Need help figuring out what is wrong with my HSUN 200GY - Page 4

FastDoc · 05-05-2009, 11:09 AM

Many answers lie in a high resolution close up photograph of that plug.

pizzarider · 05-05-2009, 01:28 PM

Quote:

Originally Posted by FastDoc

Many answers lie in a high resolution close up photograph of that plug.

Will post that tonight. -cory

forchetto · 05-05-2009, 02:07 PM

Quote:

Originally Posted by FastDoc

This brings up some relevent issues for all of us. Are our bikes timed correctly from the factory? Are they jetted too lean? Excessive advance would have done that. What is our true compression ratio? Has anyone else had or heard of similar catastrophic failures? Is 7,500 RPM too fast for these bikes? Was this a material failure? (That's the conclusion I am leaning towards).

The ignition timing maximum advance figure is fixed by the position of the pulser coil, and from what I gather from people that have moved this pulser to advance the overall ignition it is set very conservately, several degrees below the optimum for best performance.

The fuel mixture however, is, at least here in Europe, set far too lean overall. The obsolete engine designs and basic unsophisticated carburettors make this obligatory for the makers if they're to meet emissions regulations. Most just scrape-by. All of my bikes hace benefitted from tweaking the jetting and other carburettor parameters to obtain satisfactory mixtures right through the range.

My Qingqi's (Qlink XF200) Mikuni carb runs better with 125 main jet, although it came with a 122.5. That's two sizes up from OEM specs. Curiously enough the Brazilian Qingqi QM200GY models (called STX Sundown) has an even larger main jet as standard, 127.5. Even so mine still a bit on the lean side and will be changing to the larger jet shortly.The needle setting came on the third groove from top, the Brazilian specs are on the fourth groove and so on.Their emissions laws are not quite as strict as ours.

Over-lean mixtures are the cause of lots of running troubles, poor starting, cold-blooded engines that take ages to warm up, poor throttle response and slow running. Continous, sustained full throttle and high revs with a lean mixture can have a devastating effect on engine internals.
Basically the makers don't care as long as they get the homologation certificates. Eventually they'll fit electronic injection and engine management systems on the bikes and all this will be solved.

FastDoc · 05-05-2009, 02:16 PM

The fuel mixture however, is, at least here in Europe, set far too lean overall

Over-lean mixtures are the cause of lots of running troubles, poor starting, cold-blooded engines that take ages to warm up, poor throttle response and slow running. Continous, sustained full throttle and high revs with a poor mixture can have a devastating effect on engine internals.

I BET that's what did PizzaRider's engine in. Maybe those of us with stock jetting need to richen it up a bit.

katoranger · 05-05-2009, 04:14 PM

I think it was running lean. That piston looks to have melted. I changed from a 98 to a 108 main when I changed the exhaust and air filter. I think alot of these bike could be be bumped up one or two sizes without mods.

Really for the number of bikes here I think there have only be a handlful of engine failures like this.

Allen

Dragon · 05-05-2009, 04:25 PM

Quote:

Originally Posted by forchetto

Eventually they'll fit electronic injection and engine management systems on the bikes...

I much rather replace jets than to diagnose a faulty electronic injection system. And cheaper too.

FastDoc · 05-05-2009, 04:30 PM

I was originally planning on leaving my entire system stock, presumably for the purpose of reliability.

With this new information, I'm thinking that maybe ratcheting up my main jet would be a smart way to go. And of course if I'm going to do that, I may as well put a pipe on it. I would probably leave my airbox and induction system stock, this just gives me more to think about.

FastDoc · 05-05-2009, 04:31 PM

That piston totally looks melted from an overlean condition.

SeerAtlas · 05-05-2009, 05:59 PM

I'd really like to see that plug also. i'll second that overly lean condition. Usually the piston makes a big BANG when it lets go, but yours appears to have melted down. When you tear down the engine, let us know what setting the needle in the carb was set at, and also, what jet you had in it.

at least we now know we apparently have cast aluminum pistons.

seer

pizzarider · 05-05-2009, 09:26 PM

Here are two cell phone pictures of my spark plug. Sorry for the quality but this is all I can do. -Cory

http://chinariders.net/gallery2/main...serialNumber=1

http://chinariders.net/gallery2/main...serialNumber=1

TeamCheap · 05-05-2009, 09:49 PM

its awefully white.

Cal25 · 05-05-2009, 09:52 PM

It does look awfull white.

katoranger · 05-06-2009, 09:05 AM

Yep too white. Lean condition. The porcelin part should be a tan color when the fuel mixture is correct.

Diagnosis. Fuel mixture loo lean at 3/4 to WOT. Piston starting get hot. Detonation started to occur and piston started to melt resulting in piston failure which in turn destroyed the top end.

Preventative measure. Larger main jet. I don't think the higher octance gas would have made that much difference. It was more a lack of it. Higher octane may have bought you more time, but these engines don't run that high of compression.

