Spark plug woe

[Revvers]

Hi all. I’ve wrestled my Scootopia exhaust on and now I can’t get the bloody spark plug to screw in! It feels like it’s stripped as it only goes a few turns into the barrel and stops. It came out fine. I don’t know what to do. I’ve never had this before and try as I might I cannot get the damn think to go a long way down. Stupid question I know but it has to go right down the barrel doesn’t it???

[Warkton Tornado No.1]

Oh Heck!

The spark plug relies upon the captive washer sealing in the combustion process, so all the way in or not @ all.

It can be sorted, but unless you have the kit, will involve a strip down.

[Revvers]

Bugger

[Revvers]

I don’t even know how it happened! Plug cane out ok but I’m just trying to screw it in and it goes down to the last 3 threads. Infuriating

[al pushpak]

Could you maybe try another spark plug?

[Revvers]

Tried a new one mate. Didn’t screw in either. It’s hard to decide how much oomph to give the spanner

[Knowledge]

A spark plug tap should clear the path.

I bought one a few months back and it was not too expensive (eBay) and has been quite useful since.

Ok, you have got to drop the engine, remove the head, but you will probably find it won’t take as long to fix as you imagine (a bit like mowing the lawn. The longest part of the job is plucking up the energy to get the lawnmower out of the shed)

[Warkton Tornado No.1]

I have a proper double ended spark plug thread chaser. It's like a tap but doesn't cut any metal, only rolls it back in place. Inevitably though, there will be little bits of swarf which will drop into the bore. When I have used it, I tend to have the head off & work from the inside. I would advise against the use of a tap simply because chasers exist for that reason.

I suppose if plenty of grease was applied, you may capture the swarf. Or you get piston to TDC & get some tubing as an extension to your vacuum cleaner to suck out any cr@p.

I make these suggestions as I imagine you are really reluctant to dismantle the engine, but it really is the safest way.

[trotsky]

Hi Revvers,

I had a similar issue with a Casa 185 head. I used one of these to sort it ( Sealey Reverse Action Damaged Spark Plug Thread Tap Chaser Restorer 14mm MS003 ).

It might save you having to drop & pull the motor apart. Just liberally grease the threads & bottom, the grease will catch & hold any filings as you use it. I ran it through a couple of times, cleaning it & re-greasing, increasing the tension a very little until the plug ran cleanly in the head.

I hope this helps, Steve.

[Warkton Tornado No.1]

Hi Revvers,

I had a similar issue with a Casa 185 head. I used one of these to sort it ( Sealey Reverse Action Damaged Spark Plug Thread Tap Chaser Restorer 14mm MS003 ).

It might save you having to drop & pull the motor apart. Just liberally grease the bottom & the grease will catch & hold any filings as you use it. I ran it through a couple of times, cleaning it & re-greasing, increasing the tension a very little until the plug ran cleanly in the head.

I hope this helps, Steve.

You live & learn!

That looks like a great piece of kit & could be the solution that some of us didn't even know existed!

With respect, I would suggest that you take your time to get things right if you purchase this tool, or even ask a good engineer to do the job for you. An engineer should possess the 'eye' to ensure perpendicularity & 'feel' that things are right.

If you can keep the piston @ TDC to limit any swarf invasion, a good airline to blast out anything may be better than my previous suggestion

[CHRIS in MARGATE]

"Perpendicularity"

Fabulous word. Never seen it before but I like the sound of it. Got a nice ring to it.

[trotsky]

Hi all,

As WT1 says, if in doubt ask someone mechanically / more confidently minded, or utube it for examples of how to use it.

Ideally if you have access to an old head you can have a practice on that. I find that if you just tighten it very slightly so it just loosly bites in the thread & give it a wiggle & turn, you will get it to "centre" itself on the thread. Usually the bottom most threads are ok & you can get it to start running nicely to know it's running true. Obviously you will feel resistance where the thread is damaged.

Run it out completley a couple of times to get a feel for the threads & then tighten it slightly to start cleaning the damaged threads.

I hope this makes sense & good luck, Steve.

[Revvers]

Well guys, I took the plug out again and tried screwing it in 3 or 4 times, and it kind of started screwing in by hand fine. Then I gently used the plug spanner and it stopped. I’m no engineer but it was a kind of definite stop, rather than that ‘grating’ feeling you get with a dodgy thread. There was about 3 threads above the barrel. I decided to try and start it and she started 3rd kick! Took her for a couple of laps of the block and all seems ok! She didn’t idle but I’ve changed the air filter and it did that before I started work on the exhaust. The Scootopia exhaust sounds great and I just need to sort the jetting out now. But for belt and braces I may take her to my local scooter garage to get it checked. I haven’t got the bottle to attempt any of your fantastic suggestions. Thank you for your help and advice. Now where’s that post about jetting???

[MK Monty]

Just a thought, are you sure the barrel cowling is in the right position to line up with the spark plug hole. If it’s on the piss you could be cross threading the plug hole. Try loosening the cowl