teague adams Posted December 1, 2009 Report Share Posted December 1, 2009 Hello all, recently bought a 01 banshee yfz 350 that runs on alcohol...HERE IS MY PROBLEM...this particular banshee i was told has tons of mods unfortunately honestly i cant hardly tell what would be stock or not...but you gotta start somewhere...i took the banshee out probably about 3 times for about an hour and all of a sudden the left side started backfiring badly...loaded it up and saw that the spark plug was just trashed at the end...put on new spark plug and still backfires...took it all apart and found that there is a big hole in the piston where it looks like the spark plug punched through it or something? (so i replaced the piston and put it all back together...) took it out a few days later and rode it for almost 45 minutes and it starts backfiring again...havent taken it apart yet but im sure its the same situation...any ideas what i could do to figure out the problem? please help...thanks. Quote Link to comment Share on other sites More sharing options...
No Limit Powersports Posted December 1, 2009 Report Share Posted December 1, 2009 Unfortunately you probably blew it up again. In order to get different results your going to have to do different things. A hole in a piston is usually from detonation, which can be caused by a couple of different things. One, running to lean, either from a air leak, or just not properly jetted. After you put a motor back together it needs to be leak down tested, and did you split the cases and make sure everything was clean and free of pieces of the piston? The second thing is too much timing, how much timing is in the bike now? Quote Link to comment Share on other sites More sharing options...
teague adams Posted December 1, 2009 Author Report Share Posted December 1, 2009 Unfortunately you probably blew it up again. In order to get different results your going to have to do different things. A hole in a piston is usually from detonation, which can be caused by a couple of different things. One, running to lean, either from a air leak, or just not properly jetted. After you put a motor back together it needs to be leak down tested, and did you split the cases and make sure everything was clean and free of pieces of the piston? The second thing is too much timing, how much timing is in the bike now? 1. i am quite new to all of this...leak down test? how do i go about doing this? 2. yes i split the cases and cleaned everything out... 3. how much timing is on the bike? i have no clue...how would i be able to tell? Quote Link to comment Share on other sites More sharing options...
00sheerzr Posted December 1, 2009 Report Share Posted December 1, 2009 a leakdown test is when you pressurize the inside of the case and make sure it holds pressure i think there is a good sticky in the banshee repair section at the top, the timing is under the left side cover , the cover that is somewhat over the chain , only aftermarket timing plates are adjustable and slotted im not an expert on what to run for timing maybe +4 Quote Link to comment Share on other sites More sharing options...
No Limit Powersports Posted December 1, 2009 Report Share Posted December 1, 2009 Basically a leak down test is pressurizing the crankcase to make sure there are no leaks. You have to plug the exhaust, intake and spark plug holes have a way to air it up and a way to measure the pressure, do a quick search you will prolly find some how to's. With methanol you can run 7-10* on the plate with the stock cdi safely but i dont know who built your motor and what it will like the most. Quote Link to comment Share on other sites More sharing options...
blowit Posted December 1, 2009 Report Share Posted December 1, 2009 1. i am quite new to all of this...leak down test? how do i go about doing this? 2. yes i split the cases and cleaned everything out... 3. how much timing is on the bike? i have no clue...how would i be able to tell? I would highly recommend finding a reliable engine tuner that can look at your bike. To be honest, you may spend more on engine parts than a tuner will charge to properly set it up and explain what is going on. Also, we will rarely setup a Methanol bike for anyone unless they are very experienced with tuning. Reasons are that Eth and Meth require nearly constant attention to jetting due to the chemical composition of the fuel. It may also be that your engine was not jetted properly or a jet is clogged. There is a long list of possibilities but getting the right answers is key. Let us know where you are and I am sure someone will know of a local shop to you. Mull Engineering Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 1, 2009 Report Share Posted December 1, 2009 What carbs are on it? If you don't know, post some pics up. Your probably better off putting some stock carbs back on it and running gas, but you need to locate the problem first. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.