Plug Caps and Plugs?

[Shedman]

Hi guy's, just a quick question that I hope someone will know the answer to. The Haynes Bible states NGK DR8ES plugs for a UK 750 which I believe are resistor plugs, do I need to have non resistor plug caps with resistor plugs? I've been reading on the interweb that using resistor plugs and resistor caps creates too much resistance and reduces the spark causing the engine to be under powered. Is there any truth in it?

[dcf750]

Hi Shedman, the Kawasaki handbook shows NGK DR8ES for Canadian bikes and NGK D9EA for others, see picture attached. I’ve also attached a pic from spark-plugs.co.uk of NGK symbol codes. Sorry but I do not know about resistor plugs and caps being an issue. Hopefully someone else can give you more info.

Handbook info

NGK codes

[Shedman]

Thanks for the input Den. Haynes has the UK C1, C2, C3 and C4 as DR8ES and D9EA for the US C1, C2, C3 and C4 and the DR9EA for all other models. So according to Haynes only the US models run with non resistor plugs, I wonder why that would be?

[dcf750]

I checked my Kawasaki workshop manual and this aligns with the handbook, so the Haynes manual is at odds with the spec by Kawasaki. Incidentally my C3 and C4 both have the resistor plugs (I have not change these yet), so have previous owners used Haynes guidelines? I would expect Kawasaki to be correct

[Shedman]

I checked out Cradley Heath Kawasaki and they list DR8ES for the UK bike, strangely they also have the DR8ES-L on the same page but with the part number as DR8EA but that it is no longer used. I agree that if Kawasaki say what plugs to use then that must be correct. Who'd have thought it could be so confusing trying to change a set of plugs?

[Shedman]

I've just ordered 4x D9EA for £7.56 with freepost. For that price I may as well give them a go, it does seem to make sense of having a resistor plug cap with a non resistor plug. I did a search for non resistor plug caps and the vast majority were listed for old British bikes and they were mostly made of rubber so I can't see that being right. All of this came about because my bike has always been a slow starter, I had the volt meter on everything and it all checked out, the carbs are clean, new jets......anyway I checked the plugs and caps and they both have resistors I'm pretty sure I must have changed the plugs at some time in the past but I have no idea why I would have put DR8ES-L plugs in unless I ordered DR8ES plugs from ebay as suggested by Haynes and the seller sent DR8ES-L plugs instead They all sparked equally when laid on the head and the motor was cranked but there was never what you'd call a big fat blue spark. I'll try the D9EA's with new resistor caps when they arrive and report back. Thanks Den

[dcf750]

Where did you order your plugs from? £7.56 sounds pretty good

[Shedman]

ebay, item number 323745197299 I never buy them from M/C Dealers. Still waiting for them to arrive, hopefully today.

[dcf750]

Thanks for the details, I will get some on order.

[Freddy]

For what its worth, I recommend paying a little extra and using iridium plugs.

I don't run them just because they last longer (which they do). I run them in the knowledge they are running at peak performance over the full distance I run them, and IF they result in a slight better performance, that's a bonus and one the 750 engine certainly can benefit from.

I find them not that expensive to buy a pack of 4 on Ebay. Usually that's from a supplier in the UK, postage being not much.