Small Hirth engine & last build...

[ruppluver]

Picked up this Hirth in June,at swap meet in Detroit Lakes,MN.
Isn't she purdy?

This is where I'm at now.Engine looked really clean
inside.I'll take the coils out from UNDER the engine
& mount them somewhere else,once engine gets in its
new NT tunnel.I'll have my engine guru check timing
& clean points & check them for normal function.The
case is all cleaned up,the recoil, all the tin covers,
& the fan housing have been cleaned & painted.

[ruppluver]

I started on the tunnel that this engine will be going in.The sled will be badged=Sprint 50,powered by Hirth 493.

72 Tunnel,Chapparal track & front shaft w/AC drivers.

The tunnel is 72 Yankee.It had bigger chaincase,so I
made a plate to cover the mounting holes,because I'm
using a small teardrop off a 71-440WT.It wouldn't
cover the existing holes of bigger case.

[ruppluver]

Went with 71-440WT secondary with brake rotor,I
like BIGGER brake pads!

I measured & am trying to figure out where this needs
to be bolted.I cut a Sachs single mounting plate the
long way,to make this mount.

[ruppluver]

Got the traction/dimple tool out & made a few on both sides!!

[ruppluver]

Doing some glas repair on the lower front panel.

Moved the coils out from under engine,here is the coil mount.This engine has spark,but I
never started it.My Yamaha guru is coming out to check the timing,re-time if it needs it!!

[yellowlab2]

Looking good, Dan! As always, love to watch the progress of your builds...living vicariously through the mechanical adventures of others!!

[ruppluver]

Been working on lower panel.I am block sanding ALL the old paint/primer off.What
a mess.Lots of glass work to do.This panel is in really bad shape,but it will turn out ok.

Chuck,the Yamaha guru,came over & helped pull out the coils/wires from under the engine.
Will have minimal wires in my new,homemade wiring harness.Can't depend on the old harnesses
anymore.It's not that hard to wire with NEW wire,that 40+ year old wiring sucks!!!
Will use a Chaparral track & AC drivers.Track is only 118" long,so will
have to move the rear hanger brackets,1" closer to the front!!!

[ruppluver]

This is my set up for putting track/track conversion components in!! I do all my fitting,measuring,
& fitting finished pieces here.Works great.When track is finished being installed,the
tunnel is flipped over & put on my 3 wheeled cross,where I finish putting sled together.
The 4 pieces of wood,are cut to thickness needed to center track in tunnel.

Got the track to within 1/16" of being perfectly centered.Close enough for me!

Here is front shaft,I just took it out! Have to put a new bearing/seals in lower chaincase.
The driver on the splined end,can be bolted in place on shaft,BUT the driver on the cup
side,has to be slid in about 1",so shaft will clear the bearing/seal in chaincase.When I
get the shaft in,the other driver will be lined up & bolted in place.Each track that is
used in the conversions are different,mainly in width,so each driver has to be aligned
with the track you are using.

[ruppluver]

Yup,lower panel will work!!! NEEDS lot of work.A 70 lower panel on a 72 tunnel.This one
will work just fine,but sometimes after fitting,they still don't fit right.

Measuring for new location.Both have to be moved to clear the drive lugs.

Now the fun begins,cutting off the "legs".

Made a jig for welding on the legs.

Had to move both legs.

[ruppluver]

Had all the bogie assemblies welded up yesterday,put 1 in today.

Attached rear axle,track is in position.Don't you just love it when the project comes
together & you know it will work.Holes are from "picks",shouldn't bother the track too much!!
Still have to put spring,tension brackets in the tunnel!!! Will do that later,after I get
some measurements from a JD JDX4 sled.

[ruppluver]

Track in & adjusted,will need a final adjust next winter!!

[Rupp Doctor]

What you mean next winter???

[Stretch]

Looking good Dan! No kidding about the snow... been crappy the last couple of years but don't know why you would sell off and buy a Polaris? There is no snow anyway!

[ruppluver]

Hey stretch,I would paint the Polaris RED!!! I would only have 1 sled to baby sit,INSTEAD of 5 which I have now.I've been looking at the classic sleds,in the 90's,ones with more HP & better rides.

[yellowlab2]

Coming along nicely, Dan! Keep up the great work!! I'll certainly miss following your projects online when you do finally shut them down!

[ruppluver]

yellowlab2,I just hope some of the ideas I use on my sleds will be used by others,who don't
bring their sleds back to original.It was nice to see,one of the racers,use one of my paint
ideas on their hood.I know some of the ideas I have,are way out there!! Buy hey,I like to be
a little different.Afterall,YOU ONLY have to please yourself.


Engine in final resting place,clutch aligned & new drive belt on. Also tried a handlebar
support from a 71,it is in better shape than the 70,so this might wind up a 71.I now have
lots of odds/ends parts to clean up,paint & install. I will work on the exhaust next!!

[ruppluver]

Painted the belt guard & torque convertor? today.


Heres the painted filler plate installed.
I'll paint up 3 different versions of the convertor,no weights,weights & small holes.
Before I got the spec sheet on the convertors,I would just put any one on,paid no attention
to what they looked like.Afterall,one should be as good as the next one,RIGHT? .I think thats where
I was running into the shiftout problems & colored springs.

[ruppluver]

Clutch guard in place.

A few parts,cleaned,painted & installed.Still have a
few more to get done.

I think I'll go with a backrest/storage compartment
on this sled.This is one I fixed up awhile back.Also
have an extra seat made up for this sled,have to use
these parts up.Last build people!!!! The light at the
end of the tunnel,IS REALLY GETTING BRIGHT!!!

[yellowlab2]

I hope it's not an oncoming train, Dan, I was still hoping you'd build another Rupp ATV...once I retire, I'll make road trip out there!! Couple more years....

[ruppluver]

I have a few tunnels left for an ATV.It is on my list,its not a sled,so it could still get done.Every time I go out to the shed,I see the rear wheel/tire/axel.I've saved enough parts to do one,we'll see Richard.It would be a way of using up some MORE extra parts,I'd just have to throw away or give away!! I'm junking out one of my riding lawn mowers,good parts off it could be used. Once I get this sled done,I'll see what kind of shape my body is in & go from there.later.