nitrosport_5
New Member
Im having trouble tuning my engine with pair of Mikuni BN38s off a 717 of some sort. I have them currently installed on a 1998 Skidoo 670 engine in a buggy.
RIght now i have it running great, but starting is another issue TO start it, i have to prime them, and then it will fire for a second and crank and crank and crank until it slowly starts to sputter its way to 1500RPM and fire. At that point if i dont give it another shot of the primer it will go ahead and die. Once running, it wont idle, have to hold the throttle open slightly. From where i have it to 2.5-3k RPM it is really boggy. Above that it runs like a champ. has a ton of power and is awesome but once it drops back down it just bogs like it is too rich and has to fight the fuel i think. I put 75 low end jets in nd it did not seem to want to return to below 3k rpms so it was too lean. I started back at 80 and it didnt act too lean. I started leaning it out and got to 77.5s and it runs okay but it still has the same bog and wont start worth a damn. the settings i am running now are
77.5 low jet
low needle 2 turns out
130 high jet
high needle 1 turn out
2.0 Needle valve
95g spring
Any help at tuning these carbs would be extremely extremely eXTREMELY appreciated. i have been playing with them for a few weeks now and cant make them work any better than right now. Thanks in advance.
RIght now i have it running great, but starting is another issue TO start it, i have to prime them, and then it will fire for a second and crank and crank and crank until it slowly starts to sputter its way to 1500RPM and fire. At that point if i dont give it another shot of the primer it will go ahead and die. Once running, it wont idle, have to hold the throttle open slightly. From where i have it to 2.5-3k RPM it is really boggy. Above that it runs like a champ. has a ton of power and is awesome but once it drops back down it just bogs like it is too rich and has to fight the fuel i think. I put 75 low end jets in nd it did not seem to want to return to below 3k rpms so it was too lean. I started back at 80 and it didnt act too lean. I started leaning it out and got to 77.5s and it runs okay but it still has the same bog and wont start worth a damn. the settings i am running now are
77.5 low jet
low needle 2 turns out
130 high jet
high needle 1 turn out
2.0 Needle valve
95g spring
Any help at tuning these carbs would be extremely extremely eXTREMELY appreciated. i have been playing with them for a few weeks now and cant make them work any better than right now. Thanks in advance.
