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Discussion Starter · #1 ·
I recently bought a 2003 Raptor 660R. It always ran great and started right up everytime. I took it out balls to the wall on an open road and it was running fine....and on the way back....i was slowing down to turn into the drive way and i noticed the raptor had shut off as i was slowing down. I coasted it into the drive way and tried starting it again and it wouldn't fire. I checked the plug, it was getting spark, it still had plenty of gas (almost a full tank), and yet still couldn't get it started. We eventually had to pull start it and it fired up fairly quickly, but with lots of white smoke from the exhaust. I checked the plug, it actually looked as if it was running a little rich rather than lean. It then started up by pushing the button, so I took it for another run down the road and noticed one hell of a vibration from the engine. It practically made my feet vibrate off the foot pegs. Also, there is a really loud knocking noise now and the quad lost A LOT of power. I checked the valves, they were all within spec except the one exhaust valve was a little tight. I checked the cam chain and tensioner, the tensioner seems to be ok. The cam chain does have a little play at the top of the sprocket, but i don't know if this is normal. Can anyone provide any suggestions on what this problem might be? Any help would be greatly appreciated!!!!
 

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Would you say it was steam or smoke from the exhaust when it pull started? Did it disappate quickly or linger in the air for awhile, trying to figure out if it was steam or oil smoke.

are there any internal mods to the bike or pipe/filter etc? Do you know it was jetted correctly?

To isolate the problem, do a leak down test on the cylinder and pressureize the radiator, let us know what those two tests turn up.
 

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Discussion Starter · #3 ·
Thanks for your response... It was definitely smoke and not steam. Not exactly sure how to do the tests that you mentioned.

The wheeler would not start at all today. It just cranks and cranks and then every now n again it will backfire really loudly. Didn't try pull starting it, figured since all it does is backfires on it's own, it prolly doesn't wanna be started and i don't want to screw something else up more than it already is...

I checked the jets, and I believe .140 and .145 are standard, but apparently the guy who had it before me put .145 and .150 in it. I don't know if this could be the problem cuz t's my first yamaha and i'm not really sure how finnicky they are with the jetting, etc...

Also, any suggestions on what the really strong vibration could be? I could be way wrong, but I'm thinking possibly something to do with the counter-balancer??? Thoughts???
 

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You would have to take it to a shop to get a leak down test done. That's definitely the first step after what you've already done though. The counterbalancer is a good guess but with the smoke and not wanting to start I wouldn't suspect the counterbalancer. Possibly a head gasket.

How does the oil look? Any metal particles? Milky looking?
 

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Discussion Starter · #5 ·
oil looks fine, but was just changed right before this happened, hasn't really been ridden since the oil change. Looked fine when I changed it, was just VERY black...

My guess is something broke and caused other things to not work right... am pretty positive it's not only one thing that's wrong...

Anyway...keep the thoughts coming!

Thanks,
RaptorGirl
 

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if not a leak down test, a simple compression check will probably reveal you have a problem. It could be several things but the smoke is a telling sign of a piston problem.
 

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Discussion Starter · #7 ·
Well, we did do a compression test just now....15lbs of compression....but still not 100% sure if that's accurate... we tested an engine in a car and the tester said low compression, so now we're wondering if the tester might be screwed up... will check the compression in the Honda TRX450R tomorrow (since it's late) just to see if the tester is working correctly...will provide an update then....

so what should the compression actually be at? let's say the tester IS accurate and it's got that low compression, guess i would need a new piston, might as well put a stage 2 hot cam in it then too :thumbsup: any other recommendations????
 

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if the compression is that low, you're gonna need more than a new piston :(

It should be 130-135PSI but you have to spin the motor over with the starter, not by hand.
 

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Discussion Starter · #9 ·
What all would I need? Never came across this problem before... Thanks for all your help thus far!
 

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You will also no doubt need to get the cylinder bored/honed, because if you lost the piston you may have scored the cylinder walls.

So basically, you'll need a gasket set, a piston, and you'll need a machine shop to work the cylinder. Depending on what the machine shop has to do, you'll probably need an oversized piston. Of course, that's assuming that the piston truly has failed and didn't take anything else out with it.

