Page 1 of 1

GT 550 K can't get spark timing right

Posted: Sun May 21, 2017 6:25 pm
by jumbafiction
Hello

I have problems with spark timing. I'm using ohm meter and the "windmill" behind the main plate in adjusting.

Problem is, when left cylinder is OK and right is approximately OK, center cylinder is way too advanced. I can't retard center cylinder plate more.

Before I started adjusting spark advance, I checked point gaps and they were about from 0.35 to 0.4mm each.

Photos:
http://i.imgur.com/1jqOcBL.jpg Right
http://i.imgur.com/rPErUH1.jpg Left
http://i.imgur.com/2znqA3X.jpgCenter

Re: GT 550 K can't get spark timing right

Posted: Mon May 22, 2017 10:40 am
by oldjapanesebikes
Was it working properly before ?

If these are original points, then possibly the heel is worn on one ? And if they are new points then possibly they are not all the same type (OEM vs aftermarket) ? There were also two different types used - Denso and Kokusan - and the breaker cams differ, as do the points themselves although you seem to have a Denso setup. I'm sure a 550 expert will be along shortly with additional suggestions ...... 8)

Re: GT 550 K can't get spark timing right

Posted: Mon May 22, 2017 10:55 am
by tz375
In addition to those checks, timing is a bit of a compromise. You could for example open or shut the left set of points and re-time the whole plate to get an individual cylinder back in bounds. You could also close the right points slightly to advance the point at which it opens, or you could extend the adjustment slots for the plate or an individual cylinder.

It is also possible that the propeller is in the wrong place. The locating slot is much wider than the pin on which it locates. That's why many of us use a dial gauge until we know for sure where the propeller /windmill marks are. Sometime you get lucky and they are spot on but they are often out by quite a long way.

If you don't have a dial gauge, you can use a degree disk bolted to the alternator rotor. Use a piston stop to get an accurate TDC and go from there.