Topic: Mmm... First cafe racer project ever 81' CB650 engine into a 71' CB500 frame :)

[daewon774]

Carbon, and... more carbon.



Pistons, eww...


So, after taking a look at how my head and pistons look like, I decided that I would take charge and get that nasty carbon deposit off.  Clymer suggested using broad flathead screwdrivers and wire brushes to take the carbon deposit off.  I started with some bronze wire brush on my angle grinder.  What I didn't realize till after I was done was, maybe I shouldn't have done that.  I now have wire brush scraping where the head gasket sits between the valve assembly and the pistons.  Can anyone chime in on this?  Am I now locked into getting resurfacing done?  Are these scrapes ok and will sitting a gasket in between these two joints be enough to seal properly?





 

Also, I have a question about valve removal.  Is a valve compression tool absolutely required?  I could have swore that I read somewhere that someone used a socket and hammer to remove the pin from the valve spring?  I tried doing a search and couldn't find this.  Is this true or is the hammer and socket trick for something else?

[Roach Carver]

you may be right about hitting it with a socket and hammer, but you will still have to have the compressor to put the valves back in.

[manjisann]

You could try one of the local autoparts places, a lot of them will rent out tools for a very reasonable price. That being said, car ones might not work for bikes, but it may be worth a shot.

Brandon

[daewon774]

Alright, I'll try the local autozone to see if they can lend me out a valve compressor. 

Can anyone advise me on the surface pics?  My bronze wire wheel did some left some scrapes and marks on the aluminum head.  Will I need a resurface even if I find no warpage? 

[Ogri]

I think it would need to be taken down a bit. Some of those marks are could possibly cause a problem. There's no reason why you can't do it yourself though. A big piece of wet and dry paper glued to a flat surface (like an old kitchen top or piece of plate glass), place the 'head on it, rough side down, and move it in a big figure of eight pattern. It's not hard, just use light, even pressure and keep it moving.

Then again, a local engineering/motor shop might be able to polish it down for an affordable price.

 (no sound)



A valuable lesson learned. Mating surfaces should be considered sacred and only cleaned with tools less hard than the material (lead, brass, plastic etc.)

[MRieck]

 DO NOT use the socket hammer method to remove the valves. The valve angle combined with the 5mm stems makes them very easy to bend.

[Yak]

Sheik and i picked up a craftsman valve spring compressor from sears for $19.99, which isn't too bad. It seems rather large, but from what i have read quite a few people have had success with it. I'll let you know how well it works for us ....as soon as we actually bust it out of the packaging

Yak

[daewon774]

Sheik and i picked up a craftsman valve spring compressor from sears for $19.99, which isn't too bad. It seems rather large, but from what i have read quite a few people have had success with it. I'll let you know how well it works for us ....as soon as we actually bust it out of the packaging

Yak

That would be great if I could get some info on that.  I thought it would cost a bit more.  I was going to go to Autozone to see if their loaners would work.  If it's only $20 from Sears, i rather just pick one up for the growing tool collection, lol.  It gives me more of an excuse to get a tool box I guess too...

[daewon774]

DO NOT use the socket hammer method to remove the valves. The valve angle combined with the 5mm stems makes them very easy to bend.

Mike, I sent you a few PMs from yesterday and today.  I was wondering if you received any of them?

[daewon774]

Ok, another update.  I got some time to go out to the garage to take the cylinder head off.  BTW, comments would be much appreciated.  I would like to know what everyone thinks about my pistons and cylinder walls.  The only things that I noticed were the piston walls had some wear on the sides.  I don't know if this is normal.  Also, I noticed that my first cylinder had some rusting at the top. 

I attempted to measure the bore of the cylinders and diameter of the pistons, but I think my cheapo Harbor Freight micrometer isn't reading the measurements right.  All my measurements were not in spec.  When I say not in spec, it measured as if the cylinder wall bore shrunk, and the piston diameters grew.  I don't know.  I don't trust this micrometer.  I'll probably just get this professionally measured when I get the resurfacing done on the valve assembly.  Just need to find a machinist...

ALSO, PLEASE COMMENT ON THE FOLLOWING!  I found this metal shaving stuck between the cam chain tensioner and the wall of the cam chain opening.  WTF???  I couldn't find the culprit of where this came from.  Any ideas?



Pistons...  From left to right: piston 4, 3, 2, 1


Piston 4



Piston 3



Piston 2



Piston 1



Surface rust on cylinder 1



I hate chipping...

[daewon774]

Just a short update.  Today I finally found some time to work on the bike.  Results are below

Carb is reassembled!


Valves removed


For the valves, I stopped by Sears the other day to pick up their valve spring compression tool.  It was only $19.99.  You can see it in the image below.  It's at the top right of the pic.  This tool work flawlessly to remove the valves.  Anyone needing to do this should definitely pick up this tool for their collection.

[manjisann]

For the valves, I stopped by Sears the other day to pick up their valve spring compression tool.  It was only $19.99.  You can see it in the image below.  It's at the top right of the pic.  This tool work flawlessly to remove the valves.  Anyone needing to do this should definitely pick up this tool for their collection.

How bout for reassembly. It seems to me that I read a thread where the tool that was being used allowed the person to dissassemble the valves, but for some reason (I can't remember) they couldn't use it to get them back together. Sorry, not trying to be a downer just curious. If it works for both directions, I'll be buying one as well. I'm always happy to "need" another tool 

Brandon

[daewon774]

I'm not sure about reassembly.  I'll test it out one valve tonight and see what happens.  I'll let you know how it works out.

[faux fiddy]

What happened?

I fear this build could have been  terminated in an untimely manner. First it's all greasy in the garage,,, then it moves to the kitchen table.  Then it's  gone without a trace?

[lucky]

110509 Begin head removal...

So today I took the initiative to take apart the top end of the motor.  I have quite a few questions.  Now I just want to remind everyone that this is the first time I have ever attempted to rebuild a motor.  It is also the first time that I have seen the inside of one as well.  So...  I'm still not sure what even wear or uneven wear is when it comes to identifying properly worn parts.  I do have a micrometer and some other tools to check specs, but I will definitely be asking some questions on this thread to get some advice from you all, the experts.

So here we go!

 All of them are in spec.  I'm just unsure if they are still reusable.

Thanks in advance!

Yes you can reuse the parts.
If there is a scratch feel it with your fingers.
Just lightly sand it a little with some black carborundum sandpaper.
About 600 grit. Go easy. Do not sand very much -just make sure it is smooth.
If the entire surface of the cam lobe is scratched you cannot reuse it BUT the cam can be resurfaced. Do not throw it away. Trade the core  for machine work. one little scratch -no big deal as long as it is in spec.

You did not give us the milage. An engine like this with 20,000 miles is not much at all. Those engines were good for 150,000.

Just make sure nothing is sticking above the smooth surface-no burrs.
The chip on the edge of that came lobe is common. Don't worry about it.
The tappet never gets near that edge.
If the tappet(rocker arm) faces that contact the cam are scratched,
the must be replaced. If mating surfaces have turned blue from overheating that part must be replaced.

Put engine oil on the parts on reassembly. Follow the manufacturers instructions on the oil for piston ring break in.
Often in those days non detergent oil was used when new. to let the rings break in and after that just regular oil.

Make sure to check the cam chain tensioner and replace the cam chain with the newest kind for that model. All chains are better now than when that engine was made.

I was a former dealer mechanic.