T140V 1976 Composite Gasket

[Migsan]

Champion NC3 are the recommended, and what many use. I swapped to an equivalent, NGK B8ES which I think runs better (just my opinion for my bike). NGK B7ES runs hotter, could try them.

Did you tune the carbs for idle? The 1.5 turns out is a starting point. Could be more. Do you want a link to carb tuning?

So I placed new NKG B7ES went for a 6 mile ride no idle! Carbs mixture screws were 1 +3/4 turn neddle in the middle position. Plug chop looked like this

Was able to check the cylinders with the endoscope back home and it looked like this

Similar on both barrels but it looks worst on the exhaust side. it appears there is still oil there!
I guess I have no choice than to remove the head and recheck everything. Could it be coming from the valve guides?
Cheers

 

[solomon]

To me the plugs look sooty, not oily (dull, not shiny) .
Another thing to check is float height in the carbs. To high a fuel level can cause too-rich running.

 

[Migsan]

To me the plugs look sooty, not oily (dull, not shiny) .
Another thing to check is float height in the carbs. To high a fuel level can cause too-rich running.

I agree they are not oily. But there is oil in the barrels not as much as before.
So I removed the head and the gasket sealed perfectly. Rechecked the head and is straight.
I removed the valves and believe I found the culprit I had some significant play in the valve guides. HAd good compression 150 psi on both barrels so I guess the rings are sealing properly.

To me the plugs look sooty, not oily (dull, not shiny) .
Another thing to check is float height in the carbs. To high a fuel level can cause too-rich running.

Thanks @solomon
I went ahead and removed the cylinder head. Confirmed that both pistons were with oil but far less than previouslly. The gasket was sealinh everything perfectly.
Had good compression so decided to check the valves and valve guides. Valves were sealing properly but there was play in all of the valve guides!

 

[solomon]

What are you going to do now?

 

[Migsan]

What are you going to do now?

I was gonna replace the valve guides and maybe the valves as well. Still reading about it to see if it´s safe doing it myself! I understand is very easy to damage the head by either enlarging the holes or not fitting the apropriate size.
What do you think @solomon?
Thank you very much!

 

[solomon]

I was gonna replace the valve guides and maybe the valves as well. Still reading about it to see if it´s safe doing it myself! I understand is very easy to damage the head by either enlarging the holes or not fitting the apropriate size.
What do you think @solomon?
Thank you very much!

I'm not experienced in this! I like you have read it's easy to damage head. I would send it off myself, I think, if I found somewhere and it was reasonable price. A good condition head is expensive to replace, and might not be all that good condition.
If you do want to try yourself, I think Lunmad has a video on YouTube.

 

[solomon]

Here's the man. He died recently, RIP




Edit
Actually, Lunmad is inspiring. I'd probably give it a go, be ultra careful. Stop if things weren't going well
View: https://m.youtube.com/watch?v=GEg18pE0PHQ

 

[Migsan]

I'm not experienced in this! I like you have read it's easy to damage head. I would send it off myself, I think, if I found somewhere and it was reasonable price. A good condition head is expensive to replace, and might not be all that good condition.
If you do want to try yourself, I think Lunmad has a video on YouTube.

I have seen Lunmad video but he skips the removal part. I believe you need to warm up the head to 100Cº and also make sure all the carbon deposits around the valve guides are clean!
To insert the new valve guides Lunmad just hammers them in after boiling the head in a water!
I guess it´s on removal that you can enlarge the hole!
Lunmad videos will be a reference for years to come! May he rest in peace!

 

[solomon]

Think I'd use the kitchen oven rather than water. Could maybe be a bit hotter than 100⁰C. Worked well for me when removing bearings from a crankcase.


https://www.enginebuildermag.com/2011/07/cleaning-cylinder-heads-and-blocks/
Above warns of too high a temperature. Also warns valve guides might come loose!

 

[Migsan]

Think I'd use the kitchen oven rather than water. Could maybe be a bit hotter than 100⁰C. Worked well for me when removing bearings from a crankcase.


https://www.enginebuildermag.com/2011/07/cleaning-cylinder-heads-and-blocks/

I think i will go for the Norman Hyde set with the inlet seals!

 

[solomon]

I think i will go for the Norman Hyde set with the inlet seals!

Look good. Well according to Norman Hyde!
No point going cheap on the guides.

You'll soon have an excellent bike.

Take pictures if you do it yourself. Would be of interest to someone if selling the bike ever.

 

[Migsan]

Look good. Well according to Norman Hyde!
No point going cheap on the guides.

You'll soon have an excellent bike.

Take pictures if you do it yourself. Would be of interest to someone if selling the bike ever.

Will do @solomon
I will let you know how I did in a couple of weeks when I return form the UK.
Thank you very much for all your help!

