Bridgestone Motorcycle Parts Discussion Board
Bridgestone Tech Talk => 350 Talk => Topic started by: Kenneth Pagel on October 11, 2018, 01:28:39 PM
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I'm looking for a good source for the screws on the points plate for the GTR. Also need the tiny screws in the handlebar switch that holds the small plate that anchors the wiring to the switch. Hardware store metric screws, altho seeming to be the right diameter, have a different pitch. Thanks in advance!
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Bridgestone used Japanese Industrial Standard (JIS) screws which were the Japanese norm prior to the change to ISO screws in 1972, I think. Hardware store screws will be ISO. You will know the 6 & 8mm screws have the same pitch in both standards, so can be interchanged.
However, the smaller JIS screws are harder to find. We have a company in the UK who can supply the 5X0.9mm pitch JIS screws, here https://www.mrmegapack.co.uk/philips-screws-bzp-30-c.asp (https://www.mrmegapack.co.uk/philips-screws-bzp-30-c.asp)
Although he advertises 3 & 4mm JIS screws, I believe this refers to the screw head design, not the thread pitch. Check with him before ordering.
What you need are :- Points plate, 4 X 0.75mm pitch JIS screws (ISO is 0.7mm pitch). You can get away with ISO screws for attaching the points, just, because there are only 3 or 4 threads through the back plate. ISO are not suitable for the longer screws that hold the back plate, condensers or the cover. These could be retapped to ISO as a last resort.
Handle bar switches, 3 x 0.6mm pitch JIS screws (ISO is 0.5mm pitch). I have recut ISO screws to JIS before now using a good quality HSS die. Not best practice, I know, but needs must !!
You could also try Suzuki or Yamaha dealers to see if they have any old stock screws.
Hope this helps, Brian.
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BRT-GTR: Thanks for the reply and very useful information!
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You are correct Brian...the 3mm and 4mm screws that Megapack sells are ISO thread (0.5 and 0.7 respectively) :(
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Steve: So the M3, M4, etc., screws that Mrmegapack lists as "JIS phillips: are in fact ISO thread?
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If I'm reading correctly what he says on the website, then yes, that is my understanding. He advertises M3 and M4 as JIS but when you look in the section headed 'useful information' it states...
"Unless otherwise stated here is a general guide to the sizes we supply:-" He then goes on to list the M3 and M4 as ISO pitch threads of 0.5 and 0.7 respectively. The same chart also lists 5mm as the ISO thread, but where you order the 5mm screw, they are clearly stated as 0.9mm pitch, which is JIS.
It seems a slightly confusing way of showing this and I did send him a question to clarify this but didn't get a reply...I'll try him again today and will confirm when known.
Steve
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All this talk about BS screws, has any one asked Richard if he has what you guys are looking for? I know he has bin after bins of tiny BS screws. ??? Jeff Bar
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nysz1b,
I don't believe Megapack is trying to mislead buyers with their 3 & 4mm'JIS' screws, they can be made with any pitch the manufacturer chooses and still be JIS. Our issue is that, prior to 1972, BS and a couple of the other Japanese makers simply chose to use a coarser pitch (than ISO) screw in the aluminium parts.
The JIS standard also covered the design of the screw head and the cross recess. The original side case screws were notoriously difficult to remove and often stripped the head, primarily because most of us were using phillips type screwdrivers. If you haven't got any, try a set of proper JIS head screwdrivers and you will find they work much better. Vessel are one of the better makes.
More info here http://bridgestonemotorcycleparts.com/index.php?topic=4028.0 (http://bridgestonemotorcycleparts.com/index.php?topic=4028.0) Brian.