Smoking Triumph

[Boo]

I have a Triumph Tiger 90, I have just rebuilt the entire engine. I goes well but, On start up it smokes like a train. Now I know all about nortons doing this with wet sumping, but Triumphs just do not behave this way. Compression is good and the oil returns well enough as far as I can see and it does not smoke after a few minutes of running. However, after a rest it will smoke again on start up. If I drain out the sump after running it contains 165 cc's of oil. If it is then left for a week, no more oil fills the sump, so no leakdown . I think the problem may be the pump sucking in air and not oil. Has anyone had this before and if so, what needs to be done. I don't want to go inside and randomly look for clues as it is easier to find out the problem beforehand.

[33d6]

I've had something similar with a VB Ariel outfit. These also have a plunger pump similar to the Tiger 90. With the Ariel it used to get a minute piece of muck on the non-return ball at base of the pump which would just hold it enough off its sea to cause bother.

The cure was quick and simple with just a wipe over the ball required to clean it but despite flushing out the system, the oil tank and lines etc, it would still do it occasionally yet the 350 NG Ariel I ran beside it never did it. Nor did any other Ariel I ever owned.

Looking back on it possibly the return spring was a little tired and not quite up to it but the message is there. Engines with plunger pumps can still wet sump like any other and drive you nuts doing so.
Cheers,

[mark2]

sounds like the pump return , the oil is draining back down the return pipe and the rocker feed pipe , after this has drained back there will be no more , reseat the ball ,

[wink]

165 ccs sounds a lot just from the rockers and cam chamber.

[mark2]

how much is normally there ?

[Boo]

I drained out the sump on my T100 and that too had approx 165 cc. BUT, I drained out the sump after running and again a week later, only a thimble full of oil came out. Once emptied, it does not refill again so leak down does not seem to be the problem, only the ability to scavenge.
 Is it possible to have a leak on the scavenge side of the pump and suck in air?

[john.k]

Short period of smoke after starting ,is usually oil running down exhaust guides while stopped.A flooded sump will produce copious smoke for ages as the oil in the exhaust system burns.On cars ,if the valve seals are worn,there will be a puff of smoke on startup,thicker smoke on revving after prolonged idling.A more viscous oil may be the cure.Some poor oils are thin as water when hot.Regards John.

[Boo]

All new valves and guides fitted less than 100 miles ago. It smokes on start up only and goes away after a minute or two. If it were guides then it would only smoke a bit and only on overrun and all the time it was running.
 I took the oil pump out today, cleaned it to within an inch of it's life and re fitted it. Everything seemed ok, but have not yet started it as I would like the gasket goo to harden first. I also checked the scavenge pipe for leaks by fitting a rubber pipe to it and sucking and blowing through it, no air leaks.

[john.k]

There is a very simple way to check, run hot then leave an hour and take the exhaust pipes off,and you will see streams of oil down each valve.All aircooled engines have some clearance in the exhaust guides,and unless stem seals are fitted,oil runs down.When the motor is running,exhaust back pressure keeps oil from running down. Consider this-if your car used oil at the same rate as a British bike you would use over a gallon between oil changes,you would have to add a quart of oil each time you filled up with fuel.Which is exactly what we did when I was young."Fill er up,and a quart of oil".to the pump attendant.Do you even bother to check your car oil? I dont.Regards John

[cbranni]

My Tiger 90 does exactly the same thing, rebuilt the engine, re bore new pistons, new valves n guides, Morgo oil pump and engine runs sweetly but from start up it smokes for about 3 minutes then its fine. If I drop the oil from the sump before starting it doesn't smoke, I fitted a new pressure relief unit incase that wasn't sealing properly but no time as yet to check it has made any difference.

Colin

[Boo]

Just checked my T100 this evening. It is doing the same thing, but nowhere near as bad. It must be something in the air. It's the only logical explanation left as far as I can see. Iv'e tried swearing (profusely), threatening and vallium, neither works so far! I have to set the timing this weekend and will see what happens when it fires up. She should have got a Norton.

[john.k]

Whats wrong with a bit of smoke?Have you never seen a vintage blower Bentley being driven by a burnt out popstar.More smoke from the exhaust than a sixties band.And it cost"free millyin nicker".If you object to the smell,change to engine oil made for a 2stroke Detroit diesel,it burns with less smoke and a much more pleasant smell.I used to love the smell of all the oil smoke on vintage bike rallies.Regards John.

[Boo]

There is smoke, and again there is SMOKE! This is can't see the back of the garage smoke. And on a rebuilt motor with all new bits there is no reason why it should do it. Can't come up with a logical reason yet, but am hoping someone here can help. I don't want to take the motor apart without some idea of what to look for. 

[murdo]

Could it be too much oil in the system?

[mark2]

could be over delivery to top end , is the oil tank standard , try radius the back of the rockers , notch in valve spring lower cup etc , every little helps , this sounds like the oil is draining down when standing from the rest of the motor , fly wheel scrapper ?