I am sure I will be corrected, but here is the right way to remove carburetor screws that have factory thread locker on them:

Buy yourself the smallest Weller Soldering Iron that you can find, I have the original SP23 version before the LEDs.

http://www.amazon.com/Weller-SP23L-Marksman-Lighted-Soldering/dp/B00018AR4A/r...

One way or another make sure you have all of the gasoline removed from the carburetor, if not you may be a fatality. You place the point of the soldering iron in the JIS head of the screw, some may call it a Phillips head. Turn the heat on, if you can do without your head phones and anything loud for a few minutes, when the thread sealer melts you will hear it sizzle. STOP! Put your JIS screwdriver in the screw head and twist counter clockwise. If you have a small impact driver use it instead of the screwdriver.

If you don't hear the it sizzle in a minute or two just assume your hearing is gone and that you missed hearing the sizzle. The screw will come out with head intact.

If you have a source for Metric Stainless Steel Allen Head Machine Screws I would substitute them for the factory screws.

Kenny G

Doesn't hurt to give the screwdriver a whack with a hammer to help shock the screw loose, either.

justin_o_guy2 wrote on 04/27/15 at 17:04:29:


It appears as if a Phillips #2 fits well, but don't quote me on that!

Cronyschism wrote on 04/27/15 at 18:54:40:



Japanese bikes use fasteners with JIS heads.  Phillips screwdrivers just don't fit properly and they will remove screws that are not horribly tight OK - but if the fastener it tight the Phillips will either deform the screw head...or strip it out.

If you are going to work on the motorcycle...buy a couple of JIS screwdrivers.
http://www.vesseltools.com/hand-tools/screwdrivers/screwdriver-sets/900/kit/f...

And as Jog suggested....you can adapt a #2 Phillips by grinding a small amount off the tip so that the bit seats fully into the JIS fastener.  Look at the photo below and you can see that the rounded corners of the Phillips screwdriver just don't fit well into the square corners of the JIS fastener.

Once I got enough years of experience I stopped just jumping into things if I could schedule it. Penetrating oil, every day for a few days before,,,
The right tools
Technique

Patience,,  ugg, took years to develop.. crucial for minimizing damage..
Less damage equals, well, I don't have the patience to do the math for you..

Amazon also has JIS screwdrivers, too: you need #1, 2, and maybe 3 if you have any older Japanese bikes that use big honkin screws for the cases
http://www.amazon.com/Hozan-JIS-4-JIS-Screwdriver-3rd/dp/B00A7WAHTU/ref=sr_1_...

Thanks everyone for all the awesome tip and tactics. I made sure the carb was completely dry before using my soldering iron to heat up the screws, it felt like I was holding it forever with no results. Next, I tried my ant death ray gun, aka heat gun, to no avail. Lastly, I went ape crap (in a positive way) and drilled out each of the screws with my cobalt bits and used my KD Tools shank-shape bolt extractors (I'm buying some JIS screwdrivers so it will never get to this extreme ever again) to remove each screw. That definitely took some time. Went to the mega sized Ace Hardware down the street and picked up Allen head screws as recommended.

So the inside of the carb was pretty foul, the float bowl was riddled with this red beach sand grit, the vacuum cylinder diaphragm and cylinder were loaded with tar varnish and the spring was sticky like pancake syrup. When I removed the main jet (145), there was red sand underneath the o-ring, ughh. Oddly, nothing was clogged inside the main jet or pilot jet fittings, nor the top jets either. I  noticed the needle seat contained a filter screen; never seen this before!

So, is it safe to say all I need for a rebuild is just the basic kit that includes the float bowl gasket and the needle seat o-rings? Besides needing a deep cleaning and the brasso treatment, I don't see anything else that needs replacing, but you guys would know better.

Hi all, this is just my follow up post regarding the carb cleaning -

I soaked all the parts in Berryman cold parts cleaner, hosed off with water, followed by immediately drying with compressed air. Some areas such as the transient enrichment valve cavity needed some extra cleaning as carbon and varnish was more prominent. Next, I assembled the unit with new parts from the kit along with the hex cap screws (so much better than those horrible factory fasteners) and reinstalled on the bike. I think the toughest part was reinstalling the throttle cable sleave into the bracket..took some finesse for sure. Cleaned the fuel tank with some acetone and compressed air and inspected the condition...no rust or debris. Installed the Yamaha petcock, installed tank on the bike and put in fresh fuel...it started right up. Had some black smoke in the beginning (after letting the throttle off) but after allowing it to warm up, I closed the choke and then turned the idle mixture screw ccw. Not only did the black smoke cease, but the idle seemed to have an overall even consistency.

Thank you all for your help in making this a successful project. I'm quite pleased an alternative no-nonsense petcock exists   for this model and I've also learned a valuable lesson about JIS fasteners!