Topic: Project: The Hundred Dollar Special (what have I gotten myself into?!?!)

[Old75_ratafe]

I've been visiting my folks in CT for the weekend, so no progress to report. I'll dig back in tomorrow night.

TheGabriel - the head that I pulled from the '72 engine has a few broken cooling fins on one side. I have a '76 engine for parts, so I was going to pull that head and use it. Any reason not to do this? I figured I'd swap the cam and valve springs over to the '76 head, and give it a mild port, polish and gasket match...

Alan - I'm in Somerville, MA. I just moved up here a few weeks ago, so I'm looking forward to meeting people that are local here.

Old75 - Thanks for the info man - I'll start measuring stuff up! I need to do some thinking on the direction this project is going to go. I had originally planned to hardtail the frame, but it seems a shame to put a performance engine in a hardtail, so I'm rethinking that plan. I definitely want to go for spoked wheels though, so I'll pass on the comstars. I'll definitely let you know when I start collecting parts, though!

Later,
Josh

I hear ya rust bucket I love my spokes I would never go to comstars I just happen to have a buddy who has a mostly stripped rolling frame.

[rustbucket]

So I spent some time measuring things up today, and for the most part it seems like I'm in good shape. I was hoping folks might have some insight on a few items that are confusing me, and one that concerns me.

1.) Cam Lobe height is 33.8mm on the intake, 33.3 on the exhaust on all four cylinders. The service limits are listed at 35.85 and 34.45, respectively. The cam doesn't look worn...

2.) Piston ring side clearances are all very good (less than .038mm, my thinnest feeler gauge), except the top ring on cylinder #4, which is .120. That's within the published service limit of .180; should I look to replace this ring?

3.) My clutch discs are 3.17 - 3.29 in thickness. The factory lists the standard as 2.7mm. Are there aftermarket discs that are thicker? Is this likely to cause a problem?

I'm still waiting on the darn bolt to pull my stator before I can split the cases. To kill some time, I detired and despoked the better of the two back wheels I have - you guys think this rim is salvageable?

[Old75_ratafe]

Mine looked worse.... But then again I painted mine lol.

[rustbucket]

I'm thinking I'll go that route too, thinking about it. Shiny things are overrated.

[goaarongo]

1+ on keeping all the pictures in the thread.  The moss on the engine is cracking me up!

Interested to see where this goes - good luck with everything.  Looks like you have a nicely modified top end - shame about those busted fins.   

[rustbucket]

I edited my posts to put all the pictures inline - I hope it's easier for folks to see that way. Hoping to get some work done today - damn rotor puller finally arrived today.

For reference, it's just an M16 X 1.5 metric bolt. I got mine from Bolt Depot (http://www.boltdepot.com/product.aspx?cc=20&cs=77&cm=21&cd=1385).

[goaarongo]

If its not too late, I vote keep the moss.  Hard to come by a natural patina of that caliber.

[rustbucket]

goaarongo - if I was careful, maybe I could cultivate it over the entire bike. It would be the ultimate camouflage!

A few more baby steps today - mostly getting the cases all ready to split. Now how in the heck to you actually get the dang things apart?!?!?!

Here's what I did:
Took the gear shift arm off. Couldn't find the neutral stopper(?!?)
Took the bolts off the bottom of the case
Took the bolts off the top of the case
Whacked the engine with a rubber mallet for a while.

The manual says to gently tap the upper case with a wooden mallet, and the cases will seperate. I got all the bolts (95% sure anyway), but not luck actually separating the cases. Pulled 22 bolts out of the bottom, and six out of the top of the case. I did have one outlier - anyone know what that's for? It seems like they might need to be pried apart, but I'm hesitant to do that for obvious reasons...



