i have a 2003 tw200 and i love it but i have recently started having problems with it and i am hopeing someone could help every morning when i go to start it. It wont start unless i rev the throttle will doing so and the choke makes it worse this just started about 2 weeks ago before that i could give it choke and it would fire right up with no problems. the other problem is the spark plug i gapped it at .028 and will running the bike you can hear a knock from the spark plug so i stop and wait for the motor to cool look at the plug and the plug wont even fit back on the gapper it is so tight what would cause the plug to do this is it hiting the piston if so why is it and how to fix it i do not over tight my plug thanks
help please
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What kind of spark plug you got? NGK? D8EA? If not you probably have the wrong size, may be too long...
-sS
-sS
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7,044 Posts
Sounds like the wrong plug, as sS said.
As for your carb problem, did it start when you swapped plugs? If so, maybe the plug is the problem.
Sounds like it's time for a little troubleshooting. If it went wierd all of a sudden, something changed, like a chunk of crude stuck in or came unstuck from a fuel or vacuum passage, or a vacuum hose has a hole in it, or a critter built a nest in the air intake, or any one of 100 different causes.
With a proper tune, it is not necessary to use choke to start in warm weather. However, a cold engine sometimes will die after starting, and if you try to twist the throttle to quickly it will stall. Typical of an engine running a bit lean, which is okay. It'll run richer as it warms up and sort itself out. Adequate warm-up for a slow ride-off is about 10-15 seconds in warm weather. Take it easy the first couple miles to allow the oil and engine to warm up well before getting on it.
No, Tdub isn't running rich. She returns a consistent 77-80mpg.
As for your carb problem, did it start when you swapped plugs? If so, maybe the plug is the problem.
Sounds like it's time for a little troubleshooting. If it went wierd all of a sudden, something changed, like a chunk of crude stuck in or came unstuck from a fuel or vacuum passage, or a vacuum hose has a hole in it, or a critter built a nest in the air intake, or any one of 100 different causes.
With a proper tune, it is not necessary to use choke to start in warm weather. However, a cold engine sometimes will die after starting, and if you try to twist the throttle to quickly it will stall. Typical of an engine running a bit lean, which is okay. It'll run richer as it warms up and sort itself out. Adequate warm-up for a slow ride-off is about 10-15 seconds in warm weather. Take it easy the first couple miles to allow the oil and engine to warm up well before getting on it.
No, Tdub isn't running rich. She returns a consistent 77-80mpg.
it is an ngk.
Yes it is
yes it is but even when the plug new when i put it on for the first time it did not want to tighten all the wat so i took it off put it back on and it seemed to fit fine.
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I think the R means resistor--not a bad thing. That is the correct plug. If the gap is being knocked shut, something is bad wrong inside the combustion chamber.
D means 12mm
R means resistor type
8 is heat range
E means 19mm reach
A means manufacturer's (Yamaha's) special design
That is the correct plug.
I run the Champion PowerSport plug because the tip is copper core and runs cooler than others due to better heat transfer. The inner insulator is thinner than most which makes it harder for fouling to get started, a concern with cooler running spark plugs. I had the 2nd NGK foul riding home one night about 2:00 AM in freezing weather, and the only place open was Walmart, so I bought one of the Champions to fit and it's been in there for 35,000 miles. I take it out, look at it, put it back in. It's that good. I think the number is 8809, but look it up to make sure.
D means 12mm
R means resistor type
8 is heat range
E means 19mm reach
A means manufacturer's (Yamaha's) special design
That is the correct plug.
I run the Champion PowerSport plug because the tip is copper core and runs cooler than others due to better heat transfer. The inner insulator is thinner than most which makes it harder for fouling to get started, a concern with cooler running spark plugs. I had the 2nd NGK foul riding home one night about 2:00 AM in freezing weather, and the only place open was Walmart, so I bought one of the Champions to fit and it's been in there for 35,000 miles. I take it out, look at it, put it back in. It's that good. I think the number is 8809, but look it up to make sure.
