I had the same issue the first time I removed my gas tank.  It would slide to the rear about 1" and then acted like it was hitting something.  I found that if you hold pressure on the rear of the tank pushing to the left it will clear whatever it bumps into.  Then it's just a matter of lifting the tank off rear first.  wiguzziman

Hi, I have a quick question for the first post. The carb spec chart. I have a 86 in Canada. Is there a different carb spec list for a Canadian 86 or would they be the same at the time (1986)

Ok, we’ll thanks for clearing that up for me anyways.

This good old post needs a bump.

I bought a cheap rebuild kit on E.Bay.  I knew many of the parts wouldn’t be ideal or correct, but I mostly just needed the float bowl gasket and to study the other parts.  

After some messaging with the seller, here’s a list of specs for the components.  My notes/questions included.

1 Float Bowl Gasket (actually good quality)

1 Viton Tip Needle & Seat #2.8 (This is the float valve - is 2.8 big enough, there’s no mention of this in posts/thread above.  I know the Mikuni VM36 uses a 3.4.  I don’t know if these numbers are flow rates or mm sized.)

1 Main Jet #130 (Way too small.  Advised seller to talk to his supplier to include a 145 with extra 147.5 and 150. The extra larger jets would be a nice marketing plus for the kit.)

1 Main Jet #70 (I believe this is misnamed and should say ‘pilot air jet’.  It’s the same physical size as the Pilot Air Jet that should be 67.5.  What would be the affect of 70 vs 67.5?)

1 Pilot Jet #47.5 (Advised seller this should be 52.5 for more current models and only older models used 47.5 - suggested including a 47.5, 50, and 52.5 in the kit for better marketability.)

1 Needle Jet (seems to match stock, good quality)

1 Needle #Y379S (Has 3 grooves, but what about the taper?  This will be interesting and fun to dial in. What the heck is a “Y379S”?.)

1 Needle Clip (The inside diameter is too large to fit securely in the needle groove.  I had to pinch and manipulate it with needle nose pliers to crimp it snug and tight in the groove.)

1 Fuel Mixture Screw (seems good quality and the tip was protected with a plastic cover)

1 Fuel Mixture Screw Spring (seems fine)
1 O-Ring (seems fine)
1 Washer (seems fine)

I have an authentic Mikuni 150 Main and 52.5 Pilot jet coming from JetsRUs.

After reading all the carburetor stuff I could find on this forum, I went at it myself, and had good results. The engine accelerates smoother, power seems a little more readily available, and no backfiring. This forum has been such a great help to me, I figured I'd share what worked for me.
I live in New Jersey at about 315 meters above sea level.
I started with a stock '96 bike. #145 main jet and 52.5 pilot jet.
I have this air filter in the stock breather box, nothing special:
https://amzn.to/4c7ewhD
Instead of drilling jets I bought these Mikuni jet sets with a range of sizes:
Main-https://amzn.to/3Wzzksp
Pilot-https://amzn.to/3LSVKzU

I wrestled removed the carb from the bike.

I opened the top and replaced the nylon spacer with a metal washer I had in one of my cans of misc nuts and screws. I eyeballed it as 1/3 the thickness of the nylon spacer. Closed it up.

I opened the bottom and replaced the Main Jet with a 147.5 jet, and replaced the Pilot Jet with a #55 jet. Both one size up from stock.

I put it back together (some spray lube on the engine carb gasket to coax the carb back into place) and turned the idle mix screw all the way in--be careful not to over tighten, it felt like it bottomed against a coil spring. The warmed-up engine seemed to idle fastest and best at 1 to 1-1/2 full turns out. Then I adjusted the idle with the idle adj finger screw, I left it fast enough to idle smoothly.

Then I took it out. I rode it hard for about 10 minutes and experience no backfiring on deceleration. I pulled into the garage and dropped down to idle. Then I gassed it and let it drop down to idle again and quickly cut the ignition, which used to give me a nice honey-I'm-home BANG! But now, just a sweet little kitten fart.

Thanks to all you guys who share your experience and take time to answer questions. This is a great forum!

The stock OEM mix screw sits recessed in the hole about 1/4-3/8” depending on the adjustment.

I’ve bought and used an aftermarket mix screw that was about 1/2” longer than OEM.  It’s the same length from the first thread to the tip of the screw (the important length).  The portion of the screw on the other side of the threads is longer so it sticks out more.  At 2 turns out, it’s flush with the carb body/hole.  This photo is of the aftermarket screw I used (yours may be similar in length or longer).

I wouldn’t worry about it unless it’s sticking way out and you had to adjust the carb richer and set it more than 3 turns out from the fully seated position.  If you have to go more than 3.5 turns out, I’d worry about it vibrating loose. If that’s the case, use a pilot jet 1 size smaller.

Be careful when you turn it all the way in and gently seat it.  Just barely turn it until it  gently stops.  Don’t force it in real hard or you can break the tip (you’re not trying to install a door latch or something like that).

And how it sits fully sits seated in the carb