Tim Mohr Posted May 29, 2016 Report Share Posted May 29, 2016 Hey guy's. I'm new to the board. I bought a J arm Banshee that had been sitting in a barn. The engine specs are .40 overbore, 19cc domes Toomey T6 pipes , Light porting and stock stator plate advanced 4 degrees . The I bought it It ran great on the test run. Then when parked gas was coming out of the overflows. After I got it home I've had a hell of a time starting it. I've checked the reeds, Re cleaned the carbs and did a compression test. It seems to only want to fire when I give it gas. I think this is on account That one cylinder has 120 pounds of compression and the other 30. I did not pay much for the machine. So I expected its fair share of problems. But I didn't want to do a rebuild right away. Is it possible my low compression issue could be a gasket? I'm going to get the parts to build a leak down tester. Also, The carbs had rebuild kit put in. Could my leaking actually be from the parts in this kit not being up to Mikuni Tolerances? I'm new to Banshees So any advice would be appreciated. Quote Link to comment Share on other sites More sharing options...
wayne_smith97 Posted May 29, 2016 Report Share Posted May 29, 2016 Shindy carb kits are junk and that motor is toast. Quit trying to run it before you make it worse than it is. Leak down test it before tear down. There is no riding in the condition it's in now v Quote Link to comment Share on other sites More sharing options...
Tim Mohr Posted May 29, 2016 Author Report Share Posted May 29, 2016 I don't plan on running it anymore. Basically it's leak down test and tear down time. I'm assuming it wouldn't be a bad idea to tear the bottom end down also. Quote Link to comment Share on other sites More sharing options...
sangheraent Posted May 30, 2016 Report Share Posted May 30, 2016 Id run it. Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted May 30, 2016 Report Share Posted May 30, 2016 No on the gasket. If head gasket was leaking you would either be burning coolant or blowing combustion gasses into radiator. Presume you did comp test more than once? Best advice is get a Clymers Repair Manual sounds like you will need it. Quote Link to comment Share on other sites More sharing options...
Tim Mohr Posted May 30, 2016 Author Report Share Posted May 30, 2016 I've got a manual ordered. After multiple compression tests showed the same results. I pulled the head. Near the exhaust port there was a more rounded ridge. On the low cylinder. It has 40 over Weisco pistons and what appears to be very mild porting. As the previous owner stated. The heads supposed to have been cut to 19cc domes. But, it doesn't look like anything has been done. I'll probably go to the next overbore size and cool head for this rebuild. Quote Link to comment Share on other sites More sharing options...
rubberneck Posted May 30, 2016 Report Share Posted May 30, 2016 Me personally id pull it all the way down and inspect and weld the crank. Ive had 2 bikes lose cranks shortly after acquiring them. If youve got it half way apart just go all the way and make sure its in good condition. While youve got it apart you can mod the shift shaft, shift star and put a pancacke bearing on the clutch and new water pump impeller and seal at a minimum. If necesarry billet clutch basket and new clutch. Those are the areas that always seem to take a shit so you may as well do it now and be done. As far as the rebuilt carbs. The last set of stockers i have leaked worse after the rebuild than before. I dont think the aftermarket needle and seats are worth a shit. Quote Link to comment Share on other sites More sharing options...
Tim Mohr Posted May 30, 2016 Author Report Share Posted May 30, 2016 The engine will be torn down the whole way. I don't want to do a top end. Only to have the crank take it out. I was hoping to ride it for the summer then do a frame up restored in the Winter. While the motors out. I'll get the frame blasted fix any cracks then have it powder coated. Who do you guys recommend to weld the crank and do a better port job on my cylinders. 1 Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted May 30, 2016 Report Share Posted May 30, 2016 Good idea on the crank! Close inspection of rod big end !! It ain't pretty when a big end bearing ends in the combustion chamber !! Quote Link to comment Share on other sites More sharing options...
sangheraent Posted May 30, 2016 Report Share Posted May 30, 2016 (edited) you should send the cylinders off to jeff at fast while you opened that motor up better now then later. if your going to do crank might as well go 4mill now then later. Edited May 30, 2016 by sangheraent Quote Link to comment Share on other sites More sharing options...
Tim Mohr Posted May 31, 2016 Author Report Share Posted May 31, 2016 I've thought of going 4mm on the crank. But, I'm not sure if my cylinders would work being they have a light port already. I think I read the Hot Rods stroker cranks are somewhat welded . If I go that direction. Would it be advisable to send it out for truing and welding? I would like a good all around motor. I'll probably be riding trails and coal. Possibly try some dirt drags. Quote Link to comment Share on other sites More sharing options...
bigweav81 Posted May 31, 2016 Report Share Posted May 31, 2016 Fast could hook you up. They will put extra weld on crank as well. Send you cylinders to them, and they could tell you if the current porting would be useable Quote Link to comment Share on other sites More sharing options...
Tim Mohr Posted June 2, 2016 Author Report Share Posted June 2, 2016 I'm going to try to get the motor out and tore down by the weekend. I'm sure there will be a more surprises. Previous owner said it never had any crank issues. I'm tearing it all down to make sure everything is good I'm hoping my frame is still somewhat straight. What are the areas that the frames normally bend and crack? Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted June 2, 2016 Report Share Posted June 2, 2016 Steering stem hoop, rear subframe Quote Link to comment Share on other sites More sharing options...
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