blowit Posted March 17, 2014 Report Share Posted March 17, 2014 No way would I recommend to ride one with a noise like that ever. Hard to define in a video but sounds like good old piston slap. Ride it until you finally break the piston skirts off and you will not like yourself. I would highly recommend taking it apart and having an experienced pro check things. If this pro does not have the tools and skill to mic the bores and pistons, you found the wrong guy. Wrist pin failure is very rare in Banshees. Piston wear and crank failure is more common but usually cranks just pop, they don't develop too much knock before locking. Also, when you rev it, I hear a pfffttt sound in the exhaust. That is either lean condition, carb balance, or improper tuning of the TORS system. Lean condition could certain have created the problem you have there. People go ride a Banshee when they are not right and the good running cylinder kills the other one. Case and point, plugged pilot jet on ONE carb. This can lead to overheat in one pistons, weld the rings into the piston, more overheat due to lack of ring seal and blowby, and the grenade pin is pulled. Brandon Mull Engineering Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 17, 2014 Author Report Share Posted March 17, 2014 I should have noted that this video is from September, since then I've done a few upgrades and actually jetted the carbs right, the lean condition is gone. However the knocking noise isn't. I thought it was piston slap too but I'm not experienced enough to give myself a 50% that I'm right. I figured it wasn't the crank for the reason that if it was it wouldn't even run. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 17, 2014 Author Report Share Posted March 17, 2014 I would love to send it to a proper builder but I don't think I have the money to do it. My dad races oval track go karts and has 15+ years experience with 2 strokes, so if I tear apart the top end he'll be there to keep a watchful eye over things and I'm sure he'd spot anything that might be funky with it. hopefully I just need to have it bored and honed for the time being until I can send it off to have it properly gone through because I desperately need to change things over to a new frame. If anyone has an estimate of how much it'd cost to have it shipped and gone through by a sponsored builder I'd love to have that information. Quote Link to comment Share on other sites More sharing options...
blowit Posted March 17, 2014 Report Share Posted March 17, 2014 If money is tight, you likely will not want to pay someone. Doing a topend in these is SIMPLE! One bit of advice, WASH YOUR BIKE beforehand and push compressed air between the cylinders before taking apart. There is always crap caught in there that gets in the bottom end. As I said though, one of my biggest peeves is people boring engines just because they don't know how to mic an engine. In most cases, we don't bore engines. Get the book, work your numbers. Knowledge is FREE! You have to inspect the bore for imperfections, first. believe it or not but grooves below the transfers is rarely a problem. You check for taper, out-of-round, and overall dimension. We wrote a quick sheet in Excel for this for our techs to follow. They have to record each measurement, then the taper and roundness is calculated. Then we enter the piston data and the clearance is calculated. With a knock that bad, I would expect to see a skirt hanging on by a thread or rings welded up. It does NOT have to cost much. You DO NOT need to buy Wiseco pistons. Research my threads and you will find that I am a strong supporter of hypereutectic pistons like Namura coated pistons. The high silica content and casted design gives a harder piston (less wear), more uniform expansion, thus a tighter clearance. I have seen stock engines last 15yrs! A piston kit might cost you 150 bucks. I don't buy into forged pistons unless they are required. They are softer thus take a little more abuse but that does not mean they are better for all applications. If you wait until the pistons break, you are pulling the engine and likely get to buy a crank. Now you are in for at least 500 in parts. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 17, 2014 Author Report Share Posted March 17, 2014 I looked at the skirts while I had the intakes off to check the reeds, there was no visual wear or cracks in the skirts, that being said that doesn't mean the back side wasn't a mess, I can't see that said so I don't know. My buddy races sprint cars and he has a guy who does all this engine work, I can imagine they know what they're doing when if comes to boring and honing but I'll do some research and see if there is any local guys that would know better about a banshee. A wiseco kit cost $190 for a complete rebuild kit, but I'll definitely look into those other pistons. I definitely don't plan on riding it much until I decide if I'm keeping it or selling it. Quote Link to comment Share on other sites More sharing options...
quadgod211 Posted March 17, 2014 Report Share Posted March 17, 2014 I would check the clutch basket out to make sure the coushins are not shot. Hold the basket in one hand and try turning the gear on the back with the other. If there is play then its shot. Most of the time guys get a billet basket and bolt on the old gear. I had a buddy with the same sound it was his basket...it viberated a lil as well Quote Link to comment Share on other sites More sharing options...
blowit Posted March 17, 2014 Report Share Posted March 17, 2014 You know, trying to give that another listen on a better sound system, I might get an experienced ear on that before tearing it down. It does sort of sound like the old clutch cushions too. It would be obviously quieter on the left side of the bike. Use the old stethoscope trick to try and isolate the noise. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 17, 2014 Author Report Share Posted March 17, 2014 I'll borrow my sisters stethoscope as soon as I can haha Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 17, 2014 Author Report Share Posted March 17, 2014 (edited) What are the clutch cushions anyway? What's their purpose? as far as I know that engine hasn't had any work on it since it was first assemblied in 87 I could record a new video and go on both sides, if that would help anyone Edited March 17, 2014 by TroyBrock Quote Link to comment Share on other sites More sharing options...
blowit Posted March 17, 2014 Report Share Posted March 17, 2014 Why not! I will see if I can help. Another thing to do is put the bike in gear with the clutch in and lets see if the noise changes. Typically if it is a clutch issue, just pulling the clutch will change the sound. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 17, 2014 Author Report Share Posted March 17, 2014 Pulling in the clutch lever didn't do any to the sound Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 18, 2014 Author Report Share Posted March 18, 2014 (edited) Why not! I will see if I can help. Another thing to do is put the bike in gear with the clutch in and lets see if the noise changes. Typically if it is a clutch issue, just pulling the clutch will change the sound. I just reread this, I did not put it in gear when I pulled the clutch in. It's too late to go out there now but I will go out as soon as I get back home tomorrow and do it again. Edited March 18, 2014 by TroyBrock Quote Link to comment Share on other sites More sharing options...
beez33 Posted March 18, 2014 Report Share Posted March 18, 2014 It's toast. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 18, 2014 Author Report Share Posted March 18, 2014 It's toast. Thanks for the response but I'm trying to narrow down what's toast Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 20, 2014 Author Report Share Posted March 20, 2014 (edited) Anyone? I'm considering opening the top end tomorrow, what should I look for/ check? I did a compression test today and it was 112/110 at 145F and that's down from 113/113 at 150F in September Edited March 20, 2014 by TroyBrock Quote Link to comment Share on other sites More sharing options...
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