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YB701 Iseki Shindaiwa Chainsaw Pictures

Following the request of certain owners of this chainsaw, and in view of the obvious lack of information about it, I have included in this article some photos taken during the intervention on my machine.
It goes without saying that to achieve them, its complete disassembly was necessary.
It is not inaccessible, but it requires a minimum of tools and attention.


punctuation iconBefore reading the following, please know that I can in no way be held responsible for any damage that your equipment may suffer during or / and after this type of intervention.


View after removing the handle and the housing :

view of the machine being dismantled ...

We can see on the right in blue the ignition coil, and in the background, the engine cylinder. In the center, the wheel with the fins ( which are used to cool the engine ), it is the magnetic flywheel, which delivers these impulses at each turn via small magnets, which are an integral part of an electronic hall effect ignition. . The transistor that receives these pulses is located just under the flywheel, attached to the lower part of the chassis. On the far left are the 2 fuel and chain oil tanks.

The fuel tank :

view of the fuel tank ...another view of the fuel tank ...On this tank, apart from the filler cap that I still left in place, we can clearly see the end of the fuel inlet pipe fitted with its strainer ( still in place in the tank ... ), and a little further to the left, a round hole which accommodates the vent nozzle ( round black rubber cap located on the top of the machine, at the front behind the safety handle, etc. )

The pipe with its strainer :

view of the fuel hose fitted with its strainer ...view of the deterioration of the fuel hose ...For information, the pipe is approximately 130mm long. The rubber material of which it is made becomes very soft over time, or even crumbles under the fingers. This obviously requires its replacement, under penalty of malfunction. The photo on the right shows the problem. This is the part that fits into the tank, and acts as a seal.

The magnetic flywheel :
view of the tool installed on the flywheel ...view of the tool installed on the flywheel ...

These 2 photos show the use of the tool I made to remove the flywheel. On the bar there is a hole left free, it is used to fix the tool to the frame by means of a large Ø4mm bolt.

The clutch :view of the oil pump gears ...

Once the tool is positioned on the flywheel, it is completely immobilized. Turn the machine 180 ° and clamp the tool in a vise. Remove the clutch using the method already explained on the previous page . The 2 visible gears are used to actuate the oil pump.
This done, we can now remove the steering wheel. Be careful, it is a keyed axis, and a small 'plop' will occur during detachment. A trained eye will have noticed the 2 marks on the field of the steering wheel: which I suppose to be notches made in the factory for balancing purposes.view of the magnetic flywheel removed ...

The carburetor :

multiple view of the carburetor ...internal view of the carburetor ...The carburetor that drives this engine is a Walbro membrane. Whatever problem you are having, don't touch the settings or open this delicate component! I did it on my machine, but I knew its engine was tight ... In addition, my carburetor problem was not one, the failure was due to the damaged fuel hose, which generated a significant air intake. I opened mine for you to show you precisely this famous membrane. The brass shutter in the center is called the butterfly, it is the throttle control. The 2 adjustment screws allow adjustment of the idle speed and the richness ( dosage of the air-fuel mixture ).

The oil pump :
view of the oil pump in place ...

Below the motor shaft is the oil pump, the flow of which is adjustable thanks to a small screw accessible on the top of the frame.
The exhaust :
view of the exhaust baffles ...Be careful when removing this very important part which serves as a load for the engine! I had the clumsiness of not paying too much attention to it, and I realized afterwards that it was possible to make a mistake during reassembly ( look closely at the photo, especially the baffles ... ). Not too bad in my case since the engine is definitely out of order, but on your machine, it is better to be careful!
Once the machine has got rid of all its little accessories that have become unnecessary for the moment eek, this is what the engine block looks like.
We can also distinguish the rubber connection serving as a flexible interface between the carburetor and the cylinder block.

view of the engine block ...

The engine :
view of the motor body ...

Come on, I'm happy, the last on the engine still assembled!
 

inside view of the cylinder ...inside view of the cylinder ...And now, drum roll ...
I'm going to show you the pictures of an engine that screwed up!

Here, it is true that we do not see much ... it is after that it becomes clearer ...

At the bottom of the image, we see the thread receiving the spark plug and, below, it is the light of the exhaust outlet. There are already emerging what I will call 'traces of fire' ...

On these other photos, at the foot of the exhaust light, we can see a trace ... more than a trace ... material has been removed !!!
inside view of the cylinder ...close-up view of the streaks ...

The piston :
view of the burnt piston ...

On this piston seen on the exhaust side, we can clearly see the ridges caused by the tightening.

Conclusion :

The consequences of all this mean that it would have been necessary to replace the piston ( equipped with the connecting rod, inseparable ) as well as the cylinder, no liner on this type of engine. We still manage to find second-hand engine blocks but I didn't want to venture ( that's the word! ) In an engine that was probably badly lived ... Suddenly, I scrapped my machine, and I bought from my usual dealer ( HONDA among others ...) a STIHL MS250 C-BE , equivalent model in terms of power and guide length. I admit I am not disappointed at all, it is an excellent machine, flexible and comfortable in use.

In spite of everything, I hope that these few pages will be useful to you, either to free you at first from what the dismantling of your machine can represent, whether in terms of technical knowledge or tools, or to directly repair it. and maintain it.

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