Glowing downpipe

Just run my bike for a few minutes to keep it ticking over every now and again through the winter.

It was running for about 3 minutes with a good dose of choke and when I came to switch it off the downpipe was glowing, I mean really GLOWING!!

When I did switch it off it let out a load bang with accompanying fireworks show from the exhaust.

So what do you think the problem is?

Putting my optimistic hat on I'd say that the engine turning at above idle speed (choke on) without cooling airflow is bound to warm the pipe a little, and the backfire was just coincidentle, or caused by a little unburned fuel ingniting in the hot pipe.

Or, could an exhause valve been not completely closing, exposing the exhaust to the combustion.

Fuel making it in to the downpipe, you do not need the choke on for more than a minute let alone three.

Cheers, it wasn't intentional!

I think you'll find that by running it for 3 minutes you are actually doing a lot more harm than good - Most of the wear in an engine happens during start up and tick over - it can take up to 2 minutes for an engine oil to fully circulate, and in the 3 minutes you've run the bike, you will have introduced water vapour into the oil which with the by products of the combustion will produce strong acids.

If you are not going to ride for a while, I would suggest leaving it. as the oil film will protect it anyway - if you really think you need to circulate the oil, then you could take the plugs out and just turn the engine over a few times ( bearing in mind how long the oil takes to circulate ) without starting it.

Also - change your oil just before you lay it up as this will also mean that any acids built up in the summer during riding will have been removed and the fresh oil will be able to protect the bike better.

If you are going to run the bike - go and ride it properly for 1/2 an hour so that everything gets properly warmed and any water is burn off.

Just my opinion

Spokey

Thanks for the advice.

The purpose of running it just now though was to keep the battery charged. I came to use it the other week, and after 2 weeks of not running the battery was too weak to start it.

I'm only home briefly atm (from uni) and I might need my bike to work on thursday.

Not ideal, I know!

I'd invest in an Optimate or something similar
It's a 2 minute job to take the battery off if you need to keep it indoors to charge.

Spokey

[dizzyblonde]

Originally Posted by Spokey

If you are going to run the bike - go and ride it properly for 1/2 an hour so that everything gets properly warmed and any water is burn off.

Just my opinion

Spokey

+1, during winter I use my bike every week but only for short journeys, which SVs hate. When there is a dryer day midweek I get whichever one is being used( I only use one battery between them I'm a stinjy northerner!) and get it run on a good 20-30miles, so its got a good charge in it.
Which brings me on to,,,

Originally Posted by MrTom

Thanks for the advice.

The purpose of running it just now though was to keep the battery charged. I came to use it the other week, and after 2 weeks of not running the battery was too weak to start it.

I'm only home briefly atm (from uni) and I might need my bike to work on thursday.

Not ideal, I know!

After two weeks, you should be able to start it, unless you've only been out on it for a mile or three, in the previous outing....I can leave mine for 3-4 weeks in a cold shed in winter, and they'll start. However I did leave it two months this time and it was pretty naff, it wouldn;'t turn over, so I had to resuscitate it with my zapper pack. Took it for a 40 mile run and its fine now

[northwind]

An engine is basically a box full of explosions, when you ride around the air cooling keeps it cold but if you rev a bike at a standstill for any length of time stuff gets hot. Do you have an alarm fitted? Battery shouldn't really flatten that fast like Dizzy says. Just starting it to charge it isn't very effective, best to actually take it for a proper run. It's not going to kill it- mine does loads of short runs all winter, has done for 4 years, it's still faster than yours But it doesn't like it.

Dizzy, the battery wasn't completely dead after two weeks, but it wasn't enough to start an engine that was bound to be a little stubborn having not run for a while.

Northwind, nope, no alarm fitted.

Think I might make time in future to get all my kit on and to take it for a proper run.

[dizzyblonde]

Originally Posted by MrTom

Think I might make time in future to get all my kit on and to take it for a proper run.

Its the only answer hun I'm pretty certain they flatten quicker in colder weather, so that may be one reason it was weak after two weeks.