echo cs-400 seized?

[bomba88]

Took the muffler off. There's one scratch on the piston that I can see.

 

[James Miller]

Can you post a picture?

 

[bomba88]

The one really noticeable scratch.

 

[FlyingDutchman]

Scratching associated with failure usually looks like it got drug down the highway... As far as I'm aware.

 

[bomba88]

Well I can get it started, it starts up but instantly going at full rpm without touching the throttle. If I unlock the brake the chain goes on it's own. As soon as I touch the throttle and release it, the chainsaw shuts off.

 

[James Miller]

If the limiters are pulled try turning the low 1/4 richer see if the saw stays running. That mark on the piston shouldn't effect anything.

 

[bomba88]

They are still on but there is some room to turn them slightly.

 

[James Miller]

Turn the low all the way counter clockwise. It sounds like it's not getting enough fuel to stay running when its kicked off high idle.

 

[bomba88]

Should I do anything with the high?

 

[bomba88]

I took off the limiter caps because it still was not having any effect on the saw.

 

[Old2stroke]

Sounds like your engine seized because it was running too lean, usually caused by induction air leak or a reduction in the fuel coming out of the main jet. The fact that it races at fast idle start and won't idle when fast idle is kicked off, probably means those faults still exist.

 

[bomba88]

Any solutions? If you haven't noticed I do not have much experience working on chainsaws.

 

[Old2stroke]

Any solutions? If you haven't noticed I do not have much experience working on chainsaws.

Start with a careful inspection of carb mount and fuel lines. A loose carb or cracked boot between carb and engine (if it has one) can cause air leaks. Cracked or broken fuel lines can reduce the carbs ability to suck fuel from the tank. A clogged fuel filter will do the same. The carb has to be dismantled and inspected. There is a fine screen in the inlet passage leading to the inlet valve that should be clean. All the passages, especially the high speed circuit to the main jet and the low speed ports under the welch plug have to be checked. When you put it back together, throw away those damn limiters and start with a rich setting of 1 and 1/2 turns out on both L and H screws. A pressure test of the crankcase would be good to ensure the seals are good. Don't run the saw until you find out what caused it to seize or it will just do it again. You are lucky there was so little damage, most engines that seize have SERIOUS scratches and gouges in the piston.

 

[bomba88]

Could this be as simple as a fuel mess up? Not enough oil in the fuel mixture?

 

[Old2stroke]

Not too likely unless the mixture was way leaner then 50:1 or a very inferior oil was used. 50:1 is a pretty scary mix ratio, but saws seem to survive as long as a good synthetic oil is used, mixed accurately and the carb is properly tuned so that the saw is not running lean.

 

[rd35]

bomba88
I just now read through this post. Old2stroke is telling you the straight story! I totally agree with everything he has stated! Good advice! And, yes, you don't want to run it anymore until you figure out and fix whatever caused that seizure! Most likely an air leak since you are getting this high idle issue. But could also be dirt in the low speed jet (L needle adjuster) leaning out the low speed mix. Just needs to be taken apart and checked thoroughly along with performing a pressure/vacuum test.

 

[BVdog]

From the manual it states 1 3/8 for L and 2 3/4’s for H to start after seating them.. turn CCW as usual. Also start with Idle screw out 1 3/8’s also. I would than tune with a tach H for just under 12,000. Book says 12,000-12,500. A little lower should insure decent richness. If you don’t know the idle procedure I can give you some on that also good luck. Compression tester and tach 2 great tools. For some reading info checkout my post on tach tool. Good luck


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