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BF225 sparkplug rethreading

James t

Member
I pulled a plug today which was seized. Tried to soak it in plusgas penetrating oil to free it up, but still pulled a bit of the alloy thread material with it... the plug hole is too deep in the head for me to tell how bad it is...

so what I’m thinking of doing but I’d really like a second opinion on is: 1. First run a tap through with plenty of grease to catch swarf and then see if new plug will torque up in the hole. If plug doesn’t strip the remains thread out then I’ll leave it in there after greasing it up with high temp grease. If it strips the thread then 2. Install a Time Sert (rather than a helicoil) bush.

i want to do the above without taking the head off if that’s feasible (was thinking of stuffing oily rag down into cylinder before any drilling cutting of 2. Then use compressed air or a vacuum poked down into cyclinder to get any remaining swarf out.)
 
The worst that can happen is swarf will get stuck under a valve and cause compression loss. Just be aware that when the engine is running the combustion pressures are immense, have have seen a spark plug push the igniter out and go right through the cowl like a bullet.
 
Just a little update...
I used the Wurth Time Sert deep spark plug hole repair kit to fix two of the spark plug holes on my BF225 (I had to import from the US but imho was money well spent!). I haven’t had a chance to fire up the repaired engine for a couple of months because I was also waiting on a gearbox repair. The upshot is that once the plugs were put back into the newly rethreaded and bushes holes the engine fired up first time and I ran her for five minutes. I’m hoping that confirms that the job was done ok.
assuming the repair holds... all I can smash is that I couldn’t recommend the Time Sert kit highly enough, really easy for a moderately competent amateur like me to do just following the instructions. A really nicely put together set of tapping and cutting tools including bushes and insertion tool with instructions. My heart was in my mouth whilst doing the job...
 
Good show!
My heart is always in my mouth doing anything like that and I've been a pro mechanic for more years than I care to admit.

Time-Sert is a far superior method than Heli-Coil for doing this repair so you chose your path wisely.

Congratulations on what sounds like a job well done!
 
I had to do this on my 07 BF225 a couple of years ago. I had my local garage fit the TimeSert at a total cost of £40!!

There was quite a bit of swarf in the cylinder afterwards but I adapted a shop vac with a piece of fuel pipe and sucked quite a bit out. I was informed that any bits left would be blown out when the engine ran and I've not had any problems since.

Just be aware that if the plug was one of the bottom two then it's an indication that water may be getting sucking in through the idle exhaust and causing corrosion - this is what I've just discovered.
 
Hmm - how does water get sucked up into the cylinder at idle and is there anything I can do to stop it? I had to do both bottom plugs - I assumed it was down to poor maintenance procedures in the past...
Btw you did very well at £40! I had to buy kit from US - cost a lot more than that!!
 
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James - there is a problem with the design of the original exhaust tubes that allows water to get sucked into the bottom two cylinders under certain circumstances. It is all covered in Honda Service Bulletin #56, which includes instructions on how to replace them with redesigned exhaust tubes. If you need a copy, send an e-mail to me at [email protected] and ask for it.
 
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