Hard to start when cold; vs hard to start when warm

[roeme]

Hi all,

I have some maintenance due on my GS550, as it became quite hard to start recently - but that on it's own not exactly a reason to create a new forum thread. The thing is, I've got a '84 Guzzi that I brought back onto the street just recently, doing a lot of work on the carbs, ignition & of course valve clearances. Weirdly, around the same time as the GS started acting up, the Guzzi became hard to start when hot.

That made me curious. I've learned so far that hard-to-start is usually down to valve clearances. At the same time, I know that the valve clearances are good on the latter bike, and might need to be done on the former (need to check mileage though). So the hard-to-start when hot doesn't quite fit...

Thoughts? Your experience? I'll check the clearances anyway and I'll dig into the carbs on the GS anyway (need to rejet* them, and resync them), but maybe you guys/gals know something that I should be on the lookout for as well.




(*) reason: PO put in bigger ones, shop I used for time reasons reverted back to stock to make sure to pass inspection, engine now not fun)

[Who Dat?]

When you are assured that your valve clearances are in-spec, THEN you can tackle the joys of carb tuning.

What year is the 550?

[Rijko]

Like WhoDat said, valves first.

With a new to me bike, valves and compression test always are the first thing i do.
If you have a burned valve or clearance out of spec, worn piston rings ... the rest
is secondary, maybe even pointless.
And it would make hard to start make perfect sense.

I'd advice NOT to rejet before you have the 550 running perfectly, tuned with a standard setup,
as it gives you the best point of reference.

[roeme]

Neither bike is new to me, as I had them both running very well up until recently, the 550 even with the bigger jets previously. The 550 is a '78.

Guess i'll dig into the valves. I felt would be a bit early for the 550, but let's see...

[Suzukian]

If it was running with the jets you have in them now, I would not touch them until you do the valves, and check all the other stuff (some other carbs stuff too). After you get it running where it was at, then you can try jetting it to get it running better, if you think it needs that.

[Who Dat?]

Guess i'll dig into the valves. I felt would be a bit early for the 550, but let's see...

It's never 'too early'. I have adjusted valves and found one to be a bit farther out of spec than the others. After adjusting it and cranking the engine over several times to settle things, I checked it again and found it out the other way. Evidently a small piece of crud got stuck between the valve and the seat, giving me a false reading the first time. After the adjustment, the crud found a reason to leave, now I had a bunch of 'extra' clearance.

[Sandy]

A '78 means it could still have points and condensers. Bad condensers as well as points could also contribute to hard starting among other poor running gremlins. I'd make sure all basic maintenance is up to date before second guessing what the problem is.

[Suzukian]

If it has points and Condensers, that's the first place to start. A bad condenser (which is a capacitor) will cause the points to burn on the fixed side if it's lost it's ability to store electrons. You will see the points burned on that side, or both. Too much (which doesn't happen unless you put one of greater value in there) would cause the moving point to burn. You can clean them with a point file, and if this cures the problem, get a new points set and a new condenser immediately as it won't last very long (usually).

[roeme]

Huh, as it happens I've got both a digital points replacement plate for the 550 on the shelf, could just as well use that when I get the chance to dig into the bike.

The Guzzi has already been converted as such by a PO.