Lucille pulls another one on me....

[MaxPete]

Howdy timing chain noise and guide enthusiasts!

So, it has indeed been a busy week. Work has gone completely non-linear again, but that’s another story.

On the bike front, I took my parts (barrel, head, cam cover, pistons etc) plus the rest of the engine to Terry Wolfe’s motorcycle machine shop (Wolfe Worx) in London, ON to develop a plan. My goal is simply to get Lucille back together ASAP - so that I can trial her and then take that long ride to to the VYR event North Carolina in September. On the way, I stopped at another Forum member’s home where I picked up a cylinder barrel and a set of 2+ pistons. If my parts turned out to not be suitable for further service, my plan was to use his set.

Anyhow, I got to Wolfe Worx when they opened at 9:00 AM and Terry quickly determined that my barrels are OK, but my pistons and rings should be replaced. He suggested getting a +1 set of OEM pistons and rings from Yamaha and he’s confident that he can get the parts quickly. My head, cam, rockers etc. are all good.

My front timing chain guide is obviously totally baffed (the plastic has fallen off the metal shoe) and so I need a new guide chop-chop. I had found an early model XS1 flat guide but since it isn’t suitable for a late model '76 engine, I have already re-sold that guide to 2M in Texas - he’ll have it on Monday.

One key development is that when I took Terry out to my vehicle to check my wrist pins and con-rods, (they’re fine too) he asked me if I was putting it back together myself. I said “yup”, but frankly, a wave of fatigue washed over me and he asked if I’d like him to do it. He quoted me a decent price for the assembly work (in addition to the cost of the machine shop work) and so I went for it and left my entire engine there. I simply have too much travel coming up to mess with it and his shop is a 2 hour drive away, so even if I get all the machining work done and then had a problem - I would lose at least another day.

On the issue of the critical timing chain guide, I am attacking this problem in a systematic fashion and have several plans for a new guide underway:

• My Forum member buddy loaned me a used OEM guide - but it has slightly cracked edges unfortunately (that being the standard failure mode); nonetheless, it is perfect for a measuring model against aftermarket guides;
• Terry’s parts man is searching for an NOS guide for me - but I’m not hopeful, frankly;
• I am appealing to the privately-held parts stocks of the Forum - anybody got an NOS guide to sell me?
• A Forum friend found two used ones in Buffalo, NY which I have bought online (they should be here on Friday);
• I bought two aftermarket guides from XS650 Direct and they look pretty good actually.

I will be posting a bit of a review of the aftermarket (XS650 Direct / MikesXS) guide and a comparison of it to an OEM guide in a moment.

All in all - a good day.

I will be heading back to London on Tuesday or Wednesday to give the rest of the necessary parts to Terry and see how he’s doing sourcing the pistons and rings and other items from Yamaha Canada.

Cheers,

Pete

 

[5twins]

Pistons and rings will be expensive from Yamaha, if you can even get them. Did you mention the Cruzinimage eBay ones to him?

Yes, check your new aftermarket guides. Seems like things can change from batch to batch. Maybe they've straightened up the mounting holes. Other than that issue, I think they might be an OK part. I think I mentioned it but I'll do so again - I had the opportunity to get a look at one last year that we installed maybe 5 or 6 years ago. The engine developed some bad noises so had to come apart again. My first thought was that aftermarket guide but it turned out to be just fine, still new looking. Problem was a cam bearing gone bad.

 

[MaxPete]

REVIEW & COMPARISON: Timing Chain Guide
This note provides a quick review of the front timing chain guide - Yamaha P/N 256-12231-01-03 “Front Stopper” (how the heck do they come up with these names?) including servicing this component, the common failure mode and the present state (as of August 2018) of supply of replacements.

LOCATION & FUNCTION: The guide attaches to the inside front surface of the central cavity between the cylinder bores in the cylinder barrel by means of two machine screws which pass through two hollow bolts that thread into the cylinder barrel. It supports and guides the timing chain which actuates the camshaft. It also ensures that the cam and ignition timing is correct between the crank and camshafts by taking up the slack on the driven side of the chain run. Symptoms of a failure of this part can include:

• Bits of hard black plastic in the oil and especially in the sump strainer. The bits can range in size from small particles right up to chunks 1-2” long with a cross section much like a toothpick (see photo below);
• A noise the sounds like a loose tappet or even a mild connecting rod noise up high in the engine;

SERVICE: Changing the front or rear timing chain guide entails removing the engine from the bike and then dismantling the cam cover, cylinder head and barrels. It cannot be replaced with the engine in the bike, nor can it be done with the cylinder barrels in place. Fortunately, removing the engine and dismantling it are not particularly difficult tasks.

