MY 1975 ST70

Having failed to take any photos of the bike when I bought it a few years ago I have been prompted to take some prior to the rebuild taking place so here it is!



I bought it as a taxed / MOT'd runaround and initially it looked very good & original but the more I got into it the more I realised it needed a lot of work doing so I started to strip it down, did a bit of work on it but then lost interest.
I first thought that all that was needed was some new tyres, brakes, chain & sprockets, service etc so I got to work doing these but when I cleaned out the oil-filter I discovered a lot of swarf and on splitting the crank-case discovered lots of debris (mainly from the camchain & tensioner assembly) so a full engine rebuild was undertaken. With that done I then put some oil in the engine, wrapped it up and put it away at the back of a cupboard in the garage while I started to dismantle the bike but it was at this stage I discovered the damage to the frame and I lost all interest so it has sat in the garage ever since. This week I have almost completed the strip down and with some help of photos from Tufty & Waynus will rebuild the steering-lock bracket on the headstock plus weld the frame where it has cracked at the forward engine mounting hole. When that is done I will send the bare frame, forks, swinging-arm etc off to be stripped & painted in candy red.
Luckily it was 99.5% complete when I bought it and was missing just the battery-box (battery was lodged in a plastic tray) but I managed to track down a NOS one in America so nothing is actually missing, it also had a brand-new (genuine) exhaust & guard so they were treated with oil and are nicely preserved in the garage (I see they have gone up in price recently). At the time I purchased a large stock of new items from David Silver & CMSNL and these have been stored in my study ever since, I am currently putting together a list of other parts that are required and now it is in pieces I can see what can be reused and what needs to be bought new. I will have some items re-chromed / painted but others I have just bought new as that way I am not paying for refurbishment and know I will recover some money on selling the old parts.

The one thing that I am now disapointed about is that I didn't take the time to refurbish the engine cases when it was apart.
At the time I thought it was just going to be a quick overhaul and then I would put it back on the road and use it so I did all the mechanicals but wasn't too worried about the exterior finish of the engine however now I am rebuilding the whole bike I feel the look of the engine will let it down. What I intend to do to overcome this is put the engine into the newly painted frame, run it for a little while to make sure all is well and then I will remove the engine, strip it right down again and deal with the cosmetic side of things. Luckily these engines come apart very quickly and knowing the engine is mechanically good will encourage me to make a nice job of the exterior.

Everything seems to be there, and everything seems to be original so I'm looking forward to see the result.
Another piece of history will soon strat its second life!
Have fun!

LITCH wrote:Having failed to take any photos of the bike when I bought it a few years ago I have been prompted to take some prior to the rebuild taking place so here it is!



I bought it as a taxed / MOT'd runaround and initially it looked very good & original but the more I got into it the more I realised it needed a lot of work doing so I started to strip it down, did a bit of work on it but then lost interest.
I first thought that all that was needed was some new tyres, brakes, chain & sprockets, service etc so I got to work doing these but when I cleaned out the oil-filter I discovered a lot of swarf and on splitting the crank-case discovered lots of debris (mainly from the camchain & tensioner assembly) so a full engine rebuild was undertaken. With that done I then put some oil in the engine, wrapped it up and put it away at the back of a cupboard in the garage while I started to dismantle the bike but it was at this stage I discovered the damage to the frame and I lost all interest so it has sat in the garage ever since. This week I have almost completed the strip down and with some help of photos from Tufty & Waynus will rebuild the steering-lock bracket on the headstock plus weld the frame where it has cracked at the forward engine mounting hole. When that is done I will send the bare frame, forks, swinging-arm etc off to be stripped & painted in candy red.
Luckily it was 99.5% complete when I bought it and was missing just the battery-box (battery was lodged in a plastic tray) but I managed to track down a NOS one in America so nothing is actually missing, it also had a brand-new (genuine) exhaust & guard so they were treated with oil and are nicely preserved in the garage (I see they have gone up in price recently). At the time I purchased a large stock of new items from David Silver & CMSNL and these have been stored in my study ever since, I am currently putting together a list of other parts that are required and now it is in pieces I can see what can be reused and what needs to be bought new. I will have some items re-chromed / painted but others I have just bought new as that way I am not paying for refurbishment and know I will recover some money on selling the old parts.

The one thing that I am now disapointed about is that I didn't take the time to refurbish the engine cases when it was apart.
At the time I thought it was just going to be a quick overhaul and then I would put it back on the road and use it so I did all the mechanicals but wasn't too worried about the exterior finish of the engine however now I am rebuilding the whole bike I feel the look of the engine will let it down. What I intend to do to overcome this is put the engine into the newly painted frame, run it for a little while to make sure all is well and then I will remove the engine, strip it right down again and deal with the cosmetic side of things. Luckily these engines come apart very quickly and knowing the engine is mechanically good will encourage me to make a nice job of the exterior.

Great work! I'll be chacking on your progress as you go. - Looks just like mine. Almost. Where is the oil filter on the bike? I better check mine.

