GTR Anti-ringing pins

[BRT-GTR]

Guys,
   I just don't remember my original  68 registered machine having anti-ringing pins in the cylinders.  Were these a later addition or did they always have them?

  Have two part built engines (879 & 6052)and will assemble one good one from wreckage using later or best parts. I am aware of most of the factory mods. When completed should I carry out a piston clearance check to be safe and maybe balance the two pots, if necessary?

  Have just checked the repaired/replated cylinders (one pair) that came with the bikes, luckily they are the shorter post mods barrels. Phew!!!!
Brian the Brit

[slawsonb]

Still have an original 68 and it does not have the anti-ring pins...
...bert

[BS Mechanic]

My original 350's engine, 2390 came with pins.  Early in it's life I cracked the exhaust flange and had to buy a replacement cylinder.  The replacement had no pins, but a much better exhaust flange design. 

From what I have seen, at least many early 350's came with the pinned cylinders.  Most spares I think were the stronger exhaust flange design, but without the pins.  I can't say for sure, but there may have been all combinations over the build of 350's.  Possibly it depended on the supplier at the time. 

If someone has more positive info let us know!

Here are pic's of two configurations:
http://bridgestonemotorcycleparts.com/index.php?action=gallery;sa=view;id=864

http://bridgestonemotorcycleparts.com/index.php?action=gallery;sa=view;id=863

http://bridgestonemotorcycleparts.com/index.php?action=gallery;sa=view;id=862

[slawsonb]

I should modify my statement. My bike was fist registered in '68, but was built in '67.
....bert

[moonpup]

Brian, here's some more discussion about the cylinder differences. I vaguely remember my head hurting near the end of it all! 

http://bridgestonemotorcycleparts.com/index.php?topic=2822.0

[Bikenstein]

Still have an original 68 and it does not have the anti-ring pins...
...bert

Can you post some pics so we can see the exhaust flanges and letter stampings? Brit....My 67 has 2 different cylinders, but I've got a reasonable idea of which is the oldest and possible original. I'm thinking the pins came first because of the weaker exhaust flange and injection pin cutouts. I would like to clear this up and also get a set of matching cylinders. Mine are a oops. Mine are ashtrays

[BRT-GTR]

(rewrite)  Hey Guys,  Thanks for input.  I never knew there was so much history behind BS bikes.          Moonpup,  See what you mean about previous post 2822, Oct 12, just read about 6 times, pass the painkillers, my teeth itch as well .
Will try to summarise what we can infer for definite from info available :-

                 Think you will agree all earlier cylinders had weak exhaust flange and A/R rods, later cylinders had beefed up exhaust, no real doubt about that. (If you can disprove this, email me, please don't post , my brain couldn't handle it )

Moonpup.    Think you have accurately listed (your post 26th Oct 12) the 5 main type of cylinder known, as below:-
Early
1. Has rods/weaker exhaust flange/has cutouts
2. Has rods/weaker exhaust flange/no cutouts
Factory Mod exhaust flange
3. Has rods/improved exhaust flange/no cutouts
4. No rods/improved exhaust flange/no cutouts
5. No rods/improved exhaust flange/has cutouts.
Late
So (1-2) is in right place timewise and (3-5)ok,  but not necessarily in right order if there is one.

 Additional points noticed on photos.
1)  When looking at cylinder with exhaust mod made, its not totally clear but it looks like they may have slightly thickened and flattened all the fins (early fins seem to be more tapered out from barrel wall) and could do away with the A/R rods. This would also be helped by small reduction in fin length/area  as the overall shape of the cylinder & head was changed ( See post by Steve, 22 Oct 12) Steves comparison photo confirms this, I.E.Rodded cyl and head is bigger, (Steve, which is first, small or bigger cyl/head, can you say)
2)  There's no doubt that cylinder fin cut outs were added to provide recessed push out points for mould ejection pins (Post by Oldswartsout, Oct 12) Didn't know that before.
3) Also notice that all cylinders with cut outs have a second pair of push out points at the cylinder base that line up with the top two.

