Best Banshee Build for J-arm banshee

[salmon_slayer06]

I bought an 87 J-Arm banshee last year. It was in decent shape. I've always liked the banshees, and never thought I'd actually own one. It was fun while it lasted. This summer I had an unexpected problem with the machine. I went up North to go riding for the weekend and had the motor seize up on me. I didn't tear into it right away. Before the break down I installed a new clutch kit. I had all the tools to do the job right and that was installed correctly. But I was wondering if the clutch nut backed off and decided to come off and get jammed in the gears. When the time came I decided to start a complete engine tear down. Off came the plastics, carbs, pipes, etc. I knew right away that the clutch wasn't at fault when I took the right cylinder pipe off and out came metal bb's, or metal type shavings that looked melted. Oh boy... Right away I thought new pistons, new head, bore and hone.... so I thought. Well I proceeded to remove the clutch cover, nothing wrong in there, the stator side.... same thing. Next I took the head off. Right side had divots in the top dome like somebody took a center punch to it all over. The top of the piston same thing. I thought maybe a ring had broke and that caused it. Off came the cylinders and out came the pistons. Left side was unharmed. I stopped right there. I rocked the connecting arms side to side on each and found the right side had a good amount of play in it. Must be the crank connecting rod bearings. Thats as far as I got. Assumeing I need a new crank.... thats where I'm at now.

 

I been sold on the Hot Rods +4mil crank, paired with the biggest pistons I can put into the stock cylinders. Theres a set of pistons that must be used with this crank. I don't know about the head though. Is it useless now. I don't know if its worth keeping the old damaged one, getting it machined to match what I may get done or what. I did like the phatheads racing ones, but kinda shyed away from that company not making them anymore and that they are pricey. So I'm left with what I should do.

 

This is whats on this machine now... A nice set of Toomey T'5s that came with it, Kehin carbs I don't know what size they are but seem to be plenty big enough to flow more fuel if needed, and also has Boyesen Reeds. Bike was always jetted and I adjusted the needles so it never  ran lean. The other owner didn't mess with the motor, he did have the top end rebuilt. The original crank must of had just too many hours on it and the bearings must have been original.

 

The type of riding I do.....

 

In the upper part of Michigan we are blessed with the best trails around. In fact there are citys and towns that actually raise money in clubs and donations to prune, grade, and take care of the trails summer and winter. The section I ride on is all sand. Wide, curving sand trails. The same sand as you find in the dunes but even finer. So I always have my paddle tires on this. In fact the ones I have are the infamous Taller Haulers, from Skat Trak, but are no longer made. These were made in the USA and have more paddles than any set I can find. At times on these trails its wide open for a minute, than winding curves with hills, berms, woops. At times there might be a section with not so much sand and I slow down and just let the motor cool off and open it back up once I hit the sand again.

 

I haven't bought anything yet. My plans are to keep the stock cylnders. I don't know who can machine the cylinder head to the proper squish, or whatever its called... but would like to know who can do this and when it should be done. Any info on who does this is appreciated. Now.... I may go this route... Stock crank trued and welded with the Blaster pistons and matching connecting rods. I don't know too much about this set up and I will be looking into it. Also would I be better off to get the cylinders ported and what port job would I want? Who would you recommend?

 

I have been wanting to post this for a long time now and have finally took the time to do it. I have access to bridgeports and CNC machines if theres something I may do myself like finishing the head if I could. So I appreciate the replys and I know some of you on here have a wealth of knowledge on these motors. Thanks in advance. -Jason

[Jereme6655]

Jason.....the +4 crank is gonna really help that bike with power.....HOWEVER....going with the largest pistons you can fit will NOT help. You do NOT want to waste bore sizes on the pursuit of power.....2 strokes don't see much power at all from that.

 

When it comes to heads.....you can find decent shape heads on here (stock) for about $15-20. However if you want a +4 crank.....you should go with a aftermarket head with interchangeable domes. You can usually pick one up on here for around $100.

 

You will want your cylinders ported for the +4 crank too.....that will really wake that motor up.

 

 

[salmon_slayer06]

Thanks for the info. What head would you get? I know of at least 4 different ones... phathead, coolhead, NOSS, and I can't think of the other right now. I'm unsure of what dome size to use. I would be running 93 octane gas with bel ray 2 stroke oil 50:1.