Better CHECK Your SParkPLUGS at 3/4 to Full Throttle...

SeerAtlas · 05-06-2009, 11:17 AM

After what happened to Pizza Rider melting a piston, I think it might be a ggood idea for all of us to go out and do a quick SHORT run at 3/4 to full throttle, chop power, pull in the clutch, coast to stop, let the head cool a bit then pull the plug and have a look see. It appears that almost all of these china bikes *may* be tuned too lean for anything but high altitude operation. PLUS it would be interesting to compare plugs. Whadya think?
lets see some pics on what we've got. i'm pretty sure mine is lean and I'll check it today if it quits raining LOL

One other thing, check the mating surfaces of your airboxes, carb manifolds etc. Mine was leaking air due to a poor seal between the air filter element and the manifold. Fixxed with a modded UniFilter which improved my idle immensely. Fixxed it so i could dial down the idle from around 2k indicated to around 1k, and it no longer just randomly stops. Fortunately caught that problem early as at full throttle such a leak can lean out your mix, not to mention allowing grit into the motor.

Seer

katoranger · 05-06-2009, 12:13 PM

Another good thing to check. Didn't think about the possibility that his carb manifold may have been leaking some.

Allen

phil · 05-06-2009, 01:23 PM

seer, have you ever tried av gas in yours :wink:

katoranger · 05-06-2009, 02:12 PM

http://www.4strokes.com/tech/4sjetting.asp Good Jetting read.

Allen

SeerAtlas · 05-07-2009, 01:53 AM

Ok, here's my plug.

Couple of things, you should be able to really zoom in on this if you download the photo. If you do the color at least on my computer is a bit misleading as its actually a very nice shade of tan, the photo shows a bit darker than it really was. REALLY zoom in, tho and you see some interesting deterioration around the gap. Looks like I'm getting a wee bit of deposit or perhaps remnants of earlier detonation somewhere else in the range, so going to have to go check the needle setting, and idle screw. Altitude here is about 1200 ft, weather in the high 50's to mid 60's and lots of moisture in the air. Oh, and plug is I think an NGK DEA8

Seer

BUG · 05-07-2009, 09:03 AM

Did you pull your plug immediately after a full throttle run?

suprf1y · 05-07-2009, 10:14 AM

I have done a lot of engine tuning over the years, so I'll add my 2 cents.
Based on my experience, you can't use plug readings to determine (proper) jetting. There are a few reasons, and one of them is that fuels have changed a lot since this became an accepted practice.
The other is that these small, single cylinder motors tend to load up, and sputter at high RPM. Whether this is due to short intake tracts, and poor atomization, I'm not exactly sure, but thats my guess.
The closer you are to rich, and the higher your motor revs, the worse it happens. Loading up, and misfiring because of too much fuel, the plug gets washed, and looks really lean. Its actually really rich.
If you do a high RPM run/cut, and check the plug and its white, thats not necessarily bad. The thing to watch for is little balls of aluminum on the ground strap, or shiny flakes anywhere on the business end of the plug.
If you find that you have a nice tan colour, you are almost assuredly rich.
How much, its hard to say, but in my experience, about 4-5 jet sizes, so just leave it, and be safe. None of us are after max power here, anyway.

SeerAtlas · 05-07-2009, 11:40 AM

Hmmm, Superfly, if you don't use a plug reading to know whether or not you are safe...what did you use? Seat of the pants max power or timed accell over distance runs have always gotten me to the knife edge of engine eating 'lean ness' from which I've always backed off based on plug readings. I'm running 92 US Premium fuel and Bug, no, not exactly full throttle cause I'm still in break in, but enough to get into the mains, about 3/4-4/5's. (that explains the sooting on the circumference of the plug btw

Interesting stuff, I guess alcohol containing gas would distort the readings even more now that i think of it, not to mention all the detergents like Techron etc....but this is the first I've heard of not using the plug as an indicator.

As Dan says in his online motorcycle course...
http://www.dansmc.com/sparkplugs1.htm

this is pretty much the technique I grew up with. And his reference to the visual plug reading pages found here:
http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

is pretty much in agreement with what I was taught. I do note that the chart was 1977 (good year for me

but still, perhaps while not leading to perfect tuning, as he points out, and has pizzarider has recently demonstrated...a plug reading of snow white taken in advance just *might* have averted his catastrophic engine failure...and frankly, I don't know a quicker or easier *down and dirty* way of at least ensuring you're not tearing something up...
btw, I also agree with Dan. in my experience #20 is too damned hot for my tastes...If it was my bike, I'd richen up.

