Gasket day.

toglhot

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I spent the morning cutting gaskets, I didn't want to use the commercial gasket sets, particularly the green barrel gasket, they are impossible to remove. The stuff I'm using usually peels off pretty easily.

The gaskets I removed were .6mm. I've used .8mm, actual size is .7, which should compress pretty close to .6mm

For the points buckets gaskets I've used .4 actual size .3mm. I fear if I use thicker the seal will slip over the cam lip and leak, which was a problem previously. When I first stuck this engine together, I had terrible trouble getting the points bucket seal over the cam, to make it easier, I relieved the edge a little, unfortunately, too much. It leaked just a tiny bit. Hopefully a thinner gasket will solve the problem.

I haven't cut the clutch cover gasket yet. That has a new gasket I cut a while back from the same material.
Just waiting on a head gasket and a couple of circlips, then I can throw all the bits in, seal it up and use my lifting/tilting/rolling thingie to shoehorn the engine back in the frame.

No scratches getting the engine out, and I didn't even wrap the frame, isn't that amazing?
 

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I like really thick (about 1/8") intake manifold gaskets, just like originals. I think Yamaha used the thick gaskets there to help isolate the manifolds and carbs from the engine heat.
 
I spent the morning cutting gaskets, I didn't want to use the commercial gasket sets, particularly the green barrel gasket, they are impossible to remove. The stuff I'm using usually peels off pretty easily.

The gaskets I removed were .6mm. I've used .8mm, actual size is .7, which should compress pretty close to .6mm

For the points buckets gaskets I've used .4 actual size .3mm. I fear if I use thicker the seal will slip over the cam lip and leak, which was a problem previously. When I first stuck this engine together, I had terrible trouble getting the points bucket seal over the cam, to make it easier, I relieved the edge a little, unfortunately, too much. It leaked just a tiny bit. Hopefully a thinner gasket will solve the problem.

I haven't cut the clutch cover gasket yet. That has a new gasket I cut a while back from the same material.
Just waiting on a head gasket and a couple of circlips, then I can throw all the bits in, seal it up and use my lifting/tilting/rolling thingie to shoehorn the engine back in the frame.

No scratches getting the engine out, and I didn't even wrap the frame, isn't that amazing?
What did you find when you opened the engine up. What had failed?
 
Quite annoying. When I originally tore the engine apart three years ago, the valves and seats were badly pitted. I had a local guy rebore the barrel and also asked him to recut the valve seats, they being too far gone for lapping. When I picked them up, the guy had installed the valves and said they were right to go, prefect.

Like a fool, I trusted him and never checked. It went ok for a while, right up to the test ride by the guys next door. But next day it wouldn't start.

Initially, I thought the timing was out as it was spitting and backfiring, then I thought perhaps the cam chain had jumped.

I checked the ignition and cam timing dozens of times, but could find nothing wrong. Same with the carbs.

So, I pumped air into the combustion chamber via the plug holes and discovered the inlet valves were leaking quite badly. After removing the engine, tearing it down and inspecting, I found the inlet tracts were blackened quite badly. Funnily enough the exhaust valves weren't leaking.

I spent some time lapping the valves and checking for leaks, all good now. I gotta tell you though, I really do hate trying to insert valve spring collets. Fat, unbending fingers don't make it easy either. Somebody should blow the damn things up.

Can't find anything else wrong, so, that has to be it. I'll find out in the next few days anyway, picking up a head gasket and circlips tomorrow, so I'll start chucking all the bits and pieces in the cases tomorrow.

Moral of the story: Never trust anyone! This is the first time I've ever farmed out work, never again...
 
Quite annoying. When I originally tore the engine apart three years ago, the valves and seats were badly pitted. I had a local guy rebore the barrel and also asked him to recut the valve seats, they being too far gone for lapping. When I picked them up, the guy had installed the valves and said they were right to go, prefect.

Like a fool, I trusted him and never checked. It went ok for a while, right up to the test ride by the guys next door. But next day it wouldn't start.

Initially, I thought the timing was out as it was spitting and backfiring, then I thought perhaps the cam chain had jumped.

I checked the ignition and cam timing dozens of times, but could find nothing wrong. Same with the carbs.

So, I pumped air into the combustion chamber via the plug holes and discovered the inlet valves were leaking quite badly. After removing the engine, tearing it down and inspecting, I found the inlet tracts were blackened quite badly. Funnily enough the exhaust valves weren't leaking.

I spent some time lapping the valves and checking for leaks, all good now. I gotta tell you though, I really do hate trying to insert valve spring collets. Fat, unbending fingers don't make it easy either. Somebody should blow the damn things up.

Can't find anything else wrong, so, that has to be it. I'll find out in the next few days anyway, picking up a head gasket and circlips tomorrow, so I'll start chucking all the bits and pieces in the cases tomorrow.

Moral of the story: Never trust anyone! This is the first time I've ever farmed out work, never again...
Glad it wasn’t too serious, but unfortunate you had to pull the motor. I’m sure you’ll have it up and running soon.
 
After a valve job, I always like to fill the combustion chamber with a light fluid (mineral spirits, etc) to verify the valves are completely sealed - holding fluid for a period of time with no leaks.
 
Most seem to use water, I use petrol. As water is denser than petrol its less likely to show up leaks. Water also tends to rust steel, and there's more than a little bit of steel in the combustion chambers.
After filling the combustion chambers with petrol, I covered over with a sheet of aluminium to prevent evaporation and let it sit overnight. - didn't leak a drop
 
I use kerosene, but I take the testing a step further past just letting it sit. I blow compressed air into the ports .....

BlowGun.jpg


BlowGun2.jpg


Any leaks will show as streams of bubbles. Even the smallest of leaks will show up ......

Leaks.jpg


Leaks3.jpg


This takes a bit of practice. Get the blow gun too close to the valve and you'll actually blow it open, so it looks like it's leaking like crazy, but it may really be OK. This also cuts the testing time way down. No need to let it sit over night, you can test immediately.
 
I don't do any leak checking.... never saw the need. After you lap the valves in, you should see a dull grey continuous ring on the seat and the valve face. If you have that, it's not gonna leak.
If you don't have those rings... git back to lappin'. :wink2:
... or maybe consider recutting the seats and faces.


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I'm a dinosaur, l like to do everything myself, I like points, gaskets, carburetors, lacquer paint, mudguards, manual fuel taps, et al. But most of all, I like to check, double check, triple check and sometimes even fourple check. Sadly, I failed my own ideal in this case.
But, this is probably my swan song anyway, so no more checking, that'll also mean no more chequing.
But $#!t, I'd love another Triumph, a real bike!
I'm a dinosaur, l like to do everything myself, I like points, gaskets, carburetors, lacquer paint, mudguards, manual fuel taps, et al. But most of all, I like to check, double check, triple check and sometimes even fourple check. Sadly, I failed my own ideal in this case.
But, this is probably my swan song anyway, so no more checking, that'll also mean no more chequing.
But $#!t, I'd love another Triumph, a real bike!

Here's a tip: You know when you punch holes in the gaskets you make (assuming you do). The wad never gets cut all the way around, chuck the cutter in the lathe (if you're lathe challenged, use a drill) and using a file sharpen the cutting edge. No more half cut holes with frayed and bent over edges.
No one makes decent hole cutters (wad punches) anymore. I have the remnants of a set I bought back in the mid 70s, they still work, never been sharpened.
 
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No magic involved just lots and lots of time and effort amd thinking and lots and lots of bits that didn't look right until they went in the bin. Almost everything in the bin looks right...
 
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