Running/Idle RPMs

[Hammermechanicman]

Another big problem is that people don't replace the flat o-rings on the intake manifold and they have air leaks. The OEM get hard and compressed and the cheap AM swell from the ethanol. I stock a dozen of them as i change a lot of them.

Biggest problem Next to the jet o-rings on the 2 bbl carbs is the tiny passageways under the w shaped plate. Ultrasonic cleaner usually gets them clean but the carb cleaner spray guy usually miss them.

 

[amentac]

Thanks for your help folks. I just cleared the first snow of the year and the tractor ran smoothly, no backfires or sputtering, valve adjustment must have fixed it. Coincidentally the RPM gauge stopped working, this is the digital type with the sensor wire that wraps around the spark plug wire. Not sure if related, the sensor wire is well insulated to prevent any possible arcing but I thought I'd mention it, might help someone else in troubleshooting.

 

[shadetree#1]

amentac wrote:
I just cleared the first snow of the year and the tractor ran smoothly, no backfires or sputtering, valve adjustment must have fixed it.

Thanks for the comeback.

 

[StarTech]

Another big problem is that people don't replace the flat o-rings on the intake manifold and they have air leaks. The OEM get hard and compressed and the cheap AM swell from the ethanol. I stock a dozen of them as i change a lot of them.

Biggest problem Next to the jet o-rings on the 2 bbl carbs is the tiny passageways under the w shaped plate. Ultrasonic cleaner usually gets them clean but the carb cleaner spray guy usually miss them.

Yes those o-rings need changing during carburetor service. I had one engine to come that was sneezing at idle because of a bad square cut o-ring. On the V-twins the same problem except you can have the area where the carburetor mounts to warp especially when the tech over tighten the carburetor mounting screws but heat does it too.

On the most recent repair of a v-twin with dual barrel Nikki. It called for the 695241 manifold superseded to in my case 797503. I used the 595606 instead and the only real difference was the 595606 had the stud for the auto choke spring. They also used a new o-ring design. It was well worth to try anyway at the cost difference for both me and my elderly customer. I will use this from now on.

 

[shadetree#1]

May have already mentioned this. I usually just add a paper gasket (not really paper, it's a automotive gasket material about 1/16 inch thick) over the old intake manifold o rings. Sometimes these paper gasket material come in a kit in addition to the intake o rings. I trust the thicker intake gasket material more so than the rubber o ring for a good seal.

I save them plastic intake manifolds when sending the engine to the salvage. (after seeing the replacement prices)
Some plastic intakes for the single cylinder Briggs Inteks are specific to the type of air breather required.

 

[StarTech]

That what someone did here then they tighten down the screws so tight that spacers had cut right the gaskets and I could see light through the area. Still wasn't sealing.

 

[shadetree#1]

Wow, Bubba must have used a big impact driver.
Some of them plastic intakes have a steel sleeve through the bolt holes to limit the tightening and prevent breaking the plastic so no really need in trying to do the extra leverage, it's just distorting things.

And them kind of people get to vote.(at our expense)

 

[bertsmobile1]

Things sealed by O rings should have some wiggle when tightened because you are trying to SLIGHTLY compress the O ring so that the parts have some relative movement as they heat up to account for different amounts of expansion
Most British motorcycles used this from around 1960 on
The US distributors invented a tool to straiten the flange which US mechanics warped because they over tightened the mounting nuts and that was even after the factory changed to a very lightweight split washer and a 1/2 nut .
O rings must have a solid FLAT surface to seal against
Putting a paper gasket under the O ring defeats the whole system
Aussie distributors had a similar problem but we ended up fitting a soft composite gasket and deleting the O ring so the gasket extrudes into the O ring hole .
I fix a lot of power torque engine that are "impossible to start" simply by doing the 10 year maintenance and replacing the 4 O rings that are not obvious which go hard thus stop sealing