MS341 "parping"

[Matthew Arnold]

Over the past couple of weeks we have noticed that one of our MS341's pops through the carb on warm starting. It has done it atleast 15 times when i have been there. Any idea what may be causing it and if any damage is being caused as it is a little bit rich (blue smoke when under load and under high revs)?

[GardenKit]

Matt, have you tried giving it a tune? It sounds, just like you say thats its running a little rich. No harm should come from being rich, but you may lose just a little power.

 

I know you follow the threads, so you will be aware of the danger of being too weak, so tune carefully.

 

You should not really get blue smoke from a rich mixture, it is normally associated with excessive oil in the petrol/oil mix (or oil of poor quality).

 

Others may have more info to add, or a different opinion.

[blazer]

As Above ; Blue smoke = oil, black smoke = extra fuel, as in been overtaken by a hot motor.

 

I assume your oil/fuel mix is ok, if it's not that I could be oil getting into the crankcase, 2 ways of doing that crank oil seal or a crank case oil leak.

 

I worked on my old 266XP a while ago on the oil pump with the crank oil seal out and some oil got onto the crank bearing, on restarting - yep it belched blue smoke for a while, but yours is doing it all the time?

 

You could try draining all the chain oil out, remove bar etc and run it for a while - if it clears then you have a crank problem or go for plan B and take it back.

 

Always hard to tell from a distance:thumbup1:

[spudulike]

Not sure how th esaw is Parping through the carb as the only time the inlet port is open is to let fuel in to the lower crankcase.

 

If the saw is down on power and is backfiring then it may be the flywheel key has sheared - maybe worth checking! Other than that, is your plug black, if so, you are running rich and would be worth setting the carb back to factory but make sure of the correct carb settings - the ones on the side of the airbox are with the limiters fitted!

 

The above is assuming the 361 has got a standard carb and not one of these electronic adjustment ones:001_rolleyes: I havent done one of these yet - the MS441 is the closest I have got to it!

[blazer]

Have you had many flywheel keys shear Spud? bit odd as they are not on load. Had a few go in motor bikes but I'm sure it was due the damage on the taper shaft, bit like a big drill with the load on the drill tang.

 

Popping back through the carb is a bit odd, as I have heard of old scooters with the timing a bit advanced sitting at trafficlights and when the lights changed they shot off backwards - the engine had reversed crank direction:lol:

 

It's always hard when the patient is not in front of you

[spudulike]

Have you had many flywheel keys shear Spud? bit odd as they are not on load. Had a few go in motor bikes but I'm sure it was due the damage on the taper shaft, bit like a big drill with the load on the drill tang.

 

Popping back through the carb is a bit odd, as I have heard of old scooters with the timing a bit advanced sitting at trafficlights and when the lights changed they shot off backwards - the engine had reversed crank direction:lol:

 

It's always hard when the patient is not in front of you

 

Had an 028 come in, scared the poop out of me when it backfired, a 335XP and a 338XP - a bit more common than I would think. I guess it is probably down to the flywheel becoming loose. The backfiring is down to ignition on the downward stroke when the exhaust port is open.