Hi all,

So I was removing the spark plugs to test compression and No 1 & 3 were a sod to remove, all are black and buggered. after testing compression (aroud 124 on all four points, still need to see if this is in range) went to put the new sparks in and the same holes wouldn't take the spark they locked out after a turn or two so i'm presuming they have been cross threaded at some point.

So am I going to need to look at dropping the whole engine out to rethread the cylinder head and if so how much of a job is it as i've never removed an engine before and is it a one man job, also has anyone done a rethread?

Advice greatly appreciated.

Dropping out is a few bolts once you've cleared wiring, pipes etc. one long one at the back and two in the head (on 3tj) or remove cradle on 3en1. I've done it on my own with a jack and block of wood beneath or with a mate I've supported engine and lifted the bike up off the engine. Not done a rethread though. You could try chasing it with a tap to clean up the threads first, if not I think it's a helicoil job.

I had a similar problem with my 3en2, I used a Spark Plug Thread Chaser to clean up the thread.

Don't force it, take a little at a time and back off/start again if it seems to get too tight.

It doesn't sound like the end of the world as we know it
Yes the plugs are a pain and doing this job might be complicated but you might not need to drop the engine. Take the front mudguard off, drain the coolant (disconnect the left hose of in the bleed screw on the hose), and remove the radiator. Now look for the locating bolts on the rubber shroud and get that out the way. Take the airbox off and you should be able to get more access to the plug holes.
Take off the generator cover, find the timing mark and line it with the joint in the crank cases at the front. This TDC 1 + 4 so you can work on 2+3 ... Then move the flywheel 180 deg and work on 1+4.
What you need now is a thread restorer like 261794348636, coppaslip it and then screw it in 2 revolutions then back 1/2

That should keep you quiet for a while

Yeah you shouldn't need to take the engine out to clean the threads up, either use a thread chaser or a tapper tap and plenty of copper grease and work slowly you shouldn't drop much swarf in the bores, and its worth while making sure the cylinder your working on is on its exhaust stroke then you can blast out that cylinder with compressed air aswell.
Done a couple of cars like that an never had a problem.

Cheers
Ian

Cheers guys, will look at doing it with the engine in place and let you know how I get on.

Si.

If you start by turning the thread chaser anti clockwise first you can find where the thread starts

What you need is a "Spark Plug Thread Repair and Restoring Tool"

No need to remove engine also saves costs of Gaskets

You drop it through the Hole. Wind it open. It will locate on good Threads at the bottom of the Hole, so no chance of Cross Threading.

As it is cutting from the bottom, no Swarf drops into Cylinder

That looks the kiddie
It chases the thread fom the bottom where it's intact

Yep.

And I can Verify it is worth every Penny

Not Expensive either

http://www.toolandfix.com/automotive/to ... tools.html