SUPPLY of PARTS: In a word: limited.
Until a few months ago, most Yamaha parts suppliers listed this component and people were buying them in the normal way, but that supply seems to have suddenly dried-up and suppliers all over the world are now listing them as “Unavailable”. Even the usual supply of NOS parts that are usually found online, seems to have suddenly disappeared. I’ll keep looking but the only OEM guide I’ve found recently turned out to be the early model “flat” version which isn’t suitable for my 1976 bike.

There have been a number of used parts online recently. I’ve bought two of them but haven’t yet received them yet. I suspect that many of them may suffer from the primary failure mode which is a crack in the corner of one or both sides of the U-shaped channel that is moulded into the plastic guide.

If that crack is present - the thin side of the plastic component of the guide will likely separate and wind up in the sump. I don’t know how long that process takes, but that seem to be how many of these parts fail. The photo below shows some of the bits that were in my sump last week along with the metal “shoe” of my failed timing chain guide which is completely naked:

Fortunately, there is an aftermarket guide available at low cost (around $36 CDN) - MikesXS p/n 05-0006. This part is a reasonable replica of the original Yamaha part in most respects, but there are two noticeable differences:

• The threaded mounting holes are not drilled at right angles to the mounting pad bosses;
• The polymeric material used on the guide is a much softer rubbery compound than the hard plastic of the OEM part.

It has also been suggested that the mounting holes were not drilled deep enough in the MikesXS part. However, the photo below shows four guides (top to bottom: MikesXS-#1 and MikesXS-#2, my failed OEM guide and the borrowed OEM guide) each with identical M6x20 machine screws inserted and screwed in.

As you can see, there isn’t a marked difference in the depth of screw engagement. I could measure them, but the differences are small among them and in fact, the MikesXS parts appear to have, if anything, slightly deeper mounting holes.

While I can detect a difference in the alignment of the mounting holes, I really don’t think it is enough to affect the function of the part.

The major difference between the OEM and the aftermarket MikesXS parts is that the plastic component of the OEM part is a very hard and likely brittle plastic while that of the MikesXS part is a much softer "rubbery" compound. Basically, you can dig your fingernail into the MikesXS part but you definitely cannot do this on the OEM part. You can see this in the photo below - the MikesXS part (on the left) has a dull surface while the borrowed OEM plastic component (right) is shiny and reflects the overhead light in my workshop.

Of course, the OEM parts are all now 35-45 years old, so who knows what their properties were back when they were new. One thing is for sure, the OEM parts I have seen are hard and brittle now.

On my rebuild of Lucille, I am going to put in a MikesXS part unless one of the used parts I have ordered comes in and looks awesomely new. I will monitor the oil carefully - watching for bits of rubber - and I’ll be prepared to swap in a new guide if debris begins to appear in the oil.

Pete

 

[5twins]

Yes, the guides we find in our 650s are usually the originals and 35 to 40 years old, but the O.E.M. replacements we were able to buy until just recently probably aren't that old. I say that because a few years back, the supply went dry for a while, then Yamaha had them again. I'd like to think that was a new production run. And I was hoping they'd do it again since the supply dried up, lol. I'm not sure this small group of dedicated 650 enthusiasts has a big enough voice to make that happen.

 

[MaxPete]

Pistons and rings will be expensive from Yamaha, if you can even get them. Did you mention the Cruzinimage eBay ones to him?

I did and he said that they look fine too. I’ll use them in Lucille, or likely in my cafe bike when I dig into it. In the meantime, I’ll give Terry a chance to try to source the OEM pistons and rings and we’ll see what the price is this week.

QUOTE="5twins, post: 559906, member: 156"]Yes, check your new aftermarket guides. Seems like things can change from batch to batch. Maybe they've straightened up the mounting holes. Other than that issue, I think they might be an OK part. I think I mentioned it but I'll do so again - I had the opportunity to get a look at one last year that we installed maybe 5 or 6 years ago. The engine developed some bad noises so had to come apart again. My first thought was that aftermarket guide but it turned out to be just fine, still new looking. Problem was a cam bearing gone bad.[/QUOTE]

Thanks 5Twins. MikesXS do seem to have sorted out the depth of thread engagement issue and the hole alignment isn’t too bad, but still not quite right. Nonetheless, I think they will mount OK and work fine. I’m happy to hear that the rubber portion seems to be durable.

 

[MaxPete]

Yes, the guides we find in our 650s are usually the originals and 35 to 40 years old, but the O.E.M. replacements we were able to buy until just recently probably aren't that old. I say that because a few years back, the supply went dry for a while, then Yamaha had them again. I'd like to think that was a new production run. And I was hoping they'd do it again since the supply dried up, lol. I'm not sure this small group of dedicated 650 enthusiasts has a big enough voice to make that happen.

Well, we will see I guess. There seems to be more XS650s coming onto the road every week so perhaps they’ll listen.

