Am ms440 carbs

[MG porting]

Now I'm not sure if this makes any difference but I've never paid much attention to it it until now it just struck me to be odd that the am main nozzle is longer than the OEM main nozzle can this be some of the issues of the am carb other than the butterflys aren't perfectly round?

 

[MG porting]

 

[tree monkey]

why waste your time and money on junk?

 

[Wonkydonkey]

I'm glad you picked this thread back up

I had been playing with my 044,,, I got the new fuel line in,, and swapped most of the AV mounts... I also put the timing back to stock.

Now this AM carb seems to work with the little bit of testing I did..but it was loading up and dying,, and saw that I was running out of time... and ended up putting the c3m back on.. I did notice that this was also loading up and if I tipped the nose/bar down it died.. I tried to tune it differently, but the day light diminished.. but I was half way there...with the oem

I think will get a chance to just run it with the oem carb and try to tune it in the morning...

I do think I need to play with the intake, it may help with the loading up issue... once I get that sorted, I will play some more with the AM carb..

Oh one last thing, since I put the timing to stock I found the AM carb was not as rich on the low jet and it was easier to set the low jet than before

Cheers..

 

[MG porting]

why waste your time and money on junk?

I'm not I'm putting the Walbro on the saw but there's a few difference between the OEM and the SM carb which is supposed to be a copy and the more I look the more I see why the AM carbs are a pain in the ass to get to work right so I'll stick with the Walbro carbs don't take much to make them work the way you want them to.

 

[MG porting]

I'm glad you picked this thread back up

I had been playing with my 044,,, I got the new fuel line in,, and swapped most of the AV mounts... I also put the timing back to stock.

Now this AM carb seems to work with the little bit of testing I did..but it was loading up and dying,, and saw that I was running out of time... and ended up putting the c3m back on.. I did notice that this was also loading up and if I tipped the nose/bar down it died.. I tried to tune it differently, but the day light diminished.. but I was half way there...with the oem

I think will get a chance to just run it with the oem carb and try to tune it in the morning...

I do think I need to play with the intake, it may help with the loading up issue... once I get that sorted, I will play some more with the AM carb..

Oh one last thing, since I put the timing to stock I found the AM carb was not as rich on the low jet and it was easier to set the low jet than before

Cheers..

Make sure that the needel lever in the carb is set right if the lever is set to low any sunden movements will cous it to stumble or die heck who knows you might have more payshents than I do and be able to get a carb to work right.

 

[Terry Syd]

the am main nozzle is longer than the OEM main nozzle can this be some of the issues of the am carb

It may be, there are different airflow velocities through a venturi at different positions within the venturi, from fast along the surface of the venturi to slower in the middle (also in the area after the venturi). The guys that were flying ultra-lights had a problem with excessive richness when they throttled back at altitude. They corrected the problem by using a longer main discharge nozzle.

When the engine was throttled back, the airflow through the center portion of the venturi dropped off quickly, that allowed the longer discharge nozzle to run leaner in the 'cruise' throttle position.

I've made small changes to the discharge nozzle position to decrease the restriction to airflow through the venturi. I didn't notice a big change in the fuel mixture, but then I was also modding other jets at the same time.

If you change the position of the stock discharge nozzle you have to make sure that the passages in the carb will still feed the nozzle. I've had to mod the groove on the nozzle to make sure it was still provided with fuel. I've also had to 'notch' the back of the nozzle to clear the metering lever as the nozzle then stuck deeper into the wet side.

Ain't modding carbs fun!!

 

[MG porting]

It may be, there are different airflow velocities through a venturi at different positions within the venturi, from fast along the surface of the venturi to slower in the middle (also in the area after the venturi). The guys that were flying ultra-lights had a problem with excessive richness when they throttled back at altitude. They corrected the problem by using a longer main discharge nozzle.

When the engine was throttled back, the airflow through the center portion of the venturi dropped off quickly, that allowed the longer discharge nozzle to run leaner in the 'cruise' throttle position.

I've made small changes to the discharge nozzle position to decrease the restriction to airflow through the venturi. I didn't notice a big change in the fuel mixture, but then I was also modding other jets at the same time.

If you change the position of the stock discharge nozzle you have to make sure that the passages in the carb will still feed the nozzle. I've had to mod the groove on the nozzle to make sure it was still provided with fuel. I've also had to 'notch' the back of the nozzle to clear the metering lever as the nozzle then stuck deeper into the wet side.

Ain't modding carbs fun!!

Yes I don't mind modding them but wow you would think sense these are copies of the Walbro that it should at least set up the same but nope the more you look and look again there's not much about them that's the same lol. But now I'm going to see how the hd18b feeds the ported ms460 I took the .56 jet and drilled it out to .68 ish might be more close to .69 but we shall see.

 

[MG porting]

Welp took the AM carbs and tost them in a drawer I put the HD carb on after much thought on which hd carb I should us well figured out that after reading other threads that it doesn't really matter which one to use as long as the jetting is correct for the saw this saw Love's ether of the HD carbs I've got and she's happily forstrokes at 14,500 so it staying there darn AM carbs just not good enough for my money anymore...........