 

[solomon]

Will do @solomon
I will let you know how I did in a couple of weeks when I return form the UK.
Thank you very much for all your help!

I didn't really help. You did it all yourself. Think I learnt from you.

Straightening your own head is something I've not read anyone doing, even the most experienced owners.

If using the oven, put the head in cold, so it heats gently, doesn't distort. Maybe even lightly cover it with foil (I have a gas oven, so would for sure).

I think I heated my oven to 160⁰C when removing crankcase bearings. Left in a while, maybe 30 minutes. Bearings dropped out in the oven!

 

[Migsan]

I didn't really help. You did it all yourself. Think I learnt from you.

Straightening your own head is something I've not read anyone doing, even the most experienced owners.

If using the oven, put the head in cold, so it heats gently, doesn't distort. Maybe even lightly cover it with foil (I have a gas oven, so would for sure).

I think I heated my oven to 160⁰C when removing crankcase bearings. Left in a while, maybe 30 minutes. Bearings dropped out in the oven!

Thanks @solomon
That´s a good tip! I had a go yesterday and I realized I will get the proper tools to do it. It needs a nice fitting drift and the inserting tool to keep it nice and center
https://normanhyde.co.uk/meriden-triumph-bsa/triumph-t140-tr7/valve-guide-tool-kit.htmlIt's price tool on norman hyde because I´ve seen similar kit for half that price. Not sure if it´s specific for the T140 head. Regardless even with the added cost it will come out cheaper than to send it out!

 

[solomon]

Leave the new guides overnight in the freezer, wrapped individually in cling film.
Take one out at at time when the time comes.
I'd take my time. If the first drifting takes a long time, I'd reheat the head if it's noticeably cooled. No hurry, no cry.

 

[solomon]

norman hyde

How does this kit work? Can't find anything on the internet.

 

[Migsan]

How does this kit work? Can't find anything on the internet.

It's a drift punch for removal. The other is a press that allows the guide to be aligned on insertion!
I managed to remove the inlet guides easily but the exhaust one won't bugde!
Removed all the carbon residue as best as I could.
The outer diameter of the inlet guides is aprox 11.5mm would that be standard?
Can't find the measurements!

How does this kit work? Can't find anything on the internet.

 

[solomon]

I managed to remove the inlet guides easily but the exhaust one won't bugde!

The bronze guide will have expanded too. Squirting WD-40 on one just before drifting might cool it enough to make a difference.

.
The outer diameter of the inlet guides is aprox 11.5mm would that be standard?

I don't know. Think they are measured in thousands of an inch though.

 

[Migsan]

The bronze guide will have expanded too. Squirting WD-40 on one just before drifting might cool it enough to make a difference.

I don't know. Think they are measured in thousands of an inch though.

I will get back in two weeks time and let you know @solomon

 

[Mark T120]

Hi everyone
After reading several posts about blown gaskets I am still left with several doubts. Before start taking the engine head appart I will describe the issue I am having.

Done the top end recently, used composite gasket with hylomar smear. torqued 22 ft-lbs and 18 ft-lbs on the inner 5/16´´. Done a heat cycle and retoqued them to 18 and 16 ft-lbs respectively. Had good compression on both sides aprox 150 psi with open throttle valve. Done 100 miles and retorqued. Engine running strong. Was gonna make the 500 miles retorque but started having issues 150-200 miles after the last retorque. One day engine running like a dream and the next time I took the bike for a ride the engine started boging and running poorly untill it stoped. Had oil on the spark plugs and the pistons were really dirty. lots of smoke from the exhaust
Retorqued the engine head again placed new spark plugs and it started really well. less smoke but figured it would require time to burn the oil first. Took the bike for a 20 miles ride, was pulling strong but when I got home engine started running erractly at tickover and eventually dying. Rechecked the torque again and it seemed the bolts were still tight. Tried to mark the bolts to see if they would move.
New set of plugs and good as new again! still some slight smoke. Again after 20 miles ride my plugs were fouled again plus the tickover wasn't has acurate like when I started the engine.
My question is this still from residual oil or the gasket is blowned and requires replacing again? Do I need to go through a couple more pairs of plugs to clean those barrels and pistons?
Plus the valve guides seemed quiet tight and the head seemed flat but again I am no expert, perhaps it will require rectification?
I am using the wide washers and I could see there were minor indentantions from previous narrower type of washer but because they werent too deep I didn't thought it would be signifincant.
Other information that might be usefull is this was a complete engine rebuild and had a brand new morgo oil pump. Drained the sump and had around 170ml of oil wich is quiet near the 150 ml required for priming, plus I have a really strong oil return flow. Knowing that the compression is good I think that oil ascending to the combustion chamber from the rings is not very likelly correct?
Any thoughts?
Thank you very much in advance!

Is there evidence of a blown gasket, i.e a witness of oil. It sounds like it is running rich to me too much fuel in the mixture.