Seer

Cal25 · 05-07-2009, 12:48 PM

When I opened up the exaust and added a sock type filter, I bought 3 bigger jets skipping the next size up. I started with the biggest and was over rich. I went down 1 size at at a time till it was running rite. Ended up being 2 sizes bigger than stock.

recently changed the plug and it looked OK. I did not try the throttle chop method. I think that is the only true way to read the plug.

Personally, I think the jetting is pretty safe from the factory. Any mods or extreme elevations change that. Of all the bikes and quads we have, there really has'nt been that many melted pistons. Perhaps as stated earlier Pizzarider might have had a leak at the intake manifold?

FastDoc · 05-07-2009, 01:44 PM

As a pilot I have access to Avgas and would not run it in the bike. The lead content is high and will foul the plug and valves and plug the catalyst. Any performance gain would be minimal, and it would cost more in upkeep and fuel price.

Dragon · 05-07-2009, 01:58 PM

My bike is one year old. I notice the rubber intake manifold (or whatever it's called) is starting to show cracks.

SeerAtlas · 05-07-2009, 07:27 PM

Well I just checked the plug again after a nice little run up the mountain. On the way back held a steady 5k for a couple of miles, chopped power, clutched, and coasted to a stop. Plug looked perfect

Soooo, I seem to be set up about right. Bike seems to run strong for a 200, but that's most likely seat of the pants impression from the low gearing which I'm loathe to give up just yet.

Seer

suprf1y · 05-07-2009, 07:43 PM

Quote:

Hmmm, Superfly, if you don't use a plug reading to know whether or not you are safe...what did you use?

AFR gauge.
I don't know of anybody who tunes with plug readings anymore. Its just not accurate.
The good thing is, like i said, if your plug looks perfect, you are probably 4-5 jet sizes rich, so you are very safe.

forchetto · 05-08-2009, 09:44 AM

Quote:

Originally Posted by suprf1y

Based on my experience, you can't use plug readings to determine (proper) jetting. There are a few reasons, and one of them is that fuels have changed a lot since this became an accepted practice.
The other is that these small, single cylinder motors tend to load up, and sputter at high RPM. Whether this is due to short intake tracts, and poor atomization, I'm not exactly sure, but thats my guess.
The closer you are to rich, and the higher your motor revs, the worse it happens. Loading up, and misfiring because of too much fuel, the plug gets washed, and looks really lean. Its actually really rich.

This is worth looking into further. Suprfly could be right. I have read about the impossibility of determining carburation by plug readings with modern unleaded and alcohol fuels.

Another thing is the loading up and sputtering issue. In the past putting a larger than needed main jet just produced a higher fuel consumption and you consoled yourself with the thought that a richer mixture meant that the engine ran a bit cooler. Racing guys do this all the time.

I have noticed that on most Chinese bikes a main jet that's too large produces just the effects Suprfly is talking about, but I didn't know why. Perhaps his theory of a short inlet tract is valid. I have read accounts of engine tuning where they experimented with spacers to position the carb further away from the inlet port with worthwhile power gains.

kens97sto171 · 05-14-2009, 06:33 PM

I saw this on some carb tuing web site... Looks pretty cool.. You replace the spark plug with this thing and it allows you to actually see the combustion event... the color of it will tell you the mixture. I think it's about $60 Check out the video.. kinda cool to "see" the burn..