Allen

BUG · 05-06-2009, 01:53 PM

Quote:

Originally Posted by katoranger

Yep too white. Lean condition. The porcelin part should be a tan color when the fuel mixture is correct.

Diagnosis. Fuel mixture loo lean at 3/4 to WOT. Piston starting get hot. Detonation started to occur and piston started to melt resulting in piston failure which in turn destroyed the top end.

Preventative measure. Larger main jet. I don't think the higher octance gas would have made that much difference. It was more a lack of it. Higher octane may have bought you more time, but these engines don't run that high of compression.

Allen

Judging by his plug how many sizes would you increase the main jet size?

katoranger · 05-06-2009, 02:11 PM

I am no expert, but going with he probably has a stock 98 maybe to a 102-104. Two sizes max.

I would say you also need to account for elevation. I am 1100 ft. I have a UNI filter and an opened up exhaust and I run a 108 main. I could probably go to a 110 too.

So others are running a 115 with similar mods to me. I am guessing they may be at a lower elevation.

If you are in Florida you probably need to up it some more on a stock bike.

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

Even jap bikes can be jetted "wrong" from the factory. Elevation plays a big part.

Allen

05-05-2009, 11:09 AM	#1
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	Many answers lie in a high resolution close up photograph of that plug. __________________ Happy to serve.
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05-05-2009, 02:16 PM	#4
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	The fuel mixture however, is, at least here in Europe, set far too lean overall Over-lean mixtures are the cause of lots of running troubles, poor starting, cold-blooded engines that take ages to warm up, poor throttle response and slow running. Continous, sustained full throttle and high revs with a poor mixture can have a devastating effect on engine internals. I BET that's what did PizzaRider's engine in. Maybe those of us with stock jetting need to richen it up a bit. __________________ Happy to serve.
	0

05-05-2009, 04:14 PM	#5
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	I think it was running lean. That piston looks to have melted. I changed from a 98 to a 108 main when I changed the exhaust and air filter. I think alot of these bike could be be bumped up one or two sizes without mods. Really for the number of bikes here I think there have only be a handlful of engine failures like this. Allen __________________ You meet the nicest people on a Honda Clone.
	0

05-05-2009, 04:30 PM	#7
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	I was originally planning on leaving my entire system stock, presumably for the purpose of reliability. With this new information, I'm thinking that maybe ratcheting up my main jet would be a smart way to go. And of course if I'm going to do that, I may as well put a pipe on it. I would probably leave my airbox and induction system stock, this just gives me more to think about. __________________ Happy to serve.
	0

05-05-2009, 04:31 PM	#8
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	That piston totally looks melted from an overlean condition. __________________ Happy to serve.
	0

05-05-2009, 05:59 PM	#9
SeerAtlas Join Date: Apr 2009 Posts: 770	I'd really like to see that plug also. i'll second that overly lean condition. Usually the piston makes a big BANG when it lets go, but yours appears to have melted down. When you tear down the engine, let us know what setting the needle in the carb was set at, and also, what jet you had in it. at least we now know we apparently have cast aluminum pistons. 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
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05-05-2009, 09:26 PM	#10
pizzarider Join Date: Jun 2008 Posts: 144	Here are two cell phone pictures of my spark plug. Sorry for the quality but this is all I can do. -Cory http://chinariders.net/gallery2/main...serialNumber=1 http://chinariders.net/gallery2/main...serialNumber=1
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05-05-2009, 09:49 PM	#11
TeamCheap Join Date: Jun 2006 Location: directly under the earths sun............NOW Posts: 2,302	its awefully white.
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05-05-2009, 09:52 PM	#12
Cal25 Join Date: Feb 2008 Location: Terrell and Grapevine Tx. Posts: 1,585	It does look awfull white.
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05-06-2009, 09:05 AM	#13
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	Yep too white. Lean condition. The porcelin part should be a tan color when the fuel mixture is correct. Diagnosis. Fuel mixture loo lean at 3/4 to WOT. Piston starting get hot. Detonation started to occur and piston started to melt resulting in piston failure which in turn destroyed the top end. Preventative measure. Larger main jet. I don't think the higher octance gas would have made that much difference. It was more a lack of it. Higher octane may have bought you more time, but these engines don't run that high of compression. Allen __________________ You meet the nicest people on a Honda Clone.
	0

05-06-2009, 02:11 PM	#15
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	I am no expert, but going with he probably has a stock 98 maybe to a 102-104. Two sizes max. I would say you also need to account for elevation. I am 1100 ft. I have a UNI filter and an opened up exhaust and I run a 108 main. I could probably go to a 110 too. So others are running a 115 with similar mods to me. I am guessing they may be at a lower elevation. If you are in Florida you probably need to up it some more on a stock bike. Good read on jetting. http://www.4strokes.com/tech/4sjetting.asp Even jap bikes can be jetted "wrong" from the factory. Elevation plays a big part. Allen __________________ You meet the nicest people on a Honda Clone.
	0