Cam Chain Guide Mod

Jim

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If you want to read the conversation that precipitated this modification, it starts here. It's quiet the slog.... 'bout 10 pages... and I'm not gonna re-hash it all here. The short and sweet of it is that I... and others... feel that the Mikes XS chain guide is unacceptable.
Either twomanyxs1b's or 5twins suggested modifying the SR500 guide awhile back... so I decided to run with it.
Here's the shot guide out of my SG....

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As you can see, the rubber's separated from the guide. Now here's the SR500 guide from Boats.net...

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And here's the two combined to make a guide for the XS that I believe is better than the original design (more on that later).....

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The guide in the background is the one from Mikes just for reference.
So.... here's how you do it. The rubber on mine was already gone, so what's left is a C-channel we have to get rid of. I did that on a disk sander...

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A quick point here, make sure the table is square to the disk before you start. You only get one shot at this.
Drill a hole in one end of the guide (I'll add the dimensions later if anyone wants them)....

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Flip it over and remove the spine from the back. I used a roloc disk to do this....

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Now take the SR500 guide and cut off the 90deg mounting tabs. Actually, let me backtrack here.... I cut the mounting tabs, drilled and installed it... and it sat too tall. I had to take it apart and completely remove the mounts. Each one is held in place with two spot welds. I used a cutoff wheel to grind the welds off....

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Go slow!!! If it gets too hot, the rubber might delaminate. Don't let it get too hot to the touch.
Once the tabs are gone, flip it over and use a hole punch to remove the rubber where the holes go....

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You can get a set of these punches from Harbor Freight for less that twenty bucks. They're great for making gaskets and such. The rubber on the SR guide is much too hard to punch through so I chucked it up in a drill press and used it like a drill bit....

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Once it cuts to the metal base, use an exacto knife to remove the rubber from the hole. Do this on both sides of the new guide. Flip it over and drill holes in each end....

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Now flip it back over and countersink the holes with a 100deg. countersink...

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Lay the new guide on top of the old and mark then drill the hole for the other end, then grind the spine off that side.
To fasten them together I used Hi-loks. They're shear type, so the heads smaller than your average countersunk screw. Boeing uses these to build their wing spars. They have incredible shear strength...

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And there you have it.... an XS cam chain guide with a $25 replaceable rubber rub strip....

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Pertinent info.
Hi Lok:
Part number is HL41-6-2 (or HL19-6-2 if you can find em'. I think the 41's superseded em') They can be sourced here. The damn things are $3.68 each. I've got a handful of them. So if anyone wants some, I'll let you have 4 of them for the cost of shipping.... 'till they're gone. PM me if interested. If anybody finds them cheaper, gimmie a link and I'll put it up here.

Nut:
Part number is MS21042-L3 It's self locking so no locktite is required. They can be sourced here. 36 cents a piece. I usually order in batches of a 100, but I'm almost out right now. When I order more, I'll include 4 with the Hi Loks. Till then, you're on your own.

Yamaha SR500 Guide:
Part Number is 583-12231-00-00 It can be sourced here. It's $24.38.

100deg. Countersink: Unless you're in aviation, you might not have one of these. You can get them here. You want the #12 at $8.90 each.

Hole size: .190"

Hole Punch: 5/16"

Sand down old guide to these dimensions +/- .01"

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Drills holes
in both ends

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Note: The SR500 guide is about a half an inch shorter than the old guide. I just centered mine on the old one.

Note 2: DISCLAIMER.... I haven't installed mine yet 'cause I'm not to that point on assembly. I can't guarantee that it fits...yet. I'll update this when it's in. DISCLAIMER 2... Use at your own risk. I take no responsibility for what you do to your motor.
Edit 8/7/18: Guide is installed. It fit without further modification.
 
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Unbelievable Jim! Wow! You blow me away. Nicely done. You have built the solution!

Nice work and well documented. You could start a business selling these.

Good for you man.
 
How 'bout I just say it's unacceptable to me?
Sorry 'bout your luck :) Mine is still going after a couple of years and 10,000 mi. I think so, anyway. When the rubber disappeared off my original I was surprised how close you had to listen to hear anything was wrong.
 
Yes, very nicely done. For others of us who may like to try this, could you provide us with more of the detail info? Like, for instance, how did you figure out the thickness to sand the old guide base down to? And where was it measured at? And those fancy fasteners. I assume you got them from work over the years but where could "mere mortals" like us get some? Also, size and length used, and are the nuts special? Did you install the fasteners dry or with loctite? Last thing I guess would be the size of the punch used for the rubber removal.

I must have at least a half dozen old guides laying around I could do this to, and at least one old SR500 one to play with. If I can accomplish it, I'll buy new ones to adapt.
 
Awesome thanks for summing up 10pgs, much appreciated.
I read that the rubber on the new guid from Mike's is softer, is the sr guide from yamaha comparable to original xs or new Mike's?
 
Add in all the relevant part numbers and as many key words as you can think of?
could you provide us with more of the detail info?
Thanks guys. I started adding all the pertinent info to the original post above.
EDIT: I just finished adding all the pertinent info. Let me know if I missed anything
 
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Awesome thanks for summing up 10pgs, much appreciated.
I read that the rubber on the new guid from Mike's is softer, is the sr guide from yamaha comparable to original xs or new Mike's?
Thanks Joe. The rubber on the SR500 guide appears to be about the same consistency as the new MikesXS guide. You can dig your fingernail into it, but it doesn't leave a mark when you remove it.
 
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Looks like you've got it all covered, thank you. The hole locations in the old guide can be determined by placing the drilled 500 guide strip on top of it. I'm thinking it would be best for a perfect fit to mark and drill one end, attach the 500 guide strip, then drill the other end through the hole in the 500 strip. That should insure perfect spacing between the holes.

I managed to find some of those fasteners on eBay. I got the exact nuts but couldn't find the exact screws. Instead, I got HL63's, the 1st oversize for the HL19. But at only a 64th larger diameter, I think they'll work just fine. I also couldn't find the exact #2 grip length (1/8"), and went with a #3 (3/16"). Again, I think this will work fine. My only concern is clearance inside the head for the top bolt/nut. That might even be an issue with your slightly shorter screws. But, probably nothing a little Dremel work can't fix, lol.
 
.....for a perfect fit to mark and drill one end, attach the 500 guide strip, then drill the other end through the hole in the 500 strip. That should insure perfect spacing between the holes.
Yeah, guess I wasn't that clear..... that's how I did it.
But at only a 64th larger diameter, I think they'll work just fine.
Should work just fine. Of course you'll have to go up a size with the hole....
But, probably nothing a little Dremel work can't fix, lol.
And that's my plan when I fit it..... nothing a little grinding can't fix. ;)
 
Great job Jim - very nicely done indeed.

Now - question (and forgive me if I missed it along the way) - if a person had an OEM. guide that was worn out - would there be any issues with simply getting an SR500 guide and adapting it as you have above? That way, you could simp,y skip the entire step of fiddling with the MikesXS guide and it’s wonky holes...

This is an excellent contribution to the community Jim - thanks so much!

Pete
 
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Thanks Pete. If I understand your question, yes. This involves just the SR guide and the OEM XS guide. The Mikes guide has nothing to do with it.
 
Yes, and the whole point of this is so you don't have to buy that questionable MikesXS guide. It's cheaper and may even prove to be a better alternative than an O.E.M. 650 replacement. Like I mentioned in some other threads, I've never heard of an SR guide going bad. The rubber never comes loose and they don't fall apart. I guess bonding rubber to steel works better than trying to bond it to aluminum.
 
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