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Old 01-18-2011, 12:24 AM
Ralph140 Ralph140 is offline
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Join Date: Jan 2011
Location: Yakima WA
Posts: 2
Groundsmaster 72 Carb help

I am tinkering on a 300 series GM72 model 30780 serial # 90897 with a solex carb. It has a poor idle, has a tendency to pulsate/surge. High speed it is not there or I just cant tell it. The owner sent out the carb for a rebuild and it still does it. So now I am looking at the problem. Any suggestions would be appreciated on what I might be concerned with. It does not appear that the folks who rebuilt the solex did any re-bushing on the throttle plate arm. They did manage to screw up the O ring on the float bowl and insert a different float that doe snot appear to be adjustable (like the old one). Before I blow myself up with starting fluid looking for vacum leaks thought I would try this forum for a little advice. Thanks... Sure would be nice to find a blow up on this carb too.
Old 01-18-2011, 01:34 PM
The Toro Company The Toro Company is offline
LawnSite Senior Member
Join Date: Feb 2009
Posts: 354
The product you are referencing is a 1979 vintage unit. Since the surging only appears to occur at idle, this could validate your suspicion of a vacuum leak. I would suggest that you test for the leak, however my suggestion would be to use propane (vs. starting fluid).
Test first with the air cleaner hose off. Add a small amount of propane to the intake of the carb and if it smoothes out, this would indicate a leak may be present and is leaning out the mixture. Reinstall the hose and now test the common vacuum leak points with propane to see the response. This is much safer than using starting fluid, and the propane is heavier than air so it "sinks".

As far as obtaining drawings of the carb, do a google search on Solex 32 DIS carburetors. There is quite a bit of information available on the internet over and above our old Service Manual for the GM 72.

Eric Baumeister
The Toro Company
Old 01-20-2011, 12:17 AM
Ralph140 Ralph140 is offline
LawnSite Member
Join Date: Jan 2011
Location: Yakima WA
Posts: 2
Thank you I will do the propane approach vs the starting fluid.

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