2017 Yamasaki 50cc manual clutch - Page 2

China Rider 27 · 07-04-2021, 10:38 PM

The first video it sounds great idling. I don't know if the choke was on. The other two videos you can hear the valve tappets suggesting they are too loose. The rev is hanging suggesting a lean pilot but you say the plug has black soot indicating it is rich. The way that rev hangs suggests an air leak, check all those pollution removal EGR fittings you removed which have connection to the intake to be sure they are all sealed or not leaking. Check make sure no leaks around the carburetor or manifold. Check operation of the throttle to be sure it is closing all the way and is not held up by the cable some way. An adjusted carburetor should rev up and come right back down to idle. I would set the needle position to the middle, stock, or 3rd position. You need to know what jetting you have so you know where to go?

4T_Goblin · 07-05-2021, 10:21 AM

Yes the choke was on in the first clip

The valves felt so tight, I could not get my feelers in there at first. Going to open them back up today and try again.

I was trying to find vacuum leak by lightly spraying carb cleaner around the gaskets after the air intake to check for revs and I couldn't really hear a difference but I'll take another look at that.

I'm confused as to why I have rich and lean conditions lol

The needle is in the stock, 3rd down from top. Forgot to look at the jetting, but it's a stock pz19,
F/a screw 2 turns out
C clip 3rd position
Float -10
pilot 38 and main jet 73

China Rider 27 · 07-05-2021, 11:52 AM

The plug color doesn't really matter at this point because it has been carbon fouled (rich) maybe because you ran it on choke. It takes awhile to clean that up (running at speed). It can be rich and lean at different parts of the throttle range. I would concentrate on how it runs and reacts to throttle. Get it to idle and start well then go from there. The fact you were using choke to run it suggests overall likely lean.

4T_Goblin · 07-05-2021, 03:52 PM

Ok I adjusted the valves to .005in. same noise . I can idle the bike with choke off. , plus I accidentally ran the battery out last night.

Throttle is responding with choke off

Gonna try again next weekend with the tappets.. I an trying t pinpoint the noise
I believe I'm at TDC, the rockers are slightly loose at that point so I adjusted the valves accordingly.

I did discover a hole of on the head itself. Laying down looking up I can see it. It's not leaking anything.

Here is the bike running with choke off and reacting well to acceleration
https://youtube.com/shorts/XVzXD1vKrNE?feature=share
Next step is valves once the bike is cooled off

China Rider 27 · 07-05-2021, 05:04 PM

When you start it next turn the idle speed screw in some and once it is running adjust it to 1500 rpm. If it is real fast at start up turn it out or counter clockwise or, if needs more speed turn it in clockwise. Then adjust the pilot screw for the mixture from 1.5 turns out. The valves can have some tap to them which is better than too tight. After you set them, turn the engine over a couple full revolutions and watch the TDC mark, the piston, and the valves to confirm you set them on the compression stroke.

4T_Goblin · 07-05-2021, 07:42 PM

I think my valves need to be .002 inches or
.051mm instead of .005 inches like I made them.. Every video recommend doing the valves after a long time of cool down so tomorrow I'll make that switch.

Bad weather- get around to it on the weekend

4T_Goblin · 07-07-2021, 10:15 AM

Ok valves set to .002 inches.. Sounding good.

Now I'm having trouble with the idle.

The A/F screw is 1.5 turns out... Idling weakly... The idle screw I don't know where to begin with that one

I'm back to where I started with it not idling with choke off. So that was good learning the valves, that's an easy thing. But the carb is next..I think I'm close to getting this ready but every time I get closer it seems like I'm getting further away lol

Carb smelling like it's flooding... How can I keep the bike running and be able to adjust the carb without it dying and I have to start it several times... Over and over... The hard part here is the idle spring...

Here is.002" clearance

Here is the carb
https://youtube.com/shorts/IpEdNzGn_6Q?feature=share

4T_Goblin · 07-07-2021, 02:46 PM

I might try the valves at .003" or .004" later on...

