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Discussion Starter #1
I'm tearing into my 660 to re-ring it. I have a few questions. I'm following the service manual to the best of my ability (its a little confusing). I have the valve cover off, the timing chain tensioner off and the 2 bolts on the cam gear loose. The service manual says to fasten a safety wire to the timing chain. I understand the reason for this but where do I tie it to since I have to remove the cam gear still and will need to rotate the chain to get the other bolt out. I will also have to remove the cylinder and the chain will have to pass through that. Hopefully that makes sense.

I'm also wondering what the purpose of the cooling fan is? It seems to blow air through the tube and onto the muffler. Does it draw heat out or create some sort of vacuum or something? unless I am missing some ducting it seems pointless and maybe a waste of HP.

Thanks for any and all help and I'm sure I will have more questions as this job progresses. If anyone is interested I can take pics of the progress.
 

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Use a LOOONNNNGGGG wire... :)

tie to the cage...yes pass it thru to completely remove cylinder...

Most people ditch the fan...

Its purpose is to blow air in the rubber in the exhaust mount...might melt if you take the fan off...

Not a big waste of hp but if you get under water it won't be a good thing to have...
 

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Discussion Starter #3
Thanks for the reply ruttingrhino. That does make some sense my front rubber mount is still there. The back mount does have the center broken out though.

I also took a members tip and used my dremel on the exhaust manifold and ground down the welds a bit and just from the looks it has to flow better.

Any other tips or tricks anyone wants to pass along will be appreciated.
 

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OH...you mean like get a hot rod sheave...or better still one of my air intakes...

:)

Yeah...do both... :lol:
 

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Discussion Starter #5
I do want a hot rod sheave, but that will be down the road. Got to get this thing running without smoking and make the wife happy first.

Does your air intake put the filter under the hood? Any pics?
 

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You can remove the cam without pulling the gear off. Thats the way I have always done it. Be careful with that chain....it is a PITA to get back on the lower gear if it falls off. It usually takes 4 hands and a long scredriver. a long wire to the cage would be your best bet...and an extra set of hands when the head/cylinder comes off.

good luck
 

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Discussion Starter #7
I was wondering if there would be enough slack to get the cam out with out removing the gear, but didn't want to chance it and didn't think to ask. Thanks for the tip biggjim. I will have the wifey on hand to help. I'm scared that I'm gonna drop the chain in the case. I might use 2 long wire incase one slips. I do not want to pull the motor.
 

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Discussion Starter #8
Down to the case halves. WOOHOO. Everything went smooth with the exception of a dowel pin falling into the crankcase. Luckily it was right at the counter weight on the crankshaft and I got it with a magnet.

Findings:
1. Lots of evidence of oil burning on the valves and combustion chamber and in the exhaust ports. Will take some elbow grease to get it clean.

2. Some movement of the piston in the bore with the head off. Piston looks good.

3. Bore looks great, no scratches or grooves. Not even a lip at the top of the stroke.

4. I noticed the oil ring on the piston was compressed inside the diameter of the piston. Other 2 rings decompressed like normal. Piston moves freely on wrist pin, no evidence of galling.

5. Measured the bore and piston with some small calipers. Bore - 99.8mm about a half inch from the deck. Piston - 99.4mm from the top ring up. Just read the service manual, and realized I measure in the wrong places. But I also don't have the proper calipers.

Did the stuck oil rings cause oil to get into the combustion chamber. Is there anything else to check?
 

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Discussion Starter #9
Forgot to ask. Gasket set and rings where is the best place to get them? It appears Yamaha doesn't sell a gasket set. I would like to get them quick as possible.
 

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Discussion Starter #10
I measured the piston in the correct place (on the skirt) and the diameter is 99.9mm. I will have the bore measured tomorrow at a machine shop hopefully.
 

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Discussion Starter #12
Thanks for the link. I forgot to mention I stopped by the dealer saturday and checked prices and availability. He quoted $52 for a head gasket alone. I asked about aftermarket gasket kits and he reluctantly went to a catalog and looked up a Moose gasket kit for $65.
 

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The only ones I am familar with at all are to cometic aftermarket and only for 102 mm bore... which is what I am pretty sure John at racers edge would have...

You can also check with Chis at Benchmark performance...he sells some oem parts and knows as much as anyone on the planet about what's available....
 

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Discussion Starter #16
Bore checked out in spec. Minor taper of .002nds top to bottom.

Nate gave me a good deal on some rings and gasket so I ordered from him. Thanks Nate.
 

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Discussion Starter #18
Honed the cylinder tonight, and cleaned the burnt oil from the combustion chamber and exhaust ports. Taking to work tomorrow and gonna use the parts washer to clean the head.
I do have a question about re-assembly. Do you need a ring compressor or does the taper at the bottom of the cylinder do that for you?
 
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