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 Post subject: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 12:57 pm 
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80 cc

Joined: Tue Jan 03, 2017 2:42 pm
Posts: 15
Hi,
I broke the thread on my KTM 250 excf while looking at the oil screen. The thread ended up in the engine ! :shock:
I'm ashamed, feel stupid, and don't understand as it was not really resisting :oops:. I've just bought this used bike, when I've unscrewed it, there was some red rubber which fell apart(we can still see some on the photo), I don't know if it's normal or not. I've cleaned the bolt from this red mess before to put it back, but ripped everything off :-(.

So now, I need to fix it (after I finished slapping myself).

Do you think I need to replace the left block of the engine, if so do you know anywhere I could find the part?
Did someone have this kind of issue, do you think we can redo the thread?

Thanks a lot!

I'll ask the local group if they know a good mechanic where I live


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 1:30 pm 
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650 cc Monster

Joined: Fri Apr 03, 2009 3:08 pm
Posts: 4440
Don't beat yourself up.

It looks to me like someone previously stripped the thread...easily done as KTMs seem to be made from cheese...and bodged the replacement repair.

You can get threads repaired using helicoil inserts

http://www.bollhoff-armstrong.co.uk/en/ ... lassic.php

by someone who knows what they are doing.

Sadly, it looks as though someone who didn't know what they were doing had a go, realised they'd messed up, and sold the bike.

There are two problems you have:

1) You need to recover the wire thread insert. It is steel, so you might be able to do something with a magnetic probe.

2) You have to repair the hole, which is already drilled too big (why the initial repair failed).

I don't know if it's possible to replace just one crankcase half on that engine...some engines need the crankcases replaced as a matched pair (on my KTM 950, if you crack a cam bridge then you can't just replace the bridge...you have to buy a complete new cylinder-head!)

Sorry this isn't better news!


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 2:05 pm 
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125cc
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Joined: Mon Nov 05, 2012 10:56 am
Posts: 195
Location: Burton on Trent
I'd have thought it was possible to make an interference fit bush to press in there after it's been cleaned out. With a smaller drain hole screw it could work. You just need someone local you can trust to do it. EG a classic bike restorer.

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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 2:40 pm 
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80 cc

Joined: Tue Jan 03, 2017 2:42 pm
Posts: 15
It sounds like it's not lost. I've seen some used crankcase as well, around £200. I'm wondering how much a garage would take to change it.
I was full of enthusiasm to do more work than usual on this new bike, after what just happened I lost confidence!


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 6:50 pm 
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200 cc

Joined: Thu Jan 14, 2010 1:08 am
Posts: 312
Just a thought ,when i was employed as an engineer , if a thread was beyond repair by means of a helicoil the next step was called a time sert i think ! this is similar to a helicoil but larger and a solid insert rather than just the thread replacement .
It would still be able to do in place ,no need to strip to do but plenty of flushing out of the motor afterwards .
We did loads when i worked at Alex E Carr engineers in Hull East Yorks , down Spring Bank Extension .I aught to know the phone no as i worked there for thirteen years.
Not sure if this helps , just ask around about a firm who can do you a TIMESERT !
good luck , pity about your problem but it does look like someone has used gasket sealer on it before to stop a leak .
Julian East Yorks trf Group rep :cry:


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 7:00 pm 
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80 cc

Joined: Tue Jan 03, 2017 2:42 pm
Posts: 15
I'll have a look into this as well. Thanks!

Quote:
no need to strip to do but plenty of flushing out of the motor afterwards


Ah, you mean I might not have to remove the whole block? There is no oil in the engine anymore, and obviously I hadn't turn it back on.So not much should have gone inside. I thought if we were doing anything on the thread it would end up putting some pieces in the engine, which was a big risk.

What do you mean by flushing out? Put some clean oil and let it drop by the "fixed" thread?

Cheers


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 9:15 pm 
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80 cc

Joined: Tue Jan 03, 2017 2:42 pm
Posts: 15
I've just found a company which fixes thread, and even have a digital camera to look inside and do the cleaning. The time sert helped me to find it. It looks pretty cool.
I've look and it seems the space for the oil screen is not too risky, it should be ok to clean it.


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 9:22 pm 
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200 cc

Joined: Thu Jan 14, 2010 1:08 am
Posts: 312
Hi , just looked up about Timeserts ,they do exist ,they are a different thing to helicoils ,most small size helicoil kits are cheap enough to buy for home use, but in larger sizes i dont think the timesert kit is for the DIY market . ring around your local engineers or garages .You will probably be able to screw the remains if the helicoil back out ,anticlockwise ,with some long nose pliers but try to get it out in one piece ,gently .
i would be suprised if the person who had the helicoil fitted striped down the motor ,therefore there is the possibility that bits of alloy were already in the motor ,the same as will probably happen with the timesert ,but if you ( THEY )drill the pilot hole with plenty of grease on the drill bit and on the tap you will minimise this .
To flush the engine out after fitting try something like parafin , pour plenty in the oil filler hole and allow it to flow out through the oil screen hole hopefully taking any swarf out with it . Do not run ,People can offer alternatives if they can .Not sure if your bike has two screens ,mine did and two oil filters ,but remove all drains and flush through . You also can get flushing oil that you use to clean the engine out ,change the filters a couple of times and drain ,do not ride the bike on flushing oil just run it through . When it`s done take it for a steady run with your fingers crossed . :shock:


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 10:18 pm 
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80 cc

Joined: Tue Jan 03, 2017 2:42 pm
Posts: 15
Quote:
To flush the engine out after fitting try something like parafin , pour plenty in the oil filler hole and allow it to flow out through the oil screen hole hopefully taking any swarf out with it . Do not run ,People can offer alternatives if they can .Not sure if your bike has two screens ,mine did and two oil filters ,but remove all drains and flush through . You also can get flushing oil that you use to clean the engine out ,change the filters a couple of times and drain ,do not ride the bike on flushing oil just run it through . When it`s done take it for a steady run with your fingers crossed . :shock:


Thanks for the update! I'll probably try this. I'll use a magnet too, just in case.


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 Post subject: Re: Broke thread while servicing
PostPosted: Sat Jan 28, 2017 10:49 pm 
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650 cc Monster

Joined: Fri Apr 03, 2009 3:08 pm
Posts: 4440
Can you use a magnet to drag it over to the oil drain hole?


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