97 600MM jetting with smart carbs

[Fasterblaster]

I just took my new (old) MM600 out today and have a few questions about jetting. The manual is being sent to me, but won't arrive until next week, so any help would be greatly apprecited. Where I ride, its usually not too cold, -5 to -10 C. Do I need to jet the smartcarbs? At 4500 feet is was running fine but the plugs looked wet and oily. At 6000 feet, it ran well flat out but was smoky and ran fat (blap, blap, blap) at lower rpm.

Also while climbing up a long winding switchback from 3500 up to 6000 feet it started to either run too hot or too lean. It started sounding too bright and I pulled the choke on, but it didn't seem to make much difference???? Is this because of the smartcarbs???? Or was I about to seize up??? Or was it just getting too hot climbing on the hard pack snow...ie maybe not enough snow of heat exchangers. Sorry lots of questions.

 

[Wilson]

You are not suposed to have to jet the smart carbs but they come to rich Ilive in Manitoba 700ft I went down 2 sizes from 160to 156.3 ,I also tried 155.0 but was to worried about melt down and went back to 156.3 . No one seems to know exactly how smart carbs work so its all trial and error Iam going to try and att a jetting chart that may help you . If you pulled the choke on and it didn't make any difference I don,t think you are to lean . If you get to lean the plugs will be white .

 

[marcush]

Smart carbs

I would be very carefull leaning out these carbs. With the stock jetting at 160 and leaning them out to 155 you now changed where they start to lean out. I had these carbs on my mm600 and was very disapointed with them so I took them off and put on a set off a 95 600 with jetting at 152.5 and pilots at 52.5. It works great now. My problem was that these carbs were rather more stupid than smart. She would load up on fuel to the point where you could smell raw fuel and have large backfires on bottom end. Also it would pull very hard for awhile at wot and when you slack off it would load up on gas and bog like crazy. I would give these carbs a major thumbs down. The yamaha dealer said to me in in different words IF THE SMART CARBS WERE ANY GOOD THEY WOULD BE STILL USING THEM. He could not say these words exactly,but it did not take me long to figure out what he was trying to say.

 

[flying dutchman]

Don't get too disappointed first time you ride your new machine. Since you just purchased, did you do a good clean up and check up, or did you take the previous owners word? Personally, I always check everything.
On your jetting question, you do not have to change anything once it's set up. You can do it but you need to know what you have to start with.
This system does have a range that it operates under, so by changing the main jet, your changing the whole scale. On my 98, I have altered my main jets and the needle setting, and it has ran excellent for the last 5 years. If you decide to pull the carbs and do a cleaning, there are several extra wires or hoses so make sure you tag them. Pull the whole assembly and you can still get at everything for cleaning.
I will dig out my archives and see how mine is set.