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Triumph 650 Cylinder Head Plug weld drill + retap
#809652 05/20/20 6:00 pm
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I have a Triumph Tiger 1970 that was fitted with an insert in the spark plug hole. I would like it removing and the hole welding up and redrilled and tapped for a standard spark plug Champion N3C. I am in Houston Texas. Does anyone know a good machine shop that can do this work ?

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Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809668 05/20/20 8:02 pm
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Maybe a replacement head would be cheaper and get the bike back on the road quicker?

Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809676 05/20/20 8:33 pm
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Is the implication that they used a different thread form to a standard 14mm sparking plug thread? Some companies use thread inserts in alloy castings as a stronger thread as standard. Back in the day, a few of my bikes had spark plug inserts after some ham fisted oik (sometimes me) had stripped them, but always back to the original thread size.

Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809687 05/20/20 9:46 pm
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I have found that the present inserts sold on the market today tend to oxidise and burn away inside the head. This can cause damage. I can buy a new head for $850 or used for about $250 however I figured I would like to repair the one I have.

Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809689 05/20/20 9:52 pm
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Originally Posted by thackero
I have a Triumph Tiger 1970 that was fitted with an insert in the spark plug hole. I would like it removing and the hole welding up and redrilled and tapped for a standard spark plug Champion N3C. I am in Houston Texas. Does anyone know a good machine shop that can do this work ?

Cliff Holland at Gulf Coast BMW should be able to help if it can be done. I doubt they would do something like this in their shop, but if it's doable they would know a shop that can. Getting a weldment to match the surface texture of the cast head would be some trick, far more difficult than the drilling, welding and maching, but anything is possible these days with enough $$.

Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809709 05/20/20 11:05 pm
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If you are not concerned with shipping it, you could try E&V Engineering in Michigan.

https://www.shopevengineering.com/services


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project
1971 BSA A65 650 - Project
1972 Norton Commando 750 "Combat"


"Every time I listen to AC/DC, so do my neighbors"

Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809719 05/21/20 12:41 am
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+1 for E & V. They did an exhaust spigot for one of mine. Beautiful craftsmanship and great customer service.
Seems to me it was only about $100. Long time ago.

Last edited by desco; 05/21/20 12:42 am. Reason: addition

1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809756 05/21/20 4:13 am
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Hi thakero, What exactly do you mean by insert? Helicoil or timesert?

Houston is a big city. More than likely there is a good specialty machine shop that does this sort of work. Needless to say these shops are getting fewer all the time.

Remove head. Take sharp detailed photos if what you have from both sides & overall photo of head. Thing is good specialty shops can do anything to any head, including machining the top edge of plug bore to replicate factory machining. A good shop can repair it properly even if they never seen a Triumph head before.

That said, you have recommendation for EV. Call them & have a chat. Email your photos. Then decide.

You would probably find gold nugget before a good used head. I've not seen the new production heads in person. I don't know anybody that's used them. If you could get your head fixed, probably the best bet in long run.
Don


1973 Tiger 750
Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809757 05/21/20 4:18 am
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Quote;
You would probably find gold nugget before a good used head.

Great line.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809777 05/21/20 9:03 am
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Just use a timesert on it...problem solved....and on your own workbench!!! They don't erode or back out.

Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809806 05/21/20 12:59 pm
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In the past, I did what tridentt150v recommends. I used the Stanley M14 sav-a-thread kit (https://www.toolsource.com/spark-pl..._763/savathread-kit-m14x125-p-72402.html), which is specifically for spark plug applications. The kit comes with everything needed to do the job. I was very nervous at first about doing it but I went slowly and followed the instructions. In the end, the repair worked out great and no issues with the insert backing out.

Noel

Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809844 05/21/20 5:03 pm
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That’s why we need to know what’s in there now. Can a repair insert be installed? Is there enough metal left?
Don


1973 Tiger 750
Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809862 05/21/20 8:17 pm
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It's a little unclear what you mean. What type of plug is in there now with the insert? What type of insert, helicoil or timesert? If it works well as is I would leave it alone. I would think you risk warping the head by welding it. Then skimming a Triumph head can lead to some bad problems. What happens is with the head skimmed the pushrod tubes and seals hold up those parts of the head and when you torque it down you warp it again. Do a search on crush height. Timesert is excellent quality stuff and makes an oversize insert that takes a standard 14mm spark plug. These guys have done machine work for me in past. Very competent.
https://www.yellowpages.com/houston-tx/mip/motor-reconditioning-co-544209216
You could also try Big D cycle in Dallas. They are a first rate shop that deals exclusively with vintage Brit Bikes
https://www.facebook.com/pages/category/Motorcycle-Dealership/Big-D-Cycle-190119784358276/
Not sure about British USA here in Houston. Think they mainly deal with modern bikes anymore

Last edited by htown; 05/22/20 3:21 pm.

1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2018 Kawasaki Z900RS


Everything will be alright in the end. If its not alright, its not the end.
Re: Triumph 650 Cylinder Head Plug weld drill + retap
thackero #809891 05/22/20 3:57 am
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You shouldn't skim heads....instead get them straightened.


Moderated by  John Healy 

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