BansheeDFW Posted July 19, 2011 Report Share Posted July 19, 2011 Ok..I have a question on the amount of piston rotational play. I bought one of my banshees last fall and havent been into the motor unitl now. I was told it had a big bore and needed race gas.....yada yada. I am getting ready for another trip to little sahara and decided to break into the top end to find out what is really in this motor and inspect it. Here is what I found. Stock stroke and rods, stock cylinders appear to have a quite a bit of porting, 66mm bore, and cant for sure but it appears the head has been shaved? Domes in stock head appear to be stock. I pretty amazed this motor is only 369-370cc! It runs hard! Cylinder and rings look good and compression seems really good. The only thing I noticed was quite a bit of rotational play in both pistons. The worse of the two probably has .020-.030 of movement. Not side to side rock but rotation. I assume this should be very little to no movement? I plan on just slapping it back together with new gaskets until after I get back from this trip. Bad idea? Quote Link to comment Share on other sites More sharing options...
Rotax Raptor Posted July 19, 2011 Report Share Posted July 19, 2011 If you have it apart, I would at least put new wrist pin bearings in it. That's easy and cheap. I wouldn't think both lower rod bearings would be bad. Quote Link to comment Share on other sites More sharing options...
BansheeDFW Posted July 19, 2011 Author Report Share Posted July 19, 2011 Yeah Im thinking about it. I was thinking it could just be the wrist pin bearing. Im just concerned it may be the wrist pin bearing and rod wear. Is this pretty common? I just don't know. This is gonna be my beater back up shee on this trip. I was hoping to limp it along unitl I get back and then fully go through it. Maybe sleeve it to 68mm and maybe a +4mil crank...idk just rather save for a full build! I guess new wrist pin bearings would be cheap and easy. Should I replace the pin also? Don't the pin, bearing, and rod all kinda of wear together? Quote Link to comment Share on other sites More sharing options...
Rotax Raptor Posted July 19, 2011 Report Share Posted July 19, 2011 I just had the same problem on one of my banshees. I could feel the piston rotating a bit through the exhaust ports. Changed the wrist pin bearings and it was as good as new. Quote Link to comment Share on other sites More sharing options...
BansheeDFW Posted July 19, 2011 Author Report Share Posted July 19, 2011 Really! I guess that was my main question. I was wondering if the wrist pin bearings tend to wear more than the rest, or if the rod main bearings, wrsit pin, bearing and rod all wear pretty evenly together. If I can just replace the wrist pin bearing and hold off on a full rebuild for a while that would be better. Rather save my $$$ for a cub or cheetah build on one of my other shees anyway. Ill just replace the wrist pin bearing and see how much play is still there. Ill update later. Thanks Quote Link to comment Share on other sites More sharing options...
BansheeDFW Posted July 19, 2011 Author Report Share Posted July 19, 2011 One more thing. Any recommendations on bearing brand? Example OEM vs Vito's vs Wiseco? Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted July 19, 2011 Report Share Posted July 19, 2011 Well 2 brgs @$16 or risk not having anything to work from or sell off Quote Link to comment Share on other sites More sharing options...
okbeast Posted July 19, 2011 Report Share Posted July 19, 2011 I don't know what the actual spec is, but I would think it would only be .5mm to 1mm of rotational play just from all the tolerances in the separate components. Replace the bearings and see if it helps. Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted July 19, 2011 Report Share Posted July 19, 2011 If you have pistons off also check crank/rod. Quote Link to comment Share on other sites More sharing options...
BansheeDFW Posted July 19, 2011 Author Report Share Posted July 19, 2011 If you have pistons off also check crank/rod. I agree Larry. So it looking back over it today, it appears to only have about .010 -.020 but still excessive to me. I ordered some wiseco wrist pin bearings. Once they arrive I will pull the cylinders and check everything. I will inspect the rod main bearings, rod end, wrist pin, and ring clearance while i have it apart. I'll update next week. Thanks Quote Link to comment Share on other sites More sharing options...
BansheeDFW Posted July 19, 2011 Author Report Share Posted July 19, 2011 I don't know what the actual spec is, but I would think it would only be .5mm to 1mm of rotational play just from all the tolerances in the separate components. Replace the bearings and see if it helps. Haha manual actually says "there should be no noticable for the play" got it! Quote Link to comment Share on other sites More sharing options...
okbeast Posted July 19, 2011 Report Share Posted July 19, 2011 Ya, hell make sure you put a rag under the piston when you pull it apart in case any pieces decide to fall apart. If you run into any issues holler at me, I'm just over by Cleburne. Quote Link to comment Share on other sites More sharing options...
