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[Ducatifreak]

I have a 2004 Bullet 500. I get a gungy, frothy mess coming out of the Breather pipe. It is so bad that it filled the Breather Catch Tank up. I have disconnected the Crankcase pipe at the Catch Tank end and just have it venting to air. Also, when the bike gets hot (>10 miles travelled), and I put the engine under load, I get a loud popping/banging noise. It is definitely NOT a missfire but it could be a backfire. I cannot tell where the noise is coming from because it only occurs under load.
Replies from anyone who has actually suffered from and cured this problem would be greatly appreciated. Replies from people who think they know what could cause this problem will also be appreciated.
Thanks.

[Tim NZ]

I have lost count of how many time I have posted a reply about breather pipe work?


Condensate which is being expelled from the engine is accumulating in the pipes and partially blocking them, most often this is in a Low point dip in the main breather pipe off the top of the oil tank.


First up: ALL the breather pipes will need to be removed and cleaned out, or soon there will be Oil being blown into the catch-can AND the Air filter gets showered in oil and elephant phlegm!


The main breather pipe of the top of the oil tank has to be refitted so that there is no dips in the run up to the catch-can.


Take the main breather pipe off and reverse it, turn it around so that the acute bend is reattached to the bottom of the catch-can, and so that the run of pipe down to the oil tank is a constant drop, it passes under the battery, over the frame bar that the gear box mounts are hung from, and straight onto the top of the oil tank. It is a tight squeeze but is do-able.

[PeteF]

Have a look here for breather information.
http://www.whfolk.co.uk/REOCHUMBER/Arti ... eather.htm
I'm afraid the popping banging noise is difficult to diagnose just from a descripion, but could it be pinking? Do you know if the ignition is timed correctly? Some people describe pinking as a noise like marbles rolling around in the cylinder head. This would happen under load is the ignition were advanced to much.

[Bullet Whisperer]

The excessive breathing and the popping / banging noise you describe might be connected. It may just be you have a blow or leak at the head gasket. This may not have to be blowing outside, where you can see it, but could be internal, going down one of the barrel stud holes where a bit of base gasket might blow internally and allow gasses past, or maybe there is a blow across to the pushrod tunnels, I have seen both before. You could try tightening the cylinder head nuts - they might need it - or a new head gasket and possibly, a new base gasket might be the answer. At the very worst, you might have a loose liner [alloy barrel only], I have also come across that one before now. Worth seeing if the head nuts will tighten a bit, though. Regards, Paul.

[Tim NZ]

Misfiring on hard acceleration when mtr is hot is usually LEAN on the needle setting...


BUT you plug may be fouled with caked on gloop that passed from the engine breather...


Clean and regap the spark plug, and check that its heat range is suitable and retest.

[Ducatifreak]

Thank you for the thoughts on my problems. Tim NZ - As I said in my initial post, it definitely is not a misfire. However, your description of setting up the Breather is very interesting. PeteF - Ignition timing is OK and I have heard Pinking before and am confident it is not that.

I think I will remove Breather Ass from Crankcase (Is there some sort of assembly under the Outlet pipe?) and if that seems to be OK then I will go along Bullet Whisperer's route and remove Head and Barrel and work my way through them.

Cheers. Mick.

[PeteF]

Nothing under the breather spigot.