What area are you from? There are several reputable shops that sponsor this forum that would no doubt be able to fix your problem.
 

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Sorry you had problems, but maybe you just needed an excuse to upgrade?
 

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if the compression guage is right and you really do have just 15PSI, you probably have a few bent valves and possibly something wrong with the piston and rings.
 

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Discussion Starter · #13 ·
Well the mystery is no longer... I took the engine apart this evening...and yeah....the piston is pretty much toast....i'll try to get some pics up later, but yeah, the piston actually has several pieces broken completely off...surprisingly, the cylinder walls don't look too damaged, so will just get the cylinder machined a bit....apparently it also got pretty warm and heated the crank up a bit too, it's sort of discolored from the heat, as long as nothing is bent or out of place with it, would i still need to replace it?

as for the piston, i was eventually going to upgrade anyway, so i guess there's no better time to upgrade than now, since it's all torn apart...any suggestions on what i should go with? not only dealing with this, but just upgrades in general, any suggestions? Here is what it has so far...

FMF slip on (I'm eventually going to get a whole system once i decide on what to go with...)
has +2 a-arms
rear wheel spacers
has ITP rims, don't remember what kind of tires it has right now, but it needs new ones anyway so suggestions???
for some reason dude i bought it from had it jetted to 145 and 150, doubt the slip on would have made it necessary to jet like that, but i could be wrong...


it might have more, but that's all i've noticed so far and all guy i bought it from told me about, but with the engine that messed up (it broke on my first ride)... i guess i shouldn't really count on anything that guy told me...


also, someone asked what area i was from, i'm near Reading, PA...i think i might deal with Ray's Yamaha, I've heard they are pretty reputable...


anyway, i'll get some pics loaded soon.....the damage to the piston is unbelievable....it's a miracle the thing even ran at all when we pull started it and then it fired up on it's own after that.....


Thanks for all the input from everyone!!!

RaptorGirl
 

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Before asking for suggestions for a motor build you should add what type of riding you do, or expect to do in the future and what your budget is.

That sucks that you just got it and already have it tore down.
 

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Discussion Starter · #15 ·
I like to ride hard and fast....wait, that sounds pretty dirty...there are a lot of trails where i ride, but any open area i get, i like to romp on it...area also has a lot of coal hills, so would be plenty of climbing potential too, but mainly the trail riding and also want something that will have lots of power...

my boyfriend just got a 2007 honda 450R...and he put the HRC kit in it....i want my rappie to show him up! :lol: :thumbsup: lol
 

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where did the broken pieces of piston go? Was it the stock piston? Just asking because I build these motors and I've never seen a broken stock piston.
 

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RaptorGirl said:

my boyfriend just got a 2007 honda 450R...and he put the HRC kit in it....i want my rappie to show him up! :lol: :thumbsup: lol
well that is not a problem lol, just talk to sto (mike from coalshedracing.com) and he will point you in the right direction.
 

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Discussion Starter · #18 ·
well, we are still looking for the pieces.... i'm pretty sure it is stock piston considering it has 3YF stamped on intake side... and in case you haven't seen busted up stock piston before.....see pics attached! :unsure:
 

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Discussion Starter · #19 ·
Here are some pics of the crank, is the bluish discoloration normal or not? Some people have been telling me it's just the way it's tempered and that it's not from over heating. Also, does the crank normally run in an oil bath or not? Some people are saying yes, some saying no... There was no oil in the bottom of the crank case... if there is supposed to be oil in there, means i have another issue.....suggestions?
 

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you got bigger problems than that piston. You have yourself an oil starvation problem, look at the scoring on the piston skirt and wrist pin. Both clear signs of an oiling issue. From the looks of the wrist pin, I'd say you also need a new connecting rod, post some pics of the small end of the rod. Either it was low on oil or your oil pump isn't delivering proper lubrication. I recommend you split the cases and replace the oil pump, crank/rod, main bearings and inspect the rest of the case bearings for wear. Also inspect the cam journals.
 
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