Planet Minis

Branyers

Up until now, I've been an advocate of the Kitaco Ultra SE heads. After all, I liked the first one enough to buy a second one. For the money, I thought they were a damn good bit of kit, very powerful. I never complained about the special 8mm iridium plugs they require, even though they run upwards of $15 a piece. They're supposed to have an ultra long life anyway.

No, the real problem, is when you strip the threads on the spark plug hole. It happens to everyone at some point, especially if you're taking repeated readings during tuning. It isn't so cut and dry as the standard M10 x 1.0 spark plug. You most certainly will have to special order your solution because most shops don't carry the special M8 x 1.0 helicoils or time-serts. I opted for the time-sert because I deem them more reliable. But it was a pain in the ass to install. Read on.

Another problem with the SE heads is that the plug threads are countersunk to accommodate the extra long electrode of the special iridium plug. A standard electrode is 10mm long. Well, the special iridium plug is almost 20 mm long! The first 5mm or so of the plug hole on the SE head is not threaded. If you simply widen the hole and drop in a 11.7mm time-sert, the tip of the electrode will not reach the combustion chamber! What you have is a plug whose electrode tip is still up inside the plug hole. Sure, it will run, but combustion will be far less than optimal.

A helicoil (inferior to time-serts, IMO) in this case isn't a much better option, requiring removal of the head in order to install it. That is, unless you could remove the 'tang' with a needle nose. It would still be difficult to tell if the helicoil was flush with the chamber opening. Again, the problem is that the base of the electrode is wider than the drill bit used to tap the hole. So you're still stuck with a plug that won't screw in all the way!

So, widen the hole with the drill bit provided, then use a slightly larger bit to widen the first 5mm of the hole and accommodate the wider electrode base of the iridium plug. If you take your time and keep it straight, you won't completely trash your $400 cylinder head.

Pictures worth a thousand words...

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Blackwoodz

If you run an anti seize lube you will not gald those threads.

FastMC

Nice repair job.

Branyers

I did eventually, but by then it was a goner. Lives and learns.

Branyers

Thanks. The time-serts install so much nicer than helicoils.

FastMC

I know, I've installed hundreds of them over the years . Recessing one like you did is tricky to get it right. Helicoils are crap IMO.

50r

my friends spark plug blew out of the head when he tried to bump it

kgmx744

Being a kitaco fan like you are, and after the headaches you went through, would you buy another one? or recommend it to someone who doesn't want to go through the same troubles you just went through? Just wondering how you feel about it now....Thanks for your input on the fix

Branyers

Well, the simple preventive solution of applying anti-seize to the threads might have prevented my mishap. I might still recommend the Kitaco kits if you can get a good deal on one. The power and quality is there, and other than this, mine have been very reliable. Just know that when you're buying something that takes a non-standard, "special" part, you'll be on your own if something goes wrong with it.

Just for the record, I feel the same way about some of the Takegawa heads that use special o-rings and seals instead of standard Honda paper gaskets. Just my $0.02 worth though.