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Ben Sidaway
Member
Username: b_sidaway
Post Number: 4
Registered: 08-2011
| | Posted on Wednesday, June 15, 2016 - 01:41 pm: | 
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I having trouble getting my M60 to idle. Idled fine last year. I always take off carb (Zenith) and service during decommissioning. Put everything back together and engine will start and run at medium revs but when I idle back, the engine wants to die suddenly. I have had tried adjusting the choke cable thinking I tightened it down in the wrong place - no help. I have rotated the main jet screw in and out - this seems to have no affect on the engine at all, even when all the way in. Could it be a timing issue, I have never touched the distributor and wouldn't know what to do. The manual does mention something about rotating the cap if I remember correctly. Any advice would be appreciated. I have always had problems with the carb every yr with crud blocking it. I am used to taking the carb off many times a season. Thought I fixed the issue though by cleaning tank and draining it over the winter, and installing a high quality fuel filter, |
J.B. Castagnos
Senior Member
Username: jb_castagnos
Post Number: 1179
Registered: 07-2002
| | Posted on Wednesday, June 15, 2016 - 09:40 pm: |
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The high speed jet won't affect idle. The idle screw is near the mounting flange, has a spring behind it, snug it closed counting the turns, open it about 2 turns, see if it idles. Check for vacuum leaks at carb, manifold, any vacuum lines. Check for a stuck intake valve, compression check. A quick compression check is to remove and ground the coil wire, spin the engine over continuously for a bit and listen for a repeated skip, rrrrrrrrr normal, rrrRrrrRrr and a huff from the carb, a stuck valve. If all of this checks OK the carb probably isn't getting fuel through the idle circuit. Separate the top from the bowl, look for the passage that leads down from the idle screw, check the gasket where it meets the bowl, should be a matching hole, no tears in the gasket. Get a can of carb cleaner with a tube and wash the passage down in to the carb and up to the idle screw, making sure it's going through, probably coming out of the main jet. |
Ben Sidaway
Member
Username: b_sidaway
Post Number: 5
Registered: 08-2011
| | Posted on Thursday, June 16, 2016 - 08:49 am: |
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Thanks for advice. I meant to say I adjusted the idle screw (not the main jet) in my post. Moving the idle screw in and out does not change anything. I will take the carb off again and clean. At the end of every year I always take the carb apart and clean with a can of carb cleaner. Everything looked clean but I'll check again. How exactly should the choke wire/valve be positioned during running (choke off)? Spinning the engine without starting it sounds fine. There is a distinct nonlinear decrease in rpm as I gradually and slowly throttle back. At a certain point in throttling back there is a distinct precipitous drop in rpm until it stalls. |
Ben Sidaway
Member
Username: b_sidaway
Post Number: 6
Registered: 08-2011
| | Posted on Thursday, June 16, 2016 - 02:39 pm: |
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Good call JB. When I took the carb off I found one of my flange gaskets had a crimp in it (never done that before) so I guess that probably crated a vacuum leak. Cut a new gasket. Purring like kitten now. Thanks. |
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