http://www.gadgetjq.com/ctune.htm

Ken

05-06-2009, 11:17 AM	#1
SeerAtlas Join Date: Apr 2009 Posts: 770	Better CHECK Your SParkPLUGS at 3/4 to Full Throttle... After what happened to Pizza Rider melting a piston, I think it might be a ggood idea for all of us to go out and do a quick SHORT run at 3/4 to full throttle, chop power, pull in the clutch, coast to stop, let the head cool a bit then pull the plug and have a look see. It appears that almost all of these china bikes may be tuned too lean for anything but high altitude operation. PLUS it would be interesting to compare plugs. Whadya think? lets see some pics on what we've got. i'm pretty sure mine is lean and I'll check it today if it quits raining LOL One other thing, check the mating surfaces of your airboxes, carb manifolds etc. Mine was leaking air due to a poor seal between the air filter element and the manifold. Fixxed with a modded UniFilter which improved my idle immensely. Fixxed it so i could dial down the idle from around 2k indicated to around 1k, and it no longer just randomly stops. Fortunately caught that problem early as at full throttle such a leak can lean out your mix, not to mention allowing grit into the motor. Seer __________________ Seer's First LAW-"FLY THE PLANE!", fail that, and nothing else matters. 12th Law- Consider what marvels you might do if only you had tomorrow to live over again. Third Law-When someone tells you some thing "Can't Be Done", what they're really saying is They can't do it!!14th Law-Just because something "IS", doesn't necessarily mean it SHOULD be.. Eighth Law-The only true personal security is anonymity.Ninth Law-Humans tend to learn very little when speaking.10th Law-Some lives ARE worth taking
	0

05-06-2009, 01:23 PM	#3
phil Join Date: Jun 2008 Location: wise va Posts: 636	seer, have you ever tried av gas in yours :wink: __________________ halls auto l coolster, modcycles, yanmar & zongshen, dealer fired roketa,lifan and jet moto and apollo quit me who's next
	0

05-06-2009, 02:12 PM	#4
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	http://www.4strokes.com/tech/4sjetting.asp Good Jetting read. Allen __________________ You meet the nicest people on a Honda Clone.
	0

05-07-2009, 01:53 AM	#5
SeerAtlas Join Date: Apr 2009 Posts: 770	Ok, here's my plug. Couple of things, you should be able to really zoom in on this if you download the photo. If you do the color at least on my computer is a bit misleading as its actually a very nice shade of tan, the photo shows a bit darker than it really was. REALLY zoom in, tho and you see some interesting deterioration around the gap. Looks like I'm getting a wee bit of deposit or perhaps remnants of earlier detonation somewhere else in the range, so going to have to go check the needle setting, and idle screw. Altitude here is about 1200 ft, weather in the high 50's to mid 60's and lots of moisture in the air. Oh, and plug is I think an NGK DEA8 Seer __________________ Seer's First LAW-"FLY THE PLANE!", fail that, and nothing else matters. 12th Law- Consider what marvels you might do if only you had tomorrow to live over again. Third Law-When someone tells you some thing "Can't Be Done", what they're really saying is They can't do it!!14th Law-Just because something "IS", doesn't necessarily mean it SHOULD be.. Eighth Law-The only true personal security is anonymity.Ninth Law-Humans tend to learn very little when speaking.10th Law-Some lives ARE worth taking
	0

05-07-2009, 09:03 AM	#6
BUG Join Date: Nov 2008 Location: United States Posts: 144	Did you pull your plug immediately after a full throttle run? __________________ 2008 HSUN MDL-200GY 2009 KLR650
	0

05-06-2009, 12:13 PM	#2
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	Another good thing to check. Didn't think about the possibility that his carb manifold may have been leaking some. Allen __________________ You meet the nicest people on a Honda Clone.
	0

05-07-2009, 10:14 AM	#7
suprf1y Join Date: Oct 2007 Location: SW Ontario Posts: 408	I have done a lot of engine tuning over the years, so I'll add my 2 cents. Based on my experience, you can't use plug readings to determine (proper) jetting. There are a few reasons, and one of them is that fuels have changed a lot since this became an accepted practice. The other is that these small, single cylinder motors tend to load up, and sputter at high RPM. Whether this is due to short intake tracts, and poor atomization, I'm not exactly sure, but thats my guess. The closer you are to rich, and the higher your motor revs, the worse it happens. Loading up, and misfiring because of too much fuel, the plug gets washed, and looks really lean. Its actually really rich. If you do a high RPM run/cut, and check the plug and its white, thats not necessarily bad. The thing to watch for is little balls of aluminum on the ground strap, or shiny flakes anywhere on the business end of the plug. If you find that you have a nice tan colour, you are almost assuredly rich. How much, its hard to say, but in my experience, about 4-5 jet sizes, so just leave it, and be safe. None of us are after max power here, anyway.
	0

