In the 4rt owners manual it states:

" using a spark plug with the wrong heat range can damage the engine or cause the plugs to foul. be careful to select the correct spark plug for the conditions"

standard plug: NGK CR6EH-9

optional for cold temperatures: CR5EH-9

so should i now start using the spark plug for cold temperatures? and what is the difference?

cheers

Due to a shortage of these plugs in the USA I Have used 5's, 6's and 7's in all outside temperatures. I have found no differences in performance.

Before I have the spare 6's from factory, shortage at my area. I did try 8's, a common spark that I could have, the low end response is not as quick as the 6's.

if your not riding in hot temp (30 degrees C) then a 5 is best. my bike became smoother at low revs

I remember when my local dealer got his delivery.Normal spark plugs were about

should i now start using the spark plug for cold temperatures? and what is the difference?

There have been some good discussions on this board int he past, might be in archives.

'Hot' and 'cold' plugs do not refer to the outside air temps, nor to whether they make the engine run hotter or colder. It means the operating temperature of the tip of the insulator. Hotter plug burns off deposits better, but becomes hot enough to cause preignition at heavy loads and high opeating temperatures. Selecting the plug range is defined by speeds and loads and engine design. Only very small effects by outside temperatures, and that is probably due to air density and rich/lean effects, not actual air temp. If the tip runs several hundred degrees due to the flame, then + or - 50F in incoming air temperature won't mean too much.

send me an address off line and I will forward some short articles on plug information.

k