DarkWingDuck

My Feedback: (1)

I am presently trying to correct a problem with my 140 DZ. The engine hand starts easily, has a good idle but will only turn up to 6,000 with a 16x12 APC prop; well below what it should be getting. Fuel is 15% Cool Power with a O.S. F plug. The valve timeing checks out and the compression seems to be O.K. I suspect the fuel delivery system. Before I can go any further, I need to fully understand how it works. I have not come across any articles that address this. I do have considerable experience with overhauling all the older generation YS engines, but like I said I need some more info on the pump system.
Thanks.
Dave G.

Troy Newman

I wrote and article that is in the June Kfactor. It describes the system and shows a diagram of the fuel system.

Yes 6000 rpm is way low. It might not be the fuel system. it could be the rear disc valve and or a problem with the ring or sleeve.



Troy Newman
Team YS

SpectrePilot

My Feedback: (9)

I've been searching all day for information about the YS fuel system as I am having horrible problems like so many. Now I find I have to join another organization to get a diagram....argh.

Troy Newman

No you don't have to join an organization to get a diagram. I just refered you to it the article as I thought you might already be a member.

My bad. The DZ engines are different than your 110...and all the other pressurized engines. The like below is for the pressurized systems ONLY

See the result of your other post.

http://www.centralhobbies.com/instructional/lines.html

The information is free.

Troy Newman
Team YS

DarkWingDuck

My Feedback: (1)

Troy,
I got the article in the June K-factor, thanks. Still haven't come up with an answer. What is the valve timing on the DZ? I checked the valves as per the instruction sheet but could the cam still be out one tooth?

Dave G.

Troy Newman

To set the timing on the cam gear. I place the dot on the crank down at 6 o'clock. This is TDC on the piston. The Cam gear dot is at 12 o'clock. Actually when it rotates into the worm gear the final position is about 12:30. This is as close to 12 as you can get.

This is the correct timing on all YS engines.

Troy Newman
Team YS

DarkWingDuck

My Feedback: (1)

Troy,
I finally came up with the answer as to the low power on my 140DZ. The intake valve is leaking badly. When turning the engiine over slowly by hand the air escaping thru the carb is quite noticeable. Also, when I do get the engine running, there is a lot of fuel spraying from the carb. Looking at the valve under a magnifying glass shows it to be "cupped" and the seat is grooved. Is it possible to lapp the valve again or am I faced with getting a new head assembly? I am also curious as to why this would happen to the intake valve while the exhaust valve is still O.K.
Thanks
DWG

Troy Newman

The cupped valves and seats happens....I have not see it be a big issue in many years but it can happen. Depends on how bad it is. I would try to Lap it with a dremel turning slowly and some lapping compound. Work slowly. Usually if the valve is not seating its because something is up with the head. Try cleaning it up well and see what you find. My first thought is if you think a little lapping time will fix it do it.....If its a little worse then look at getting a new valve. Then lap the new one in place to get it to seal.

New intake Valve part # YSE2160

Make sure there is no carbon in the seat.....This is common if you are using a certain fuel...Carbon on the intake is rare...but make sure the seat is in good shape.

Troy Newman
Team YS

DarkWingDuck

My Feedback: (1)

Troy,
Can you suggest a proper compound for doing a valve job on 4 strokes? I understand that automotive valve grinding compound is much too abrasive.
DWG

Troy Newman

Tooth Paste

The car finish rubbing and buffing compund like Maguires cutting compounds. There are various grades.

Depends on how much you need to remove...

Troy Newman
Team YS