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352 Posts
I, too, can say that you've got some bad going on inside the chamber. I've been running D8EA/DR8EA (stock spec), and no, the resistor plug won't do any harm.. just means your cellphone will continue to work while you ride the bike
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However, I've also run a slightly longer tip plug without any issues.. it's a DPR8EA -- I verified that it doesn't hit before starting the motor with it. Doesn't seem to change how the motor runs much, so I removed it, but it ran fine for a few hundred miles.
qwerty: any idea what the "P" decodes to?
OP: I'd be getting a small light and trying to see if you can figure out what's wrong with the top of the piston before pulling it apart.
However, I've also run a slightly longer tip plug without any issues.. it's a DPR8EA -- I verified that it doesn't hit before starting the motor with it. Doesn't seem to change how the motor runs much, so I removed it, but it ran fine for a few hundred miles.
qwerty: any idea what the "P" decodes to?
OP: I'd be getting a small light and trying to see if you can figure out what's wrong with the top of the piston before pulling it apart.
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Funny...I've never had anything but BAD experiences with Champion spark plugs! I won't even run one in my lawn mower!
How do you feel about the Iridium types?
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Never used one. Regular plugs work fine for me. I've never had a spark plug fail, no matter the type, as long as it was the correct plug for the application. There are a bazillion lures in a tackle shop, and most are designed to catch fishermen, not fish.
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1,815 Posts
OK...here we go!
1974 Gran Torino: Did a complete tune-up, oil and filter, points, dwell, timing etc. and installed a fresh batch of Champion spark plugs. Within a few hours, she was running like crap. By pulling leads off the plugs, I was able to determine that TWO of the eight NEW Champion plugs were faulty. Replaced with Autolites..ran fine until the day I sold her two years later.
1976 Evinrude 9.9 HP Outboard: Despite starting easily, she would start missing shortly after warming up. Replacing BOTH Champion plugs with NGK's ended this problem for three more seasons until I replaced the Evinrude with a Yamaha.
2004 Yardworks Lawnmower: Ran fine for the first three cuttings, then completely refused to start. No spark at the plug. Replaced stock Champion plug with an NGK and it ran trouble free until we bought an electric.
Maybe it's my Chi, or maybe I'm just a magnet for lemons, but ALL instances of Champion plugs I've used have been troublesome. In contrast, I have NEVER had a failure with NGK, Autolite or Bosch plugs.
Go figure.
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428 Posts
I hear you TW-in-BC, we use mostly NGK in our shop. A few plugs are only available from Champion and we have had lots of plugs go bad fast! Spark Plugs are like tires on a new car, they use them cause they can buy them cheap in bulk. My Mazda had a miss at highway speed for two years and the dealer couldn't find it. Finally I changed the plugs and not only the miss went but the fuel milage went up too.
As for the knock and the damaged plug...something is not adding up right, if it is the correct plug then it has to be something foreign on the top of the piston. Remove the plug and shift the bike into high gear, raise the rear wheel and roll the engine over slowly. No knock? find TDC and shine a flash light down the hole or borrow a bore scope and inspect the top of the piston for marks or something embedded into the top. You may have to pull the head first, but I would do a compression test before you do that... just to check over all health of the cylinder.
As for the knock and the damaged plug...something is not adding up right, if it is the correct plug then it has to be something foreign on the top of the piston. Remove the plug and shift the bike into high gear, raise the rear wheel and roll the engine over slowly. No knock? find TDC and shine a flash light down the hole or borrow a bore scope and inspect the top of the piston for marks or something embedded into the top. You may have to pull the head first, but I would do a compression test before you do that... just to check over all health of the cylinder.
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"Finding" TDC is easy. You dont even need her on a stand. Just remove the two plugs on the left-side crankcase cover; use the tools that came with the bike (or not) and crank the bolt counter-clockwise until the mark lines up with the one marked "T". Pro Tip: A quarter held with vise-grips works great for taking those plugs out without damaging them. Give them a few good knocks with a hammer first to help things along.
-sS
You can even remove just the top plug on the crankcase cover, put the bike in 5th gear and roll it until the line is visible. You got some options for getting it to TDC
I can't imagine your wrist pin bearing or connecting rod bearing ate themselves up, but would potentially allow additional travel of the piston. Sounds like you need to remove the head...not a bad gig for an air cooled engine, at least!
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