Old Husky

[bdalameda]

When my son Ben was 13 I gave him a 1973 Husqvarna 250 for his birthday as he loved tinkering with bikes. Well the old Husky got taken apart to restore and like many projects ended up in my garage attic in pieces. Now Ben is approaching thirty, is married and has a child on the way. He has a Phd in Chemistry and works at the Lawrence Livermore National laboratory in Livermore, CA. He still loves tinkering with bikes and we took the old Husky down out of the attic and he took it home about 6 months ago. He started the restoration and it's coming along nicely. He brought me the crank and cylinder a couple of months ago and I rebuilt the crank and bored the cylinder and fitted a .020 over piston. He recently sent me this picture of the old Husky as it is taking shape.

 

[SMSW]

I rebuilt the crank and bored the cylinder and fitted a .020 over piston.

What does one do when you 'rebuild a crankshaft'? Do you mean blueprint it...make sure all the dimensions meet factory tolerances? The bearings fit in split halves of the con rods, so I would assume they play no part in the rebuild. If you fitted oversize pistons and rings, then you checked all dimensions, fitted new bearing shells as needed, gapped the rings and put it all together, right?

 

[St-Gerard]

How in blazes did he get the sides of the tank to reflex like a mirror?

 

[bdalameda]

What does one do when you 'rebuild a crankshaft'? Do you mean blueprint it...make sure all the dimensions meet factory tolerances? The bearings fit in split halves of the con rods, so I would assume they play no part in the rebuild. If you fitted oversize pistons and rings, then you checked all dimensions, fitted new bearing shells as needed, gapped the rings and put it all together, right?

All two stroke bikes have pressed together cranks and use a one-piece rod with a caged roller bearing for the big end. To rebuild one of these cranks you need a hydraulic press along with a set of fixtures to press the crank apart and push it back together again. A new crankpin, rod and bearing is installed and then the crank halves are pressed back together again. The trick is to press the crank back together with the correct clearance for the rod and bearing and after pressing it back together it has to be trued up. I have a crankshaft truing stand that supports the crank on ball bearings and it uses a dial indicator to check for run-out. The crank is trued by checking the runout and using a brass mallet to hit it in the proper spot on the flywheels to shift the two halves into alignment. Sometimes the halves will need to be wedged or squeezed to bring it back into alignment. It is a bit of an art to know where to hit and how hard to hit to get the crank to shift properly. I've rebuilt hundreds if not thousands of roller bearing press fit cranks over the years. I used to even rebuilt 2, 3 and 4 cylinder press fit cranks. Many four stroke engines also use press fit cranks.

Here's a video that shows how a crank is rebuild.

 

[bdalameda]

How in blazes did he get the sides of the tank to reflex like a mirror?

Old Husky's like these are chromed before painting.

 

[bdalameda]

What does one do when you 'rebuild a crankshaft'? Do you mean blueprint it...make sure all the dimensions meet factory tolerances? The bearings fit in split halves of the con rods, so I would assume they play no part in the rebuild. If you fitted oversize pistons and rings, then you checked all dimensions, fitted new bearing shells as needed, gapped the rings and put it all together, right?

As to the cylinder. I measure the bore as it was and ordered an oversized piston for it. The piston I got was .020 over standard bore and th engine was still on standard bore. The original bore was worn around the intake and exhaust ports so I made sure to get a piston that was large enough that the cylinder would be cleaned up when bored out. I have a very old Boremaster cylinder boring machine and the cylinder is placed and centered on the machine boring bar. I use and inside and outside micrometer to adjust the cutting tool and remove a few thousandths at a time until I get the proper piston to cylinder clearance as specified by the manufacturer originally. One must take into account that the cylinder has to be honed inside to get the proper finish andafter honing the clearance is again checked. All ports in a two stroke engines must be carefully deburred to prevent the rings from catching on the ports. The top and bottom of the cylinder needs to be deburred as well.

Here's another video on cylinder boring

 

[dduelin]

Old Husky's like these are chromed before painting.

Bruce Brown's 1971 On Any Sunday was a great influence on me. I think I saw it 4 times in theater even taking a date to that movie who was not impressed. My hero Malcolm Smith! I had a Kawasaki F7 175 painted red at that time and I took sandpaper to the tank trying to duplicate the trademark Husky chrome spot. It did not come out as shiny of course but I was pleased.

 

[St-Gerard]

Ah, that makes alot of sense, did they chrome the inside as well?

 

[St-Gerard]

Yeah I have no idea how you chrome something , might stop the tank from rusting inside or make it worse.

 

[Larry Fine]

How in blazes did he get the sides of the tank to reflex like a mirror?

Would you believe it's actually a picture?

 

[St-Gerard]

I loved Husky's in my younger days.
View attachment 324839

Is that picture from the movie "Vanishing Point"?

 

[the Ferret]

The epitome of motocross bikes in the early 70s

 

[bdalameda]

Bruce Brown's 1971 On Any Sunday was a great influence on me. I think I saw it 4 times in theater even taking a date to that movie who was not impressed. My hero Malcolm Smith! I had a Kawasaki F7 175 painted red at that time and I took sandpaper to the tank trying to duplicate the trademark Husky chrome spot. It did not come out as shiny of course but I was pleased.

It's interesting that you mention, "On Any Sunday". I loved that movie when it came out and watched it many times. I was way into Flat Track at the time and raced short track myself and some TTs at the time. I have a DVD copy and when Ben was a kid we used to watch it, he liked it too. If you liked that movie watch "From Dust to Glory". It's a great one too.

 

[bdalameda]

Ah, that makes alot of sense, did they chrome the inside as well?

Good question, I'm not sure. The entire outside is chromed but only the exposed areas are buffed out. The rest of the tank is flat unpolished chrome probably so the paint would stick.

 

[St-Gerard]

Close but no Cigar

 

[Fawlty]

Close but no Cigar

 

[klaproth]

Although I've worked on many engines, none of them had a more than one piece crankshaft. I knew they existed, but not the process for rebuilding an engine that includes them. Impressive!

 

[ST Gui]

Would you believe it's actually a picture?

DAMN! I was going to post it's a picture!

The epitome of motocross bikes in the early 70s

The mirrored finished helped but I always like the simple clean look of the Huskys and similar bikes back then.

 

[mello dude]

When my son Ben was 13 I gave him a 1973 Husqvarna 250 for his birthday as he loved tinkering with bikes. Well the old Husky got taken apart to restore and like many projects ended up in my garage attic in pieces. Now Ben is approaching thirty, is married and has a child on the way. He has a Phd in Chemistry and works at the Lawrence Livermore National laboratory in Livermore, CA. He still loves tinkering with bikes and we took the old Husky down out of the attic and he took it home about 6 months ago. He started the restoration and it's coming along nicely. He brought me the crank and cylinder a couple of months ago and I rebuilt the crank and bored the cylinder and fitted a .020 over piston. He recently sent me this picture of the old Husky as it is taking shape.

Soooo Coooool! I cut my motorcycling addiction on those old 2 stroke motorcross bikes.. I was around plenty of Huskys, Maico's, Yamahas, Suzukis, and Hondas. I had a tricked out Honda Elsinore. A fun thing about that time... Ohio 675 was being built, the path was bulldozed... then the state decided that they didnt have any more money to complete and what was left was about a 16 mile dirt path... the perfect motorcross track... Good times.

sorry for the hijack...