P

 

[Jim]

and the hole alignment isn’t too bad, but still not quite right. Nonetheless, I think they will mount OK and work fine.

My biggest concern with the hole misalignment (other than the obvious uneven stress loading) is that oil will weep from the bolt holes. The bolts use copper crush washers to seal. If the bolts don't lay flat, it ain't gonna seal. So.... along with the coppers, I'd strongly suggest some red RTV on the washers and bolts during assembly.

Bein' as how the bolts are on the front of the motor... if they weep, they're gonna make a hell of a mess.

 

[5twins]

On the first guide in your pic, the bolt hole angles don't look too bad. The second looks off a little more. But yes, maybe they'll mount up and work just fine. Really, what choice do we have at the moment?

Jim makes a valid point about oil leaks. None I've used in the past leaked, but who knows, they may have had straighter bolt holes back then. The angle of the holes was something we never checked, never even thought to check for that matter.

The guide doesn't actually get mounted to or against the cylinder casting, it sits/mounts against the bottoms of those chrome nuts/sleeves that the mounting bolts go through. If you happened to have a couple of them loose or off the cylinder, you could loosely bolt them to a guide and see how they sit. I think what you'd be looking for is if the tops of them are aligned and parallel to one another.

 

[MaxPete]

On the first guide in your pic, the bolt hole angles don't look too bad. The second looks off a little more. But yes, maybe they'll mount up and work just fine. Really, what choice do we have at the moment?

Jim makes a valid point about oil leaks. None I've used in the past leaked, but who knows, they may have had straighter bolt holes back then. The angle of the holes was something we never checked, never even thought to check for that matter.

The guide doesn't actually get mounted to or against the cylinder casting, it sits/mounts against the bottoms of those chrome nuts/sleeves that the mounting bolts go through. If you happened to have a couple of them loose or off the cylinder, you could loosely bolt them to a guide and see how they sit. I think what you'd be looking for is if the tops of them are aligned and parallel to one another.

Yup - I’ve already done that and they seem to be OK from what I can tell. One good thing is that the oil pressure in that portion of the engine is essentially atmospheric - the lubrication is just by splash and not oil pump pressure. I'll put a little dab of Hylomar Blue on the underside of the crush washers.

It really is a shame that they have been sloppy with such a simple detail. I'm certainly going to raise this point when I am in Stecoah. In fact, that is why I bought two of their guides: I can use one on Lucille and I'll have one to show them right then and there.

Thanks for the thoughts - any additional comments are most welcome!

Pete

 

[XS650D]

Hey Pete, thinking of finding someone in Ontario that knows all the tricks and what to look for in
working on one of these old 650,s.Have them do the install, new cam guide ect.
Does this guy in London know these bikes well.We have bike shops round here but they dont want
to touch my bike. Mostly Harley guys. Thinking of takin a trip to London!!
If anyone knows anyone in Barrie,Orillia Muskoka area that has good knowledge on these bikes please advise.Thx I think I will just go ahead and order the XS650 Direct guide and topped gasket kit regardless!

 

[MaxPete]

Hey Pete, thinking of finding someone in Ontario that knows all the tricks and what to look for in
working on one of these old 650,s.Have them do the install, new cam guide ect.
Does this guy in London know these bikes well.We have bike shops round here but they dont want
to touch my bike. Mostly Harley guys. Thinking of takin a trip to London!!
If anyone knows anyone in Barrie,Orillia Muskoka area that has good knowledge on these bikes please advise.Thx I think I will just go ahead and order the XS650 Direct guide and topped gasket kit regardless!

Hi XS650D:

Terry Wolfe and his folks certainly know the XS650 intimately. He has at least two beautiful bikes in his personal collection - in the mezzanine above his shop. I would certainly take it to him without hesitation.

I don't know anyone else who does know the XS650 however.

Most of us do our own work (Terry is assembling my engine this time because I am swamped at work and I need it for a trip in September). Most shops don't even know what to do with a carburetor, let alone a double set of Kettering ignition points. There is tons of good advice and info on this Forum and if there is anyone nearby, I am sure they would be happy to walk you through any task.

On the matter of the gasket set - I would hold off on that. SOME of XS650 Direct's gaskets/seals/carb parts etc. are not of the best quality and you can often get real OEM Yamaha parts on line at places like Partzilla (www.partzilla.com) or other spots for about the same money.

Apparently, the best gasket set for a full rebuild is made by an Italian firm called Athena and they are readily available online (eBay etc.) at low cost.

