Thought it was bad fuel, now I don't know what to check next

[gs450dave]

G'day,

I dropped my bike a couple of weeks ago whilst moving it with the centre stand on (I know I shouldn't do it but my garage is small, BTW the bike fell on the side where the choke and fuel tap are).
Anyhow since then the bike has almost no power. When ever I'm riding on a slight incline upwards the bike strugles to make it.

I thought it was bad petrol as i've had the same petrol for 2 months but I drained the tank, the carburators, put fresh fuel, let the petrol flow on the carburators, tried it and still the same gutless result.

I've had a look to see if there are any out of place parts nothing obviously visible.

I'm a new rider and DIY guy so I don't know where to begin.
I'm gonna take another look tommorrow but I wanted to know what are some of the obvious places to start checking.

Thanks in Advanced,

Dave.

[DimitriT]

Sounds like you need to do a complete fuel/ignition diag. I think someone posted something like that a few weeks ago. Check spark and fuel in the bowls and go from there.

[Redman]

Wide range of possibilitys.

Here is one thing you can do to start diagnosing problem: When you start it up up from cold, try feeling each exhaust pipe. Tell us if they all warm up about the same rate, or if one or two do not warm up, and tell us which one or two that is.

Another thing you can do: Turn out one plug at a time, try to start engine and watch it to see the spark (keeping plug grounded to head of course). Tell us which do and which dont spark, or describe if one spark is a lot different than others (like big fat orange verses white-blue snap)

Another thing: Turn open the drain on each carb float bowl. See if each gets good fuel flow (flows more than just what has been stored in bowl).

Check ouy some of these things and what others might suggest here and let us know, may then get to looking in right direction.

[focus frenzy]

hmm ran fine before it fell over, check the intake boots at the head, a big hit like that could have torn them loose causing a bad vacume leak.

[FTGRET]

Also check that you didn't damage the choke causing it to stay on.

[DaveDanger]

ftgret hit the idea that I had... sounds like maybe the choke was knocked outa whack and possibly staying on even when ya think it's off.

[gs450dave]

Thanks Fellas,

I Checked the choke - and from what I could tell it moved in and out freely with a little bit of friction same as before.

I checked the exhaust pipes and realized the right one DID NOT heat up at all after starting + a 2 minute ride.

I didn't check the spark plugs or do any more carburettor checking.

Does this mean I'm running only on one cylinder?
Also does this mean I should replace the spark plugs?

I bought the bike 5 months ago, its a 1980, it has 45,000 Kms and I don't know the age of any of the parts and habits of the previous owner.

Many Thanks in Advanced,

David.

[DaveDanger]

just for a real quick and dirty check to see if your plugs are both good, swap them from cylinder to cylinder and see what happens. If the cold cylinder (pipe) stays in the same place, you probably have either an ignition wiring or coil problem, or fuel. If the cold cylinder switches to the other side, then you have a bad plug.

[bgmart450]

Can't soaking a spark plug in gas foul a plug pretty quick? (at least running extra rich will I noticed)

I'd switch sides on the plugs as was mentioned above to see if the problem switches sides. Might get away with a real cheap fix

[gs450dave]

Thanks for your help,
Here is an update.
I put in a new Spark Plug what-do-you-know the POWER came back.
Its possible the plug was strugling until it eventually died.

When I took the plug out the bottom end was a consistant black color through out and at first it was a bit shiny, I didn't bother trying to clean it, I just replaced it, although the black stains looked like they were permanent.

Initially the exhaust with the new plug belched out grey smoke but cleared after a minute or so.

Does this mean there is an oil leak to the cylinder?
Or the bike is running too rich in fuel?

I only have a few minutes to work on the bike on week-days ( I gotta juggle the bike, the wife and work) but I will post a picture of the plugs after running the bike for a while.

What are the best tests I can do to test the condition of the engine?

Many Thanks,

David.

[DaveDanger]

That cylinder hasn't been firing for quite a little while now, so it's been loading up on fuel and oil... unburned. When it finally began to fire when you installed a good plug, it had to clear out all that excess crud. That was the initial burst of smoke. Ride it for a little bit, I'll bet you have no further problems.