Engine rebuild: General concensus?

TeeCat

TeeCat

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Hi, guys -

Having had my '73 for nearly 4 years (this coming August), I think I'm finally getting to the point where I might be able to put a few fun miles on her this season, instead of just troubleshooting, dialing in, fixing, etc.. It's a good feeling. I have been painfully slow and deliberate about it, perhaps not always doing things the recommended way, admittedly, because of time and ability constraints, and so on... but I have the bike (bought as a non-runner) to the point where everything seems to work except the missing high-beam indicator light and the neutral light. Plus, in the process of fixing things, I often replaced/upgraded them. And she sports some pretty trick bits, like a single carb conversion. Not bad for a hack like me, I suppose.

Anyway, the one thing that continues to bother me consistently is a lingering oil seep that, as far as I can tell, is likely coming from between the case halves forward of, or around, the alternator. I have replaced the crank seal in situ, and the output shaft seal. Both of those replacements seem to have worked, and the clutch rod seal was dry at the time, as was the shift shaft seal.

But I still encounter weepage/seepage. It's not terrible, but it's enough to make a little mess of the left underside of the bike if I don't practice cleanliness regularly. I just about have my single carb conversion dialed in (I hope, after some minor air induction changes... still need to test), and the bike seems to run well, doesn't smoke, etc.. But I think that the reality of this oil seepage is, at some point, going to be at least a bottom end scenario at some point.

The upshot is that it might make practical sense, at that point, to refresh/rebuild this motor. The reality of my life, though, is that I will likely not have the ability or time to approach anything like that because it may never get completed. Dirty Harry said, "A man's got to know his limitations."

So, basically:

1. What is the general consensus among you on the need for a rebuild? When is when?

2. What does a rebuild of a running XS motor generally cost if an ethical pro or skilled amateur does it?

3. How much cost/labor can be saved by my pulling the motor myself, or is it wiser to just take the bike to the willing/qualified mech and approach it that way?

Thoughts and recommendations welcome. I'm going to evaluate further this season, weather permitting. Right now, MD is a swamp, so this is all hypothetical at the moment.

Thanks, all!

TC
 
if your just doing top end and a little research then you will be fine. i didnt know shit when i started, i did everything the hard way. spent waaaay to much time and money. just be organized and in research figure out what you will need to replace.

pulling the engine aint nothing either. just get everything out of the way. linkages, wiring, exhaust, carbs.

i just reread your post and you said it might be comming from the case halves in front. ive heard that a retorque can help alot, but then again i dont know what im talking about.

your welcome for the pointless advice.
 
TC, if the only issue is the crankcase joint, there's no point pulling down a good top end. The lower crankcase half is easily removed with the top end intact. Having a shop do the job (pulling engine, pulling lower case half, sealing, reinstalling) would probably involve 6 to 8 hours of labor, assuming they know what they're doing. Around here rates vary between $50 and $80 per hour. The worst-case (and least likely) scenario would be finding the case warped.
 
cros and griz, thank you for the input!

griz, this is very helpful to know. Assuming that I can get some trouble-free (read: enjoyable/fun) miles on the bike this season, maybe I'll have enough of an idea as to whether this oil issue is something I'll want to address in the coming winter.

If I were to take it to a shop (there is Maryland Motorcycle Classics, about an hour from me, who reportedly specializes in vintage Jap), the high end of that would be just under 7 bills... not cheap, but not off the planet, I suppose. Expertise is worth a lot. So it might be worth asking them about.

The other option, if we're just talking about bottom end here, is for me to enlist a willing and knowlegable XS-er, hopefully local, to help me make short work of it, and buy the beer, meal, etc.. But it's reassuring to know that you think a full-on rebuild might not be necessary. Last time I checked the sump, for instance, I didn't see any plastic, metal, or anything like that.

Thank you, sirs.

TC
 
"If I were to take it to a shop (there is Maryland Motorcycle Classics, about an hour from me, who reportedly specializes in vintage Jap)..."

That's funny...if that's the same place I'm thinking about, that's where I bought my bike.

Bought it on ebay, drove up to Maryland (from NC) and picked it up. PeeWee's Big Adventure.

The owner seemed like a straight shooter. He teaches motorcycle-riding and "how to build a chopper" classes at the local community college.

http://www.mcofmd.com/
 
Dude, you just have a little oil drip? Fire a piece of cardboard under it if your better half wants to protect the garage floor and wait till a real problem develops.
 
- moovova, thanks for this. So, you had a pretty good experience there, then? I have looked at their website several times, and it might be worth an e-mail with some attached pics, or a phone call. They're about an hour from me and they seem to know what they're doing, based on their bio.

- Oak, I have been telling myself exactly what you said, and for the most part it may be true... you're quite right. However, I'm seeing light at the end of a (thus far) nearly 4-year tunnel that suggests I may actually want to keep this bike. So, I'm just doing a little preemptive research to see what I'm going to be looking at if I decide I have to finally sort out this weeping once and for all.