Under the clutch cover, it is a slide-out gauze which you wash out and re-use.

And there is a centrifugal filtre as well in the clutch housing.
Do not forget to clean this!

You are correct, I forgot that one! I did mine as I was rebuilding the clutch anyway but am I not correct in thinking that it doesn't need cleaning as often????
It was lack of good clean oil that used to kill these engines but having been brought up on them I pretty well knew how to look after them and by the time I was 16 and riding one on the road (I had been using them around the track for a few years before this) I knew all there was to know about them. Unfortunately that was nearly 30-years ago and now I am having to learn it all agan!

When I rebuilt my ST engine a couple of years ago I replaced the oil-pump with a high-volume one as I had it at the back of my mind that I might one day fit a big-bore kit and by all accounts they require the greater oil-flow. I probably won't do this now as I want it to be standard but the oil-pump is in and should help provide a decent flow of oil to the top end.

LITCH wrote:You are correct, I forgot that one! I did mine as I was rebuilding the clutch anyway but am I not correct in thinking that it doesn't need cleaning as often????
It was lack of good clean oil that used to kill these engines but having been brought up on them I pretty well knew how to look after them and by the time I was 16 and riding one on the road (I had been using them around the track for a few years before this) I knew all there was to know about them. Unfortunately that was nearly 30-years ago and now I am having to learn it all agan!

When I rebuilt my ST engine a couple of years ago I replaced the oil-pump with a high-volume one as I had it at the back of my mind that I might one day fit a big-bore kit and by all accounts they require the greater oil-flow. I probably won't do this now as I want it to be standard but the oil-pump is in and should help provide a decent flow of oil to the top end.

Thanks, I'll check them both if I can do it. I have not got a manual so just have to look and go by trial and error. Is it a fairly easy job to clean them both? Have you any ideas where I might find an online manual to see how the process is supposed to go? Thanks again to you both!

Bit of an update but unfortunately no new photos.

Frame, stand & one fork-leg were delivered to the welders today so with any luck I will get them back fairly soon so I can sort out the painting & chroming side of things.
The list of new parts purchased has grown again, I seem to have given up on any kind of budget at am just throwing money at the thing but hopefully the end result will be worth it? As I said before, there seems to be a ready market for old parts so hopefully I will recoup some of the outlay when I have a mass sell-off of all the spare components.
The indicators are pretty much sorted out and I am really glad I went for the larger units. I can't have the rear mounting brackets weled on until I have done a dry build as there is the danger of the OS lamp being too close to the exhaust if I get it wrong so that will have to wait. It means a return trip to the welders but better safe than sorry.

Which are the best frame stickers to get, is the reproduction set sold by MBUK any good or is it a case of buying the genuine ones where available and using pattern ones for the rest?

LITCH wrote:am just throwing money at the thing but hopefully the end result will be worth it?

Of course it will! It easy to see you're doing a good job. Great thinking, good parts,... looking forward to see the result!

LITCH wrote:Which are the best frame stickers to get, is the reproduction set sold by MBUK any good or is it a case of buying the genuine ones where available and using pattern ones for the rest?

All the small decals and warning stickers are widely available oem.
Some of the frame stickers are still available as well, the reproductions are most of the times pretty good.

Got the frame, stand & forks back from the welders yesterday and am really pleased with the results, I just have to do a dry build (to make sure everyting fits together ok) and it will time for painting & chroming.

As far as chroming goes I am inclined to use Classics & Chrome Ltd in Hinkley, does anyone have any first hand experience of them please?
There are other places closer to home but I have personal experience of the one at Stotfold so won't be going back there, the one in Luton has been known to hang on to stuff longer than seems reasonable and I want one that is within travelling distance so I can pick the parts up in person and check the results being paying for them.

Painting is a bit more of a problem, so far I have had three quotes which vary quite significantly.
The parts to be painted are as follows:- frame, forks, swinging arm, shock covers & chain guard (all candy red), footrests, stand & tail-light bracket (all black), three mudguards, two pairs of wheel rims, two hubs & centres (all silver). The painting will extend inside the frame so the finish when you lift the seat is as good as the finish on the outside.
1. A local bodyshop (which I have used before) has quoted £300 + £150 for paint but I have to get all the parts blasted, he is good and I think the finish would be quite acceptable. The biggest problem here is finding someone who will be willing to blast as all the local places only deal with contract work.
2 & 3. Banbury Powder Coating (who did my Laverda) have quoted £1000 for blasting & painting with a guarantee that the finish would be concours. They have also quoted £500 for blasting & powder coating with the proviso that the finish would be excellent but couldn't be to the same standard as their paint finish.
4. My nephew is a bodyshop manager and I can get him to do it at cost (no price yet) and while I know he will do an excellent job it might be months (or longer) before I get the parts back.
I think someone on here has used Roadrash in Leighton Buzzard. What did you have done, were the results good and what was the approximate price please?

Anyway, when this rain stops I will post some more photos.