A couple of anomalies:
- I don't seem to have a neutral stopper. In the manual, it goes off the gear selector stopper.
- One of the case bolts in the bottom with really hard to remove. The head is damaged, leading me to believe it was really hard to. put in. I'm going to try to remember to chase that thread before it goes back together.
-my engine had an oil cooler, with an adapter plate under the oil filter. This covered a couple of the bolts holding the cases together, so they didn't get loosened until later. Hopefully that won't cause a problem down the line...

Now how do I get the dang things apart?!?

Thanks guys!

[rickmoore24]

Yes; tap, tap, tap with the rubber mallet, dont be shy. Make double sure all the bolts are out and I don't know if I'm remembering this right but I want to say there is a notch somewhere on the stator side that'll take a flat head screwdriver and not f@kc up the mating surfaces. I could be tripping though. Lots of fumes in the garage during my build.   

[rustbucket]

Got 'em apart last night!!!! That dang bolt under the oil pan needed to come out, and I tapped a razor blade around the seam with a hammer to cut the gasket goop. After that a little tapping, a little cursing, a little more tapping, a little more cursing...





Looks nice and clean in there. The PO may have liked pipe wrenches, but at least he kept the oil fresh!

Look what I found first thing!


The little bastard that cemented my need to split the cases in the first place. Hey buddy!

My family is in town for the weekend, so I probably won't get anything done on it until Monday night or so. I'm trying to figure out what I should order for parts right now though - any help would be appreciated. I'll dig into the gasket set I have on Monday and see what I have there...

The big questions are - do I need to rering the pistons? Any good sources for those rings?
Should I replace the wrist pin circlips?

[horror]

It's the best when an engine is opened up to find performance mods. I would use that head regardless of the broken fins.
adds character and history. they can be fixed maybe.
Did You say a racer owned/did the engine previously? I would be excited to try the motor with that head.
nice find.

[rickmoore24]

I say yes on the new pin circlips. Mainly because the manual said to replace the old tired ones. Check ebay for the rings too. 

[the technological J]

if you are getting new spokes you could always clean up the rims and have them powder coated

[Old75_ratafe]

if you are getting new spokes you could always clean up the rims and have them powder coated

+1 black rims = bad ass

[rustbucket]

Yeah I'm definitely thinking I'll do black rims & hubs with chrome spokes. A buddy of mine builds bike frames (bicycles), and he has them powdercoated, so I need to see if I can get any kind of a deal there... I'd really like to swap to a drum front wheel, just for the aesthetics, but I don't know if there are any out there that stop worth a damn...

[the technological J]

yikes!!!! find a disk for the back!.... chances are your gonna be testing the limits of this bike... its a racer i would try dual disks up front your gonna want all the stopping power u can get... this bike will able to hit 110 mph you want lousy brakes? just saying ive had my share of close calls and im thankful for good brakes.... but its your bike and your neck... just my 3 cents worth

[syth82]

So I spent some time measuring things up today, and for the most part it seems like I'm in good shape. I was hoping folks might have some insight on a few items that are confusing me, and one that concerns me.

1.) Cam Lobe height is 33.8mm on the intake, 33.3 on the exhaust on all four cylinders. The service limits are listed at 35.85 and 34.45, respectively. The cam doesn't look worn...

Reground cam. Measure across the base circle and subtract to get total lift.

[Old75_ratafe]

yikes!!!! find a disk for the back!.... chances are your gonna be testing the limits of this bike... its a racer i would try dual disks up front your gonna want all the stopping power u can get... this bike will able to hit 110 mph you want lousy brakes? just saying ive had my share of close calls and im thankful for good brakes.... but its your bike and your neck... just my 3 cents worth

Yea I'm with you on that one stock mine stops like a brick from 50mph I can't imagine drums on both wheels, I'm converting to dual front disks and air forks over the winter as it is.

[rustbucket]

Alright, I finally got off my ass and dug back into this today. I had the usual reasons for not working on it, but things have settled down a bit so hopefully I can make some forward progress next week.

