into the cases of the blown up engine. All good. With luck I'll be riding the Swamp Rat on the weekend. It's like playing tetris with CB750 engines.

27 Nov 2019 Swamp Rat autopsy.  5 by Terry Prendergast, on Flickr

[PeWe]

That's a reminder to remove pan and inspect the oil pump strainer for debris blocking it.
Especially after a rebuild when sealer might come off.

Every 10.000 km at closest oil change feels right.

If you had good oil with plenty of zinc, damage not that bad?

[MCRider]

Yikes! That's a mess!

[PeWe]

A thought..
Can that engine been parked before due to oil starvation? Nothing done, parked and forgotten.

[Terry in Australia]

Yep, if you go back to the very beginning (Julie Andrews, Sound of Music) I pulled the sump pan, cleaned all the gloop out of it and the pump, primed everything and reassembled before I tried to start it.

As you'll recall, I did a top end rebuild because two pistons had rusted into their bores, but all of the top end bits (cam, towers, rockers etc) were good, and I blew out the oil jets in the head, so I don't think it was the reason the bike was parked. Gary, the previous owner bought a new Harley and stopped riding the 750, and stripped it to "restore" the bike, and gave up. (and somehow lost all the parts he'd taken off)

Anyway, no biggie, I needed a good set of cases to install the guts of that other engine, so I might do that before I install it into the bitsa. First priority is getting the Swamp Rat up and running again.

[spotty]

i just had one of those ' i remember' moments....

when i had my ill-fated xs650, i decided to treat it to a good service, oil, plugs, filters, new exhausts etc, as it turned out the oil passages must have been a bit clogged as the new oil flushed a whole load of smeg out and straight into the crank bottom end, this did immeasurable damage to the bearings to the point that one big end bearings ( hefty roller bearings on the xs) completely collapsed, taking the conrod, piston, bore, valves and head with it

maybe something similar with mr swampy ?

[Terry in Australia]

Yeah mate, I reckon thats probably what took it down, the oil came out pretty clean considering what was washing around in it, but the metal in the sump pan yesterday was mostly non- magnetic, which leads me to believe that a main, or pehaps big end might be the contributor.

 I may do the case swap sooner rather than later as I can't see much point in installing the engine into the bitsa then pulling it out again, so when I do, I'll make sure all the oilways are thoroughly cleaned out. (Might be a job for my 5000 psi pressure washer)

[BPellerine]

the top end oiling is always in the back of my mind with these engines,just a little bit of crud and it is toast,not the best system in my mind terry.bill

[Terry in Australia]

Thanks Bill, the CB750 was a wonderous beast for it's time, but not as forgiving as say, a Z1 or GS1000 (or even a Harley) in that regard, there's a lot to be said for roller bearing cranks and fat oilways.

[754]

So I have to ask , you said debris on the screen was non ferrous ? At any rate it does not look very shiny, as in fresh wear.

Back to my engine that had water in it, I suspect that my frosty , puckered , etched looking main bearings, would likely come apart should I try to run it.

 Be  interesting to see yours once apart..

[BPellerine]

never even thought about stuff like that untill I started taking them apart and seeing what makes them tick,they are tough when they are working right,hope the damage is not too severe.bill

[web]

That is some serious crap in there though, and the blackness of the oil in the drain pan is also not what you'd expect from one ride.

[Terry in Australia]

Thanks guys, well my first priority is to get "Christine" up and running again, so it might be awhile before we see what lurks within, because the year is rushing headlong towards Christmas and as I need my Kawasaki Z1000 "Mad Max" bike on the road by February to go on the "Stone" run, I need to stop farting around with CB750's and make a start on the big Z.

That's the worst thing about setting priorities, you have to stick with them.

[PeWe]

Terry, you have another ready to go  engine to throw in?

I remember you had dragged some home a year or two ago.

[Terry in Australia]

G'Day Per, I've got a few engines lying around, but only a couple of K2 engines, so I'll swap the engine in from tbe K2 Bitsa, as it's a "known" engine in great condition thats done a few hundred miles since I built that bike in 2017.

It'll be a good opportunity to address the oil dribble from the cam cover that's annoyed me from day 1, because the Bitsa doesn't have a "frame kit" installed, so as I've come up with a better version of my redneck frame kit in the last week or so, I'll install a frame kit on the bitsa while I'm at it, which will also make engine removal/replacement dead simple.

The weather for the weekend hasn't been promising, but hopefully the rain gods will allow me to get this done.

[Terry in Australia]

Well it was raining by the time I got home from work today, so no work on the Swamp Rat, but there was a parcel waiting for me. I've got a Morgan Carbetune which I love, but when I saw this I had to do the "Buy it now" thing, just because it's so cool.

Honda vac guages 2 by Terry Prendergast, on Flickr

Honda vac guages by Terry Prendergast, on Flickr

[PeWe]

I understand you completely!
That is a must buy for all us CB horders if not too expensive and money can be squeezed out.
Save the box. Half price without, right?
You can soon build a Honda shop that look like a time capsule from the 70's....

[Jerry Rxman Griffin aka MuthaF'er]

That's a good score. Better than scoring good weed! 

[strynboen]

if you go for a stone run...is it end,, in the coffin???vith your luck...

[Terry in Australia]

if you go for a stone run...is it end,, in the coffin???vith your luck...

Ha ha, geez I hope not mate! The big Z build will only be stage 1 of a multi stage build, the first stage is just to get it going and on the road legally, then I can modify it to make it handle better and stop much better. Hopefully I'll be on that ride with a slightly rough looking Z in February, it should be a great event, there are folks coming from all over Australia and overseas to be there.