Chasing 250SL problem

[Darrell]

Hi Everyone,

I just tried riding my 250SL after leaving it sit for 3-4 months. It was working fine when I put it away.

All went well (for the first 30 seconds to a minute from cold) but then it bogs above quarter throttle and doesn't generate enough power to get out of its own way. It still starts and idles fine, but just won't run at higher revs or under load.

I understand carburetion much better than ignition so I did a carb inspection, cleaning, and adjustment, with no significant improvement I've also inspected and cleaned the connections to the stator -- still runs the same.

What's likely to blame here, the secondary coil, or the CDI, or...? Note: the bike craps as soon as its warms up.

If I'm advised to test the coil should I take another reading after warming it up with a hair dryer? I don't even have an idea how to test the CDI box.

Many thanks. The answer is out there, somewhere.

[Bullfrog]

Check for mouse nests in the exhaust (plugged exhaust)
Ed

[thrownchain]

The CDI is usually a go, no-go unit. Either it works or it doesn't.

[olddogs]

If it starts and idles, its usually not the ignition. Overheated ignition parts usually quit until they cool, or start to break down from excess heat resulting in engine missing and backfire. It does sound classic plugged pipe, or critter nest in the air box restricting airflow.

The new fuel blends also go stale very quickly, leaving sludge that can plug a main jet in a bottom feeding carb like the 250 uses.

Process of elimation should get you going.

[Darrell]

I'll take a clogged exhaust over an electrical gremlin anyday. Tomorrow I'll try running the bike without the Skyway silencer -- may as well repack it too.

Thanks guys, will keep you posted.

[Darrell]

Epilogue:

OK, in the Skyway silencer the conical screen spark arrestor was completely carboned over, as was the inner silencer pipe and packing.
Fixed that, as well as soaking the expansion chamber with over cleaner overnight; also repacked that 3" section of the inner pipe that forms the stinger.

I set off to ride again, all happy thinking that this was the root of the problem...nevertheless the bike stil resumed bogging within a block or two from a cold start.

Then, I remembered that I put a new "200" (up from a 190) main jet in the carb after I parked the bike at the beginning of the year. As I previously mentioned, the bike seemed alright up to then.

So, I removed this new main jet and had a good look at it in the sunlight. I'm very far-sighted but could easily recognize that this "200" jet had a big whompin' Texas-sized passage compared to the 190. So then I put the new jet (that I bought packaged as a 200) under a loupe to see the stamping -- and it reads 360.

The conclusion of the matter is that I reverted back to the 190, and the bike now winds up a lot better than it has in recent memory so I'm at least happy to have been pointed towards this overdue maintenance item.

As a building contractor I overlooked one of my main tasks -- which is to check everyone else's work!