Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board 1970 Lightning "Y" Bike Project...

Hi Kev,




'70 BSA twins used the same stanchions as the singles, including the TR25 - Googling "97-3906" says they're down the road from you at Classic Motorcycle Spares.

The 97-3921/2 sliders are common to the entire '70 Triumph range and BSA's except the twins.

I'd use Triumph 650 springs.

All the seals, washers, etc. are common to both the Triumph and BSA ranges and thus widely available. When Googling several of the part numbers of the larger parts, both Burton Bike Bits and Hawkshaw usually come up. As well as them consider Grin, TMS, Yeomans and - just up the road from you - Reg Allen, most of whom do the large bits second-hand as well.

I.e. none of the Triumph bits are exactly rocking-horse poo ...

Hth.

Regards,

I have a 70 A65 front end laying around unneeded PM me if you want them. Its got stanchions but they are V rusty, the sliders should be useable.

Hi Gavin, I did not see this reply, it was just pointed out to me. Sorry I can't PM you your inbox is over limit?

Kevin.

Engine is all bolted up now ready to go, I put some spacers between carbs and head today, bought some new cables at Kempton yesterday, close now, just the front end to get sorted. bought a Triumph front end from the bay, fitted new stanchions bushes etc, took it to the lockup to fit on the bike, but the stanchions don't fit the BSA yokes? Too loose in the lower yoke, and wrong taper for the top yoke. so now I have a set of Triumph forks I don't need. Just going around in circles with this whole front end situation.

Hi Kev,


Certainly if you tried to fit "Triumph ... stanchions" in the current '67 lower yoke, yes, they will be too loose. And, in the recent thread, A65 Fork sliders different lengths, "kommando" posted that Triumph and BSA top yoke tapers are different.


I appreciate that you might not have the interest to read many threads here, but the knowledge is available if you ask before you buy "from the bay"?

At worst, Gavin will be back in a few days (I think shift work stops him contributing for periods). As you posted, you've waited six months; a few more days is better than wasting your money on bits that won't fit? As the post before Gavin's says, the correct BSA stanchions were (still are?) available new not far from you? You're going to need these even if you buy Gavin's front end.

Regards,

PM sent to Kev regarding forks.
I no longer work/ retired but I am busy occasionally on sailing trips/ gardening.
The donor bike for the forks was a V low mileage 70L, it had smashed a lump off the gearbox when the chain snapped, I am fairly sure the Front end with the 8 inch TLS is original.

Thanks Gavin & Stuart, help appreciated.

Thanks to Gavin, I now have the correct forks for my 1970 "Y" bike, so time to get this ready for the summer.

Making progress..... https://backstreetthunder.wordpress.com

more next week when the forks should be fitted :bigt

Good job Kevin. I dig the blue Tygon lines. You'll get it on the road before the end of Summer for sure.
Fine looking motorcycle! What tires did you select, I don't recognize the tread?


Don in Nipomo

Cheers Don, the fuel line is Italian Ducati line, the tyres are Mitas dual sport enduro tyres

I see, the MC 24 Invader 70/30 DOT approved and rated.
New to me but an attractive tread! I like 'em.

You'll be sure to tell us what you think of them.

Don in Nipomo

Anybody got a good quality scan of the 69/70 wiring schematic they can send me?

Hi Kev,

You have incoming.

Regards,

Thanks Stuart

Ok then every weekend I am a little closer to the road, so back to the forks....

Can someone please tell me the thread form/ stud size of the four lower axel cap retaining studs.

Kev.,

I did not fully understand with which forksyou have ended up with.

Subject to your bike having proper 69 or 70 shuttle valve sliders, the bolts for the fork end caps are 5/16" UNF.

According to the spare parts list and my own experience there should be bolts, no studs. Given, a stud is a better solution for this application.

Cheers!

Phil

Thanks Phil, I now have the correct 69/70 shuttle valve forks, although mine came with studs and not bolts, I just need to get a tap to clean up the threads, I can then get the bike off the bench, where it has languished for far too long.

Hi Kev, Phil,


Mmmm ... certainly Triumph versions of the '70 sliders had studs. Most available '70 parts books showing bolts were dated for the beginning of the season in July 1969 or just after, which means they were prepared during the '69 season. However, the 3rd edition of the 1970 T150 parts book wasn't published until January 1970, and shows studs. '70 is well-known for a number of other mid-season changes (for example, grey- to black-face speedo. and tacho.).

More practically, when working on your own, sliders with studs are easier to locate positively over the axle than sliders without. :bigt

Studs are 5/16"UNF on both ends.

Hth.

Regards,

Mine is a 69 Lightning and the threads on the four fork cap bolts are 5/16 UNF.

Get one of these. This year in particular has all sorts of threads, i can confirm the studs with the forks I sent had 5/16 "UNF threads.
http://www.ebay.co.uk/itm/55-Deg-Imperial-60-Metric-Thread-Pitch-Gauge-Measure-Screw-58-Pieces-Blades/332183196481?_trksid=p2047675.c100623.m-1&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D43781%26meid%3D5c28ce961dfd45dc8ac7fafc83137fe6%26pid%3D100623%26rk%3D2%26rkt%3D4%26sd%3D371701833943

Sorry for confusing your thread with my remark on the spare parts list and bolts, Kev. I should have been more precise.
AFAIK the BSA shuttle valve sliders used bolts with the mentioned 5/16" UNF thread.

I have now a fork of a 70 Lightning basket case I recently bought with a mate on the bench, according to the wrong stanchions I am inclined to think it's a Triumph fork. These sliders have studs. But the plonker who fiddled with it before has obviously chosen to use metric M 8 studs...

Cheers!

Phil

Does anyone have a picture of the 1970 year clock bracket for the Lightning with or without clocks fitted :bigt

I suggest you search ebay. There are always a few for sale there, usually with decent pix.

I want to be sure it is the correct part, if someone has a 70 Lightning, with the correct bracket fitted I will know for sure what I am looking at