This posting with others to follow from me are a continuation of a thread started by Gordon Gray entitled "Headlight sheel question--todays dumb question" which later changed to "I love this hobby--B50 Centerstand". Rather than anything to do with headlight shells these postings concentrate solely on center stands for BSA B50s and Triumph TR5Ts.
So--I will tabulate the information in three parts as per: Part 1 relates to part numbers concerning center stands that may be applicable to a B50. Part 2 relates to the physical dimensions of the stands in Part 1. Part 3 relates to fitment of a center stand to a Triumph TR5T. This posting will cover Part 1. Parts 2 and 3 will follow in separate postings. PART 1. After going through 17 Triumph parts lists and 3 BSA parts lists gives the following results relating to center stand part numbers: a) Triumph 83-1267 1969/70 T120 and T150 (all dry frames) 83-2627 1971/72 T120 (OIF) 83-4615 1973/76 T140 83-4941 1978/79 T140 83-7532 1980/85 T140 (also TSS,TSX) b) BSA 83-2627 1971/72 A65 and A70
The "holy grail" in the fitment of one of these center stands to a B50 is 83-2627 (for details see Part 2). It can be seen that this was fitted to 1971/72 Triumph T120s AND 1971/72 BSA A65s/A70s.
PART 2. So--you want to fit a center stand to your B50. From PART 1 you know that ideally you need part # 83-2627 from a 1971/72 Triumph T120 OR BSA A65/70. You are now in a cold and windy field at a swap meet in US or an autojumble in UK. The vendor has a pile of center stands but none have part numbers. How do you find the one you are looking for? First of all many thanks to Mark Appleton, Gary and Red of British Cycle Supply. Although based in Canada their US warehouse is located in Hackensack NJ---about 3 miles from where I live. They were very cooperative to pull out stock stands and give me information from their files. There were some dimensions which are identical for all four (83-2627, 83-4615, 83-4941, and 83-7532) stands. These are: a) Distance between centers of feet of stand is 7 1/2"-7 3/4". b) Width between pivot faces on the stand is 5 3/4" -5 7/8". The pivot hole diameters are the same on three of the stand part numbers (83-2627, 83-4615, and 83-4941). All of these are 3/8" diameter and all take pivot bolt part # 21-2077. The stand for the later T140s (83-7532) has an 11/16" hole and takes pivot bolt part # 14-0147 and pivot bush part # 83-7460. The center stand spring location is the same for all four center stands and lines up with the spring location already on the B50 frame. Very importantly the distance between the pivot hole center on the stand to the center of the foot of the stand varies between stands. The relevant dimensions are: a) 83-2627 10 1/8". Measured on stand at BCS. b) 83-4615 9 1/4". Measured on my 1974 T120RV. c) 83-4941 10 1/8". Info ex BCS files. d) 83-7532 9 1/4". Measured at BCS. I have a slight concern about the 10 1/8" dimension on 83-4941 as it doesn't seem to fit the pattern. I have recently bought a barn find 1978 TR7RV and it has a center stand fitted. I intend to get this bike out and confirm or otherwise this measurement. It is bitterly cold here today which is why I am sitting at the computer rather than in the open moving bikes about! So, in summary if you want to fit a center stand to your B50 then you ideally need part # 83-2627 from a 1971/72 Triumph T120 or BSA A65/70. The dimensions are given above but you first of all I suggest home in on the 10 1/8" dimension from pivot hole center to the bottom of the foot of the stand and then confirm the other dimensions are OK. I am stopping this posting here but will continue with PART 2B detailing fitting of the center stand while still being able to use the side stand on the B50. It will also cover the mods needed to fit a non 83-2627 center stand to a B50. HTH
PART 2B So---we now have center stand 83-2627 and have fitted it to our B50. What is it like and how does it work? I have gone back to my original detailed notes and this is the story they tell: a) Rear tire 2” off the ground. b) Bike goes on and off the stand very well and very easily. c)The stand gives good balance. The bike rests on the stand and the front wheel. But with only light pressure on the rear of the seat the bike rests on the stand and the rear wheel. d) Trial on level concrete floor of garage. e)Tests carried out with tires as per: Front: Dunlop K82 3.25 X 18 inflated to 28 psig. Rear: Dunlop K82 3.50 X 18 inflated to 32 psig.
