750 roadster re build

I have been lurking around here for a bit and sifting through all of the information that I need, I don't need to ask anything in particular at the moment but it does seem that everyone likes pictures so I figured I should start a thread.

Details so far; the bike was my dads, he was going to sell it and buy something more comfortable to ride so I figured Id buy it and keep it in the family, I new it needed a new cam but when I picked it up it was in lots of little boxes, dads excuse was he didn't want to see it leave looking like a bike.....

As of now I have the bottom end is together and cylinders on, compared to pictures on here it appears to be an early 750. It already had superblends fitted, and it now has a new PW3 cam, new lifters, new crank bolts, the big ends were done at the same time as the superblends and looked new so I left them, and a new set of rings.

I had to run a boring head down the cam tunnel in the crankcase halves to clean up the damage from the old cam (it dragged something around when the hard facing wore off) and to give a little bit of clearance to the PW3, I also ran the boring head down the cam recess in the cylinder as well.

Ive had the helicoils put in the exhaust port and the cylinder studs in the head. Since the motor has been in bits for so long I took out all of the rocker gear and valves to clean everything.... Probably a good thing as both exhaust valves had pretty bad pitting/dents on there sealing faces so there is a new set of black diamond valves to go in there, however I now need to have the seats cut and new valve guides which is where I am now.

After reading on here I also drilled the inlet rocker spindles, it was not quite as easy as described, mine were hard for about 3.5mm on the ends, the only way I could do it was with a carbide ball nose slot drill in the lathe.

Now a couple of pictures:

Dry fitting to check valve to piston clearance



At least something new, I modified a cheap pair of visegrips into a valve spring compressor, it actually works really well





About where it is at now



Oh and as I'm sure many want to know it is yellow

cool, good to know u r keeping it in the family

Cheesy said:

.... but it does seem that everyone likes pictures so I figured I should start a thread.

Click to expand...

Build threads with plenty of pictures are my favourite...;-)

...dads excuse was he didn't want to see it leave looking like a bike.....

Click to expand...

He deserves a medal for that one IMHO!


Tim

Tintin said:

Cheesy said:

.... but it does seem that everyone likes pictures so I figured I should start a thread.

Click to expand...

Build threads with plenty of pictures are my favourite...;-)

...dads excuse was he didn't want to see it leave looking like a bike.....

Click to expand...

He deserves a medal for that one IMHO!


Tim

Click to expand...

Pictures and it's yellow in the first thread! I think I'm going to cry! :mrgreen:

I rather like the valve spring compressor - it isn't often we see something new here

Excellent work, and welcome aboard :mrgreen:

A lathe and a mill are Norton essentials
I like what you are doin. I have a Smithy 3 in 1. Extremely handy. I'll be watching your posts.

Well new valves in there on freshly cut seats, unfortunatly I put cast iron guides in it, as it would happen a couple of days before the threads on here about bronze guides... well the cast iron ones lasted a while anyway. Now it may not be a good idea to use the oven your friends place who you are house sitting for, to heat up the head to remove the guides, it took a good two days to get the smell out of the kitchen. I turned down one of the old valves and brazed on a bit of threaded rod to remove the guides and just used the old valves with a bit of threaded rod brazed on to put the new ones in.



Valve compressor in action



I also realised that when I put the timing cover on I hadnt put magneto cover plate on first which wouldnt have been a problem if it wasnt for it using a bolt and nut on one of the holes. Since I have to take it off I got somewhat inspired to put a breather on there with a reed valve in it



The reed valve will be mounted inside the aluminium and there will be a cover with a hose conection on the outside. The complete assebly will be held in by the original cover with a large hole cut in it. I did it this way so that no additional screws were introduced to the inside of the engine.

Nice jobs so far. Can't wait for more.

Welcome to the forum, Cheesy.

Very ingenious use of vice-grips, I like the way your mind works (also the old valve conversion to extractor/installer tool)

Should be a cracker of a Commando when it fires off. You must let your dad do the honors of the first ride.

grandpaul said:

Welcome to the forum, Cheesy.

Very ingenious use of vice-grips, I like the way your mind works (also the old valve conversion to extractor/installer tool)

Should be a cracker of a Commando when it fires off. You must let your dad do the honors of the first ride.