Pete

 

[Superjet]

XS650D you will also need a full gasket set. I had recently done the cam chain and guide this winter and replaced near every gasket and seal while it was open. Do it yourself, it is not that difficult. Worst part was removing all the old gaskets

 

[5twins]

Well, for me, the jury's still out on the Athena gaskets. I've used them in the past and really like some of them (sump plate, drain plug seal rings), but my Athena head gasket has failed me now. Granted, it lasted like 10 years, and maybe it's just a normal occurrence on these motors, but I'm starting to try some other brands now. There's also the fact that the Athena head gasket is thicker than an original (.60" vs .48"). I guess that lowers the compression a little and along with it, the power output. Can't say I noticed that after my rebuild, but with new rings, well seated valves, and all the carbon cleaned out, that probably made up for it.

Vesrah makes a nice gasket set and has the thinner stock thickness head gasket. That's what I try to find now, that stock thickness head gasket. I got a few of these and used one so far. It seems OK (been in use about a year) .....

https://www.ebay.com/itm/New-72-84-...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

 

[xjwmx]

My first thought was that aftermarket guide but it turned out to be just fine, still new looking. Problem was a cam bearing gone bad.

What did the bad cam bearing sound like? Never heard or heard of one of those.

 

[5twins]

It had intermittent squealing and screeching, not constant but every few revolutions or seconds, and some louder than normal chattering. It was really hard to pinpoint, we tried with a mechanic's stethoscope while it was idling. All we could tell for sure is that it was in the topend somewhere, lol. Disassembly revealed the issue pretty quick. As soon as we pulled the right advance/points housing off, we saw all the little metal chips sitting there between it and the outer bearing. Luckily, none penetrated through the inner bearing into the inside of the motor yet, at least none that we could find/see. Probably because the guy hardly ran it after it started making that noise. Don't know why this happened, maybe that 1980 bearing's time was just up, lol.

Yes, I never saw this before either. It doesn't seem too common of a failure but with machines this old I guess pretty much anything can go belly up on them, lol. Luckily, I found a guy on eBay selling N.O.S. ones for like half price. I even bought some spares for myself, just in case, lol. In fact, he's still selling them .....

https://www.ebay.com/itm/Yamaha-Koy...50+cam+bearing&_from=R40&rt=nc&LH_TitleDesc=0

 

[robinc]

Hey guys, just catching up.Was away at an ONDR (Ontario Nostalgia Drag Race) meet and car show. Thought I'd add some more pics here of some other comparisons I did of a new OEM guide to one of Mikes. I was wondering how those wonky bolt hole angles might affect fit so when I was doing my rebuild this spring I test fit both to see. Didn't bother posting these in my thread guide comparisons back then as they were pretty close, at the top especially where most of the wear and damage seems to occur, but we might as well have this info here.

Bottom pic of new OEM guide.

Bottom pic of new Mikes guide.

So we can see the Mikes guide encroaches about 2mm further into the tunnel at the bottom where I could measure, which means it would be even more so at the very bottom of the guide.. Not sure if this is enough to cause further contact and more rapid wear or not.

Top pic of new OEM guide.

Top pic of new Mikes guide.

So we can see they're pretty close in terms of fit at the top.

Unfortunately never thought to check fit against the chrome sleeves, but I guess Pete has done that.

Does this guy in London know these bikes well.

XS650D I can emphatically vouch for Terry and his crew. He is a licensed machinist/tool and die maker in addition to being a vintage bike mechanic. They love working on vintage bikes and are the only shop around who will. They rebuild/restore several Japanese and British bikes every year and have done several XS650's. They are racing team mechanics and build race engines. British race engines that don't leak....lol.

He did my rebore and decking work this spring. Wolfe Worx

 

[TwoManyXS1Bs]

Pete, a couple nits specific to this front guide, you may want to review with Terry. Forum things that may not be widely known.

- Polishing of the camchain sideplate edges.

- Length and seating of the hollow Cylinder Guide nuts.


They use (2) copper washers, 90430-11033 - 12x18x0.5 (Cam chain guide hollow nuts to cylinder). Wrong thickness could introduce a problem. 5twins has a better pic in here somewhere, but this pic shows the amount of protrusion of those guide nuts into the camchain tunnel. As 5twins already noted, the guide mounts atop those protrusions.


- Centering of the front guide

Then, there's other nits found in this forum relative to the rest of the top-end overhaul. Is he a member?

 

[5twins]

Proper centering is a big deal in my mind. You'll ruin your new guide quickly if you don't. This is what greeted one member here upon teardown. The guide was way off center and the chain was wearing into the aluminum lip on one side. That is, after it ate the rubber off it, lol .....

 

[XS650D]

Thx for info, i will contact them this week for a fall service.
Great info on the gaskets, will discuss that also!

 

[Superjet]

This is what I found when I opened mine up this winter. It wasnt lined up. I am not sure what the PO did but its all fixed now lol .It wore the top right and bottom left channel edges. Way important to center....and did I ever check, re-check and double check and so on.....