So the 83-2627 stand works well—what about the shorter stands? The distance between the center of the contact patch of the front wheel and the contact point of the center stand when in the down position is 32”. The wheel base of the bike I measured as 56”. With the bike resting on the front wheel and the center stand any increased stand length will lift the rear wheel by a factor of 56/32 of the increased stand length. This is 1.75 times the increased stand length. Conversely reducing the stand length will lower the rear wheel by 1.75 times the reduction in stand length. So the stand lengths for 83-4615 and 83-7532 of 9 ¼” compared with the 10 1/8” of 83-2627 ( 7/8” shorter) will lower the rear wheel by 7/8” times 1.75 = 1 ½” approx. So using these shorter stands will reduce the distance from the bottom of the rear tire to the ground from 2” by 1 ½” to ½”. This might work but if the stand pivots wear a bit and/or the bike is parked on uneven ground it could well be that the rear tire is not lifted off the ground. So the message seems to be—get a 83-2627 center stand if you can. If you cant then weld a pad onto the bottom of a 9 ¼” long stand with the pad being at least 1/2” thick. All this presumes that the long side handle on the 83-2627 center stand is removed completely. At first sight this seems essential if you also want to retain a working side stand. However it really is best if you have some form of side handle so that your boot can push on something when getting the bike on the stand. I have found that a short straight piece of the original side handle just 1 ¾” long can be welded onto the bottom of the center stand in the recess just above the foot. This gives a peg which is useful for putting your boot on in order to get the bike on the stand and at the same time enables the side stand to also be used without the two stands hitting each other in operation. However the length (1 ¾”) of the short side handle and its positioning on the center stand need to be just right. I would therefore recommend that each bike is individually measured to avoid stand clash rather than just taking the dimension that worked on my bike. So hopefully you now have your B50 with operating side and center stands, with the latter adapted from a reasonably readily available stand originally designed for a Triumph/BSA twin. HTH
I have no clue if the center stand I have on my B50 is correct/stock or not but once I get the distance pc for the side stand I'll take the center stand off and share some photos and dims. I do know that it's longer than the 83-2627 and the side handle is a lot shorter and located in a different place.
Thank you Tridentman for doing this for the hobby.
PART 3 This was originally compiled by OIFMAN of the Isle of Man. The original included photos which are referred to in the text. Unfortunately I couldn't get the photos to copy. However I think these instructions give the basics and are OK to follow if you have a center stand and a TR5T in front of you.
FITTING A CENTER STAND TO A TRIUMPH TR5T This note covers fitting a BSA/Triumph OIF centre stand to a 1974 model TR5T The centre stand used was a standard Triumph/BSA 650cc OIF unit, part number 83-2627 (which by the way fits the BSA B50). The current 83-2627 is not same as the original 83-2627: the current one is made by LF Harris (it said so on the bag!) and is based on an earlier BSA forging for the legs with a halfround bar welded on to provide the stops. This note assumes you are going to use the LF Harris version as this is widely available. The distance between the mounting lugs on the A65 (or B50) is 5.81”, the equivalent distance on the TR5T is 8.31” ie 2.5” larger. The mounting lugs on the frame are about 100 thou thinner on the TR5T and the mounting holes 3/8” dia whereas on the B50 they are ½” dia. First thing to do is to open out the existing 3/8” fixing holes to ½” with a standard ½” drill. Then cut the centre stand in the middle of the cross bar; I suggest you press the newly cut cross bar ends gently in the vice to get then sensibly round again (when cut you’ll see they are quite oval due to the bending process). Once that’s done we need to file (or carefully grind) back the half-round end stop piece on both legs: You need to remove about 1/8” off the stop bar so it clears the mounting lug and engages with the end-stop flats correctly- try to keep the original slope of the flat. This was my final measurement. The original half-round bar in quite depleted but I think there’s still sufficient meat left- otherwise you could always take if off completely and replace with a new piece in the correct position. This shows the end-stop bar nicely mating with the flat on the mounting lug this is what you’re aiming for in both the centre-stand down and retracted positions. You can also see the 100thou thick washers I used to pad out the gap between bolt head and lug. Next we need make a cross-bar extension piece- this was mine: Turned from mild steel bar, approx 3.5” long with the ends turned down ½” to fit into the original cross-bar tubing. Next assemble everything to make sure it fits: the piece of wood was to check that the legs were sensibly parallel and square with the frame. You can also see that I’ve cut off the extension leg to the stand so it doesn’t interfere with the side-stand. Here’s another view before welding- you can see the way I decided to mount the standard return spring- it is much easier to fit than on the B50! The mounting hole for the 1”x 5/16” dia bolt is existing. The cross-bar extension was tack welded in this position, the stand removed and the weld completed. Re-fit to make sure it still moves freely: And in the retracted position: I think I’d like to slightly improve the retracted position a little (and remove some of the metal from the leading feet of the stand legs) but apart from that it seems to work well- the rear wheel (with a 21” front wheel) is about ¾” off the floor.
I hope this makes sense and will be helpful in fitting a 1971/72 Triumph/BSA twin center stand onto a 1973/74 Triumph TR5T.
Following on from the above thread: a) Still not measured the center stand dimension on my 1978 Tiger (6" of snow on the ground outside is my excuse---I have to move bikes around outside to get at it). b) Stuart has kindly pointed out something possibly misleading in the stand dimensions given earlier in the thread. The holes where the center stands pivot is actually a tapped hole not a plain hole. It is tapped 7/16" UNF. The core diameter of this thread is 0.383"---so my dimension given of a 3/8" hole (0.375") is very close and if you are examining a center stand in a muddy field at a swap meet and take a 3/8" bolt with you with a portion of plain shank then that bolt should just slide nicely through the pivot holes in the center stand. c) Stuart also suggests that the earlier non OIF center stands from Triumph and/or BSA twins may also fit the B50. I don't have any data on this so if someone has a late 1960s twin center stand to hand and could measure it up and post the dimensions that would be great. HTH
Dave T of Ontario Canada (a board member) has kindly carried out the computer spadework for me to post the article on the fitting of a center stand to a TR5T with photographs. It is now up to me to get my head around it and post it here. Watch this space!
