Author Topic: Stepped in it this time...... (Read 1863 times)

britman · « **on:** March 20, 2023, 11:32:29 AM »

I had some parts left over from a Yamaha XS650 Bobber build, so not being the wasteful sort, I thought I would look around for a another cheap Yamy 650 and bring one back in the stock version. Found a 1979 model in NC, priced on the verge of saying hold out and way for another one, but being in a hurry I flipped a coin and went for it. Very rough on the cosmetic side, has not run in over 20 years, but compete and has a clean title. When I got it home and on the lift I noticed a metallic sound when kicking it over, thought it would be just a worn cam chain guide, which they are notorious for. There is no way around not pulling the head to access the part, (motor has to come out to pull the head also) and 99% of the time it will cause the jug gasket to leak when you pull the head anyway, so therefore a top end build. I almost decided to part the bike out and walk away with a lesson learned. (In all of the years I have been fooling around with vintage machines this is only the second time I have really been burned with a major engine issue. The other was a Honda CB450 many years ago that I ended up almost giving away, but one of the happiest days of my life to se it loaded.) The final straw was when I pulled the cylinders and the right side piston and cylinder had experienced a major disagreement.

I have decided to go for it even though I have not been inside of the motor in a long long time. I have been spending hours looking at Youtube tear downs and rebuilds, had to find my old hones and even discovered an old ring gapping machine in the shed. Parts have started to come in to include a used set of stock bore jugs, pistons, rings, gasket set, and all of the other assorted little goodies I have no business fooling with at my experience level and age. I am doing my best to avoid spending any more than necessary, hoping to avoid a machine shop bill by getting everything back into spec with just a good clean up and honing. Needless to say, there will be no profit on this one, but I must admit I am enjoying the process. I had truly forgotten how far a circlip can fly in garage never to be seen again. Wish me luck, I am going to need it.......

ekpent · « **Reply #1 on:** March 20, 2023, 12:21:45 PM »

I think I see that circle clip in the last picture

Good Luck getting your feet wet again.

BenelliSEI · « **Reply #2 on:** March 20, 2023, 01:54:56 PM »

Good luck, looks like a new twist. Always fun to try something different!

dusterdude · « **Reply #3 on:** March 20, 2023, 02:37:49 PM »

Aint it fun

Sent from my SM-G973U1 using Tapatalk

C317414 · « **Reply #4 on:** March 20, 2023, 04:42:16 PM »

If you do this for long enough, it's bound to happen.

I've bought many bikes in 50+ years of riding, and had never been burned until a couple of years ago. I bought a restored, 67 Triumph that was cosmetically almost perfect. The engine had supposedly been overhauled by the person that restored it, before he passed away, but it wasn't installed in the frame. The seller bought the bike from the estate and finished putting it together... according to him. It turned out that the engine had been poorly assembled. Piston clearances were too tight, and it had a slight head gasket leak. This led to a holed piston on my first long ride. When the engine was disassembled I discovered a number of worn parts, incorrect parts, etc. The engine had to be completely overhauled.

Notice the peened surface on the lifter block. These blocks are supposed to be a slight press fit on the cylinder's lower flange, with a set screw to keep them in place. This block came loose at some point, rattled around, and wore out. Instead of replacing it, someone used a punch to peen the surface, in an attempt to tighten the fit in the bore.

britman · « **Reply #5 on:** March 22, 2023, 01:32:23 PM »

Damn I hope this thing runs.........

jgger · « **Reply #6 on:** March 22, 2023, 04:05:43 PM »

You will get it! Then you will be the envy of many lesser guys........like me!

britman · « **Reply #7 on:** March 27, 2023, 12:51:37 PM »

At my advanced age there are not many things that make you feel "froggy" again. Today I am King Tadpole. This 179 pound Yamaha XS650 motor has been pulled, top end rebuilt, and re-installed by this one old beat up white guy with no ass and too much ear hair. Well it run, haven't got a clue. It does have oil pressure, I cranked it over and had a good flow out of the filter galley. If it grenades on start up or smokes like a Cheech and Chong movie marathon at least I gave it a shot. Hopefully I will report back in the next couple of days with at least a running motor but if there are no further posts to this thread, it just wasn't in the cards. I will be the proud owner of the worlds most expensive parts bike but have a life lesson I won't forget anytime soon.......