Other thoughts:-
 Maybe the push out points in my 2&3 were necessary to allow the thicker profile fins to be ejected from the mould or could just be different cylinder suppliers as suggested previously Oct 12.
 I think 2. in moonpup's list maybe would have come before 1. Difficulty getting original cylinders out of mould so added push outs.
 If I've got my logic right, the one cylinder configuration that doesn't seem to fit with all the above is  4. No rods, no cut outs.( thicker fins should need push out, therefore cut outs) again maybe different suppler.
 I have a pair of cyls  that match 3. Rods, no cut outs, improved exhaust flange, fins  have distinct taper from barrel out. Number 22031305 stamped on Cyl base at rear (can't makeout  if my other cyls have a number, much corrosion) but they also have stamped on the top to rear of head face  'NPR', National Peoples Republic? would that be mainland China, Taiwan usually stamp PRC, Peoples Republic of China. Also they don't look to be cast to usual BS high standard.  Anyone help   Did BS sell earlier pattern or mould to Taiwan or even China.
I think the cast 'O' and stamped 'M' shown on other pics , Oct12, could be Makers marks, might be initial letter of Company.
So suggest a better list/timeline might be :-

1. Has rods/weaker exhaust flange/no cutouts
2. Has rods/weaker exhaust flange/has cutouts
Factory Mod exhaust flange and maybe other Cyl mods Aug 67, VIN21SO1100 ?
3. No rods/improved exhaust flange/no cutouts
4. No rods/improved exhaust flange/has cutouts.
5. Has rods/improved exhaust flange/no cutouts (Taiwan or even China?)

We can't date any of the above but there was an official factory mod to the barrels in Aug 67, BS state Cyl shortened (99.5mm to 99mm) and exhaust port reprofiled. Did the exhaust flange and other mods happen at the same time, would make sense, anyone know
Well over to you. Please don't post details of your cyls unless you can accurately date manufacture or quote cyl numbers or it doesn't match one of the five main types above.(then I may shoot myself)

Didn't think my original post would lead to this lot but very interesting.
Regards, Brian the Brit.............(My brain 'urts)

[Bikenstein]

WARNING MOONPUP                                          WARNING MOONPUP                                                                                                    WARNING MOONPUP Moonpup. Do not read the Brit's post!! Brit, 'ow about the m's and o's? any ideas?

[BRT-GTR]

Bikenstein,
               M's & O's,  you got me there,  please expand.    Brian the Brit

[old smokey]

Warning - Bikenstein has been running the smoker again. LOL

BRT-GTR : this is what Bikenstein was refering to from your previous post. Sorry - my post from months ago brought up the "M" and "O" stamping.

I think the cast 'O' and stamped 'M' shown on other pics , Oct12, could be Makers marks, might be initial letter of Company.

[Bikenstein]

Warning - Bikenstein has been running the smoker again. .[/i]

How did you know??? Pork shoulder and Pastrami actually.   BTW How did you get the name Old Smokey?  
Brit, I think they had cylinders made from several manufacturers which would compound the problem of what came first. Thanks for your post, it was very easy to read and comprehend. Gotta go add some hikry to thu coles

[BS Mechanic]

Boy does my head hurt now!

Could the NPR be the same company as the piston ring maker, Nippon Piston Ring Company?  I'm pretty sure they made some piston rings for Japanese bikes, could they have also been in the casting or cylinder finishing business back in the 60's?

[BRT-GTR]

Hi Guys,
           BS Mech - I'd go along with Nippon Piston Ring Company, makes more sense, forget my China reference - red herring .You have probably identified one of the cyl suppliers or finishers. Did I read somewhere that you worked on BS's (clue's in your title) and were trained at Rockford's, did Rkfd have GTR cylinders cast in Taiwan?

           Old Smokey - Thought of something to do with smoke when trying to think of my 'handle', cos if there's one thing a GTR did, it was smoke. You got there first. Once laid an 'invasion screen' down the M5 motorway here in UK when I opened her up and the pipes decided to clean 'emselves out, which they did after about 5 miles.....!!!!!!! They're probably still removing the crash wreckage .  I had intended to give you a credit for cyl marks but would have meant another copy and paste, so please accept one now.
     Can anyone add any other cyl casting marks ?. Base of cyl, behind the 345cc & L/R cast in marks, that would help.

