YFZ350kid Posted October 13, 2008 Report Posted October 13, 2008 dang banshee has me confused... ok, from the top, got this 1997 banshee last year after my 89 blew up... my 89 was a pile, and i got this 97 as a trade + 1500 cash... anyway, this 97 has fmf sst pipes and power core 2 silencers, 21 cc domes in a pro design cool head, bored .030 over, stock carbs with tors removed, +4 timing. 310 mains, 2nd clip from top of 6 grooves on both needles, carbs were just rebuilt and cleaned very well. and a k&n airfilter in the box with outerwear over the filter element, no lid on airbox, new intake boots and boysen carbon reeds... i live in Las Vegas and the banshee is for use at Dumont Dunes 99% of the time... oh, im running 100 octane fuel with 40:1 fuel/oil ratio, ams oil for my oil well, i rebuilt the motor to include a new hot rods crank, all new seals, new pistons, new domes, o-ring kit for cool head, pro design water pump impeller and multiple other little things for the clutch and transmission... get it all together and started it up, fired up fine, did 10 hours of heat cycleing and re checked torque on every bolt on the motor... no problems... head out to dumont dunes yesterday morning for some test and tune style riding, just gettin in ready for the season, no major long pulls at WOT and only running 30-45 min untill a nice 20-30 min cooldown with the wind cooling down the motor... after about 4 to 5 hours of ride time just running around a small bowl on the back side of the dunes it started bogging really bad, well not having any good tow vehicle i had to get up out of the bowl before i could shut it down... get pulled back to camp, pull the spark plugs and the right side showed a bit rich still and the left had aluminum build up on it... so needless to say, blew a piston... now this is the opposite piston as what went out the last time so something changed from the last problem. any ideas would be wonderful to have, Thanks Quote
desertdeweller Posted October 13, 2008 Report Posted October 13, 2008 maybe the float level in your left carb was off starving that side some. mabe a crank seal got damaged when it was installed Quote
YFZ350kid Posted October 13, 2008 Author Report Posted October 13, 2008 maybe the float level in your left carb was off starving that side some. mabe a crank seal got damaged when it was installed i was thinking that is possible, but not very likely, i checked and doubble checked everything, i havent done a preliminary tear down yet to see how bad the damage is, im just trying to see what all everyone would check in the same situation... the odd thing is that when i push over the kick start with my hand it has equal force on both sides... i gotta get my compression tester from work and i can see what it is on both sides... im honestly looking into getting a 700R for somthing to ride thats reliable as the last 3 times ive had this one out its ended up the same, tow back and take 6 months saving up and ordering parts to repair, researching everything, then finally putting it back together as carefully as possible... the thing is as far as the carb float getting stuck im not thinking its very likely with all new components and absolutely no symptoms sooner... i'd have expected a problem within the first hour of riding not 4 hours into it... or even while doing the heat cycles... Quote
Wildcard2 Posted October 13, 2008 Report Posted October 13, 2008 I would do a leakdown test before you tear it apart to be sure you don't have an airleak. Other than that your needle looks to be lean, your main may be on the rich side masking the lean condition in the midrange. Do a good plug chop to dial in your jetting once you get it back together. Quote
akita8 Posted October 13, 2008 Report Posted October 13, 2008 Sorry to here about your bike blowing up. Might want to check your coolhead orings, maybe you pinched one during install. I had it happen to me once out at dummont. Quote
YFZ350kid Posted October 13, 2008 Author Report Posted October 13, 2008 I would do a leakdown test before you tear it apart to be sure you don't have an airleak. Other than that your needle looks to be lean, your main may be on the rich side masking the lean condition in the midrange. Do a good plug chop to dial in your jetting once you get it back together. im sorry, i said my needle position wrong, im second from bottom, not top... Quote
BellicoseBanshee Posted October 13, 2008 Report Posted October 13, 2008 Did you do a leak-down test after building the engine? What was the squish for each cylinder? Quote
Tim Potteiger Posted October 13, 2008 Report Posted October 13, 2008 (edited) Any signs of detonation? Which side did the rings stick on, exhaust (i am guessing?)? Detonation from +4 timing could cause excessive heat and soften the rings, and then cause them to seize. I know a lot of people run +4 timing advance, but I was running +4 1/2 with 112 octane and 18cc domes and detonating like crazy. Granted my compression is quite a bit higher than yours, but lowering the timing to +3 fixed my detonation, and will hopefully save me from anymore time in the damn garage wrenching on this POS!!!! The fact that you melted the last one might suggest a lean condition. Before I went riding on another new motor, I would dyno the bike somewhere that has an exhaust sniffer and make sure you aren't too lean. 310 sounds like the right jet for FMFs with stock needles, but being the 2nd clip instead of the 3rd would lean it out quite a bit. Plug chops are great, but nothing can beat a computer telling you what your fuel/air mixture is. I think you are too lean and/or detonating. Good luck, and please post back what you find. Edited October 13, 2008 by Tim Potteiger Quote
Wildcard2 Posted October 13, 2008 Report Posted October 13, 2008 I was going to add, that you should check out all of your cooling system for problems. Sounds like detonation to me and can be caused by any number of things:poor quality fuel, overheating from being lean or cooling system issues, impropper squish clearance, too much timing advance, fuel delivery problems (plugged petcock, cap not venting, impropper float adjustment, bowls running dry ect.) too much compression for octane, air leaks ect. Just a few things to consider. You need to diagnose why it burned down or it will do it again. Quote
fast500#12 Posted October 13, 2008 Report Posted October 13, 2008 i would check the water pump impellar. the stock one is plastic and if it gets hot enough once the blades will melt. and since it was on the left side check and make sure your cranks seal isnt leaking and sucking air in from the stator area. Quote
YFZ350kid Posted October 13, 2008 Author Report Posted October 13, 2008 0.046 and 0.044 are my squish results right after it was built i did a cylinder leakage test at 10 psi and the leakage gauge read 4-5% leakage, the last time the motor blew when i put a hole in a piston was due to a cracked intake boot, it leaned out the right side while running comp and boom, thats all shee wrote... my water pump was just changed to a pro design billet impeller and i had the guy in the radiator shop where i work go through and clean the tubes and straighten the fins for me, so im not thinking cooling system... would the crank seal take that long to show its not seated correctly, i mean it took 15 hours of running for it to go lean and i used propane to check for leaks before putting the covers back on and i got nothing around any seal or gasket... im gonna wait a while before i tear down again, i might pop the head off this weekend but im not too sure... ill keep you all informed as i go back inside the motor again thanks for all the replies and ideas Quote
GrMeyer Posted October 13, 2008 Report Posted October 13, 2008 check this out.. http://dunereview.com/rebuild.htm This guy had a slow coolant leak and you can see what happend. But sorry to hear that man. Best of luck on finding what has gone wrong. Quote
98_banshee_newbie Posted October 13, 2008 Report Posted October 13, 2008 You are lucky I had a piston completely disinegrate Quote
C&B Posted October 13, 2008 Report Posted October 13, 2008 If you were doin the drive around and tune, Id say the mid was lean, causing the piston to melt. thats why you ran around for so long before shee finally gave up. Pull the head, you may have to replace a piston and then try again. BTW who r u dealin with in Vegas (is that were u r at?) Quote
bansee fever Posted October 14, 2008 Report Posted October 14, 2008 dude dont give up! I know it sucks blowing up parts but its all part of learning! Quote
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