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There is a very good chance that will happen, the engine is hidding in a corner at work and I dont think I will get away with the whole bike in there so it will be put together at dads place. Also I have never ridden one and everything other than the hand controls are on the wrong side!

Best valve compressor I've seen, makes me think I could even use it and get clips on and off.
You will end up fighting your father to ride, once you feel what you've been missing out on .
Ok now tell me how I can tap the freed up head oil feed hole to get pressure to tiny oil gauge line?

hobot

hobot said:

Best valve compressor I've seen, makes me think I could even use it and get clips on and off.
You will end up fighting your father to ride, once you feel what you've been missing out on .
Ok now tell me how I can tap the freed up head oil feed hole to get pressure to tiny oil gauge line?

hobot

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Could you not just use the original banjo fitting and hose? I was planning on putting a brass elbow into the spare hole and screwing the gauge into that, pretty much cause I think it would look cool as opposed to functionality, I kind of want to keep the bars as uncluttered as possible. Mine is old enough that it doesnt need indicators so I can hard wire the headlight and all I need is hi-lo and a horn button and a small mirror, which I figure will be pretty useless on a commando.

The big dilemma I have now though is what to do with the front wheel, either keep the drum brake and get a new rim and spokes to fit or try and track down a disc hub and probably a complete front end from something else....

At the moment progress looks like two steps forward one step back. Ive started striping off the old paint/powder coat, caustic soda in a bucket does a pretty good job of this



Now the step back bit, the engine mount holes in the gearbox cradle were slogged out so I have welded them up and will re drill them, however looking at the cases the corresponding holes are bad too, it also looks like a decent size piece of the case has been worn off.



Since I have to pull it back down anyway I was thinking that the best option would be to hachine the worn bit flat again (I should be able to get in there with an end mill) and then drill/ream the holes out to the next size up. Does this sound like a reasonable plan?

So the thru -bolt hole is worn oval from this area being prone to crankcase "shuffling" and the bolt loosens up causing ovality before noticing ,this bolt needs periodic checking and retightening. Check subframe bolt holes for ovality too ,if you choose larger bolt fix described then top subframe holes will need attention too. Luckily for me when the nut loosened up quickly the sudden vibration change had me pulling over and finding the top bolt had lost nut and washer, limped home gentle driving.

Lookin' good!

Cheesy, since you obviously have the machining facilities and the skill why not put brass sleeves through the mounting holes reamed to size? Some of the racers do this to minimise crankcase flex.

Torontonian said:

So the thru -bolt hole is worn oval from this area being prone to crankcase "shuffling" and the bolt loosens up causing ovality before noticing ,this bolt needs periodic checking and retightening. Check subframe bolt holes for ovality too ,if you choose larger bolt fix described then top subframe holes will need attention too. Luckily for me when the nut loosened up quickly the sudden vibration change had me pulling over and finding the top bolt had lost nut and washer, limped home gentle driving.

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I have already welded up the subframe holes, and the centre stand holes for that matter so they can all be drilled to the appropriate size pretty easily.

dave M said:

Cheesy, since you obviously have the machining facilities and the skill why not put brass sleeves through the mounting holes reamed to size? Some of the racers do this to minimise crankcase flex.

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I was considering a fix like that, its pretty much how Mazda held their rotary engines together. A big benifit of it is if (when?) the bolts lossen again the bronze sleeves can be replaced as a sacrificial item with no further damage to the cases.

You wouldnt happen to know how big a sleeve I could use without taking too much meat out of the cases would you?

Cheers

I started pulling it apart again to fix the cradel mounting holes and I came across this







It turns out when it fell off the bench during the earthqaukes we have been having here it did actually do some damage, since non of the fins were broken I figured that I had got away with it, obviously not, looks like Im on the lookout for a timing cover now as well

Ugh, not only can the small dia bolts beat their bores up, they can let the cases twist on each other. In pre-Peel Combat case it bound the case up horrible to part and even with them empty. Had to take off .003" on each dowel to get them to mate-part normally. I bolted up cases to cradle and had machinist put in 7/16" aircraft bolts and they have stayed snug but true fit sense and I did give me hell.
Consider it now or next owner will have the same beat up bores to ponder again.