ys 140 engine question
06-30-2004, 08:24 PM
#1
Member
Thread Starter
My Feedback: (-1)
Join Date: Dec 2002
Location: Joplin,
MO
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
ys 140 engine question
If anyone can help me, it would be appreciated. I have a YS 140 FZ that I just had to put a new cam gear in because it stripped. It does not run real good now. There is actually fuel coming out of the carb as it runs. This it was doing before the gear change. Question. Off one pinion on the gear, valve not closing all the way. Too much pump pressure? What should I look for first. It still turn up 7,500 rpm on the ground with a 15X12W prop, but does not have the power it once had and runs rought, cuttion out at times. What shoul I look for? I think some of the intake O rings are not sealing very well either.
06-30-2004, 11:39 PM
#2
My Feedback: (182)
RE: ys 140 engine question
What do you mean the valve not closing all the way?
did you make sure the TDC when you install the cam gear?
How is the compression?
Have you tried disassembling the engine (pulling out the crankshaft) to clean?
If the fuel is coming out of the carb while running, how about when it is not running? throttle barrel closed & open etc. If the engine is mounted inverted, the fuel spray is possible, but not dripping out of carb.
If the O-rings are not sealing very well, you can check it by submerging the engine in a small container with fuel in it. Make sure to drain out any fuel inside the engine before doing this. plugging the exhaust & carb with something that can not be sucked in. I would put something like food wrap (saran wrap) with small rubber band.
When I removed my cam gear, I disassemble entirely to clean any small debris out of the engine even used a tooth brush to clean the crankshaft gear teeth. Check the piston, ring, & liner for any scratches.
By the way, where do you fly in Joplin, MO?
I live in Pittsburg, KS.
IP
did you make sure the TDC when you install the cam gear?
How is the compression?
Have you tried disassembling the engine (pulling out the crankshaft) to clean?
If the fuel is coming out of the carb while running, how about when it is not running? throttle barrel closed & open etc. If the engine is mounted inverted, the fuel spray is possible, but not dripping out of carb.
If the O-rings are not sealing very well, you can check it by submerging the engine in a small container with fuel in it. Make sure to drain out any fuel inside the engine before doing this. plugging the exhaust & carb with something that can not be sucked in. I would put something like food wrap (saran wrap) with small rubber band.
When I removed my cam gear, I disassemble entirely to clean any small debris out of the engine even used a tooth brush to clean the crankshaft gear teeth. Check the piston, ring, & liner for any scratches.
By the way, where do you fly in Joplin, MO?
I live in Pittsburg, KS.
IP
07-01-2004, 09:09 AM
#3
Member
Thread Starter
My Feedback: (-1)
Join Date: Dec 2002
Location: Joplin,
MO
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
RE: ys 140 engine question
Thanks for the info. In Joplin, we have a field north of 7th St off blackcat Rd just north of Belle Center Rd. I will take the engine out again, check the TDC marks and see if the intake valve is adjusted propertly. I plan to repace the intake O rings and inspect the intake valve for seating. I will check out the compression as well. There is a fine mist that comes out of the carb while running right side up. Give me a call if you want at 417 781 2339 or e-mail at [email protected]
07-01-2004, 01:21 PM
#4
Senior Member
RE: ys 140 engine question
7500 is way to low a number for that prop and that motor.
Here is what I would look to first:
How bad did the cam gear strip. Normally when a cam gear goes its an expensive thing. You need to replace the crank, and bearings too. Cam gear failures are usually caused by that quick lean burp the motor can make if the low end is set too lean. If you are getting any backfires or the likes then its lean somewhere...Could be the low end could be the regulator, could be the high end. Also if you have too much load on it. The 15-12W is a pretty good load but should not be too bad as long as you are running 25-30% nitro. I would suggest just a 15-12 if you are on 20% and 15-11 on 15% nitro. This is a standard FZ not an "L" The "L" has a little more stink and can handle the 15-12W all day long but on the FZ this is a little bit labored.
The cam gear installed properly. There is a dot on the cam gear. It gets installed at 12 o'clock when the dot on the rear of the crank shaft is at 6 o'clock.
Next thing is the o-rings on the pushrod tubes may or may not be leaking. This is not common. But since you had it apart look to see if the o-rings are seated properly. Sometimes one of them will curl up and out of the groove. I use a small flashlight and look at the O-rings.
Next is the clearance on the rocker arms to the valves. Some refer to this as Lash..If the motor has been run a long time, the tappet arms will get wear on them and be "concave" where they touch the valve stems. This adjustment should be fairly tight...2-3 thousands but a feeler gauge is sometimes not the best as the surface is "cupped" and not flat. I just use my calibrated fingers to set the clearance so that it does wiggle but barely. This insures the valve does close. If the Cam gear if off position then it may not be closed at the right time.
As for leaking fuel out the carb. Usually this is because the regulator is not sealing. Options include trash or debris in the reg or its passages. Deformed diaphram, or leaking gasket. Also if there are any other leaks in the motor, valve cover gasket, pushrod tubes, carb gasket this dripping of fuel can happen.
From the sounds of what you have...I think a trip to the YS Performance Service is your best bet. They can figure out what is wrong and you won't be paying for extra parts you don't need.
Troy Newman
Here is what I would look to first:
How bad did the cam gear strip. Normally when a cam gear goes its an expensive thing. You need to replace the crank, and bearings too. Cam gear failures are usually caused by that quick lean burp the motor can make if the low end is set too lean. If you are getting any backfires or the likes then its lean somewhere...Could be the low end could be the regulator, could be the high end. Also if you have too much load on it. The 15-12W is a pretty good load but should not be too bad as long as you are running 25-30% nitro. I would suggest just a 15-12 if you are on 20% and 15-11 on 15% nitro. This is a standard FZ not an "L" The "L" has a little more stink and can handle the 15-12W all day long but on the FZ this is a little bit labored.
The cam gear installed properly. There is a dot on the cam gear. It gets installed at 12 o'clock when the dot on the rear of the crank shaft is at 6 o'clock.
Next thing is the o-rings on the pushrod tubes may or may not be leaking. This is not common. But since you had it apart look to see if the o-rings are seated properly. Sometimes one of them will curl up and out of the groove. I use a small flashlight and look at the O-rings.
Next is the clearance on the rocker arms to the valves. Some refer to this as Lash..If the motor has been run a long time, the tappet arms will get wear on them and be "concave" where they touch the valve stems. This adjustment should be fairly tight...2-3 thousands but a feeler gauge is sometimes not the best as the surface is "cupped" and not flat. I just use my calibrated fingers to set the clearance so that it does wiggle but barely. This insures the valve does close. If the Cam gear if off position then it may not be closed at the right time.
As for leaking fuel out the carb. Usually this is because the regulator is not sealing. Options include trash or debris in the reg or its passages. Deformed diaphram, or leaking gasket. Also if there are any other leaks in the motor, valve cover gasket, pushrod tubes, carb gasket this dripping of fuel can happen.
From the sounds of what you have...I think a trip to the YS Performance Service is your best bet. They can figure out what is wrong and you won't be paying for extra parts you don't need.
Troy Newman
