Compression test

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
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Ltriumph
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Compression test

#1 Post by Ltriumph » Thu Jan 13, 2022 11:18 pm

I have a 1978 2000TC, had a compression test results as follows: 170, 150, 145, 145, 130, 150 - it does burn a little oil. I am not mechanically capable of pulling the head off etc, When I purchased it 5 years ago compressions were all within the 10% tolerance level, done about 15,000 km since. I do ant to keep this car for a long time. What course of action do you think I should take when discussing with a mechanic?
Triumph TC 2000 1978
Triumph Bonneville T120 2018

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Alec
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Re: Compression test

#2 Post by Alec » Fri Jan 14, 2022 10:08 am

Hello LTriumph,

the 170 is a bit odd, and the 130 a bit low. If you don't intend to keep it for long then the only thing I would do is to check the tappet clearances. This will affect the compression readings if they are not right, although by how much I don't know? If it's driving OK. then that is a factor as to what you do.

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Re: Compression test

#3 Post by Charles H » Fri Jan 14, 2022 4:29 pm

I will assume that you DO WANT to keep this car for a long time, therefore would firstly re-check no1 since it does seem a bit high compared to all the other cylinders. As before, check the valve clearances, and perhaps then check no5 with a little oil down the bore first to see if it is lower due to rings or a valve. Good luck.
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Re: Compression test

#4 Post by Ltriumph » Fri Jan 14, 2022 7:00 pm

Sorry about my computer skills. Yes I do want to keep it.
Triumph TC 2000 1978
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Re: Compression test

#5 Post by Ltriumph » Fri Jan 14, 2022 7:02 pm

Meant to add. Lacks a bit of power on the hills now.
Triumph TC 2000 1978
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Re: Compression test

#6 Post by Alec » Sat Jan 15, 2022 9:57 am

Hello LTriumph,

this is what I would do.
Go through setting the valve clearances, adjust the fuelling and ignition to the best they can be set and see if there is any difference.
I misread your original post, by the way, I didn't think then that you wanted to keep the car. The next step, if you are not happy with the running is to remove the cylinder head and do whatever is required to bring that up to scratch. This will also allow a view of the cylinders and give an idea of wear of the bores and pistons.

It may be that after removing and assessing the head and bores that it needs a rebuild with the option of finding a known good replacement engine, although Iimagine they will be thin on the ground. Personally I prefer to repair what I have and then I know it is right. With the best will in the world you do not usually know exctly how good a replacement engine is until it's fitted.

Alec
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