Flywheel weight install, now bike won't crank

9 replies to this topic
  • Cirus

Posted March 30, 2006 - 06:00 PM


I just installed a Dr.D 8oz. flywheel weight on my '04 450 and now the damn thing won't crank. I installed a lighter one last year and didn't have any trouble starting it afterwards. I kicked the piss out of it for several minutes using the same starting procedure I've always used and it would'nt even fire off, all it would do is sorta stumble like it wanted to try to fire. I thought maybe I fouled the plug and just did'nt realize it so I pulled the plug and it was wet with gas, so I chunked it and put in a new one and tried it again with the same results. I even put in one more plug in and still nothing. So being already pissed off into a rage :thumbsup: I tried pull starting it behind my truck and the bastard still wouldn't even fire off, it would just pop when I gave it a little gas. I need help before I take a shotgun a hold of this piece of shit. :thumbsup:

  • mkporn

Posted March 30, 2006 - 06:16 PM


Did you have to pull the flywheel to install the weight? If so you may have dropped the key and got the flywheel out of time to the crank. Just a thought.

  • Cirus

Posted March 30, 2006 - 06:42 PM


Yea, I pulled the flywheel off and put a whole new flywheel on. What is a key? Sounds like I may be screwed. How do you get it back in time?

  • targetdrone

Posted March 31, 2006 - 12:14 AM


There is a slot in the crankshaft and another slot on the inside of the flywheel. There is a woodruff key that goes in the slot so that the flywheel is lined up correctly. Pull off the flywheel and check for metal shavings (you probably scraped the key when you had it misaligned and tightened up the nut holding the flywheel, forcing it on in the wrong position). Fix it and all will be well in the world today. Well, maybe not...but at least your bike should run.

  • Cirus

Posted March 31, 2006 - 05:36 PM


Well, I pulled the flywheel and sure enough it was misaligned from the woodruff key by about a 1/4", you could even see the impression the key left on the inside of the wheel, plus there was a tiny sliver of metal laying on the inside of the wheel. This time I got a felt tip pen and made a mark on the end of the crankshaft in line with the key so I could line it up easier. It took some kicking but it finally fired up even with the choke off. One thing I noticed though, it seems a little harder to crank now and maybe its just me but when I took it down the road at steady throttle it seemed to cut out a little, not to where its bucking or wanting to stall but like its got a miss to it like on a car. Maybe its just me but is it possible for the key to be in the notch on the wheel but still not be perfectly aligned? Also, how much of the key is suppose to stick up above the crankshaft? Judging from the notch in the flywheel it couldn't be much.

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  • kid on a 426

Posted March 31, 2006 - 08:34 PM


This reminds me of my goped. Last summer I was cruising down the street at about 25mph when the woodriff key sheared on the flywheel and the flywheel started to wobble around and clipped the magneto and locked up the back tire and I ate it and since I was running no flywheel cover the whole side got all screwed up and messed up the threads. Luckily my dad chased the threads and we didn't have to replace the crank and we got a woodriff key at OSH. Gopeds are tons of fun but every half an hour of riding you have to work on it for and hour. Dang 2 strokes

  • kxman

Posted April 01, 2006 - 04:45 AM


You really need to install a NEW key if that one is messed up your timing will be off.

  • Cirus

Posted April 01, 2006 - 04:57 AM


You really need to install a NEW key if that one is messed up your timing will be off.

I ordered 2 yesterday morning. I'm gonna pull the wheel back off and put a new key back in when they come in. Thats why I was wondering how far the key sticks up over the crankshaft because mine wasn't sticking up very far and I never paid any attention until I pulled the wheel back off.

  • grayracer513

Posted April 01, 2006 - 09:25 AM


As you assemble the flywheel to the engine, you should be able to rotate the flywheel back and forth slightly and feel it catch the key. Then push it straight on from that point. There is very little clearance between the stator coils and the ignition trigger coil and the flywheel, and when the flywheel is mis-keyed, it runs out of round, possibly striking the coils and doing some damage. Look for drag marks inside the flywheel and on the raised area on the outside diameter that passes close to the trigger coil near TDC.

Hopefully, your miss will only be because of a partly fouled plug.

  • FFRacing79

Posted April 01, 2006 - 01:17 PM


Just to add to grayracers post, the key does NOT hold the flywheel from spinning out of time, the tapers do.. It's only purpose is to align the flywheel in proper time. If the key sticks to far up out of the slot, the flywheel can bottom out on it not permitting the flywheel to properly seat on the tapers. Before you install the flywheel it doesn't hurt to check 2 things. The fit of the 2 tapers...this can be remedied with a light lapping compound. And the fit of the key. Take some machinist bluing or even a Sharpie and color the key...then install and remove the flywheel. It should show no signs of contact on the top flush of the key. It sounds like a little extra work, but can save ya from future problems. Tdub

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