The '70 650's breathe through 3 holes drilled from the crankcase into the primary case, and out the top of the case into a hose that runs along the side of the rear fender. I guess the first thing to do is to see if you can find the rebuilder and see if the engine breather was altered.

Hope this helps a bit: Jim

 

'70 model was the first year without the timed breather on the camshaft.
There should be no seal on the drive side main bearing, and the crankcase breathes through the bearing and into the primary. The 3 little holes are only to allow any excess oil in the primary to drain back into the crankcase.

Has he got the breather hose running up and along the rear mudguard? Excess oil should tend to run down and back into the primary.

 

Tommy, If the breather comes out in under the engine in front of the front sprocket it's probably actually a '69 or earlier. If the breather comes out of an elbow on the primary case a few inches behind the alternator wire it's a '70 or later. In that case either the drain holes are clogged between the primary case & crankcase, or the tin baffle shield is missing behind the clutch chain wheel. If you have a small dental mirror & flash light you can look in the primary filler hole & see the shield. The front sprocket oil feed tube is attached to it as well. If he drains the primary oil overnight (or longer) he normally will get around 150-200 cc. Sometimes less with a lot of 70+ mph riding. Sometimes with slow running he might get as much as 3-400cc.
If more than that I'd say the oil holes are clogged. You'd need to pull the primary cover to check oil holes. I've tried to "dipstick" the oil level through the filler hole, but not a clear shot so stick is wiped all over with oil.
Don

 

A good engine with a breather through the primary,will emit virtually no oil or even mist from the rear mudguard breather.I would do a compression test after first making sure the valves were set right, which might suggest new piston rings are needed.My first suspect of heavy breathing would be the rings,or even,a glazed bore if its been used at low speeds a lot.

 

Post the engine number, or at least the letters so we can know the age

 

Hello Chaps, I've not been ignoring the replies I've just been away for a few days.

I think I have the year wrong, I will verify it soon. It defiantly does not have a breather exiting the primary so it must be a late sixties.

 

More than likely it has to do with the bike sitting for extended periods. What is likely happening is that the oil pump is worn to the point of allowing oil to bypass and drain from the tank into the crankcase. Then, when the bike is run, some of the excess is churned out the breather pipe.

These bikes like to be RIDDEN, not sittin'!

 

What is likely happening is that the oil pump is worn to the point of allowing oil to bypass and drain from the tank into the crankcase. Then, when the bike is run, some of the excess is churned out the breather pipe.

Never seen that on a Triumph twin.

 

Yes I'm an idiot it's a 67 not a 70 so it breathes through the timed vent in the cam.

After doing more research it looks like the timed breathing idea was to try to keep a negative pressure in the engine. The idea being that the engine is only open to the atmosphere whilst the pistons are on the down stroke and closed during the up stroke.

Is it possible to assemble this system in such a way that the opposite can happen nut the engine still run??? Can't see it myself!

The engine is not wet sumping at all. Compression feels strong but I'v not measured it, like I said before it's not burning oil and the plugs are not at all oily.

 

No unless the stationary breather disk is installed wrong and for that to happen is tough. You you can diagnose simply. Remove the timing port bolt from the crankcase behind the cylinders base so the crankcase is open to the air. Then while slowly turning the engine, blow into the breather pipe. There are three possibilities. 1) It's blocked all the time (not likely in your case); 2) it's never blocked which means the one of both of the disks were left out; or 3) it's working -- you can even tell where the pistons are when it opens and closes if you want to check that the stationary disk was installed correctly.

The breathing is through the intake camshaft. That's several inches above the bottom of the case. I don't see how oil can come out of the breather in any case without wet sumping. The only way I can think of is if somehow too much is going to the intake rocker box, dripping down through the tappet blocks, and running along the intake cam, finding the hole in the camshaft, running inside the camshaft and finally out the breather -- unlikely, remember that the camshaft is spinning so how does the oil get inside!

 

Hi Tommy, Ok... Now this makes more sense. I expect what is going on is normal. The breather hose comes out from the left inlet cam bushing down near the front sprocket. The hose loops down & back up over/inside the rear fender. Also it Ts in with the oil tank vent. The inlet cam bushing takes a certain amount of oil due to rod & flywheel fling, plus oil mist in the crank case. The vaporized oil will get trapped in the lower loop of the hose at times. Mostly from short runs. Starting the bike to show it off to friends & not riding it will put condensate in the hose also besides the oil. The hose can fill to the level of the inlet cam bushing. I don't think the motor will suck the oil back in to the crank case, but I really don't know. If you pull the hose from eng, about that much oil runs out... like the loop is full to bushing.
The hose loop is fairly low & long & can hold a fair amount of oil. After it's full of oil vapor can no longer pass & pushes the oil out the hose.
Then it spits oil out upon starting & running until the hose clears itself. May take 20 miles to really clear it well.
My friends 69 bonnie does this all the time. We ride often & I can see condensate & oil come out when we first start the ride. Until the motor warms well I can see condensate vapor come out on cold days also. Like <50f. Even after riding many miles I will see some blow by smoke come out. Surely that is by the rings. By this time no liquid though. Condensate is more whitish like steam & goes invisible almost instantly, where blow by vapor is more a tan that will linger a moment.
The other day we were on the freeway & came to the bottom of off ramp & waited at red light. Bikes were smoking hot. As it idled a small plume of blow by exited the tube. Also on curvy roads it will puff a little smoke as throttle is rolled off/on.
Bike only has 13k miles from new. It only uses a little oil & runs quite well.
Was checked for oil suction, holding vacuum, amount of oil in sump etc. All that is perfect. I've observed other cam timed breather bikes doing this on group ride also.
On the other hand, on my '73 TR7RV with primary breather I follow my bike while I'm riding John's I never see any vapor at all cold or hot & no oil comes out the tube ever. However, on lots of short rides it will gather much condensation. So much so the primary parts will rust. Me & John used to kick this around & talk about it all the time. He even made a catch can under the frame. Now he just ignores it & usually does rides of 20 miles or greater & not a problem then.
So I would do nothing on the 67. Try taking some long rides & see what happens. Let us know.
Don

 

This is why I don't route these breather hoses upward.

 

I'll use marshg's method to check the breather is functioning correctly, if it then maybe it a case of being 'the nature of the beast!' and just needs using more.

 

It's been a good Triumph week, as well as fettling my tiger looks like I've got the bottom of this one as well.

The breather system turned out to be 'Modified' by the PO, I finally had chance to take a proper look and the breather pipe was coming out of the hole in the crank case where top dead center can be located. The breather spigot on the rocker box was blanked off.

I also blew through the breather to check the the breather valve, that was working correctly-open as the piston were going down.

We returned the breather system to standard, he rode 80 miles today without a whiff of oil out the breather, he couldn't believe it!

Who knows why people do these things?