8.25.12 Oval Tracking

[kwells]

Blackie got the finish in the lead this week again. The new charging system makes my headlight super bright. The lithium battery holds a charge around 14 volts when off so it barely dims when the engine isn't running. I have a pretty good stumble that developed at around 5k but wide open throttle works just fine. Will probably pop the carbs off today and verify everything is still clean and no pilots jets decided to back out. I tried running 17psi this week and while it was more grippy I was getting a lot of oscillation under heavy throttle coming out of the turns. I just let it wobble and stayed on the gas but made it pretty challenging when getting on the front brake when the rear was trying to shake. I think next week I'll run about 22psi to give the sidewall a little more lateral strength. I really want to shave the flywheel down to give me some faster spin up so I may look into finding one across the pond from an XZ400(let me know if you're selling one).
My wife and I rode out to the track 2 up this week and with the new rear shock it handled just fine. At a couple points we were cruising around 90-95mph so I know the top end power is definitely there. Now to sort that mid range. Will post up some video later.

http://s53.photobucket.com/albums/g56/kwellzz/?action=view&current=MVI_6851.mp4

[fret not]

Mr. Wells, the XZ400 crank has a shorter stroke and would make the displacement less than 500cc, that is IF it would fit properly.  Rod length, piston pin diameter, main bearing size, etc. all need to be the same as the 550 or you will be changing more than just a crank. 

I think you could get a 550 crank for not much money, have it turned down,  fix the rod bearings, and put that in your bike.  That way you wouldn't give up any displacement or power.  That being said, a big flywheel helps smooth out the engine response which can be a big benefit for hooking up on the dirt surface.  A lighter flywheel is great on pavement where you want all the acceleration you can get and you are not worried about losing traction, but the dirt can make you think otherwise, maybe.  You might benefit from a XZ400 primary gear set which is lower geared compared to the 550.  Are the rear drive gears the same ratio or different?

More good luck to you. ;)

[Rick G]

He's not referring to the crank , but to the alternator flywheel. The fly wheel in '83's is a bit smaller than the '82's  and the 400 even smaller. . I believe the difference is in the diameter.

[fret not]

OH! Nevermind. (my favorite Rosanna Rosanadanna quote)

[The Prophet of Doom]

@Rick,
All 550 models have the same flywheel same part Numbers - only the 400 is different.

The diameter is the same. It's the depth and thus weight that is different on the 400.  You can see the difference here.  http://ridersofvision.net/rovforum/index.php?topic=13762.msg124726#msg124726

@Fret,
only the primaries are different - about 5% lower than US, 10% lower than Oceania/Euro models

[kwells]

Well I got motivated in figuring out what my problem might be with rough mid range. Here's what I discovered:








The POR15 liner dissolved into the fuel and precipitated at the bottom. It was clogging up the petcock as well but the jets were all free. I had a sintered brass fuel filter but I think the paint flakes are just too small to get screened. Have to do some test riding to see if I got the gunk all cleaned up but no more race fuel in this tank I think.

[fret not]

What is in that fuel???  Looks like it's a rather aggressive solvent as well as being fuel.  What are you going to do about the inside of the tank?

[kwells]

I'm going to re-line the tank with another POR15 kit.

[Rick G]

Roro, I read somewhere that the '83's have a lighter flywheel , I'll have to see if I can find out where I saw it. It may have been in a road test article  and the writer had his head where the moon don't shine.

kwells , I don't thing you need race gas, that stuff is like  rocket fuel ! Regular pump gas will eat fiberglass tanks and the resin ends up in the carb.

[jefferson]

I would say try to find a spare flywheel and lighten it to see how it works on the track. I removed everything on mine including the ceramic magnets on the inside of the flywheel and it helped mine alot, but that was on asphalt. Dirt might be a different thing altogether. I applaud you for your exploits. Keep up the good work.
Something else that will help if you have not already done it is run your vent lines to a catch can instead of the airbox. The difference was noticeable.

Jeff

[Hartless]

there was one guy on here that  completely removed his flywheel and ran off of just the battery, im pretty sure it was strictly a race bike though......cant remember who though... walt maybe?

[fret not]

If you remove the flywheel you will need something to replace it to trigger the ignition, as currently the flywheel triggers the pulse coils to make the ignition fire.