500cc pushrod bike project

[JimL]

Drive side case is machined, fill plates cut and bent, heli-arcing will be done tomorrow, Saturday I'll build some and get pics posted.  I was working on the d&*#ed ol' flatbed truck stuff again tonight....got woozy from the paint fumes, and forgot to take pics of the bike parts in progress.

While we're talkin'....has anybody had any problems running REALLY long chains?  Mine has quite a bit of reach, and I'm not sure if I should have some lower slides or something.  Any thoughts or ideas would sure be welcome.

thanks, JimL

[wolbrink471]

While we're talkin'....has anybody had any problems running REALLY long chains?  Mine has quite a bit of reach, and I'm not sure if I should have some lower slides or something.  Any thoughts or ideas would sure be welcome.

We extended the motocross swingarm nearly 4 inches and didn't have any chain length problems...center of counter shaft to center of rear axle is just shy of 30 inches.....not sure is this is really long or not?

Even with the length..the limited suspension travel kept the chain from touching/lashing against any of the stock mx chain guides.

Mark

[JimL]

Thanks!  I'd forgotten how long hill-climber chains were, and they really get whipped hard.

JimL

[JimL]

OK...here's pics of the welded up case (now you have an idea how tiny the flywheel is!), shaft extension, and approximate location of the outside pillowblock.  After the welding was done, I ran into a little trouble with the shifting sticking.  The line bore for the intermediate arm is a little off, so I'm hand working the bore (in the outer case) to get it working.  It's close, now, but I got tired about 10:PM and quit.

I'm planning to anchor the pillow block to the engine, only, and not the frame (using 3 of the original rear engine mounts and a fork to the main case bolts on the sprocket side of the engine.  I still have to make a seal cup to fit inside the case (it'll be a simple bolt on).

Regards, JimL

[oz]

Ive got 140 ish links in my chain so I put a little jockey roller in the middle of the run just in case,Its only an old skateboard wheel on a slide mount I thought it better safe than sorry.
Oz

[JimL]

Thanks for the thought, oz....I think I'll look at a draw slide for early 20R timing chain, to damp the whip after the countershaft sprocket.  Once clear of that, a broken chain might lay down pretty good...... I left a CB750 chain on a highway, back in 1971, and was amazed how well it just layed out and stopped about where it broke (was running over 100mph).  Weird physics there!

Anyone had experience breaking a chain at speed, on the salt?  Ideas/suggestions to control/minimize such an incident?

Thanks for any comments/ideas.

Regards, JimL

[1212FBGS]

breaking chain at speed? Oh yeah, at least 6 at speedweek '06
kent

[Stainless1]

When we broke one we suffered a little damage to the clutch push rod and the cover... but to qualify that, the 20 tooth sprocket didn't leave much room for anything to be even slightly out of place.

[JimL]

Thanks for the comments... I've set up my final drive to leave room for two different positions for the front sprocket.  This will allow me to get a smaller sprocket tagged onto the inside of the rear sprocket (a cut down one to use as a mount) and the availability of going to 520 chain (the old SL350K1 countershaft sprockets fit my shaft).  That can give me a little more clearance around the front sprocket.

This is going to be a real close deal for the horsepower needed.  The Norton has run 128 at El Mirage, and the Triumph has 117 at Bonneville.  I should be close, but it's anybodys guess and that's why I redesigned the final drive.

This is eerily similar to my situation with the CB450 in 1969.  The C motor Kawasaki 500 Triple ran just over 120 in my class (after I'd bumped a 101 to 111 the day before), and I was able to come back at 121 and make it stick....meanwhile a Norton was running about 126 in another class I wanted to chase and I couldn't get past 124! 

Is this what they call "deja vu all over again"?

I have to say, I am REALLY enjoying this little project, despite all the screw-ups, re-dos, and how-d-heck did that happen?

JimL

[Nortonist 592]

129.817 at El Mirage.  Good looking build.  I'm looking forward to see it in person and see it run.

[JimL]

Output carrier is together and mounted up.  The chain run worked out exactly where I hoped.  I can adjust the pillow block forward and back, as well as vertically, because I built the mount with shim washers under the forward tie bar.  All made from 3/8" plate.

Here's pics for today.

JimL

[Jonny Hotnuts]

What keeps the sprocket from walking laterally?

[JimL]

Jonny, I still have to cut the groove for the retainer.  It uses a steel plate that slides down the splines, then turns to lock in the groove and bolts to the two holes in the sprocket.  I've got to buy a new Dremel tool to do it, my old one died.

Good thread you're running on that engine work!

Regards, JimL

[oz]

Do you need to cut a groove? You are already on splines could you not just use smooth bored spacer tubes if they dont foul anything.
Oz

[JimL]

I will have to put a groove outboard of the sprocket.  I made a seal cup, today, and mounted it behind the aluminum plate (inboard of the sprocket).  I cannot let anything ride against the seal.

The cup is a simple "homemade 40mm ID tube" welded to a large flat washer with two 6mm nuts welded to the edge of the washer.  The holes in the aluminum case are slightly oversized, and I mounted the cup (with seal installed) inside the case using FIPB (form-in-place-gasket).  The oversize holes allowed me to assemble the output shaft onto its' bearing, then tighten the cup mount bolts (the seal centers the cup on the shaft, so I didn't have to figure out prefectly where to position the mount bolts). 

This is the same method the old Land Cruisers used in the timing cover for the crankshaft seal.  The entire cover mounted on the block with oversize holes and a cork gasket.  The crank pulley was installed first, to center the seal, and then the cover was bolted tight. 

Like they say...there's nothing new under the sun; everythings been done before!

Regards, JimL