Grey wire mod linked to engine smoking???

[clark4131]

I hate to break it to all y'all, but the grey wire mod DOES NOTHING TO THE PERFORMANCE OF THE BIKE! I work at a Yamaha dealership, and we have checked into this. All it changes is the bikes ability to rev in NEUTRAL= no performance gain. Just thought I'd throw it in while we're at it.

Another glaring example of why you should do your own work on your bike. ?? ...SC

[WheelsUp]

Indeed.... his other two pearls of wisdom are equally enlightening ?

[clark4131]

Stock boy to Master Mechanic in one week. They must have one helluva training program at that dealership. "Well Son, y'see it's called a 4-stroke 'cuz it's got four pistons, while a 2-stroke's only got a couple. Y'understand now? Good, now get that hammer and crescent wrench and get them valves adjusted"...SC

[jchantzWR400F]

The exhaust cam is supposed to be RETARDED 1 tooth, not advanced, for YZF timing. You may have worn valve guides and seals if the problem persists. go ride 3-5 more hours, if the bike continues smoking, you're seals/guides are worn out. You may also have a blown head gasket, but it's very unlikely, because steam evaporates very quickly, and wouldn't go much more than 3-4 feet out of the exhaust, smoke tends to stay airborne.

??

Someone needs to go back and read the past posts on doing this mod. The stock WR exhaust cam timing is retarded (13 pins between 12:00 timing marks on ex cam and in cam) If you advance the ex cam 1 tooth you will have 12 pins between 12:00 timing marks. Therefore, you have advanced the timing to near YZ spec.

[steve lemley]

Jesus guys didnt mean to start a pissing contest..... Although I would like to know what dealership txaggie929 works at ? Just kidding Im sure he just got the two mixed up. Anyway, like I said, I'll test it on Sat. and report back. The temp. should be at least 60 not 25 this weekend. It will either fire right up like usual or be a bastard again. In any case I'll be able to rule out the condinsation and wether thing (which i beleive it is now) in a couple of days. Thanks for all the tech stuff. ?

[Flash319]

Numskull, The throttle pos sensor has a lot to do with the maping. There is no vacuum sensor on these bikes. The only way the CDI knows what the load on the engine is, is by the throttle and RPM. This is how the map is selected. Spark advance is Load and RPM specific.

[Numskull]

Numskull, The throttle pos sensor has a lot to do with the maping. There is no vacuum sensor on these bikes. The only way the CDI knows what the load on the engine is, is by the throttle and RPM. This is how the map is selected. Spark advance is Load and RPM specific.

? Roger that

[WheelsUp]

Someone needs to go back and read the past posts on doing this mod. The stock WR exhaust cam timing is retarded (13 pins between 12:00 timing marks on ex cam and in cam) If you advance the ex cam 1 tooth you will have 12 pins between 12:00 timing marks. Therefore, you have advanced the timing to near YZ spec.

Actually, this is a misconception started by one of the original magazine articles documenting the mod. While the article had the mod correct, they screwed up on the nomenclature.

When the cam is rotated so that there are only 12 pins, you have just retarded the timing (the cam's rotate top-forward, away from the tensioner).

Advancing the cam timing would entail rotating the top of the cam forward, away from the tensioner.

YZ timing has the exhaust cam closing at about 20 or 22 degrees past TDC. Stock WR timing has the exhaust cam closing at TDC. The mod retards the timing so that the cam closes later, allowing the exhaust pulse to scavenge fresh air/fuel in through the intake valves. This mod also increases the overlap timing.

[jchantzWR400F]

Actually, this is a misconception started by one of the original magazine articles documenting the mod. While the article had the mod correct, they screwed up on the nomenclature.

When the cam is rotated so that there are only 12 pins, you have just retarded the timing (the cam's rotate top-forward, away from the tensioner).

Advancing the cam timing would entail rotating the top of the cam forward, away from the tensioner.

YZ timing has the exhaust cam closing at about 20 or 22 degrees past TDC. Stock WR timing has the exhaust cam closing at TDC. The mod retards the timing so that the cam closes later, allowing the exhaust pulse to scavenge fresh air/fuel in through the intake valves. This mod also increases the overlap timing.

Good to know and thanks for the insight. I'm used to hearing people say to "advance" the ex cam 1 tooth "clockwise" in order to acheive YZ timing (12 pins). It saves on the confusion and seems to be generally acceptable. I wasn't sure if he was mixing up how to do the mod or what. Certainly don't want people going to 14 pins. It seems that when explaining this mod to someone who has not done it, one should say to advance the ex cam 1 tooth clockwise. ?