Terminally seized?

[Scruffy]

1963 CL 72 250 Scrambler engine. Had been kicking through fine, good spark, would kind of run, rough and erratic, but it ran.

Has sat with oil/atf and diesel in the entire engine, including cylinders and valve train, since it quick kicking through. I can pull the plugs, drain the engine, put a breaker bar on the stator nut, stand on the bar and bounce. Nothing moves.

My friend/farmhand has had a few older CA and CB series from that same era. He's stumped as well. Although he thinks the cam chain has become bound up somehow... or the rings are rusted to the cylinders. But, I weigh 240, stuck rings should have broken loose...

I could use a logical order check list to trouble shoot this thing. Plan to pull it out later in the week, I'd rather work on it with the engine on a work bench than in the chassis.

Thanks in advance...

 

[Big R]

You haven't taken the top end apart? If the chain jumped, and you have a piston pushing a valve......not good.

 

[Scruffy]

Not yet. Been too busy on other tasks/projects. I live on a working farm, the fossil is a bit of a back burner project, should have time this week to pull the motor and pop the top end open. Don't normally work on "modern" engines, I'm more the valve in block type. UL/VL/45 Harleys, Indians, old flat head inline 6 cylinders... completely different set ups than an OHC with timing chain.

Haven't opened up an OHC in probably 15 years.

 

[Big R]

Should have added: if you can spin the motor backwards a little, than it's not a piston & valve touching. If it's not moving at all, than you're on the right track already.

 

[Scruffy]

Not moving at all. I kinda think the kicker shaft is bound up in the gearbox, but, until I pull the engine... When I got the bike it had less than 20 hours on a full rebuild, but it sat up for a long time due to ignition base plate problems. Owner couldn't keep it timed to the cam position. Bike itself was free so I'm not out anything to open it up and take a look. If it's worth fixing I still shouldn't be in it much, I've tracked down a few sources for NOS or good used parts.

Hardest thing to find has been the correct manual, this is a right hand chain version and the books I've found are all for left side chain...

It's too little for me to ride but my grand niece thinks it is cute. She's 7, she'll sit on it making motorcycle noises until the horse distracts her... :

 

[teazer]

All CB/CA and CL72 and 77 have the chain on the same side because of the gearbox design

A CA or Cb manual will be fine for most of the powerplant details, apart from the kicker side cover where the cb kicks forwards and has an extra gear in the cover.

Do you have a picture of the beast in question?

 

[Scruffy]

I did have one up but my wife changed photo sites and I have no idea what the new addy is. Or when I'll be able to jump over to her computer where all the pics are stored before posting.

Nothing pretty to look at, no fenders, stock blocky tank, exercise machine seat, CB pipes with mini glasspack mufflers, stock headlight and a set of cheapo Emgo tracker bars with Honda "Super Bike" (Emgo) replica grips and replica Amal levers and perches (Emgo). TLS rear brakes, unknown sls front wheel (but a friend who vintage races said he thinks Penton or Bultaco). Ceriani progressive sprung rear shocks, same racer said he thinks the front forks are 30mm Ceriani (I think he's full of beans, look stock to me).

Typical crusty west coast fire road beater...

 

[Scruffy]

Pulled the engine out this afternoon. Popped off the top plate and gasket. Cam and bearings are spotless, cam chain is spotless. Looked in the intake ports, not pretty, fuel crystals are everywhere. Looked in the exhaust ports, even less pretty, left side looks like it is full of tar. Right side looks like it is full of burnt paper.

Tried rocking the engine via the stator bolt... it came out. Shifter does not move. Kicker shaft does not move. Engine is in neutral (I hope) can spin the front sprocket very easily.

I've got a friend on a truck forum who can get me parts at cost and has a Honda factory mechanic at his disposal. He's a former dealer/racer and they've offered their services. Conditional upon my opening up the top end and making sure nothing shattered... they'll still fix it, will just cost more that I can't spare right now.

My numbers matching (rarest of the rare, frame and engine numbers match) ratty old Honda just got expensive and worth fixing up. Serial number ends in 0001... NOT a first year, they came out in 62...

 

[teazer]

cam design on those is unique to say the least and the trans is unlike any other Japanese bike, but they are easy to work on.

When you pull the head off and remove the rocker pins, please note that intake and exhaust pins are different end diameters.

 

[jsharpphoto]

not that there isn't great info on here, but also checkout honda305.com for the CB/CA/CL 72/77 info. Those guys have seen it all.

 

[teazer]

Good recommendation. I'm over there as well Ed Moore and a few of the other guys on 305 are also very knowledgeable.