sleeper06 Posted February 9, 2009 Report Posted February 9, 2009 My buddie has a freshly built 421 cub,i rode the bike today ripped it around some for 10 min or so then I pulled slowly in my driveway it started acting up like it was really hot wuoldnt rev,bogging.I hit the bike with a temp gun rite away it read 123 rite by exhaust flange a little less by water jackets. Icant see it being that hot thAT HOT with that reading. I took carbs off and cleaned the pilots out thinking something got clogged. There was alittle shit in there but not much. The bike cooled down in the interm and started back up like it didnt miss a beat,my buddy rode it later on in the after noon and said it did the same thing after it was hot loss of power and smoking like a bitch. Im almost inclined to think he was rich today because it was 56 deg today usually 25deg.I also noticed a golf ball size dent in the radiator would this stop the core from functioning well enouphto cause it to run wierd. 421 cub 170 lbs compression +4 timing 170 main 52 pilot-1 1/2 turns out sea level 56 degrees clean-up port on cub Any suggestions wuold be great, Quote
okbeast Posted February 9, 2009 Report Posted February 9, 2009 Yes bike's will act like that (bog and what not) when they get hot. Also that jetting does sound quite high. What kind of carbs are they? I'm running 155 mains and 48 pilots on my 421 cub. Quote
dajogejr Posted February 9, 2009 Report Posted February 9, 2009 Start checking the coil, CDI and most importantly the Stator. If the bikes starts acting up after it's been ridden for a while, most of the time that's an electrical issue which makes it feel like jetting. I think you're jetted a little rich myself, but...if it runs fine at first, then acts up, I'd be looking electrical... Quote
wesw Posted February 9, 2009 Report Posted February 9, 2009 i ran a 45 pilot and middle clip dgh needle and 160-165 with my pwk 39s. Quote
locogato11283 Posted February 9, 2009 Report Posted February 9, 2009 Start checking the coil, CDI and most importantly the Stator. If the bikes starts acting up after it's been ridden for a while, most of the time that's an electrical issue which makes it feel like jetting. I think you're jetted a little rich myself, but...if it runs fine at first, then acts up, I'd be looking electrical... i agree. electrical problems are a fuckin pain in the ass. i had a bike do the same thing. it would run all day long, and then at some point would just start fagging out. turned out that my coil was not grounded properly.. i also think your jetting is too rich for that temperature. i think you need to be down closer to 162 main and 45 or 48 pilot.. dave, isnt it true that a bike jetted too rich will likely overheat at some point? i thought it was something about the oil not getting burned all the way off in the cylinder..i was thinking that buildup would cause the overheating. i thought i read that somewhere?? Quote
dajogejr Posted February 9, 2009 Report Posted February 9, 2009 If it was BIG TIME rich...yes. Unburnt fuel builds up...etc. USUALLY, it'll just foul plugs. But if you're just dumping fuel in..yes...it can overheat, even hydro lock if a float/needle/seat sticks and fills it up. But that's a different scenario. Electrical issues are the absolute worst. Quote
okbeast Posted February 9, 2009 Report Posted February 9, 2009 Check the pick-up gap, very strange how those can seem to get out of wack. Quote
sleeper06 Posted February 9, 2009 Author Report Posted February 9, 2009 Thanks for getting back havnt had a chance to really check it out again ,ill bring the bike to work with me tonight and start testing the electrical system,unfortunatly working nights is killing me so im going back to sleep. The bike has 35mmpwks and was jetted fat for break in,I put the motor together for him 3 months ago,he put three tanks of gas and brought it back to me for rejetting I took it for a ride b4 i jetted like i always do and thats when it happened. It felt like it eas overheating so i didnt want to touch jetting till this problem is worked out 170 main is fat but the bike pulled clean and it was 20 degrees out .Ill get back to u guys later let u know how it goes THANKS AGAIN Quote
dajogejr Posted February 9, 2009 Report Posted February 9, 2009 Unless you have good reason to believe it's getting hot (puking coolant, VERY VERY hot cylinders, etc.) I don't think your jetting is ridiculously fat to where that's gonna cause overheating. Smart man to start off fat and work down...cub motors love a lot of fuel.... Quote
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