Forum

[another Allan]

I've recently bought an Enfield with the Hitchcock breather mod fitted. There is a hose from the drive side crankcase spigot to the H breather, then another hose from the H breather to the 'catch tank.' Then the catch tank has another hose which leads up along the seat subframe and ends just after the end of the seat.

The bike had hardly been used before I bought it, and I've only just started using it. (It was needing quite a bit of tinkering and adjustment.)

Having ridden it, I find that it is burning oil. It is particularly bad when left idling on the side stand for a minute or so, and then blipping the throttle. (Oil not draining down pushrod tunnel, and going down valve guide, perhaps?)

My concern about the breather is that there is no sign of 'breathing' from the hose along the seat rail. No pulsing of air at all, which makes me think that the 'breather' is not actually breathing, and maybe contributing to the smoking.

I've tried to search the forum for help, but I've not found mention of a drive side breather (but lots referring to a timing side breather which I don't seem to have.) Also, from what I've read the 'catch tank' may not be much help.

The bike is a 2003 350, but it has a very low mileage 625cc engine (which may be earlier than '03)
Can anyone please give me a definitive solution as to how the breather should best be arranged? I'd rather deal with easy, external bits before delving inside the engine!

[Martin (Sale Mcr)]

Hi. May I ask.. is the engine "burning oil", or is it a case of "operater error".
The reason I ask this, is that the bikes left the factory, with a cut-out switch, fitted to the sidestand... so when the side stand was in use the engine would cut out.....
The reason for this is because when side stand is in use, the level of oil in the sump is so high on the driveside, that the part of the oil pump that sucks out the oil is starved of oil, so the amount of oil in the sump incareases.. so more oil is splashed up on to the bore.

Martin

[Barry_Q]

On my Lightning, the set-up runs like this.

The pipe goes from the spigot on the side of the engine to Mr H's conversion piece on the oil tank. I've then got the duckbill pipe that runs from the oil tank conversion piece to the rear chain.

My setup works fine. The duckbill can be seen to work when the engine is running and the chain is nicely oiled.

[another Allan]

Useful point regarding running on the sidestand, Martin, thanks. I'll not let it idle on the sidestand any more!However, it also burns oil if idling on the centre stand , but to a lesser extent

[another Allan]

Thanks Barry. That sounds straightforward enough to do to my bike, including removing the 'catch tank.'.
Am I right in thinking that there is a 'duckbill' valve in the 'catch tank' which can be removed and used as you describe?

[Norm]

Allan,
Blipping the throttle only makes it worse if the motor is wet sumped. When starting cold have it on the centre stand and just let it idle untill the scavenge pump has cleared the oil from the sump. This can take a good minute sometimes. When parking it up try and remember to leave it at top dead centre because this will help it stop wet sumping.
Cheers Norm

[another Allan]

Thanks Norm. That makes sense. Unfortunately, the bike didn't smoke from start-up, but after I had given it a run of about 6 miles - sorry I didn't make this clear to begin with. So, in this particular case, I would have thought that wet-sumping due to drained oil from the tank would have been a less likely source of smoke than, perhaps, pressurised crankcases due to the breather apparently not breathing, or maybe a fault in the scavenge pump.
Of course, there could be a problem with the piston/bore, or valve guides, but I don't want to go there yet!
The trouble is that the engine was built as a 625 in 2003, but the bike then passed through two owners before it came to me. In that time, the bike has only done a few hundred miles, so the engine certainly needs to be run-in very carefully (and I don't know if the original owner treated it with kid gloves whilst he had it.)
I'll sort-out the breather first, in the way that Barry suggested. At least then I'll be able to rule-out crankcase pressurisation.
Allan.

[Barry_Q]

There isn't a duckbill assembly in the breather box. It's just a pipe with a duckbill on the end of it. Part number 140167 is what you want. It's only a couple of quid from our hosts.

[Norm]

Allan,
Certainly after 6 miles itshouldn't be wet sumpnig from the oil draining from the tank, but still could be a wet sump problem caused by the scavenge pump not keeping up. I did notice the 625 bit in the first post but thought it was a typo and I didn't realise the bike had been around a bit because you said it had done very low miles not realising you meant just the motor. Anyway I'm still thinking wet sumping due to a scavenge pump problem or something blocking the pickup in the crankcase. How long have you had the bike and has this problem just developed?

[Midge]

It can take a few thousand miles to really bed the rings in. It could just be that it needs to be used more. Someone I knew had a similar problem and kept taking his engine apart to see why it smoked. The engine never got a chance to settle.
Re. the breather as already said, dump the catch tank completely and vent the duckbill over the chain, There's no need to keep the oil tank over 3/4 full which will also help prevent oil loss. Have you read the wet-sumping article in the technical notes section? This explains the breather set-up very well.