BansheeDFW Posted July 27, 2011 Author Report Share Posted July 27, 2011 Hey thanks for the offer okbeast! Nice to know your close by. I also met TNTS355 on here too. Yeah I definitely used a rag! Made that mistake a long time ago and never again! So I finished the tear down and unfortunately it wasn't the wrist pin bearings! I pulled the cylinders off to find the wrist pin bearings had no play and the rod main bearings are horrible! I took some video and pics of it all, and will try to post them tomorrow. Problems found: 1. Left side of the crank looks as if it wasn't pressed correctly. Maybe its just me but the left rod prolly has .100"+ of side slop, and almost zero clearance between the left side of the crank and case. The right side rod prolly has .050" and the crank looks centered in the case with equal clearance around it. 2. With the rods pressed over solid to one side there is a considerable amount of twist and rock in the bearings. I think with a stock crank and cylinders punched .080 over I'm going to clean everything and button it up with new gaskets for now. I'll run the dog shit out of it for a while as is and save for a full kit. Something like a 4mil. Any suggestions on what to plan for? I dont want full on drag but something capable of being fast trail or dune ridden but still go drag for fun occasionally. I owned a 421 long rod with ported stock jugs and high comp. years ago and loved it! Cheetah, Cub, Serval? Which one and why? No problem running 110 octane all the time also... running T5 pipes and stock carbs now. Quote Link to comment Share on other sites More sharing options...
Jereme6655 Posted July 27, 2011 Report Share Posted July 27, 2011 Hey thanks for the offer okbeast! Nice to know your close by. I also met TNTS355 on here too. Yeah I definitely used a rag! Made that mistake a long time ago and never again! So I finished the tear down and unfortunately it wasn't the wrist pin bearings! I pulled the cylinders off to find the wrist pin bearings had no play and the rod main bearings are horrible! I took some video and pics of it all, and will try to post them tomorrow. Problems found: 1. Left side of the crank looks as if it wasn't pressed correctly. Maybe its just me but the left rod prolly has .100"+ of side slop, and almost zero clearance between the left side of the crank and case. The right side rod prolly has .050" and the crank looks centered in the case with equal clearance around it. 2. With the rods pressed over solid to one side there is a considerable amount of twist and rock in the bearings. I think with a stock crank and cylinders punched .080 over I'm going to clean everything and button it up with new gaskets for now. I'll run the dog shit out of it for a while as is and save for a full kit. Something like a 4mil. Any suggestions on what to plan for? I dont want full on drag but something capable of being fast trail or dune ridden but still go drag for fun occasionally. I owned a 421 long rod with ported stock jugs and high comp. years ago and loved it! Cheetah, Cub, Serval? Which one and why? No problem running 110 octane all the time also... running T5 pipes and stock carbs now. What to plan for? it sounds like your stock stroke crank is starting to seperate.......and if that's the case then you should plan for having that crank grind to a stop against the side of the engine case. at least that's what it sounds like is happening with your crank... Quote Link to comment Share on other sites More sharing options...
bansheesandrider Posted July 27, 2011 Report Share Posted July 27, 2011 Hey thanks for the offer okbeast! Nice to know your close by. I also met TNTS355 on here too. Yeah I definitely used a rag! Made that mistake a long time ago and never again! So I finished the tear down and unfortunately it wasn't the wrist pin bearings! I pulled the cylinders off to find the wrist pin bearings had no play and the rod main bearings are horrible! I took some video and pics of it all, and will try to post them tomorrow. Problems found: 1. Left side of the crank looks as if it wasn't pressed correctly. Maybe its just me but the left rod prolly has .100"+ of side slop, and almost zero clearance between the left side of the crank and case. The right side rod prolly has .050" and the crank looks centered in the case with equal clearance around it. 2. With the rods pressed over solid to one side there is a considerable amount of twist and rock in the bearings. I think with a stock crank and cylinders punched .080 over I'm going to clean everything and button it up with new gaskets for now. I'll run the dog shit out of it for a while as is and save for a full kit. Something like a 4mil. Any suggestions on what to plan for? I dont want full on drag but something capable of being fast trail or dune ridden but still go drag for fun occasionally. I owned a 421 long rod with ported stock jugs and high comp. years ago and loved it! Cheetah, Cub, Serval? Which one and why? No problem running 110 octane all the time also... running T5 pipes and stock carbs now. Plan on spending ALOT of money because your crank is seperating and when it finally lets go there is going to be alot of shrapnel causing ALOT of damage. At a minimum you will need a crank assembly, pistons, repair your head(cut and rechamber) or new domes for coolhead,bore job or possibly new cylinders or sleeves, and possibly even cases if they break. From the way you describe it it could let go as soon as you fire it up. The bottom line is you should just fix it while it is apart and if you don't have the money, let it sit until you do. If you are going to run the dog shit out of it, it will be sitting broken while you save your money. If it was mine, I would put a crank in, make sure the bore is good with forged pistons, port it, increase your compression, bump the timing, add some reeds and jet it properly. That will make a nice all around bike for you. Quote Link to comment Share on other sites More sharing options...
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