Spark plugs

well at least its not an oil post!

I’ve been useing B7HS in both my 450 and 900 twin (Bosh ignition) The 450 has been just fine so I will continue with this. The 900SS although generaly OK, does have a habbit of flooding when not really warmed up, so a trip from the house to the petrol station is one to dread, as you know it won’t start again at the petrol station! I’ve read up on this and apparently it is a common problem with the SS models and can be cured by using B6HS plugs instead.

Now the difference between the B7HS and B6HS plugs I understand, but the Bevel Heaven site reccomends either BP6HS or BP7HS, so who knows what the P means?

I need to know PDQ as i have run out of spark plugs and am champing at the bit to order a box of plugs on line!


Righty ho, just answered the question for myself. NGK have an excellent “learning center” which tells you everything you ever wanted to know about sparkplugs. Believe it or not it is quite interesting!


BP 7 HS Means…

B- Thread size and hexagon diameter
P- Information on specific desighn features, in this case it means the plug is a projected insulator type.
7- The heat rating
H- the thread reach, H being 12.7mm
S- More construction details, S denotes a copper core
After the last letter if there is no number it means a standard gap of 0.7mm, if there is a number this is the correct gap in mm.

So I am going to order a box of B7HS and B6HS

B6HS’s are far to soft for a 900SS Bevel.
If you need anything less than a B7HS then there’s something wrong with your bike, or you’re not riding it in the way it was ment to be used!

Steve R

At least he is riding his bevel. Far to many are wrapped up in cotton wool being polished. Get em out and thrash them…I meant more bevels

Mr R, I have read in many places that a lot of the 900SS models run better with B6HS, particularly those that suffer from poor warm not hot starting. Apparently a common problem and nothing to worry about. Time will tell, and I’ve always the box of BH7S’s I’ve ordered to fall back on!!!

Now the other thing, she is due another 1000mile service shall I run W40 in the winter? (Ducks while reaching for tin hat- Incooooming!!!)

Hi again Keith,
B6HS’s are the normal fitment for the softer tuned GT models.
The folk who say their 900SS’s run better on these plugs are limped wristed wankers!!! :unamused:

I’ll state again they’re far too soft for a 900SS for anything other than pottering to the shops, if you were to take her for a ‘Spirited’ run you’d run the chance of over heating or even a siezure!
You’ve been warned chap…

Steve R

PS Happy New Year to all of the Grotherfill family, from the family Ness!

PPS From the ‘Skinney’ Mr R 44 lbs lighter and counting.

You see, all threads end up talking about oil in the end!

For what it’s worth I run Silkolene Chatsworth 40 all the while in my Darmah SS and 200GT (Castrol R40 in the racer).



Mine’s got B7HS in at the moment, but I always used to use Champion L82C I’m sure it used to run better with the Champions in?
Just bought some off Ebay I’ll give them a try again

It’s Chatsworth 40 for me…a pint before bedtime, every night!

An oil thread sneaked by the back door Keith. :open_mouth:

I always use Rock Oil TRM SAE 40/60 these days in my old girl apart from running in when I use any old cheap crap 20/50 but change it very often.
But then I don’t run her through the winter these days, although I do ride a bike everyday having never taken a car test.
When I used to run her all year round, I’d use Castrol GP50 in the summer and Castrol Product 351 or Chatsworth both at SAE 40 in the winter months.

Steve R

Hi Steve,

Ah, interesting … well for me anyways, 'cos this is what I use in my Zane Laverda and I’ve been planning to use it in my SSD as well …

I guess you meant 20/60, btw?



Its worth checking the Chatsworth and Morris oil Material Data Sheets which are both available on the web. Although they are similar the Morris oil scores slightly better both at the low and high temperature viscosities (ie slightly thinner cold and thicker hot).

[size=200]NOOOOOOOOOOOOOOOOOOOOOOOOOOO!!![/size] :astonished:
This was a nice thread about lovely spark plugs and you had to mention [size=200]OIL[/size]

My 250 would not run cleanly on anything harder than a 6 plug untill i sorted out oiling up and carb issues now its ok on 7 or 8 , a 6 will overheat with hard/ hot use and may cause damage, go easy.