Spark Plug Suppressor Caps

Moderator: Moderators

Post Reply
User avatar
Tirpitz
zxr400 oc member
zxr400 oc member
Posts: 766
Joined: Sun Dec 12, 2010 2:45 pm
My Bike: Kawasaki ZXR400L4
Location: Doncaster, South Yorkshire

Spark Plug Suppressor Caps

Post by Tirpitz »

Hopefully this bit of information will prevent other people wasting time and money and come up when people do a search. I'm particularly posting this up as there are various posts on here which are misleading. Here goes.

No after market spark plug suppressor caps fit the ZXR400. That's right - NONE. You can try as many different NGK caps as you like - 90 degree short, 90 degree long, 102 degree short, 102 degree long and even straight. NONE OF THEM ARE LONG ENOUGH.

In particular I have read 'advice' that the SD05F or SD05FM straight caps fit - they DO NOT. There are two problems with these - 1. The rubber boot at the bottom of the cap makes for a very tight fit in the plug tunnel, 2. The rubber seal at the top of the cap is about 10mm or so lower than the top of the rocker cover when inserted. This means that you have bugger all chance of getting the cap back off the plug when you have pushed it on as you cannot grab the cap, it is down the tunnel. If you try to pull it off with the HT lead the lead will pull out. I had an hour of fun today when fitting this type of cap and trying to get it off (thankfully just one to try, then I tried to get it off before doing the rest). I only got it off by breaking the top so I could get long nosed pliars on the threaded screw and levering it out, after spraying WD40 down the plug tunnel to loosen the grip of the rubber boot on the tunnel wall. I had almost resigned myself to taking the rocker cover off so that the plug tunnel could be removed.

So, don't make the same mistake, you cannot get aftermarket caps. You have two choices - 1. Used caps - but these are an electrical item probably 20 odd years old, you may be lucky and get a good set which are not leaking to ground, you may be unlucky; 2. New OEM - but at around £30 per cap, they are a ridiculous price.

The maker of the OEM caps is shown on them (I forget what it is now) so I also Googled the make and code to see if they were available direct but I can find no supplier in the UK (other than Kawasaki). As these caps are used on other Kwaks and also on Suzukis (Pretty sure same make on oil cooled Gixxers. I didn't try Suzuki dealers to see if they are cheaper) I wouldn't be surprised if they can actually be obtained elsewhere but I suspect that 'elsewhere' will be in Japan. Possibly someone like Mori Man may be able to investigate this? At £120 plus postage in the UK for a set buying from Japan (if they can be obtained cheaply there) would be a viable option.

So there we go.

While I'm at, I've also read 'advice' that it is better to buy non-suppressor caps and non-resistor spark plugs. Fine, go ahead if you know better than the person who designed your CDI unit.

Not all 'advice' on the internet is good advice. After today's little job I'm missing about 2 hours of my life which I won't see again. Be warned. :smt018
ZXR400 L4, purple / black / pink
Hel braided hoses
Pirelli Diablos
Ohlins steering damper
A16 carbon fibre exhaust can
Nitron Sport shock
Post Reply