I think of it as 3 levels of spark plugs to use:

ER9EH: is the standard plug that works for most applications until you really start building heat.

ER10EH: Bikes with higher compression (milled heads, big-bore pistons, etc.) but still have low enough compression to run pump gas. These are the plugs I recommend for guys with mildly built engines up to 428s without milled heads.

R847-10: These are what we run in our 450. They are very expensive in comparison to the other already expensive plugs. But, they keep the combustion chamber cooler and don't have a tendency to blister the porcelain and melt the diode. We definitely recommend these to anyone with built engines.

I am looking for the plugs for a customer and for some of my shop-mates with the lesser motor. www.sparkplugs.com told us these were obsolete. They also told us the R847-10 were obsolete. So, I am looking to find remaining stock to put on my shelf.

It's getting scary how many parts are becoming obsolete for these bikes

Mike Norman
G-Force Engine Development
http://www.mngforce.com

The 10s definitely aren't obsolete here in the UK at least, there's hundreds on eBay. They're just expensive, even more so than the CR8s


Oh, here's NGKs full address and phone number

NGK SPARK PLUGS INC
3255 1/2 SCOTT BLVD
SANTA CLARA, CA 95054
(408) 727-5180

Neosophist wrote: CR8's? You mean ER8?

No, I meant the CR8s for the NC24 and FZR400

Ah,

NC24 stock plug is C8EH9 not CR8 as it has resistor plug leads

Neosophist wrote:Ah,

NC24 stock plug is C8EH9 not CR8 as it has resistor plug leads

Aye, but I've never been able to get C8s, hence my reference to CR8s

thunderace wrote:

Neosophist wrote:Ah,

NC24 stock plug is C8EH9 not CR8 as it has resistor plug leads

Aye, but I've never been able to get C8s, hence my reference to CR8s

Weird. CR9EH9s are the standard plugs for so many bikes in the sates. I can get either the CR8EH9s or the CR9EH9s fairly regularly and they're not too expensive. The CR8EH9s sound very hot.

Maybe we should trade CR8EH9s for ER10EHs :-)

Mike Norman
G-Force Engine Development
http://www.mngforce.com

[quote="thunderace"]

David Silvers, 6gbp each.


VFR400 NC24 (JAPANESE)
Spark Plug (NGK C8EH9)
£6.00

Genuine Part

Just search for NC24 in the model box if you want to try any infuture :)

Or use 9805958910 part number

Thanks Neo but it's academic now I've seen the light and gone back to Yamaha

thunderace wrote:Thanks Neo but it's academic now I've seen the light and gone back to Yamaha