I chatted with a welder friend of mine, and he's stoked to build a hardtail frame, so that's what we're gonna do. Next week I'm going to get the frame together as a roller and bring it over to his shop so we can get started. I picked up a drum hub from a 1980 CM400 that I'm gonna use as a front wheel. The stock rim on that was 18" (I think), which is cool - I dig the look of the same size wheels front and back.

Today I tapped out the primary shaft, removed the crank and transmission shafts from the cases, and took a few basic measurements.

Since this is my first time getting this far into an engine, I don't know what it should look like, but it seems pretty damn good to me!





Now I'm trying to figure out what I need to order to get this thing back together, and what I need to check while it's apart. I need to get some plastigage to check the bearings. Other than that, I was wondering if I need to check all the measurements in the manual? I don't have a dial indicator, and I don't know any other way to check the runout for the valves, cam, camshaft, etc. I also don't have a bore checker. If I can get away with just honing the cylinders at home, I'd like to do that, but is there a way to tell? How about the bearing seats - the manual said they should be checked with a bore indicator too... I'm also not sure if I should even take the rods off the crank...

Should I replace the cam chain? Primary chain? Cam chain guide & tensioner?

I'm looking for a source for a head gasket, and still wondering about the piston rings, as well.

I'm feeling a bit lost right now, if you all couldn't tell, so any advice on what to check and where to source parts is greatly appreciated. Looking at the engine, I wonder if I needed to take the darn thing apart. Maybe I should just button it back up...

Here's the album from the engine teardown - http://s4.photobucket.com/albums/y144/AnotherSoul4Sale/Engine%20Teardown/ - I'm happy to take more pics if anyone wants to see anything in more/ detail!

[fantino]

You've got some really cool stuff in that engine. Nice score on the Yosh pistons and the V-stacks (nice hose-clamps too ^_^). When you get the carbon cleaned out of the ports on your head, you should post a pic of the insides so we can see how much it's been opened up.

I can't tell from your pics... did it come with an exhaust?

[rustbucket]

I'm pretty stoked on it. I'd be even more stoked if I could find a source for rings and a headgasket...

It came with a 4-1 exhaust that the PO said was a 'Bergami' - I can't find any reference to that company though... I'll grab a couple of pics of it next time I'm in the shop. As to the head, it looks like it was just gasket matched.

[Alan F.]

I'm pretty stoked on it. I'd be even more stoked if I could find a source for rings and a headgasket...

You need to send a PM to MRieck, it's likely he knows where to look.
Alan

[rustbucket]

Thanks Alan! Fingers crossed...

[rustbucket]

Well, I'm stuck on piston rings right now... I posted up another thread here asking for some info (hope that's not too much of a faux pas): http://forums.sohc4.net/index.php?topic=78820

So far, no one has replacement piston rings. 

I'm wondering if I should look for full piston sets or perhaps use the 550 jug (or the whole engine) I have - it turns over, but I don't know anything more. I could transfer the go-fast parts to it...

[fantino]

Honestly, even though old period race parts like those Yosh pistons are really neat... an extra ~15cc compared to the 550 jugs probably isn't going to net much of a difference in performance (especially not compared to cams, porting, etc.). I almost bought a Yosh big bore kit for my 500, but ended up abandoning the idea when I couldn't find rings for the set *anywhere*.

Pull the jugs on the spare motor. If the bores and pistons are in serviceable condition, I'd just clean em up and swap them over. Re-ringing will be much cheaper and easier with a stock set of pistons.

The other thing to mention at this point is that the 550 bottom end is a superior design to the 500. Don't get me wrong, I love my 500 and due to my attachment to the bike itself, will be doing everything in my power to rectify its design flaws as best I can. But that doesn't change the fact that the clutch and transmission of the 550 is far better than the 500. You won't find the shift fork wear, broken clutch rods, mangled clutch adjuster housings, slippy clutch plates, etc. One thing starts to go and it seems to be a domino effect for the rest of the clutch\transmission.

For the most part, everything north of the crankcases is 100% cross compatible between the 500 and 550. Something to consider :-)