russian rocket Posted December 21, 2017 Report Share Posted December 21, 2017 hey guys, i was seeing if you could help me out with a problem that has me at my wits end. I am working on a 1996 arctic cat jag 440 twin cylinder, air cooler, single carb, two stroke This sled uses a vm34 mikuni carb with an enrichment circuit for its choke. so the problem i have is that the sled is super sluggish down low, in fact a lot of times it will die if you only give it part throttle. this lead me to believe that the pilot circuit was plugged up. I have pulled this carb apart nearly a dozen times and have cleaned the fuck out of it. I have chem dipped it, boiled it, carb clean, and blew compressed air into every port/orifice. i dont believe it is plugged up anywhere because i get good air flow through the corresponding holes. the intake boot is also in good condition without any cracks. No matter what i do, the sled still acts the same. absolutely no power down low but runs just fine at wide open throttle. i have tried adjusting the air screw but that doesnt seem to change anything either. i just dont know where to go next. does anyone have any suggestions? the jetting is factory for what the sled should be, 300 on the main jet and 30 on the pilot. Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted December 21, 2017 Report Share Posted December 21, 2017 Is it anything like a motorcycle carb? If it has a slide with a vacuum diaphram (sp?) Check for leaks and make sure the slide is moving as it should. Quote Link to comment Share on other sites More sharing options...
russian rocket Posted December 21, 2017 Author Report Share Posted December 21, 2017 Is it anything like a motorcycle carb? If it has a slide with a vacuum diaphram (sp?) Check for leaks and make sure the slide is moving as it should. no vacuum diaphragm. the slide is moving properly. Quote Link to comment Share on other sites More sharing options...
Erieaddict Posted December 22, 2017 Report Share Posted December 22, 2017 Could be the clutch and or helix and clutch spring. Quote Link to comment Share on other sites More sharing options...
cdk 4219 Posted December 23, 2017 Report Share Posted December 23, 2017 hey guys, i was seeing if you could help me out with a problem that has me at my wits end. I am working on a 1996 arctic cat jag 440 twin cylinder, air cooler, single carb, two stroke This sled uses a vm34 mikuni carb with an enrichment circuit for its choke. so the problem i have is that the sled is super sluggish down low, in fact a lot of times it will die if you only give it part throttle. this lead me to believe that the pilot circuit was plugged up. I have pulled this carb apart nearly a dozen times and have cleaned the fuck out of it. I have chem dipped it, boiled it, carb clean, and blew compressed air into every port/orifice. i dont believe it is plugged up anywhere because i get good air flow through the corresponding holes. the intake boot is also in good condition without any cracks. No matter what i do, the sled still acts the same. absolutely no power down low but runs just fine at wide open throttle. i have tried adjusting the air screw but that doesnt seem to change anything either. i just dont know where to go next. does anyone have any suggestions? the jetting is factory for what the sled should be, 300 on the main jet and 30 on the pilot. Have you checked the crank seals, sometimes this can lead to poor part throttle performance and can be compenasated with air idle adjustments that mask the leak. Quote Link to comment Share on other sites More sharing options...
TurboRust Posted December 24, 2017 Report Share Posted December 24, 2017 Maybe the problem is that there's no snow and you're working on a snowmobile. Heheheh Quote Link to comment Share on other sites More sharing options...
russian rocket Posted December 25, 2017 Author Report Share Posted December 25, 2017 Could be the clutch and or helix and clutch spring. the only reason I am straying away from that is because the clutch engages around 2700-2900 rpms. the ideal idle speed is around 1500. it will bog before it ever reaches the clutch engagement rpms. now if i sit there and nail it full throttle. the sled will move pretty decently out of the hole. but low/part throttle, it will bog and die. Quote Link to comment Share on other sites More sharing options...
russian rocket Posted December 25, 2017 Author Report Share Posted December 25, 2017 Have you checked the crank seals, sometimes this can lead to poor part throttle performance and can be compenasated with air idle adjustments that mask the leak. thats the next thing i will be checking, im gonna yank the engine out and do a pressure test on the lower end. Quote Link to comment Share on other sites More sharing options...
russian rocket Posted December 25, 2017 Author Report Share Posted December 25, 2017 Maybe the problem is that there's no snow and you're working on a snowmobile. Heheheh never thought of it that way lol Quote Link to comment Share on other sites More sharing options...
TurboRust Posted January 5, 2018 Report Share Posted January 5, 2018 never thought of it that way lol Well there's snow on the ground how's it running Quote Link to comment Share on other sites More sharing options...
russian rocket Posted January 5, 2018 Author Report Share Posted January 5, 2018 Well there's snow on the ground how's it running i dont know, i have been working everyday since before christmas lol i honestly think snowmobiles are my achilles heel, I have messed with three of them now and have been pretty much baffled by all three. 98 polaris storm 800, this 96 jag 440 and now i have a arctic cat kitty cat sitting in my garage that is pissing me off too Quote Link to comment Share on other sites More sharing options...
cdk 4219 Posted January 8, 2018 Report Share Posted January 8, 2018 Old snowmobiles are everyone’s Achilles heel, they are hard to test in the non winter months and always fail when it snows. Some of those Alaskan shows have people who seem to travel deep into the tundra with 1970’s snow machines, and get out alive. They certainly have more patience than I do. Quote Link to comment Share on other sites More sharing options...
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