Boinker Posted February 21, 2010 Posted February 21, 2010 (edited) If the snowmobile engine are what your going to use chances are you will have too lean it out a lot. My reasoning and experience with small 2 stroke engine would be too lean it out due to the there lack of air density from the cold to warm weather change. But bare in mind this was a 3.50cc engine that is slightly different and ran on Nitromethane, methanol alcohol, and about 10% synthetic oils. im about only 90% sure I am right but you may check with a small engine mechanic to be sure. As for the suspension I'm sure you do not want to get complex by all nature but you could easily build a 4 link suspension system for it. Let me know if you want me to draw a plan or a sketch up for you. Edited February 21, 2010 by boinker Share this post Link to post Share on other sites More sharing options...
feetfats Posted February 21, 2010 Posted February 21, 2010 (edited) If the snowmobile engine are what your going to use chances are you will have too lean it out a lot. My reasoning and experience with small 2 stroke engine would be too lean it out due to the there lack of air density from the cold to warm weather change. But bare in mind this was a 3.50cc engine that is slightly different and ran on Nitromethane, methanol alcohol, and about 10% synthetic oils. im about only 90% sure I am right but you may check with a small engine mechanic to be sure. As for the suspension I'm sure you do not want to get complex by all nature but you could easily build a 4 link suspension system for it. Let me know if you want me to draw a plan or a sketch up for you. yes this is correct, warm air has less air density so you use smaller jet (leaner) But do not ever go too lean as that will wreck your motor,,, too rich will not wreck anything so when you have varying temperatures or are unsure then always stay on the rich side. also keep in mind that elevation has a large effect as the higher up you go the less air there is so you will need to go leaner. BUT if you jet lean for high elevation and then take the machine to low elevation without jetting richer you will likely burn up the motor. Try to find a jet chart for the motor that has elevation and temperature. Edited February 21, 2010 by feetfats Share this post Link to post Share on other sites More sharing options...
dr_bowtie Posted February 21, 2010 Posted February 21, 2010 Actually the warmer the air is the MORE fuel you will need...the colder the air is the LEANER it will need to be... I have had to richen 2-4 jet sizes going from cold to warm Share this post Link to post Share on other sites More sharing options...
GabrielT Posted February 21, 2010 Posted February 21, 2010 for saftey I would find / build a pair of racing seats.. make sure you buy good seatbelts.. 5/6point harness seatbelts..Make sure you have good welding skills to weld the seatbelt harness to the floor behind the seats. Go with disc brakes like stated above.. Get some good wheels/tires. Make sure the Kill switch works, I would buy a mini-fire extinguisher and keep it in the back. I would use some pretty thick Stainless metal tubing for the rollcage around it. Well we have decent seats already, the snowmobile has a big disc break already. This is going to take more time than anything. Oh yeah, might I mention that on the mechanical side of things we got it covered. I have been fixing small engines forever and my buddy works at an Arctic Cat repair shop. Share this post Link to post Share on other sites More sharing options...
Boinker Posted February 25, 2010 Posted February 25, 2010 Okey dokie Share this post Link to post Share on other sites More sharing options...
feetfats Posted February 25, 2010 Posted February 25, 2010 Actually the warmer the air is the MORE fuel you will need...the colder the air is the LEANER it will need to be... I have had to richen 2-4 jet sizes going from cold to warm This is from my CR250 manual Cold air is dence = more oxygen per cubic foot,,, so to make up for that extra air we need to balance it out with more fuel.... so larger jet Share this post Link to post Share on other sites More sharing options...
ccokeman Posted February 25, 2010 Posted February 25, 2010 Actually the warmer the air is the MORE fuel you will need...the colder the air is the LEANER it will need to be... I have had to richen 2-4 jet sizes going from cold to warm Thats kind of opposite from traditional thinking as the denser the air the more O2 there is to burn. Hence the cold start open loop part of the auto fuel and ignition system. More fuel goes in when cold due to the denser air charge so the injectors are held open longer to bring in more fuel! Share this post Link to post Share on other sites More sharing options...
cjloki Posted February 25, 2010 Posted February 25, 2010 If the snowmobile engine are what your going to use chances are you will have too lean it out a lot. My reasoning and experience with small 2 stroke engine would be too lean it out due to the there lack of air density from the cold to warm weather change. But bare in mind this was a 3.50cc engine that is slightly different and ran on Nitromethane, methanol alcohol, and about 10% synthetic oils. im about only 90% sure I am right but you may check with a small engine mechanic to be sure. As for the suspension I'm sure you do not want to get complex by all nature but you could easily build a 4 link suspension system for it. Let me know if you want me to draw a plan or a sketch up for you. ever had a 2 stroker go into lean burn ?....it's like mad hatters wild ride...heehee Share this post Link to post Share on other sites More sharing options...
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