I had the best acceleration so far with the choke off at .005" , but the rattle sounded severe. 1 variable at a time tho

4T_Goblin · 07-11-2021, 03:25 PM

Valves set to .003" intake and exhaust

Idling with choke off, getting lean bog.. However.. The tiny main jet screw is stuck in the emulsion jet. It's weak brass and my screwdriver is too much for it. I'm trying to figure out how to get a replacement emulsion jet or if there's a good 19mm carb to buy in it's place. This one was $11 from eBay. The drain screw and main jet are screwed in to tight they are getting damaged when I give them a go.

4T_Goblin · 07-18-2021, 07:20 PM

I cleaned the carb- the pilot and main were clogged

I still cannot get it to idle with the choke off.

It's still dying when I give it throttle... Sounding like too much air? I can't tell. - going to replace the intake manifold gasket. Maybe the head gasket?

What other places do air gaps happen? Could filter size matter? Or the fact that I don't have on the airbox or fairings.. Does that have anything to do with airflow here?

Today I did see debris in the fuel line from the tank.. gonna have to clean the tank and put in a filter

I can't get the main jet screw out of the emulsion tube, wasn't able to jet up a size

All I've done so far is check valve clearance, plug EGR valve at the exhaust, clean Carb, and put on a spare uni pod filter because the previous filter was old.

Still at square 1

4T_Goblin · 08-01-2021, 01:02 PM

50mph on a downhill, 45 on a straight ��️

edit to the update: the bike runs great, I took it out for a spin, top speed 39mph if the speedometer is true. This bike is a ton of fun!

update:

I took the carb off and adjusted the float bowl to allow more fuel to get in and went up a size on my pilot jet. I put on a smaller Polini filter that i had on my Tomos, and put the longer Uni filter back on the Tomos. I still was having trouble with the choke off and bogging on throttle but I could get it to rev once i got enough fuel in the carb.
Solution - I raised the throttle needle by 1 setting to allow more fuel in.

07-05-2021, 03:52 PM	#19
4T_Goblin Join Date: Jun 2021 Posts: 239	Ok I adjusted the valves to .005in. same noise . I can idle the bike with choke off. , plus I accidentally ran the battery out last night. Throttle is responding with choke off Gonna try again next weekend with the tappets.. I an trying t pinpoint the noise I believe I'm at TDC, the rockers are slightly loose at that point so I adjusted the valves accordingly. I did discover a hole of on the head itself. Laying down looking up I can see it. It's not leaking anything. Here is the bike running with choke off and reacting well to acceleration https://youtube.com/shorts/XVzXD1vKrNE?feature=share Next step is valves once the bike is cooled off Last edited by 4T_Goblin; 07-05-2021 at 05:26 PM.
	2

07-05-2021, 07:42 PM	#21
4T_Goblin Join Date: Jun 2021 Posts: 239	I think my valves need to be .002 inches or .051mm instead of .005 inches like I made them.. Every video recommend doing the valves after a long time of cool down so tomorrow I'll make that switch. Bad weather- get around to it on the weekend Last edited by 4T_Goblin; 07-06-2021 at 11:26 PM.
	0

08-01-2021, 01:02 PM	#26
4T_Goblin Join Date: Jun 2021 Posts: 239	Gas tank venting 50mph on a downhill, 45 on a straight ��️ edit to the update: the bike runs great, I took it out for a spin, top speed 39mph if the speedometer is true. This bike is a ton of fun! update: I took the carb off and adjusted the float bowl to allow more fuel to get in and went up a size on my pilot jet. I put on a smaller Polini filter that i had on my Tomos, and put the longer Uni filter back on the Tomos. I still was having trouble with the choke off and bogging on throttle but I could get it to rev once i got enough fuel in the carb. Solution - I raised the throttle needle by 1 setting to allow more fuel in. Last edited by 4T_Goblin; 08-08-2021 at 10:19 PM.
	1

07-04-2021, 10:38 PM	#16
China Rider 27 Join Date: Dec 2018 Location: PNW Posts: 982	The first video it sounds great idling. I don't know if the choke was on. The other two videos you can hear the valve tappets suggesting they are too loose. The rev is hanging suggesting a lean pilot but you say the plug has black soot indicating it is rich. The way that rev hangs suggests an air leak, check all those pollution removal EGR fittings you removed which have connection to the intake to be sure they are all sealed or not leaking. Check make sure no leaks around the carburetor or manifold. Check operation of the throttle to be sure it is closing all the way and is not held up by the cable some way. An adjusted carburetor should rev up and come right back down to idle. I would set the needle position to the middle, stock, or 3rd position. You need to know what jetting you have so you know where to go?
	1

