Author Topic: Ms 650 (Read 368 times)

jmester · « **on:** June 10, 2015, 08:35:11 pm »

Have a 650 rebuilt the carb and replaced the check valve back in the winter. I can't get the saw to really hold a tune. The main reason I rebuilt the carb to begin with. On the high side it will run at like 12500 then jump up to like 13300 and is all over the place same way on the idle set @ 2800 rev to 12500 and will come back to idle at 2200-2400. Thinking it is not a carb issue and a ignition module issue. Some of the layers have separated. I don't know. This one kind of has me licked. Any thoughts.

jmester · « **Reply #1 on:** June 10, 2015, 08:40:10 pm »

Look where the plug wire comes out of the coil the top 2 layers are pulled up. I also pressure and vac tested it back in the winter when I rebuild the carb and it checked out fine.

mdavlee . · « **Reply #2 on:** June 10, 2015, 09:10:57 pm »

Could be the coil. Swap to a good one and see if it fixes it?

aclarke · « **Reply #3 on:** June 11, 2015, 12:26:05 am »

Look at the metering needle carefully. Check if it holds pressure consistently. Sounds like a flow issue...

660magnum · « **Reply #4 on:** June 11, 2015, 06:09:48 am »

High speed check valve in the carb is blown?

jmester · « **Reply #5 on:** June 11, 2015, 06:21:51 am »

I should say this I was thinking more about it last night. It started to do this with the tillotson hs 320 I had on it . I figured carb kit time. Did not have the kit to do it. So I used a Walbro wj -69 that had a blown check valve. Replaced valve and rebuilt carb. It seemed to help just not fix it all the way. I will try another module since I have that tore down. If that does not help I will go back threw the carb.

660magnum · « **Reply #6 on:** June 11, 2015, 06:47:30 am »

jmester · « **Reply #7 on:** June 11, 2015, 08:46:19 pm »

Put a used module in it this morning before I left my house. Tune it this morning on the job. Runs great. Cut trees all day and never missed a beat.

660magnum · « **Reply #8 on:** June 11, 2015, 10:50:48 pm »

Glad it is fixed

jmester · « **Reply #9 on:** June 12, 2015, 05:59:06 am »

That has been the first ignition module on any of saws I have used that has acted like that. Glad I could experience it. Makes me think if I would use the spark tester pet 4000 I have where you can increase or decrease the gap if you could see what was going on if nice blue for some rpm range and maybe lighter blue or inconsistent spark at others. Maybe I will try it.