T-man, My goodness what a piece of work. I had a lot of trouble just finding one for my B44. Gordon helped me and while it fits and retracts nicely it is way too long and very difficult to get the bike up on it on hard pavement. When I got my b50 it had no stand at all and the side stand mount was damaged beyond repair so I made my own. I won't even attempt a center stand for the B50.
I found an OIF twin stand and it fitted easily. Had it on for many years now so sorry I don't have details. I use it a lot. I have never started any bike on a stand, - side or main. My B50 starts easily by just sitting astride the machine and using a good start technique with the decompressor. Normally a first kick machine.
When I was looking for a centerstand for my b44, I paid $45 for a stand with all the little things that go with it....even had a a cotter pin in the kit. It did not fit the B44, or my a65 or B50. Does that mean I don't have enough bikes? I'd give it to someone but I don't know what it fits. One of these days I'll take the centerstand off the B44 and cut about 1/2 inch out of the legs and weld it back together so it will work.
Mike---if you measure on your B44 the distance from the center of the pivot bolt to the bottom of the foot of the stand AND the dimension between pivot faces on the stand and post those dimensions it might be just a case of swopping one center stand for another. If you post the dimensions I will look at them and see if anything pretty simple can be done. HTH
T-man, I have those numbers in the shop somewhere and I'm headed that way today before I go fishing. I'll see what I can find out and get back to you. I would gladly trade this one I have for something that would work on my b50.
The stand I have has two numbers. One number is 68-4721 and on the other side of the leg is xx-4723. I can't make out the xx numbers, but could be 68. Inside to inside where pivot rod goes through is 2 9/16ths. Outside to outside is 4 3/16ths. Vertical to center of pivot is 8 7/8ths and the length of the leg from the center of the pivot to the end of the foot is 9 1/8th. I did not get to look at the B44 centerstand as it is in the back of the shed and I'd have to a few things to move to get to it.
Did you find the 83-4943 number forged on the primary side leg of the stand? that's a forging number, not a part number. The other leg should have 83-4945 forged on it and the part number for the stand is 83-4615. It fits most of the 750 twins. The 83-2627 (or F12627) stand you need has 83-3071 forged on one leg and 83-3072 on the other, and it's about 3/4" longer than the stand you have.
It seems my stand is off an OIF Triumph 650. Common as.. That would confirm Tridentman's observations in his post 2B of 26 November posted earlier in this thread. In Part 3 he indicates the same part is used on the OIF A65.
I have followed this thread with great interest as I have a 71 B-50T that would benefit from a center stand. I found a decent one from a 71 oil in frame Triumph and went to work. I took it to HCV in Asheville NC where the stand needed to be straightened due to it being tweaked. Jake cut the original foot lift but left about 2 inches so the stand could be deployed .It mounted up perfectly and is easy to lift onto the center stand. I would recommend this addition to your B-50!
John---you certainly started with the correct stand. IME it gives a great center stand--as you say---easy to lift onto the stand and lifting the rear tire well off the ground. Only one comment---I found that if you left any at all of the side handle in place in its original position then it clashed with the side stand. Having said that mine is a 72 B50SS. In my case I solved it by cutting a short straight length of the side hadle and welding it to the bottom of the stand. In that way you could have a center stand and a side stand and operate either as you wished. HTH
Mike---if it is 9 1/8" from pivot center to the bottom of the foot then it is about 1" too short for a B50. The dimension between pivot faces also seems very small. I need to dig out a couple of bikes awaiting restoration--a 78 Triumph TR7RV and a 67 B44 in order the measure the center stands on them. Unfortunately we are getting 6" of snow at the moment and I need to shuffle bikes outside in order to get to those two--so will have to wait for a thaw I am afraid! HTH
I left about an inch of the lifting lever in place. It is just a short stub. You are correct about the clash but that is only when operating the main-stand. It is just a matter of swinging the side-stand down first. I hadn't considered relocating the arm, I will be selling the bike soon so will mention it to the buyer.
Just to reiterate.... If you want a main-stand on your B50 then it is as easy as picking up one from a 1971-72 OIF twin. (BSA or Triumph). The spring and pivot bolts are exactly correct and the only modification required is the removal of the lifting lever.
Kevin-- I guess I am just a pedantic old fart--I wanted to be able to operate the center stand with the side stand in the "up" position. But--yes--you are correct and it is right to emphasise the simple fact: To get a center stand on a B50 you just get a 71/72 OIF Triumph or BSA center stand, cut off the side handle and it fits straight on---no further cutting and no welding etc required. HTH
On my B-50 T the center stand 2 inch peg that was left on after cutting the original lever down doesn't interfere with the side stand.The side stand swings out and down and the new center stand rests just below the side stand when both are up.No problem deploying the side stand with the center stand up.