It helps direct the oil flow to the crankshaft to lube the crankshaft bearings. As far as understood, the spring helps keep is sealed against the case so it doesn't just leak inside the case and starve the crank, and the hole in the middle helps create oil pressure for the crank bearings. I would not leave it out lol

@@Hunters_Mechanics thank so much for the response man super helpful. How is the pin meant to be affixed inside the crankshaft? Mine just sits in there loosely in the hole, and can be easily pushed out the side again. Is that how it is supposed to be? Thanks again I really appreciate the help.

@@Hunters_Mechanics referring to the small roller pin that sits sideways through the small pin holes in the crankshaft

@@aidenallran3975 There's nothing that holds it in place, it just sits on the little dowel. Forums talked about how people remove the clutch cover and that pin just falls out. It makes it easier being on a tilted stand like mine instead of inside the chassis so it has less of a chance to fall out

@@Hunters_Mechanics Ah I think we have a misunderstanding. I’m referring to the little dowel pin that sits sideways in the crankshaft. The small dowel that the oil guide and spring rest on. It fell out, and when I put it back in it seems to have a very loose fit, not held in by anything. Wondering if that was normal, really holding me up on this rebuild. Trying to make sure I do it right.

It's hard to tell when I cannot see it for myself where it could be leaking from. Usually it comes from a hose clamp that is not tight enough or worst case scenario, it's coming from the "weap" hole on the bottom of the water pump. I usually track down leaks by letting the bike run, follow the leak path until it get's dry, and it usually will tell you in the general area where the leak is coming from. Just make sure to clean the bike first so it'll be easier to tell where it's coming from. For the fan, I would unplug it and check the fan with a multimeter and see if you have any resistance. My fan went out on me and I did not know it, I just happened to check it and it had no resistance. If it does have resistance, then the temperator switch may be bad (it's what turns the fan on)

It comes from the Ford Performance paper at 4:10, I just happened to find it on a forum somewhere and it worked perfect for me. I cannot prove it's authenticity but from my experience and others, it appears to be the sweet spot

I'm still using it with no issue. No smoking/rattling and it sounds similar to the 686 I had previously. I would still check it if you get the kit and make sure you don't have excessive clearance between it and the cylinder

@@Hunters_Mechanics thank you for the information. I actually went ahead and ordered an OEM piston replacement. I figured I can’t go wrong with that. Your video on setting timing is going to help me out tremendously.

Curious to know your thoughts as well on the piston. I just got a 2003 Raptor 660. Someone rebuilt just the top end with a NICHE piston (I think). The jug and head are still OEM. I took a bore scope to verify the piston and it’s either factory or NICHE because it’s flattop with no marking except for the small intake relief and the circle in the middle. Other than that I’m pretty sure it’s a niche bc whoever rebuilt it also used a niche starter.

I would start with the needle position first always, you may be able to make the minor adjustment needed from it's position without changing the jet, if no position changes help or it makes it worse, may need a bigger main jet

@@Hunters_Mechanics ok thanks for the help I really appreciate it. One more ? Would that be the needle on the low end cab or the high end cab since it happens a little past half throttle?

@williammarlin6174 when I had the same issue, I moved the needle position to the bottom and it fixed my issue, mine was hitting half throttle then would run crappy/backfire, I think one carb is maxed and the other is one from the bottom, just kept trial and erroring it till it ran right

Sorry for the late reply: www.mishimoto.com/yamaha-yfm660-raptor-aluminum-radiator-01-05.html

@@Hunters_Mechanics don’t worry thank you for the link

Yes

Definitely should be 1-7/16", I was probably well beyond tired tearing in to this years ago lol

It's not required but I believe it's supposed help the butterflies not freeze in the winter time and assist them warming up if they for whatever reason had some ice/frost on them. I know a few people in forums said they remove them because they don't live in a colder climate

@@Hunters_Mechanics Ohhh ok. I drove it in zero degree temperatures no problem, so I didn’t know if it was vital that they were ran to the TB. I appreciate the insight Sir! ✊🏻

Was not aware that any kit came with that bearing, it's hard to tell from my own video what kind of bearing puller you'd need to remove it. It may just need a well sized socket and a hammer to knock it out but I cannot tell which direction it needs to come out or if there's a dead stop for that bearing. Do you have a kit p/n?

Sounds like some moisture got in there, depending on how long that sat in there, might be best just to remove the top end and inspect if it started rusting the cylinder

Pour some automatic trans fluid or marvels mystery oil down the spark plug hole and let it sit for a couple days and try and turn it over then

Not sure what doesn't fit because the 01-05 should be exactly the same for the cylinder kits, as for the head, I'd say your best bet is eBay or facebook marketplace because it appears the heads are no longer manufactured, I need one for mine too eventually, camshaft bearings are shot

Sounds like the sensor itself is bad or the connector may be dirty to the sensor. Should always get a reading of "something" if the key is turned so if you're getting a 000, then you must have a short or the sensor itself is faulty

www.motosport.com/oem-parts/yamaha/2001/raptor-660/carburetor-rn

That should be able to assist in seeing what the part order is

Those have hydraulic lifters if I’m not mistaken, no adjustment available or necessary. Lifters can collapse however and need replaced if so.

Facts