Smoking Left Cylinder/exhaust

[Woollybandit]

Hi,
just finished rebuilding a 1971 T120 engine which destroyed a TS bearing and thus needed a rebore.
I noticed while doing so the left side inlet valve guide was new, actually it was also loose enough to drop out into my hand when the tappet springs were removed! I have tried to fix in place with green fixing Loctite 648 with valve clamped shut to retain valve lip seal axis but when I start it now it is very smoky from left exhaust, definitely white oil smoke so looks like the gluing didn’t work although the smoke 99% disappears after a minute which leads me to think the oil is draining down from the rocker box/the valve guide is sealing upon heat up/rocker shaft feed pipe is draining down overnight then it’s burnt off on startup.
Hardly any smoke while riding but more on tick over - I don’t leave it ticking over very long as I’m only 40 miles into running in.
I'm pretty sure it is the inlet valve (the new loose one) as if it was the exhaust valve it wouldn’t have the opportunity to burn in the chamber as that’s upstream.

Do I just leave it for now?

Take head off and try and fix guide seal? Glue it in with what?

Replace with an oversize guide? Does such a thing exist?
I imagine recutting a new larger diameter guide into the head requires a proper workshop as the guide would have to match the axis of valve and it’s seat …… unless a new seat is needed and recut to suit the new guide. By that progressive logic I obviously need a new engine ….

I guess resealing the existing guide into the head would be favourable but my luck doesn’t go that way. Today I already replaced the fork seals as they suddenly popped and left oil under the forks last night……..she’s a real sulker!

Thanks guys

 

[speedrattle]

oversize guides are made to solve this problem.

https://www.fagengine.com/products/individual-650-750-triumph-guides?_pos=1&_sid=00f3c2dee&_ss=r
dan at franz and grub in holllywood sells valve guides up to 0.050 oversize, plus installation tools.

im sure someone on your side does as well.

i recommend a competent machine shop for the repair, as the valve seat has to be recut concentric to the new guide, and that takes special tools and skills.

 

[Woollybandit]

The plot thickens. This morning I checked the crankcase drain and dropped 160ml of oil out of the case. This has accumulated in 44 hours since last running. On starting the bike after refitting the plug there was very little smoke.
When I reassembled the engine last week I meticulously took apart and cleaned the oil pump pistons and ball valves, checked the suction and release under pressure of the stop valves. All good, and when the bike is running I get 60psi at tickover and 70+psi at 4000rpm.

I wonder how the oil can be draining into the case?
I will wait another 2 days and check the wet-sumping again.
Also, I made a mistake about the smoking side - it isn’t that previously loose guide side but the other. Mmmmmm?

 

[Rudie]

This morning I checked the crankcase drain and dropped 160ml of oil out of the case. This has accumulated in 44 hours since last running.
I wonder how the oil can be draining into the case?
I will wait another 2 days and check the wet-sumping again.

Did you drain the sump, say, half an hour after the last ride/engine run? If not, how do you know this is not oil that simply drains to the sump after the engine stopped? Which is normal ...

To check if it is really "wet-sumping", you need to drain the sump "say, half an hour after the last ride/engine run" then leave the sump plug out and a measuring jug underneath it for "2 days".

 

[Woollybandit]

I’ll do that tomorrow. Although 160cc sounds like a lot to me …… based on no previous experience whatsoever. Thanks

 

[Woollybandit]

Update
48 hours later and the oil drained from the crankcase comes to just under 100cc.
Enough to splash around the crank on startup I think …. Shouldn’t be dry I feel.

but to solve the smoking have just ordered four new guides for tomorrow and the oven beckons………

 

[grandpaul]

Update
48 hours later and the oil drained from the crankcase comes to just under 100cc.
Enough to splash around the crank on startup I think …. Shouldn’t be dry I feel.

but to solve the smoking have just ordered four new guides for tomorrow and the oven beckons………

Just replacing guides won't fix the problem if the valves are also worn...

 

[speedrattle]

Update
48 hours later and the oil drained from the crankcase comes to just under 100cc.
Enough to splash around the crank on startup I think …. Shouldn’t be dry I feel.

but to solve the smoking have just ordered four new guides for tomorrow and the oven beckons………

clean off all the carbon before you take the guides out. scraping a dirty guide out of the head is one way the valve guide bore in the head gets screwed up in the first place.

 

[Woollybandit]

Just replacing guides won't fix the problem if the valves are also worn...

Valve stems are in accordance with the triumph specs. They may be younger than the rest of the engine. No marks on the tappet ends ….. flat as a pancake!

 

[Woollybandit]

clean off all the carbon before you take the guides out. scraping a dirty guide out of the head is one way the valve guide bore in the head gets screwed up in the first place.

Thanks Speedrattle, will give them a clean with scotchbrite while the oven is heating up.
Would you guys remove the guides from the hot head using drift and hammer or pulling them out with a long bolt and nut over a socket on the rocker box side?

Thx

 

[speedrattle]

the best way to do it is with a factory style puller tool. i have not done this so i am quoting people who know more than me, but the puller makes getting them out of a warmed head easier. the same tool is used to pull the new ones in, centered on the valve seat.

centering on the seat means less metal needs to be removed to cut the new seat for the valve. you cant put metal back, so this makes the head last longer

https://www.google.com/aclk?sa=l&ai...MI3Jzll7Pk8wIVjITICh2MCwXGEAQYASABEgJ3bPD_BwE
even so, people tap em in and out with a drift successfully. the shop manual gives the dimensions for the drift so you dont mess em up.

 

[Woollybandit]

Put the cylinder head in 280C oven for 30 mins and the guides could have been drifted out with a toffee hammer
New ones back in within 5 minutes after cleaning bores out. A lot less work than expected. Lapped valves in the afternoon and just waiting for new wired rocker gaskets to arrive.

 

[grandpaul]

If you freeze your drift the night before you pop your head in a 250F oven to remove or install guides, it goes quite easy. Between guides, when removing, you can dunk the tool in a glass full of crushed ice water for a few seconds to re-chill it after contact with a hot guide.

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