carb swap
carb swap
has anyone done a carb swap on their vmax .i read an article that stated the powerjet carbs can be finicky with temperature changes.wich means changing the main jets.and on these carbs you have to take the carb off to do it. where on regular roundslides they arent as finicky and you just remove the plug on the bottom and change out the jet.it seems like it could be a pain in the *** to do this when you go out in the morning and its cold and by noon its 20 warmer.it looks to me that their isnt that much room in their anyway to change jets without having to take the carb out to get athe main jet.anyone have problems with the powerjet carbs or is it not an issue.
If they are dialed right and you are running the air box they work very nice and are very dependable. People who have problems with these engines usually don't know how to clean or jet a carb, try to trail ride with jetting that is to lean to be safe, use cheap gas (these things like good quality premium without alcohols), think they can run without the air box (these P jets won't work right without it and will cause high speed melt down) and /or have a clutch setup that labors the engine and doesn't allow it to run where it should.
One problem I have seen many times with all types of power jet carbs with an external feed line to the jet is that people will replace that line with new line trying to do preventitive maintenance and use the wrong line. Some of the line out there will fit the nipples good but will have a larger ID than what it should be. The P-jet system will not be able to draw fuel up as easily through larger diameter line if at all (as it is pulling the weight of the extra fuel in the line) which can cause a delay in or slower feed of fuel to the P-jet. It can be very hard or impossible to tune a P-jet that has the wrong line on it. It would be like trying to tune mains with a main needle tube that was way to large. I've tested this by holding a carb (with fuel in the bowl) in my hand and blowing air through it with an air hose. With the right sized line the fuel jumps right up and comes out of the P-jet with a fury. With line that is to big it slowly comes up and kinda dribbles out th P-jet. So only use high quality line with the proper ID on your P-jets and go with factory updated jetting, keep an eye on your plugs and you should be fine.
The pic is a little out of focuse but if you look close you can see the diff in ID of the lines. Stock is the old yellow line, the pink line is what I use and it is the same ID as stock. The blue line is the cheap stuff. It is thin walled and has a larger ID than the stock line. It actually goes on real nice and you would think if would be fine but if you look at the ID of the nipples it is much bigger. The stock line is actually kinda hard to get on and some might think it is to small because of that but it's not. I just heat it alittle with a heat gun and have a little lube on the nipple before I try to slip it on.
Phil (opsled)
One problem I have seen many times with all types of power jet carbs with an external feed line to the jet is that people will replace that line with new line trying to do preventitive maintenance and use the wrong line. Some of the line out there will fit the nipples good but will have a larger ID than what it should be. The P-jet system will not be able to draw fuel up as easily through larger diameter line if at all (as it is pulling the weight of the extra fuel in the line) which can cause a delay in or slower feed of fuel to the P-jet. It can be very hard or impossible to tune a P-jet that has the wrong line on it. It would be like trying to tune mains with a main needle tube that was way to large. I've tested this by holding a carb (with fuel in the bowl) in my hand and blowing air through it with an air hose. With the right sized line the fuel jumps right up and comes out of the P-jet with a fury. With line that is to big it slowly comes up and kinda dribbles out th P-jet. So only use high quality line with the proper ID on your P-jets and go with factory updated jetting, keep an eye on your plugs and you should be fine.
The pic is a little out of focuse but if you look close you can see the diff in ID of the lines. Stock is the old yellow line, the pink line is what I use and it is the same ID as stock. The blue line is the cheap stuff. It is thin walled and has a larger ID than the stock line. It actually goes on real nice and you would think if would be fine but if you look at the ID of the nipples it is much bigger. The stock line is actually kinda hard to get on and some might think it is to small because of that but it's not. I just heat it alittle with a heat gun and have a little lube on the nipple before I try to slip it on.
Phil (opsled)
Phil, very good information and very interesting.... ! 
https://www.youtube.com/watch?v=PFb6NU1giRA
"I prefer dangerous freedom over peaceful slavery." Thomas Jefferson
"I prefer dangerous freedom over peaceful slavery." Thomas Jefferson
p-jet carbs
thanks for the info phil that pretty much answers my question.ill just make sure the correct jets are in their. and run super. check the plugs oftenand i should be good to go. i have one more question.whats the deal with the primary clutch. isnt it suppose to have a 102 on it mine says 108 on the face arent the 102 better and why was everyone switchin over to the 108's 
These sleds all came from Yamaha with a 102 that was built by Comet FOR Yamaha and it said Yamaha-Comet on the face of it. It has a different offset than any other 102 and calibration to Yamaha specs. Yamaha/Comet's also took a different puller than all other Comets. I must assume that (contractually) part of the deal was that Comet was not allowed to sell that exact clutch to the general public and that it was only available through Yamaha. Yamaha wanted over $450 for that clutch which is alot of money even today for a clutch. Comet then offered a 108 as a replacement (different clutch) which had the same offset but is a larger diameter than a 102 so they could get around their contract to Yamaha but still have a clutch to sell for these sleds. It was about half the price and a stronger clutch so most guys just replaced the original with the 108 as it seemed to make more sense. The problem with the 108 that it does not match with the diameter of the original secondary and the calibration was not the same so getting the 108 to work as well as the original 102 is very hard to do. There are some guys here that say they have a setup for the 108 that works great but they have spent alot of time messing around to get it right. Others have had no luck and are still playing with them. Untill someone comes up with an easy solution with easy to find parts that can duplicate the original 102 the info on this forum in regards to clutching these animals is about the best I have seen. If you could find and original that was good or worth rebuilding that would be the easiest unless you are very good with clutching.
Phil (opsled)
Phil (opsled)