Where is the mixture screw on a suzuki 125cc intruder vl 2008, as it appears to be running rich and no manual, plugs get black and wet.

If the spark plugs are black, it is running rich, end of story, you are dumping too much fuel. You need someone that can do carb tuning on the bike. There is help in the Volusia Forums and it appears to be a known issue..

https://www.google.com/search?q=2004+Suzuki+Intruder+VL1500+running+rich

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Bad gasoline, old plugs, over rich mixture ( is the exhaust stock?)
Check the compression,,

Good Luck

Fouling of the spark plug makes the exhaust extremely hot due to the burning of the fuel mixture inside the exhaust pipe and the spark plug end turn to black, fouling of the spark plug may be due to too rich fuel mixture check the correct setting of the air valve.

The problem would appear to either be with the mixture or with the head. Too rich a mixture (too much fuel) will cause black plugs - when you take them out do the engine and plugs smell of petrol? You need to adjust the carburettor. Mark where the throttle screw is to start with and then slowly screw it (in - I think) to reduce the petrol flow.
The other alternative is that their is a problem in the head. Does the engine blow a lot of blue/black smoke out when it is hot. If yes it means a full engine strip down!

on your carbs on bottom side there are adjustment screws for fuel/air mix,if your air cleaner is clean and haveing this problem,you will have to get to these screws and turn them clockwise 1/8 turn to lean carbs out,it might take a few trys,so reading the spark plugs is good indicater,looking for tanish brown in color,black is rich,white is lean.

when the shop rebuilt the carbs did they reinstall the carbs on the bike?it sounds to me like the rear cylinder is running very rich,the carbs will need to be set up with the mixtures and balance done,this is not expensive to do and is critical to the good performance of the bike,most reputable bike shops will be able to do this,hope this helps

Hey, I have a 2000 Intruder 1500 as well and in the last week I have had the exact same problem and was thinking the same thing. I checked the front plug and it is pretty covered in black and changed both plugs. This did not help, still seemed like the front cylinder wasn't working just right. If you could let me know what you eventually find I would really appreciate it.

Factory recommended plugs are the best. Ask your local dealer, and he will give you the correct plugs. If you are fouling plugs, look for a too rich mixture, or carbs flooding.

as with any problem you need a clymer book for your bike or you can disconnect the wiring harness(all of them one at a time)turn the key on and use a volt meter to make sure you are getting power.does the engine turn over?