Cam Chain Guide Replacement

pereiracycles

pereiracycles

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I've searched up and down for a comprehensive cam chain guide replacement DIY, so I'm going to give a shot at making one.

History: My bike is a '75 w/ 700cc upgrade. Cylinder and head work were done by Woody G from Action Cycles back in 2000. At that time I replaced the cam chain and most bearings. For some reason I didn't replace the cam chain guide(or I lost the receipt--I try to save all of them and don't see a guide on any). Not too excited to pull the engine since summer is waning and I don't have a lot of time these days, but that tell tale metal-on-metal sound is killing me. I finished building the bike in 2002 and only rode it for a few years before a bad dirt bike wreck damped my enthusiasm and kept it parked until about 3 years ago. I estimate that the engine has less than 10k miles since the last rebuild. I have no idea how many miles it had before that. I found it as a rust pile in a garbage transfer station in 1997 or so.

Last night I dropped the sump and found some plastic bits, confirming that the guide is buggered.

I just placed my order on Mike's XS for the following:
4 x Brass cylinder head washer (01-0651) = $11.80
1 x Front Cam Chain Guide (05-0006) = $34.25
1 x Athena Premium Overhaul Gasket Set (18-0208) = $69.25
1 x Top End Copper sealing Washer Kit-9pc (18-0870) = $6.95

I believe that is all I need. I'll be doing this without cutting the cam chain.

Really wanted to order from 650 Central, but the 12-5 M-Th hours and terrible web site sent me back to Mike's. I've had decent luck in the past despite the warnings I often see here.

I'll follow up when I get my parts and begin the teardown.

-Tony
 
So, it looks like I'm terrible at making DIYs. I started taking pictures, but pretty early on I stopped. Greasy hands, limited time. I'll run through this as best I can. It seemed like a hole lot of work just to change out the guid, but there were some things to learn along the way.

First off, the repair was a success. I only took a short test ride, but the bad sound the engine was making is gone.

Basic steps:
Remove engine. I was able to do this myself, but it would be much easier with some help. Of course, you have to remove a bunch of stuff to pull the engine, but you can figure that out.
Pull top cover, points and advancer and their housings.
Remove advancer rod and reassemble so you don't lose any parts.
Remove oil delivery pipe.
Remove cam chain damper adjuster. I just un-threaded mine and pulled the rod out.
Slide bearings off ends of cam, providing room to slip cam out. This is an old trick, but I've never tried it. Works great.
Tie a piece of wire to the chain. It's not a big deal if it drops, since it isn't split, and it's nice to have the wire to grab on to later when you need to thread it back through the cylinders and head.
Pull head.

Admire your clean combustion chamber and pat yourself on the back for adjusting your carbs so well. Or think, "whoa, look at all that carbon!" I really need to lean this thing out and/or switch to lower octane fuel.

Mine was the latter. Here's where the work of this project begins. I spent a bunch of time removing the carbon from the head. I used lacquer thinner, an old, flexible, dull putty knife and a stainless steel wire brush to gently scrape the carbon off the top of the pistons and from inside the head. The head is hardened steel, so you can get a little more aggressive, but be careful with the softer alloy pistons so that they are not damaged.

Once the pistons are clean you can blow off the dust and pull the cylinders.
Stuff rags into the crankcase to keep debris from falling inside.
Start cleaning the gasket surfaces. You want every last speck of gasket material and sealant removed. This takes quite some time. I had the best luck using a box cutter with a very sharp blade. Lacquer thinner helps soften the gaskets. This might have been overkill, but I was out of gasket remover.
Most of the time spent on this job was with cleaning and prepping for re-assembly. Be meticulous and your engine will be leak-free.

Once everything is clean, replace the chain guide. The old one wasn't too bad, but definitely had some missing material and a small amount of exposed metal on the very tip.

I had read about making sure the guide was aligned, but couldn't find any description of how to do that. I lined my up as best I could by eye, so that it looked straight.

Reassembly is, as they say, the reverse.

Make sure you get the cam timed right. Line up the marks, per the manual and you'll be good to go. It's pretty hard to get wrong if you are paying attention.

Once the top end is buttoned down, you need to check valve clearnces, reassemble ignition and set timing. Re-install carbs, exhaust, pegs, tank and seat.

I also dropped the sump and changed the oil to make sure there was no left-over debris from the chewed up guide.

Kicked the bike over with the key off a few times to pump some oil through, flipped the key, turned on the fuel and it started on the first kick!

Went for a short spin and the noise is gone. Can't wait to ride tomorrow!

Sorry I don't have pics for you. Hope this helps someone. Feel free to ask questions if you have them.
 
I don't see the "confusion" here about the front cam guide. It's a simple matter of measuring. What I will say is most of you guys have no business working on bikes. You're inept to put it nicely, totally stupid to tell the truth. The "special instructions for centering my front guide" were not given because it's obvious, at least to most people. You MEASURE from the side of the cam chain tunnel to the side of the guide, from both sides. Simple shit really, but a total mystery to most apparently.
 
5twins said:
I don't see the "confusion" here about the front cam guide. It's a simple matter of measuring. What I will say is most of you guys have no business working on bikes. You're inept to put it nicely, totally stupid to tell the truth. The "special instructions for centering my front guide" were not given because it's obvious, at least to most people. You MEASURE from the side of the cam chain tunnel to the side of the guide, from both sides. Simple shit really, but a total mystery to most apparently.
Click to expand...

Wow...don't sugar coat it, buddy!
I've been riding and working on my own bikes for the past 20 years or so. Didn't have any mentors and didn't have bikes growing up, so I learn as I go. The guide didn't really have a lot of wiggle room and straight was looking pretty straight. You're right, I should have thrown my calipers on it. Pretty sure I got it right. Neither Clymer or the Yamaha manual say anything about aligning it.
You don't have to be a jerk about it.
 
pereiracycles said:
Wow...don't sugar coat it, buddy!
I've been riding and working on my own bikes for the past 20 years or so. Didn't have any mentors and didn't have bikes growing up, so I learn as I go. The guide didn't really have a lot of wiggle room and straight was looking pretty straight. You're right, I should have thrown my calipers on it. Pretty sure I got it right. Neither Clymer or the Yamaha manual say anything about aligning it.
You don't have to be a jerk about it.
Click to expand...
On the Yamaha v Star 650 I still am unsure about how the chain guides sit in the cylinders. In the service manual it only shows one chain guide in each cylinder head. On the chain guides there is no way for me to Mount them to anything, please help me understand how they fit in there. Lance
 

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