05-07-2009, 11:40 AM	#8
SeerAtlas Join Date: Apr 2009 Posts: 770	Hmmm, Superfly, if you don't use a plug reading to know whether or not you are safe...what did you use? Seat of the pants max power or timed accell over distance runs have always gotten me to the knife edge of engine eating 'lean ness' from which I've always backed off based on plug readings. I'm running 92 US Premium fuel and Bug, no, not exactly full throttle cause I'm still in break in, but enough to get into the mains, about 3/4-4/5's. (that explains the sooting on the circumference of the plug btw Interesting stuff, I guess alcohol containing gas would distort the readings even more now that i think of it, not to mention all the detergents like Techron etc....but this is the first I've heard of not using the plug as an indicator. As Dan says in his online motorcycle course... http://www.dansmc.com/sparkplugs1.htm this is pretty much the technique I grew up with. And his reference to the visual plug reading pages found here: http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html is pretty much in agreement with what I was taught. I do note that the chart was 1977 (good year for me but still, perhaps while not leading to perfect tuning, as he points out, and has pizzarider has recently demonstrated...a plug reading of snow white taken in advance just might have averted his catastrophic engine failure...and frankly, I don't know a quicker or easier down and dirty way of at least ensuring you're not tearing something up... btw, I also agree with Dan. in my experience #20 is too damned hot for my tastes...If it was my bike, I'd richen up. Seer __________________ Seer's First LAW-"FLY THE PLANE!", fail that, and nothing else matters. 12th Law- Consider what marvels you might do if only you had tomorrow to live over again. Third Law-When someone tells you some thing "Can't Be Done", what they're really saying is They can't do it!!14th Law-Just because something "IS", doesn't necessarily mean it SHOULD be.. Eighth Law-The only true personal security is anonymity.Ninth Law-Humans tend to learn very little when speaking.10th Law-Some lives ARE worth taking
	0

05-07-2009, 12:48 PM	#9
Cal25 Join Date: Feb 2008 Location: Terrell and Grapevine Tx. Posts: 1,585	When I opened up the exaust and added a sock type filter, I bought 3 bigger jets skipping the next size up. I started with the biggest and was over rich. I went down 1 size at at a time till it was running rite. Ended up being 2 sizes bigger than stock. recently changed the plug and it looked OK. I did not try the throttle chop method. I think that is the only true way to read the plug. Personally, I think the jetting is pretty safe from the factory. Any mods or extreme elevations change that. Of all the bikes and quads we have, there really has'nt been that many melted pistons. Perhaps as stated earlier Pizzarider might have had a leak at the intake manifold?
	0

05-07-2009, 01:44 PM	#10
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	As a pilot I have access to Avgas and would not run it in the bike. The lead content is high and will foul the plug and valves and plug the catalyst. Any performance gain would be minimal, and it would cost more in upkeep and fuel price. __________________ Happy to serve.
	0

05-07-2009, 01:58 PM	#11
Dragon Join Date: Nov 2007 Location: Tejas Posts: 834	My bike is one year old. I notice the rubber intake manifold (or whatever it's called) is starting to show cracks. __________________ Chinabikeless
	0

05-07-2009, 07:27 PM	#12
SeerAtlas Join Date: Apr 2009 Posts: 770	Well I just checked the plug again after a nice little run up the mountain. On the way back held a steady 5k for a couple of miles, chopped power, clutched, and coasted to a stop. Plug looked perfect Soooo, I seem to be set up about right. Bike seems to run strong for a 200, but that's most likely seat of the pants impression from the low gearing which I'm loathe to give up just yet. Seer __________________ Seer's First LAW-"FLY THE PLANE!", fail that, and nothing else matters. 12th Law- Consider what marvels you might do if only you had tomorrow to live over again. Third Law-When someone tells you some thing "Can't Be Done", what they're really saying is They can't do it!!14th Law-Just because something "IS", doesn't necessarily mean it SHOULD be.. Eighth Law-The only true personal security is anonymity.Ninth Law-Humans tend to learn very little when speaking.10th Law-Some lives ARE worth taking
	0

05-14-2009, 06:33 PM	#15
kens97sto171 Join Date: Mar 2007 Posts: 193	I saw this on some carb tuing web site... Looks pretty cool.. You replace the spark plug with this thing and it allows you to actually see the combustion event... the color of it will tell you the mixture. I think it's about $60 Check out the video.. kinda cool to "see" the burn.. http://www.gadgetjq.com/ctune.htm Ken
	0