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Yami_rider

Flywheel trouble

7 posts in this topic

This weekend as i was adjusting my valves i ran into alittle trouble i feel everyone should know about before adding a larger flywheel and a SBS racing cover. The person that owned my 2004 450 before me installed both not taking in mind that the fly wheel would rub agianst the cover. Needless to say the top dead center mark was gone and it was a pain to fix. Just thought id put in my two cents, after spending a weekend fixing my bike. Thanks

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The TDC marks on OEM flywheels are typically covered up by added weights, whether they are the bolted on types or the much superior welded in place variety. This includes flywheels from Dr.D AND Yamaha GYT-R. It's not likely that the rubbing against the aftermarket cover had anything to do with it, if it even happened.

When installing a heavier flywheel, you will usually have to locate TDC manually and re-mark it yourself.

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This may be a stupid question but how do you manually set TDC to mark the flywheel?

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Remove the spark plug, and drop a long thin screwdriver blade down the hole. Rotate the engine until you locate TDC. You will notice that at TDC, the crank will rotate quite a little way without the piston moving very much. Carefully locate where TDC actually is, and mark the flywheel at that point.

The most accurate means of doing this is to use a dial gauge (or a physical stop pin that only lets the piston travel up just so far), and make two marks on the flywheel at the same distance from TDC in both directions, and then locate the mark for TDC exactly halfway between them. Using a degree wheel increases the accuracy of this method even further. But careful eyeballing works well enough for simple service work.

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I have a GYTR flywheel and it has the marks!!!
If you have an '06 or later, that's because the weight is on the back of the flywheel. The GYT-R I have left over from my '03 has the weight on the front, and the marks are covered. Bolt-on weights for the earlier 450's never have marks.

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