new rhino rider.

1fassttdude · 2010-04-11 23:50:46

Hey All. I bought this 04 660 today. The guy I got it from told me it had a new piston and rings installed about 100 miles ago. I have the wiseco topend kit box so I belive him. (done at dealer)
Anyway, He was riding at wot on a dirt road when it lost compression and died on him.

He told me that he filled the rig with 87 octane fuel shortly before this happened. He had been running 91 up to this point without issues.

My question or questions are this:

What damage could the lower octane fuel do? Rings? Valves? I run 87 in my quads all the time and have no problems.

The motor will turn over very well but will not start. No suction on the intake = no compression/no fuel to motor Right?

Could the rings be cooked? Or could I have a Valve issue? #27 pipe, (upper left corner) is not connected to anything. This looks to me like a vacum line, is it? where does it go? Should it be plugged or what?

Reguardless, I guess the topend comes apart anyway. I just want to be sure I am not overlooking something before I tear into it.

Any help would be appreciated.

Thanks in advance.
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Fasttrax · 2010-04-12 07:14:21

Those tubes are basically breathers, don't connect to anything but form a nice T. Check your fuel pump and fuel lines first you may have the air lock scenerio going on. Pending on what compression and cam he put in would make me question the valves, aftermarket cams or more compression is extremely hard on the Yamaha engines stock components. One of the best knowledge base you can find on the Yamaha Rhino is Chris @ Benchmark performance, IMOO

Titan · 2010-04-13 07:20:55

The motor will turn over very well but will not start. No suction on the intake = no compression/no fuel to motor

It could have blown a hole in the top of the piston, snowmachines do this alot when people burn low octane fuel or run drygas in high output engines.
The engine will still turn over and seem fine but has lost all compression. I have seen this more times than I care to count and has happend to me several times in snowmachines and quads. The good side to this is in most cases (90%) it has only damaged the the piston.
Not saying this is your problem, it is just what it sounds like to me due to past experience.

elmerkit · 2010-04-29 01:31:33

that a sad news. just my option i thinks its not just the octane rating that damage the pistons but there could be some mechanical failure involved.

#1 2010-04-11 23:50:46

Re: new rhino rider.

#2 2010-04-12 07:14:21

Re: new rhino rider.

#3 2010-04-13 07:20:55

Re: new rhino rider.

#4 2010-04-29 01:31:33

Re: new rhino rider.

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