07-05-2021, 10:21 AM	#17
4T_Goblin Join Date: Jun 2021 Posts: 239	Yes the choke was on in the first clip The valves felt so tight, I could not get my feelers in there at first. Going to open them back up today and try again. I was trying to find vacuum leak by lightly spraying carb cleaner around the gaskets after the air intake to check for revs and I couldn't really hear a difference but I'll take another look at that. I'm confused as to why I have rich and lean conditions lol The needle is in the stock, 3rd down from top. Forgot to look at the jetting, but it's a stock pz19, F/a screw 2 turns out C clip 3rd position Float -10 pilot 38 and main jet 73
	0

07-05-2021, 11:52 AM	#18
China Rider 27 Join Date: Dec 2018 Location: PNW Posts: 982	The plug color doesn't really matter at this point because it has been carbon fouled (rich) maybe because you ran it on choke. It takes awhile to clean that up (running at speed). It can be rich and lean at different parts of the throttle range. I would concentrate on how it runs and reacts to throttle. Get it to idle and start well then go from there. The fact you were using choke to run it suggests overall likely lean.
	1

07-05-2021, 05:04 PM	#20
China Rider 27 Join Date: Dec 2018 Location: PNW Posts: 982	When you start it next turn the idle speed screw in some and once it is running adjust it to 1500 rpm. If it is real fast at start up turn it out or counter clockwise or, if needs more speed turn it in clockwise. Then adjust the pilot screw for the mixture from 1.5 turns out. The valves can have some tap to them which is better than too tight. After you set them, turn the engine over a couple full revolutions and watch the TDC mark, the piston, and the valves to confirm you set them on the compression stroke.
	1

07-07-2021, 10:15 AM	#22
4T_Goblin Join Date: Jun 2021 Posts: 239	Ok valves set to .002 inches.. Sounding good. Now I'm having trouble with the idle. The A/F screw is 1.5 turns out... Idling weakly... The idle screw I don't know where to begin with that one I'm back to where I started with it not idling with choke off. So that was good learning the valves, that's an easy thing. But the carb is next..I think I'm close to getting this ready but every time I get closer it seems like I'm getting further away lol Carb smelling like it's flooding... How can I keep the bike running and be able to adjust the carb without it dying and I have to start it several times... Over and over... The hard part here is the idle spring... Here is.002" clearance Here is the carb https://youtube.com/shorts/IpEdNzGn_6Q?feature=share
	1

07-07-2021, 02:46 PM	#23
4T_Goblin Join Date: Jun 2021 Posts: 239	I might try the valves at .003" or .004" later on... I had the best acceleration so far with the choke off at .005" , but the rattle sounded severe. 1 variable at a time tho
	1

07-11-2021, 03:25 PM	#24
4T_Goblin Join Date: Jun 2021 Posts: 239	Valves set to .003" intake and exhaust Idling with choke off, getting lean bog.. However.. The tiny main jet screw is stuck in the emulsion jet. It's weak brass and my screwdriver is too much for it. I'm trying to figure out how to get a replacement emulsion jet or if there's a good 19mm carb to buy in it's place. This one was $11 from eBay. The drain screw and main jet are screwed in to tight they are getting damaged when I give them a go.
	1

07-18-2021, 07:20 PM	#25
4T_Goblin Join Date: Jun 2021 Posts: 239	I cleaned the carb- the pilot and main were clogged I still cannot get it to idle with the choke off. It's still dying when I give it throttle... Sounding like too much air? I can't tell. - going to replace the intake manifold gasket. Maybe the head gasket? What other places do air gaps happen? Could filter size matter? Or the fact that I don't have on the airbox or fairings.. Does that have anything to do with airflow here? Today I did see debris in the fuel line from the tank.. gonna have to clean the tank and put in a filter I can't get the main jet screw out of the emulsion tube, wasn't able to jet up a size All I've done so far is check valve clearance, plug EGR valve at the exhaust, clean Carb, and put on a spare uni pod filter because the previous filter was old. Still at square 1
	0