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Dirt Bike Brands - Other
changing premix ratio and affect on jetting
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[QUOTE="joshp, post: 1025990, member: 60913"] Well I'm having problems jetting a 93 RM 250 and I've got all kinds of premix spitting out the back. It leaves speckes all over the ground. Part of my issue is that I have a PJ keihin carb that doesn't want to idle. I've seen other threads talk about switching to a PWK keihin carb but I just want to get it to where I can go out riding tomorrow. There is a lot of smoke coming out the exhaust so I figure it is running rich. I'm running motul 600 and I've read on this site I believe that it has a tendency to foul plugs so I figured maybe I should go leaner on the oil to try and prevent this by running 40:1. There currently is unsmooth/ hesitation until you get to 1/2 throttle and on then it pulls clean. Right after the hesitation it jumps. If you're hard on the gas it's great but with the fact that I suck at riding and that I'm riding trails that I'm not too familiar with I can't be flying down them. I'm finding that my adjustment have to be counter productive to get it close to idling for example I screw out the choke/ idle screw but at the same time I have to screw out the airscrew. I don't know if this is because essentially when I do this I'm increasing both air and fuel mixture going in allowing it to come closer to idling. I'm not too worried with idle as I figure I can compression start it going down hills if I kill it. The main thing is to make my low end power actually functional. Currently I've been playing with a 55 slow jet. A 60 is way too rich a 55 I believe is also too rich but when I go to a 52 it doesn't want to start. But if I recall right I believe I still had hesitations down low when I ran the 52 meaning I may need to go leaner correct? I printed out an article from this site about jetting but I don't know how accurate it was at telling what jets were functioning at what throttle position along with the fact that some of the jets I don't even believe my carb has like the air jet (the writer isn't referring to the air screw because he explicitly says air screw when he is talking about the air screw). [B]I can tell the feeling you get when you're running to lean when you're on the gas it does that boowahh sound but if you're lean on the bottom side of the power band (low throttle) what happens? [/B] Help appreciated. I may end up getting a PWK carb but I'm debating on spending $190+ because it's a 93 and it is only going to get harder to find parts for it. Until then does anyone have an idea of what to do on the bottom? I think I'll buy a 40, 45 and 50 since I'm switching t 40:1 and I'll buy a 160 165 and 170 for the main (currently running a 172 main) . I will be riding from sea-level to around 2,500 feet. [/QUOTE]
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Dirt Bike Brands - Other
changing premix ratio and affect on jetting
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