TC
 
TeeCat;

I'd recommend you get out on your bike and enjoy the summer riding season. Make it a goal to put on a thousand miles. These bikes are all about riding..................the re-builds are just to get to the more enjoyable part of the hobby. As the last poster said, just use a piece of cardboard and wipe off the engine after each use.:bike:
 
hell thats what i do.....

The clutch side engine cover leaks on mine....i just cardboard under it and wipe it all the time. When winter is back i'll fix it.

Don't tear something down cause of a leak...how many cars do you think weep or leak slightly, but you never see it like a bike.
 
Last edited:
RG and CDNTX... that's the plan right now, gents! :) We're on the same wavelength. Once we get some weather where kayaks are optional :p , I'm going to do a hopefully final assessment of my single carb and (new) velocity stack setup, and then try to make some local errand/other trips, and some rides to and from work. Meanwhile, I'll do a bit of cleanup afterward, as you suggest, and watch the oil level. (RG, incidentally, I'm always go thankful for the volt gauge you recommended! :) VERY useful! I ALWAYS know what my charging system is up to.)

The left clutch side engine cover leaks on mine....i just cardboard under it and wipe it all the time. When winter is back i'll fix it.

Don't tear something down cause of a leak...how many cars do you think weep or leak slightly, but you never see it like a bike.
Click to expand...

CD, our situations seem to be similar. And you're right, I suppose, about not tearing something down because of this. True, that, about cars too. Good point.

Reassuring, guys, thanks.
 
I would definitely do a torque check.

Two years ago my TX was making a thrashing sound and I sought advice on what & how to fix it. I was advised that if I could pull the engine my self & bring it in I would save a bundle of money. It turned out I had a crank problem and pulling & reinstalling the engine myself saved me a lot of money. It just took time & I got dirty. When the engine was out I thought the only thing I could do was fix it, so I took the engine down to the crank and had a shop fix that.

I took my time, used the Yamaha manual, got it back together and surprise - it works. I also learned quite a bit about my bike. Mine has low mileage, I measured, checked for wear, but everything was within spec. Unless yours has a lot of miles on it, you will probably find the same thing.

When you get done you can talk the talk, because you walk the walk.

If you decide to go forward & fix the leak, this sounds like a project for next winter when the cold winds blow.
 
spoke, yup... definitely an off-season project.

I thought about doing a torque check, and had actually gone as far as trying to sort exactly which bolts needed checked and how to go about doing it, but I vaguely recall not proceeding because of inaccessibility of one or more of the applicable bolts while the motor's in the frame... trying to remember. Someone might have even told me that it was unlikely to help... I can't really recall.

But basically, you all are right... if there's not a major problem now, I'll just try to get some warm weather oil in there and do some miles for now.

Good point about the "walking the walk", though. So far, no one's touched the bike but me, except for tire mounting/installation. I just haven't been "into" the motor yet except for the crank and output shaft seal replacements, valve check/adjustment, PAMCO installation, ATU replacement, etc..

TC
 
"- moovova, thanks for this. So, you had a pretty good experience there, then?"

I'd done some research online regarding the owner/his shop. I didn't find anything negative, called him direct before bidding, asked a bunch of questions which he answered...and haven't found any reasons since to doubt him. Owned the bike 6 months or so now and haven't had any out-of-the-ordinary problems except a miswired rec/reg which I re-did in 10 minutes. I felt comfortable enough to pay his "Buy It Now" price. I met his son at the shop the day I picked it up...never met the owner directly.

I had NO negative vibes...but YMMV. I'm new at this motorcycle thing, so still have a LOT to learn!

Of course, my wife thinks I'm an idiot...:)
 
moovova, my wife thinks I'm an idiot, too, but it seems as if I'm always providing her with fresh confirmation. :p

This is very good to know about the bike shop! I might have to even take a day trip up there while going hiking or something. Thanks for taking the time to post your impressions!

(I'm going to do a little research on retorquing. I have never done this and I have no idea as to the history of this motor.)

TC
 
Aaaaah... here is what I had read some time ago, courtesy of griz (in the context of another thread), that put me off on retorquing as a possible fix for my particular concern:

There is no gasket between the case halves; they're joined with a sealant designed for metal-to-metal joints. Cranking down on case fasteners at the site of the leak will thus accomplish nothing--the sealant has been breached, and more torque will not restore it but may very well warp or crack the cases. An external application of silicone will also accomplish nothing at all.

With the engine upside down, the lower case half can be separated from the upper without tearing down the top end. Reassemble the cases with Yamabond #4 or Three Bond 1104. Pay close attention to the torque sequence during disassembly and assembly. Spec is 14 ftlbs.
Click to expand...

Eventually, I may have to follow this recommendation to sort this, hopefully off-season. One exception might be the possibility that the case halve are/were undertorqued by a PO, which I cannot completely rule out as I have no firm history on the motor.

TC
 

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