Hi all, been working on a VMax 500 DLX that I bought used a couple of years back. The sled has 4000 mi but has never run right in the 5 years I've owned it.
Sled idles fine and runs ok at WOT but has extremely poor mid-range (3/4 throttle to run 30 mph). Gas mileage is poor at 6+ mpg and oil usage is a bit high, ~40:1. Plugs are very dark and wet. Both cylinders are the same.
Working through hints from TTY site and the service manual I have disassembled and cleaned the carbs at least 3 times. I did find the needles at 1 and 1.5, both are now set to 2 but nothing plugged or out of spec. O-rings and gaskets in the carb have been replaced as well as the needle inlet valves. Float height measures fine and all jets are stock (per markings). Have also replaced fuel filter and adjusted the oil pump. Inspected/cleaned choke linkages, they are free and appear to be seating fully.
Was able to get out yesterday (temp in 20s). Started out with fresh plugs gapped to 0.030, performance was improved from last time out but still not right. After 40-50 mi sled began to start harder (crack throttle), idle was rough and WOT was down. Road 120 mi on the day, should have changed plugs mid way thru the day but didn't. Suspect a fresh set of plugs would have got me back to where I started the day.
I'm beginning to think that the poor performance might be more of an electrical problem than carburation. First steps will be to measure plug cap and coil resistances.
Options:
1) rebuild carb with new jets?
2) rebuild fuel pump?
3) replace oil pump?
4) look into magneto/stator?
Any thoughts on where I should head with this? The sled is in nice shape mechanically but mid-range performance is really important to enjoying the ride. I've been around sleds most of my 50+ years but am a novice in the finer aspects of engine tuning and this level of repair.
Thank you!
Hank
Sled idles fine and runs ok at WOT but has extremely poor mid-range (3/4 throttle to run 30 mph). Gas mileage is poor at 6+ mpg and oil usage is a bit high, ~40:1. Plugs are very dark and wet. Both cylinders are the same.
Working through hints from TTY site and the service manual I have disassembled and cleaned the carbs at least 3 times. I did find the needles at 1 and 1.5, both are now set to 2 but nothing plugged or out of spec. O-rings and gaskets in the carb have been replaced as well as the needle inlet valves. Float height measures fine and all jets are stock (per markings). Have also replaced fuel filter and adjusted the oil pump. Inspected/cleaned choke linkages, they are free and appear to be seating fully.
Was able to get out yesterday (temp in 20s). Started out with fresh plugs gapped to 0.030, performance was improved from last time out but still not right. After 40-50 mi sled began to start harder (crack throttle), idle was rough and WOT was down. Road 120 mi on the day, should have changed plugs mid way thru the day but didn't. Suspect a fresh set of plugs would have got me back to where I started the day.
I'm beginning to think that the poor performance might be more of an electrical problem than carburation. First steps will be to measure plug cap and coil resistances.
Options:
1) rebuild carb with new jets?
2) rebuild fuel pump?
3) replace oil pump?
4) look into magneto/stator?
Any thoughts on where I should head with this? The sled is in nice shape mechanically but mid-range performance is really important to enjoying the ride. I've been around sleds most of my 50+ years but am a novice in the finer aspects of engine tuning and this level of repair.
Thank you!
Hank