           Bikenstien - Thanks for kind comments. M & O's, shoulda twigged (realised) that, had bin at it a long time and thought I'd covered it in the long post. Wondered what your smoker was until I saw the photo. Great setup, can't do that here in UK, it upsets the neighbours, another good way is to set fire to the dustbin (Trash) or start up a Saturn 5.
       I know you and others have  made reference to ' alternative cyl suppliers' compounding the issue, several times before and believe you are right. So maybe the cyl story is not as complicated as we've made it look, if we can identify some of the makers.  Need some input from Japan, someone must know.
       Your 108 cylinder does suggest that Moonpup was right in the 1-2 chronology.

           Anyone noticed the variation in fin cross-section, I.E. taper out from cyl wall, some look reasonably parallel with nice square edges and others look tapered with not so clean edges  and maybe rods or is it an illusion.See B S Mechanics comparison pictures above. Obviously, they had to be able to remove cyl from mould.

  The more I think and read/take in all previous posts, the more I suspect there were two cylinder suppliers( with & without cut-outs?), that would make it simple apart from 3-5, there's an odd one there, can't decide which. Were rods dropped at a different time to exhaust mod. It would have made sense for BS to redesign all the casting changes in at same time, new patterns, moulds etc, high cost. Maybe they realised afterwards that they could drop the rods and save cost. That would give us a definitive sequence (pretty much as Moonpup's original list). Any GTO's out there with original cyls and rods, that would mess things up unless cast in Taiwan,  as suggested  by Rocketman, Oct 12,.  Let's see what comes up.
  Will try to check all cylinder pictures I can find against the above observations.
    
Keep on Chromin,  Brian the Brit

[moonpup]

From the GTR sales brochure.    Pins & cutouts........

[BRT-GTR]

Hi Moonpup,
             Trust I'm not treading on your toes, just trying to make some sense of all the information presented and put my pennyworth in. As I say above, your original 5 cyl list could turn out to be spot on and I for one will acknowledge full credit. Certainly your brochure ad picture and Bikenstien's 108 cylinder do suggest the cut outs came first. There's a  lot of info and input to try and collate and make sense of. It would be good if we (meaning all the guys) could bottom this one out and maybe put it in the reference archive. I feel we are pretty close unless someone throws a spanner in the works with a cyl picture that just doesn't fit. The results could be presented as a forum concensus of opinion if we cant prove the correct order, number of makers etc. It must help future restorers.
  I'm amazed at what a simple question about the rods/pins has generated. Nobody has responded to my piston clearance question. If the cylinders were shortened and assuming no other changes, the compression ratio must have increased. IE more performance which is what they were trying to achieve  (See factory mod details). At the same time it must make the piston clearance from the cyl head and  clearance balance between pots, more critical.

Brian The Brit

[moonpup]

Brian,  the list I put together in the other thread was just an attempt to document all the different combinations that had been brought to light at that point in time.

The only thing we can probably be certain of at this time is that the cylinders with the weaker exhaust ports came before the beefed up ones. (funny thing the way logic works   )

I also tried to find some kind of official type of photographic documentation via sales brochures etc. for the GTO's, but those darn mufflers kept getting in the way! 

BTW... my toes are fine.  

[slawsonb]

Just wanted to add some information to this thread based on my newly acquired parts bike. I have 2 GTRs 21S01306 (July 1967) and 21U03456 (Sept 1967) the later being the parts bike which appears to be totally unmolested (not necessarily a good thing...) . 21S1306 has improved exhaust flanges and no pins as I reported earlier. 21U03456 has improved exhaust flanges and pins. This narrows the window of pin introduction to July 67 to Sept 67. It looks like BS was building about 1000 GTR/O's per month during the period  between my examples(model introduction), while using Graham's numbers the average production between July '67 and May '68 was approximately 450 per month. Food for thought...
...bert

[slawsonb]

I just realized that I should include engine numbers for this information to be useful.
21S01306 has improved exhaust flanges and no pins - Engine number 01351 - July '67
21U03456 has improved exhaust flanges and pins - Engine number 03519 - Sept '67
...bert

[Bikenstein]

. This narrows the window of pin introduction to July 67 to Sept 67.
...bert

Except mine was made in March of 67 #00108 and has the pins. Nothing on this subject is easy to narrow down  

[paul]

sometimes in a factory,parts are misplaced. Found later and used. Parts purchased  for the repair/replacement inventories  might be set aside strictly for replacement part  orders and then robbed to be used to complete a machine on the assembly line. Ask Mr. Konai, or someone who worked in the factory.