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Another issue... points cam orientation.

thumper2146
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Joined: Fri Nov 16, 2007 1:29 am
Location: santa maria calif.

Post by thumper2146 » Fri Jul 02, 2010 11:46 pm

oh no i'm starting to have flashbacks:( this is what i was going through i think. get the bike in front of you and give LM a call:)

James

MBellRacing
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Location: San Mateo, Ca

Post by MBellRacing » Sat Jul 03, 2010 3:25 pm

IT RUUUUUUUNS!!! I got it going just fine. All the timing looks PERFECT. My points cam kinda clicks back and forth a bit when not spinning (which makes the static timing a bit tricky), but once idling it settles out just great! It sounds 100x better than it used to! Thanks for the help guys!!!

Spargett
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Post by Spargett » Sat Jul 03, 2010 3:40 pm

Solution?

MBellRacing
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Post by MBellRacing » Sat Jul 03, 2010 3:46 pm

The cam sprocket was, indeed, upside down. Everything else was okay. I just did valve timing on the exhaust stroke and made sure the ignition cam was still properly oriented. As I said, it runs like a champ. Already did the valve clearancing and just have to perfect the ignition timing once its all broken in a bit better.

MBellRacing
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Post by MBellRacing » Mon Jul 05, 2010 12:58 am

Update:

It blew up... FML.

It seems it dropped a vave-- the one part of the engine I, personally, did not assemble. I'll have a speaking to with the guy that DID build it. I had a fantastic set of NOS race pistons, one of which now has a massive hole in it. Awesome. So about $1000, 10 hour of my life, and only 20 minutes of run time on this motor in break in. I haven't even SAT on the bike yet with the new engine! A high-end prostitute has better return on investment than this Superhawk at the moment. As I said, FML.

I'll keep you guys posted, I'm sure I'll need some help... and money... but I promise I'll only ask for the former.

jensen
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Post by jensen » Mon Jul 05, 2010 4:31 am

Hi,

I'm so sorry to hear that,

Jensen
assembly of Japanese motorcycles requires great peace of mind (Pirsig)

teazer
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Joined: Mon Feb 08, 2010 10:32 pm
Location: Midwest US

Post by teazer » Mon Jul 05, 2010 9:21 am

That's a bummer. Did the head drop off an exhaust valve or did it pull through the collets?

Two piece exhausts are prone to dropping heads at high RPMs on race bikes but I haven't heard of them doing that on a street motor unless it was ridden really hard. Rubber cam chain tensioner wheels break up and cause all manner of destruction but not on a rebuilt motor - unless it was an old wheel.

Hmm. I'd be very interested to see the pictures of the destruction to see what went wrong.

What was happening when the valve dropped? Was the motor revving like a banshee or cruising along quietly? What sort of revs had it been run to and what valve springs did it have in and were they new or used?

Stock springs lose tension and cause valve bounce and valve bounce causes heads to drop off valves.

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