exact sparkplug thread measurements 1979 gs 850

[GS850]

hi!

i recently ordered a sparkplug thread chasing set for my 1979 GS850 but when i checked the thread next to the sparkplug that i took out i saw it didn't match up.
the chasers were marked 14mm diameter and 3/4" reach (i believe that has something to do with the type of thread...)

can anyone tell me what the thread is for a 1979 GS850? or where i can find the information? i want to order a colourtune set but not untill i'm sure i'll get the right type....

thx!

[hampshirehog]

14mm. But buy one like this (cheap enough) and you'll never have to buy another:

http://www.ebay.co.uk/itm/Bergen-Professional-Spark-Plug-Thread-Chaser-Set-10-12-14-and-18mm-NEW-/300698596475?pt=UK_Hand_Tools_Equipment&hash=item460308747b

[GS850]

14mm. But buy one like this (cheap enough) and you'll never have to buy another:

http://www.ebay.co.uk/itm/Bergen-Pro...item460308747b

that looks identical like the one i bought but the thread doesn't match... i thought all sparkplugs had the same type thread but apparently not... that's why i'm puzzled about it! i can't seem to find any information about it, they just mention the diameter when u order a set (i ordered a set with 10-12-14 and 18mm chasers but no reference on the threadtype....) pf.. i also ordered a colourtune set but i cancelled it untill i'm sure what's going on!!

[Steve]

In the case of the Colortune, 14mm is 14mm, the reach won't matter.

The Colortune will not be in place long enough to make a difference.

.

[GS850]

In the case of the Colortune, 14mm is 14mm, the reach won't matter.

The Colortune will not be in place long enough to make a difference.

.

so the "reach" is actually the depth that the sparkplugs go into the bike? (i'm from belgium, my english is good but not flawless :-) i know the sparkplugs on my bike are the ngk BS8E and the BS7E, but even on those the only information i can find is the diameter (14mm, which fits fine) so why the hell are those chasers the wrong thread? made in china perhaps?
i contacted the seller but i'm not sure if i'll be getting more info from him...
also in the shop manual from the GS it says 14mmsparkplugs but no indication on the type of thread... is my bike THAT special?

[hampshirehog]

Nothing special about the plugs for a GS850 - that's the same thread as used in several thousand different engines. There must be something wrong with your chaser.

Have you lined the chaser up with the plug to see if the threads 'sit' in each other?

[chuck hahn]

far as I know, all plugs are the same thred pitch. 14MM is 14MM world wide. And yes that "3/4" is the depth of the threads on the plug. If you bought a 14MM spark plug chaser then you should have the right tool. Now if its just a 14MM thred chaser, then youve got different pitches to choose from. The PITCH on a plugs is 1.25 so youll need a 14MM X 1.25 thread chaser to clean the head up.

[bwringer]

Yep -- 14 X 1.25 mm threads.

Fun fact: the same thread size is used for the oil drain plug.

[Badooka]

That would be the coolest, an NGK for and oil plug!

[GS850]

Nothing special about the plugs for a GS850 - that's the same thread as used in several thousand different engines. There must be something wrong with your chaser.

Have you lined the chaser up with the plug to see if the threads 'sit' in each other?

that's what i did and it's not lining out or "sitting" in each other... 1,25mm pitch... i'll try and contact the seller again, thx!