YM1700 Starting Questions

[SailorBob]

Once you insure that you do not have any issues with the battery or electrical connections this is the procedure that I use to cold start my 1700. It always starts right up:

Pull the throttle back approximately 50%, press in the clutch, turn the decompression lever to the left, turn the key and allow the engine to turn over for about 10 seconds, release the decompression lever. I should then fire. Once the engine starts adjust the throttle to about 1200 rpms to allow the engine to warm up.

By the way my tractor does not have a thermostart. I have started it down to about 30 degrees F. It seldom gets much colder here.

 

[michaelvsmith]

That sounds like the best procedure I have heard so far. I really could not understand why the decomp feature was even there. But this sounds reasonable. Thanks for your help

 

[SailorBob]

The decompression lever helps to get the engine turning faster while warming the cylinders.

 

[dieselfuelonly]

So the engine should start with the decomp lever pulled. Is that right?

Sorry if I'm pointing out the obvious here. But the engine won't start with the lever pulled, it has no compression. You can pull this lever to get the oil pressure built up. When I first bought my tractor, the battery was in bad shape and I had to get it off the trailer I rented to bring it home. I didn't really know much about the decompression lever then, so I was trying to start it with a weak battery without the compression release. It just wouldn't turn over fast enough. However, I thought I'd pull the compression release, turn it over, then release the compression release while the starter was still spinning. I was able to get it started this way even with the weak battery because of the inertia the engine built up by spinning fast with the compression release pulled. I always use the compression release this way now, I figure its gotta be much easier on the starter than having to start out turning the engine over at full compression.

 

[kenmac]

Sorry if I'm pointing out the obvious here. But the engine won't start with the lever pulled, it has no compression.

Exactly my thinking. How would it start without compression. I have never had to use / try mine. But, this is what the book says. Pull throttle all the way,,Turn key to TS for 10-15 sec.This Ignites a small amount of fuel in the intake. pull decompression lever, depress clutch, Quickly turn the key clockwise & start the engine. As soon as engine starts turn key back to TS position go to 1/2 throttle, hold switch to TS position until engine runs smoothly. ..It also says to pull decompression lever for easy ranking 5-10 sec. until oil light goes off......I don't know mabe a mis-print

 

[California]

Here's the cold weather instructions that American Yanmar put in their manuals.
(Note the American throttle pushes forward to accelerate, the opposite of the Japan-market tractors.)

[click to enlarge]


Their warm weather instructions don't mention the Thermostart. Just full throttle, use decompression lever, turn the key, then "when starter gives enough rotation to start engine, release decompression lever. Release key immediately when engine starts."

"Important as soon as engine starts, put throttle at halfway. Do not run a cold engine at full throttle."

Then warm up 5 minutes at 1500 rpm and no load.

Below -12C +10F "Use an electric coolant heater."

 

[SailorBob]

Here's the cold weather instructions that American Yanmar put in their manuals.
(Note the American throttle pushes forward to accelerate, the opposite of the Japan-market tractors.)

[click to enlarge]
View attachment 121814

Their warm weather instructions don't mention the Thermostart. Just full throttle, use decompression lever, turn the key, then "when starter gives enough rotation to start engine, release decompression lever. Release key immediately when engine starts."

"Important as soon as engine starts, put throttle at halfway. Do not run a cold engine at full throttle."

Then warm up 5 minutes at 1500 rpm and no load.

Below -12C +10F "Use an electric coolant heater."

That is pretty close to the procedure that I developed on my own except for the amount of throttle. My starts so easily since the rebuild. I guess that I should modify my throttle setting then. From what I have been able to gather reading the YM1700 does not have a thermostart. I am not sure how cold it gets in Japan in the winter. I know that mine does not.

 

[California]

I quoted that verbatim so it wouldn't get confusing, but I don't follow it literally either.

If I haven't run the tractor for a couple of days, I spin it with the compression released until I see oil pressure. (light goes out.) Then 10-20 seconds Thermostart to warm the manifold. Then set throttle to 40% (warm weather) or 60% (cold weather).

Use the compression release for a moment as the starter cranks the engine through the first revolution (to save stress on the starter) then let go of the compression release and keep cranking until it fires. If it is flooding, ie exhausting raw fuel (white vapor) without firing, adjust throttle down and then up to find the right mixture.

When it starts don't let rpm exceed 1500. Warm up at 1500 but only a minute. Idle down to 1150, just above where it clanks painfully, and pull out of the barn carefully. I consider the drive out to the jobsite to be the warmup.

Note I don't need to operate the tractor below 40 degrees so my procedure isn't for everyone. Also I discovered the safety wire and lead seal by the governor have been cut, so I suspect full throttle on this engine asks for more fuel than it should.

I think the Thermostart was an extra-cost option on all the models. It would be simple to put on as a dealer-installed kit at the time of sale.

 

[kenmac]

Cal. That's the book I have. I was refering to # 6 & 7. Pull decompression lever then turn kek & start engine. I guess I'am just missing something..... won't be the 1 st time In # 8 in my manual It states when engine starts turn key back to thermostart position & pull throttle lever !/2 way back. Hold key in this position until engine runs smoothy. Then turn key to on position They aren't exactly the same on some of the stuff

 

[California]

Yes, they didn't write the cold weather paragraph very well. Yanmar left out the sentence that was in the warm weather paragraph:

"when starter gives enough rotation to start engine, release decompression lever. Release key immediately when engine starts."

I think the idea of that sentence is that cranking against compression *and* getting the heavy flywheel moving strains the starter. It's better to get the flywheel moving without compression resistance, then a moment later the starter will be assisted by the flywheel's inertia when it hits a compression stroke.