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Discussion Starter #1 (Edited)
Gents,

How do i keep the carburetors mixture screws from moving with the vibration?. Since I last adjusted the mixture screws to reduce the popping during deceleration, I already had to go back a couple of times to re-adjust the mixture screws. Ideally what I'm looking for is something that is not going to completely lock them in place but rather make them a bit hard to move and stay in the sweet spot ( not too lean - not too rich ) which makes the bike run like new with minimal popping.
 

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Super Moderator "Loose Nut"
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I've put an oring that fits snugly into recessed area on top if screw. It's easy to remove but keeps vibration from loosening screw. Hope you follow the concept.

91771
 

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Super Moderator "Loose Nut"
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Yep, you got it. Has worked for me.
 

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Discussion Starter #6
I forgot to mention something, I saw something that caught my eye. Last night when I was done re-adjusting the mixture screws I decided to pull my plugs to see what they look like. Both of my plugs look exactly like the third spark plug, from left to right - top row of the image below. If I'm reading the image correctly, my interpretation is that the bike is still running a bit lean. I am already out 2 3/4 of a turn in each mixture screw. Yamaha's service manual recommends 2 1/2 turns for the 01 650. In any case, I still need to go back in there to make sure those screws do not move. Is it safe to assume that based on the image below I should open up the mixture screws a bit more?. Thinking of going 3 turns out in each mixture screw and ride the bike for a few days to see if the plugs change.



91773
 

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Just curious if using the o ring...I would think if the issue was with the screw backing out the o ring would suffice...Just wondering do they ever vibrate inward?
 

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Super Moderator "Loose Nut"
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I would move the PSM screws no more than 1/4 turn at a time, doesn't take much. In my experience, the PMS screws will normally vibrate out.
 

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adjust the screws based on how the bike is running

2 1/2 turns is the recommended starting point - based on your altitude, type of fuel (e0, e10, premium...) it will change how it runs

also make sure your air filter is paper white (not dirty)

some of those plug photos are ethanol free gas, some are e10....

there are two methods for fine tuning the PMscrews, easy to google - like Les said, 1/4 turn at a time

if its popping and backfiring, or feels sluggish or has poor throttle response, then you need to adjust - dont just go by the photos of spark plugs

PS - its better to err on the side of too rich: plugs a little black, use a little more fuel
than to run too lean: plugs and valves and piston crowns start to melt!
 

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2005 V-Star 1100 Classic
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Curious, when you rebuilt the carbs, did you use new O-rings on the adjustment screws? Old O-rings form a flat spot, which results in less friction in their bores.
 

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Just curious if using the o ring...I would think if the issue was with the screw backing out the o ring would suffice...Just wondering do they ever vibrate inward?
Mine have actually vibrated inward. When I drilled out the cap protecting the PMS screw, one carb was 2 turns out and the other was actually 1 and a half turns out. This was on my 03 1100
 

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Super Moderator "Loose Nut"
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Why not use a drop of blue thread lock?
They are very soft material with small slotted head. If even blue was used you would probably strip it.
 

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They are very soft material with small slotted head. If even blue was used you would probably strip it.
Ok, in that case I would suggest using a product you can get at NAPA.
It’s a white pipe thread sealant with PTFE. It’s super smooth and when it sets it’s not as hard as any thread lock, but it is firm enough to hold the screw.
I think the product is made by “Permatex”.
 

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Loctite has a "Purple" threadlocker that claims it is good for carbs and brass screws..Never used it before but that is what there web site claims.

92239
 

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I've used a dab of fingernail polish to hold small screws. Especially on guns. Color doesn't matter, but you can match your ensemble if you want.
 
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