Boxerworks.com

The story started here: http://boxerworks.com/forum2/viewtopic. ... 876#p51876

The short version: The engine stopped while I was riding. There was spark at the plugs but it wouldn't fire at all. The coil appeared to test as faulty but it turns out that you test dual output coils differently to how you test your standard car coil. The new coil (Dyna brown) tests almost identically to the old coil give or take a few ohms.

I put the new coil in and the bike started first go and is running really well....now. Not at first.

Before I broke down I noticed that the bike was bogging down badly when accelerating from 5,000 revs in top. I had put this down as a symptom of whatever it was that made me break down. The same thing still happened with the new coil.

I believe that a hole in the diaphragm will cause this sort of problem so they were the first suspects. As I has just replaced them I thought that perhaps I had installed one badly. But as the bike was otherwise running well ( and I didn't have time to pull the carbies apart) I just kept riding it and, after a few hundred kilometres, it fixed itself.

I think it was probably some grit on the slide that worked itself loose. But I may never know.

The lesson in this (one of many) is: don't get obsessed with fixing what you think is wrong; you may have more than one problem.

Cheers and thanks for all the help,
Ray

Ah, well, at least it's a happy ending.

Things like that make me paranoid for a long time.

But......the lesson is.......you still don't know what the problem was...and still could be.
Maybe just water in the gas? I had that happen before. Easy to see in the float bowl.

mattcfish wrote:But......the lesson is.......you still don't know what the problem was...and still could be.
Maybe just water in the gas? I had that happen before. Easy to see in the float bowl.

I believe the lesson is: Airheads don't fix themselves

...except when they do.

mattcfish wrote:But......the lesson is.......you still don't know what the problem was...and still could be.
Maybe just water in the gas? I had that happen before. Easy to see in the float bowl.

That's a fair point - I don't really know what happened. But I would be keen to hear suggestions so that if it happens again I know where to start looking.

It probably wasn't water in the petrol as I'd had the float bowls off and all was fine. I did wonder if it could have been a bad tank of petrol. I filled up about 120km before I broke down and I don't recall the bike acting up before that. But wouldn't that problem be solved instantly when I filled up again? The issue seemed to fade away over several hundred kms rather than cease quickly.

I am never happy when something "fixes itself" and have seen it plenty of times. It usually returns to bite one in the a$$ when least expected.

Riding would be a bit uncomfortable in that I would keep trying to find more symptoms returning.

SteveD wrote:If it's "fixed itself" then my money would be on a fuel issue that's cleared.



Bingo. A solid piece of fuel hose had blocked the left main. Problem solved. Shame I didn't check it first.

Good point. Old rubber fuel lines desolve over time and leave goo in your carbs. Use modern Polyurethane hose and the problem is no more. http://www.aircraftspruce.com/catalog/a ... elline.php. Bing has it too.

Some of the hose material may not fall apart, but it can harden badly and then leak.