Greetings all,

Purchased a 2007 S40 (36,6xx miles) a few weeks back and discovered this wonderful site loaded with info. Anyhow, I've set forth to make necessary repairs prior to registering and insuring this bike. The main thing wrong with it from the beginning was the negation of any type of muffler; someone slipped on a straight pipe onto the existing factory pipe. Well, it was shooting out blue fire (noticeable at night) and it sounded like a handgun going off, not good at all. The idle was super low, too, I'm guessing 600-700 rpm and shot out black smoke when releasing the throttle. The night I picked the bike up, I added fresh gasoline and a small amount of seafoam to the mix; after about 3 minutes of riding the throttle response improved.

First thing I did was pull the battery (13v disconnected) and placed it on my charger overnight (about 13.10v after a full charge). Pulled the air filter which appeared to be the stock pleated fabric element. It wasn't filthy but had alot of little yellow flowers from the Palo Verde tree. I blew compressed air through it and reinstalled. I managed to find a used factory muffler on ebay, removed the straight pipe and slipped on the new muffler. Sounds much better now. I also increased the base idle speed on the carburetor and it idled so much better; the crackling sound when the throttle was released was gone, however, the black smoke remains. Changed the oil with Red Line 10W40 full motorcycle synthetic. Couldn't find any ZDDP additive in town so I just went with the "overkill" oil. Had no choice to change the oil...it was blacker than the void of deep space and reeked of "well used oil" ha.

So the next thing to do - shall I pull the carb and disassemble and clean? As a side note, I noticed the brass mixture idle plug is intact. Any thoughts?

Also, after two weeks of searching the web, I managed to locate a pdf of the Clymer manual for 1986 - 2004; is the newer 1986 - 2012 that much different in terms of content? Is the factory shop manual any good?

-Cronyschism

Black smoke.....when the throttle is closed....Have you pulled the vacuum line to the petcock to see if there is any fuel in it?

There shouldn't be any fuel in the vacuum line that connects to the front of the carb...that is an indication the vacuum petcock diaphragm is leaking.  That would allow you to learn what the Yamaha 660 Raptor petcock can do for you.

Thanks for the quick replies.

Last night, I pulled the petcock vacuum line from the carburetor nipple end and inspected the hose - it was dry inside but the brass nipple seemed to have traces of old fuel - like sticky varnish. As suggested, I think it's time to pull the carburetor and do the usual cleaning and inspection procedure. The Mikuni carburetor seems to be very similar to the Keihin (Honda) type and I cleaned & rebuilt 4 of those last October so the memories are still fresh in my mind.

On other thoughts, I'm going to pick up the Raptor petcock fairly soon - after reading the multitude of complaints and recommendations here, it's a no brainer. (Someone call me out if I'm wrong) So I take it this bike does fine with a simple gravity fed fuel system? While its a 652cc, this engine doesn't have the same demand as say, a 650cc inline 4 not to mention its a SOHC.

Are the pickup tube filters on the Raptor enough microns or is an inline filter needed? And if the petcock is left to "on" for an extended period time, will the float needle (if its in good shape) prevent engine flooding?



Thanks again for the responses. I have a bit of work to perform now.

Gravity flow from the Raptor is fine, as are the pick-up filters (in-line filters are more trouble than they are worth)...
To be safe, the Raptor should be turned off... that said, I only turn mine off if I'm parking inside my shop... otherwise, it's on day and night...  
(call me crazy)... ...

I guess you mean the screws head stripped,not the thread? If it's the case, I usually have good luck with a good vise grip grabbing the head. Otherwise, I'll dremel a slot fora big flat screwdriver. Good luck. Yamalube carb dip for cleaning it is the shiz.

The factory uses near permanent thread locker.
You should be able to break it free by grabbing the head with a small vice grip.
You might consider applying heat to break down the thread locker.
Or pen oil.

If you are going to buy a Raptor petcock, make sure you get the right size. I can't think of the correct part number off my head, but there will be a number of site members who can advise this. Don't be tempted into buying the cheapest thing on EBAY.

what size Philips did you decide was the proper fit?