MS250, not sure whats wrong!

[GardenKit]

But probably best if non-technicians leave these things well alone and stick to a simple clean and fit a new diaphragm kit. Can't go too far wrong and it normally sorts it out.

[spudulike]

But probably best if non-technicians leave these things well alone and stick to a simple clean and fit a new diaphragm kit. Can't go too far wrong and it normally sorts it out.

 

Couldn't agree more - just fixed HeavyHorses MS260 - crud in the gauze filter after pressure and Vac test showed no air leak - another happy customer:thumbup:

[GardenKit]

And I remember our PM of a few weeks ago Spud, I recon that was an example?

[spudulike]

And I remember our PM of a few weeks ago Spud, I recon that was an example?

 

I think you may be correct, funny old world isn't it:001_rolleyes:

[Megatron]

Blue - full load semi fixed jet for high speed running

No, blue is the part-load fixed jet. Opens into the venturi between the idle jets and the main jet and prevents the mixture becoming over lean when at part throttle. The low pressure causes additional fuel to be drawn off and enrich the fuel-air mixture, in response to the throttle shutter position. It does have a one way valve. Cannot be romoved.

 

Red - Part load valve jet - controls low speed running and has a built in one way valve to stop pressure changes in the carb throat effecting the fuel in the diaphragm part of the carb.

No, red is the full-load semi-fixed jet. At full load a defined quantity of fuel (~80% when H screw at one turn out) will flow through it and into the venturi via the main jet, irrespective of the position of the H screw. Thus, compared to a carb with no full-load semi-fixed jet, the change in the composition of the mixture for a given adjustment of the H screw is far less. These can be changed out and various sizes available, high altitude etc.

 

The carb is dependent on the main jet

All carbs are dependent on the main jet... in the sense they can't be independent!

Well the idle system is dependent on the main jet system. The idle system branches off after the H screw. Altering the idle fuel volume via the L screw does not result in a change to the overall fuel volume.

[spudulike]

Damn, you have found out my weakness.................................................................................................................................................................................................................................I'm colour blind and both those little circles look the same to me:thumbdown:

[GardenKit]

No, blue is the part-load fixed jet. Opens into the venturi between the idle jets and the main jet and prevents the mixture becoming over lean when at part throttle. The low pressure causes additional fuel to be drawn off and enrich the fuel-air mixture, in response to the throttle shutter position. It does have a one way valve. Cannot be romoved.

 

 

No, red is the full-load semi-fixed jet. At full load a defined quantity of fuel (~80% when H screw at one turn out) will flow through it and into the venturi via the main jet, irrespective of the position of the H screw. Thus, compared to a carb with no full-load semi-fixed jet, the change in the composition of the mixture for a given adjustment of the H screw is far less. These can be changed out and various sizes available, high altitude etc.

 

 

All carbs are dependent on the main jet... in the sense they can't be independent!

Well the idle system is dependent on the main jet system. The idle system branches off after the H screw. Altering the idle fuel volume via the L screw does not result in a change to the overall fuel volume.

All very interesting, but quite frankly useless information to the OP who merely wants to clean and re kit his carb. This will probably scare him off even trying.

 

After all, although these jets are technically serviceable items, in the real, commercial world if they give trouble you simply change the carb.

 

Looks to me like a point scoring exercise.

[Megatron]

Damn, you have found out my weakness.................................................................................................................................................................................................................................I'm colour blind and both those little circles look the same to me:thumbdown:

 

Well if this is true I am sorry.

But it is rather convenient, the only possible response you could give to suggest you were not wrong.

[Megatron]

All very interesting, but quite frankly useless information to the OP who merely wants to clean and re kit his carb. This will probably scare him off even trying.

 

That was never my intention.

 

I see no need for me to score "points". I have no need to be seen as more knowledgable or capable. I do not seek to profit from this website. Whereas others do...

[pleasant]

That was never my intention.

 

I see no need for me to score "points". I have no need to be seen as more knowledgable or capable. I do not seek to profit from this website. Whereas others do...

 

ooooooohhhh.......controversial.