BenelliSEI · « **Reply #8 on:** March 27, 2023, 02:59:37 PM »

I’ll bet it’s a total success! Go for it.

ekpent · « **Reply #9 on:** March 28, 2023, 06:07:54 AM »

Back in my younger days I moved an RC836 top end over that I had found in a 'parts' engine. Had new rings a little hone painted up pretty etc. and I was extremely proud. WELL on the first ride it smoked so much it would make a two stroke jealous

Fouled a plug trying to get home. Found out I had put the oil scraper rings in upside down

Tore it down and fixed it and still have that engine in a bike today. Life was rough before the internet and other info !!
Good Luck when the time comes ---

britman · « **Reply #10 on:** March 29, 2023, 10:37:12 AM »

Damned if it doesn't run, and not only that runs well. I have a crap battery stuck in it for the time being that is on its last legs but should be enough to get it through a couple of warming cycles for the rings. I still need to check charging and countless other things to start to bring it back, but as of right now it is saved.

jgger · « **Reply #11 on:** March 29, 2023, 10:43:33 AM »

Congrats! Funny how we will second guess ourselves sometimes.

ekpent · « **Reply #12 on:** March 29, 2023, 11:19:50 AM »

Excellent !

BenelliSEI · « **Reply #13 on:** March 29, 2023, 02:52:51 PM »

Best feeling in the world! Congrats.

britman · « **Reply #14 on:** March 30, 2023, 01:44:01 PM »

I spent the day with a test light, volt meter, and a bucket of dialectic grease. Old Yamahas have numerous starter and headlight relays, plus a reserve lighting unit which all are prone to failure and no longer available for replacement. At the end of the day everything is working, some relays have gone to electrical heaven, and there is going to be switch that will actually turn the headlight off and on which Yamaha did away with on the handlebar in 1979. I am waiting on a small blade fuse block to arrive so I can clean everything up, but I really think this "Old Girl" wants to live again.....

britman · « **Reply #15 on:** April 07, 2023, 09:58:50 AM »

Now I am at the point where I start looking for that bag of screws that go to the

I know damn well I marked them and put them in?

? It is coming along, for every little victory you complete, you find 10 more things that need attention....

britman · « **Reply #16 on:** April 10, 2023, 02:41:03 PM »

I got brakes and a back end. I thought I going to have to rebuild the rear master cylinder and caliber, but using the old grease trick I got the caliber busted loose and cleaned and the master cylinder was just full of gunk. Bolted everything back up with the the original parts and I have no leaks and good brakes. The PO must have been real cool, I found flames when I sanded the tank.......

britman · « **Reply #17 on:** April 12, 2023, 11:33:21 AM »

Laying paint at the height of pollen season in Virginia when no rain has fallen in weeks, what a PITA.

BenelliSEI · « **Reply #18 on:** April 15, 2023, 01:49:05 AM »

Looks very good!

denward17 · « **Reply #19 on:** April 15, 2023, 08:23:39 AM »

Quote from: britman on April 12, 2023, 11:33:21 AM

Laying paint at the height of pollen season in Virginia when no rain has fallen in weeks, what a PITA.

Paint looks good, what kind of of spray gun are you using?

britman · « **Reply #20 on:** April 16, 2023, 11:10:32 AM »

First trip around the neighborhood this afternoon, did a couple of miles and everything stayed inside the motor so I must not have left out any parts. I still need to order a front tire and clean the forks but the bike runs really well. Probably another week or so and I will post it and try to re-coup a little of my mad money.......Paint is rattle can and damned if I didn't put a scratch in the clear coat installing the seat prior to the ride, oh well what's life without a little cussing now and then.....

jgger · « **Reply #21 on:** April 16, 2023, 11:56:40 AM »

Came out nice!

HondaMan · « **Reply #22 on:** April 23, 2023, 10:45:52 AM »

After I finished a CB450 twin last week, I found a circlip near it. Can mail it if you need it.

BenelliSEI · « **Reply #23 on:** April 23, 2023, 04:12:31 PM »

Looks really good! Nice work, as usual......

RAFster122s · « **Reply #24 on:** April 23, 2023, 11:43:50 PM »

Very Nice Britman.

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Author Topic: Stepped in it this time...... (Read 1863 times)