Front Cam Chain Guide Replacement

Downeaster

Downeaster

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I'm thinking while I have the engine out, I should go ahead and replace the front cam chain guide stop.

Can it be done by just removing the cam cover without removing the cylinder head? I got good compression and I REALLY don't want to screw with the head if I don't have to.
 
You have to loosen the head nuts to take the top cover off then remove the cam. Once that's done, you should be able to reach the guide with a long pair of needle noses or similar. It's not difficult, but the unfortunate thing is that once you loosen the head nuts there's a real good chance the head gasket will start leaking after the motor's back together. Ask me how I know. :mad: If it does, now you have to do it twice. So it's a risk.
 
Ah. I was hoping the cam cover came off without affecting the head torque. Bummer. Won't be doing it then until there are positive indications that it NEEDS doing, or I'm in there for other service.

Thanks!
 
did you see my video on pulling the jugs? it will show you the guide . thats why I had to pull apart my engine the plastic part came unglued and slid down and the chain started riding on the aluminum.. Bare bones to do the job was $275 in parts new chain, guide,tensioner,gaskets,washers,oh yes cam chain tool too if you have one drop $50
 
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Like carbon mine came apart one piece so no small pieces showed up in the filters. I went with a new Yamaha factory guide and chain from boats.net. You get what you pay for no inferior parts to worry about. All 3 motors I have taken apart had bad front guides. I think you can see the guide bar if you remove the sump.
 
51373886087__E749BB96-3CAB-4C76-B367-0BAB371CA567.JPG About to revive an old thread! I need to chnge my front guide. I have the motor out of the frame strapped down on a pallet to work on. Should I attempt to change the guide or is this something I should bite the bullet and pay a shop? Someone ruined my confidence I had in doing this lol! it's not hard to pull the head off, remove cam, then the jugs, then bolt in the new guide once it's in the tunnel correctly. Then wouldn't you just put the cam in exactly how it was on for re assembly? Put the chain on it and done. Or am I missing a bunch!
 
Go for it Jake. Save your hard earned $. Not that big a deal at all given the info on this site. There's a notch on the cam sprocket u can use to position it. FYI that front guide can still be purchased new. I think I paid around $60 at my local Yamaha dealer a couple of years ago.
Here's a link to "I am Carbon"'s video on how to position the cam when reassembling. Don't forget a gasket kit.
 
I already ordered the guide from mikes. If it isn't up to par for me when it comes in I'll send back and get one from elsewhere. So just a couple questions; If the motor is at TDC before I take it apart, the cam mark WILL be vertical at 12 o'clock correct? I'm not changing the chain, just the front guide. Once I put the jug back on and re install the cam, put the mark at 12 o'clock and install chain? Do I need to put the chain back on the exact tooth it came off? Thanks!
 
The position of the chain doesn't matter, the position of the chain master link doesn't matter. Only the timing marks matter. The motor should be positioned at TDC and the notch on the cam should point up. But, keep in mind that the cam has a 36T sprocket on it and the crank has an 18T. One full turn of the crank will only move the cam a half turn. For that reason, the notch on the cam may not point straight up at TDC, it may point straight down. That's OK, just give the motor another full turn and the cam notch will be straight up when you reach the TDC mark again. Then you can take it apart.
 
Thanks Guys! I'm trying to get this done and my bs34's to operate smoothly. I can see a couple small light passages in my diaphragms so I need to get those. Don't want to pull the float bowls off because someone really mangled the Phillips heads on them. I had to dremel the diaphragm Phillips to flat heads lol.
 
Some disassembly tips - loosen the cam chain adjuster way up. You can even pull the adjuster and plunger right out if you like. Loosen all the valve adjuster screws so all the rockers have play. You don't want any pushing any of the valves open. Remove the 4 outside large acorn nuts with the rubber washers first, before loosening any of the other nuts/bolts. Remove the rubber washers. If you loosen all the top fasteners at once, the top cover lifts and pinches those rubber washers in place. They will be even harder to remove than they're already going to be.
 
5twins said:
Some disassembly tips - loosen the cam chain adjuster way up. You can even pull the adjuster and plunger right out if you like. Loosen all the valve adjuster screws so all the rockers have play. You don't want any pushing any of the valves open. Remove the 4 outside large acorn nuts with the rubber washers first, before loosening any of the other nuts/bolts. Remove the rubber washers. If you loosen all the top fasteners at once, the top cover lifts and pinches those rubber washers in place. They will be even harder to remove than they're already going to be.
Click to expand...
Your tips are all going to be used thank you very much. Feel free to chime in at any time this is my first tear down of an xs650, I just want to ride!
 
5twins said:
Loosen all the valve adjuster screws so all the rockers have play. You don't want any pushing any of the valves open.
Click to expand...
For my own curiosity, is this because when you're torquing the head back down, if you have a rocker pushing on the valve it will cause an uneven torque reading on the head bolts? Or is there another reason? Thanks.
 
I don't think it would throw the torque reading off. What you're trying to avoid here is bending or warping the top cover. You don't want to be pushing valves open with the rockers as you're tightening the cover down. Maybe it wouldn't hurt it but why take the chance? It's a simple matter just to loosen all the adjuster screws up.
 
Jake Violando said:
I already ordered the guide from mikes. If it isn't up to par for me when it comes in I'll send back and get one from elsewhere. So just a couple questions; If the motor is at TDC before I take it apart, the cam mark WILL be vertical at 12 o'clock correct? I'm not changing the chain, just the front guide. Once I put the jug back on and re install the cam, put the mark at 12 o'clock and install chain? Do I need to put the chain back on the exact tooth it came off? Thanks!
Click to expand...
There's actually 3 reference marks to line up:
Crank at TDC mark.
On right side of camshaft gear there is a punch mark, that must be exactly even with top surface of head.
On left side of camshaft there is a slot that should be at 12:00 position.

Replace all of those damaged phillip screws with allen head screws, and life will be wonderful, for your next carb work session.
 

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