bricktop2011

Just a little update, I had the domes cut at by Lew at Twister. I put everything back together, sealed it up, put the timing plate back to 0 to be safe, and ran it at Sandlake a couple different days now. Working real nice. Previous engine I was running was a pretty strong dune ported 350 that put out 60HP on a dyno. This thing is nothing like that one. I can now pretty much can do anything one higher gear now, with much better low end power as well. Haven't done any top speed runs, but I blew by a friends Maverick who was doing 60, and I was only in 4th with plenty of pull to go. Kicks hard, but does not kick back as long as I pay attention to what I am doing. No broken side cover, stripped gear or bruised foot to report. Real happy with this motor, now just to grow into it...

Reed cage off, pic of the intake side.

Came with FMF pipes, but they have been modified into "big bores" I suppose. The outlets were cut off and bigger pipe welded on, also the stingers are much bigger around than any others I have seen. Basically, the ends that get clamped together are much bigger than your avg T4 T5 FMF, etc..

O-Ring is in the cylinder. You can see it (brown) in the pics of the cylinder tops. But yes, seems like 3bond was smeared everywhere too. It was sealing fine, I know that.

Came with FMF pipes, but they have been modified into "big bores" I suppose. The outlets were cut off and bigger pipe welded on, also the stingers are much bigger around than any others I have seen. Basically, the ends that get clamped together are much bigger than your avg T4 T5 FMF, etc..

AWOL for a while, back now. Glad you guys like the thread. Latest update is that I have the kicker gear replaced, side cover back on, and I will be taking the head over to Louie at Twister tomorrow to have him recut and polish the chambers. You guys are probably gonna hate me for taking this bike apart, but here it was before I stole the parts I wanted from it. I didn't realize it was such a "period piece" It's hideous, but in a really good way.

Sure thing. I should be able to get to them in the next day or so. So back to my problem, I am thinking a cool head would be impossible, probably never find one to fit the stud spacing, and I don't think its a good idea to try and seal an O-Ring against another O-ring. Re working the chambers sounds correct, and I left a message for Louie, but have not heard anything back yet. For a less permanent solution. how about a thick gasket or machined spacer between the head and cylinder? Is that a reasonable idea? I read that once Vitos made a 2mm plate, but I don't know if that would be thick enough or would even seal with an O-ring on one side but not the other. Thanks again for the great info guys, here is that pic with Chad. Has anyone ever attempted to scan and archive those old Dirt Wheels magazines?

A few pics of the 10mil X 72mm. Cylinder appears to be sleeved with O-ring cut in. Piston is 423P6 72.5mm jetski piston Bottom of the head, showing chamber width Top of head showing closeness of inner holes Approximate center to center spacing of head studs Piston protrudes from deck approx 1mm at TDC. BDC and ports

Thanks for the tip justwannarace I'll see if I can track him down. If he could modify what I already have, that would be sweet. At least I know it will bolt on!

No worries, ClaudeMachining, I am a noob here on BansheeHQ, no shame in that. And yep, it really looks like a stock head to me. No removable domes. Engine runs pretty strong, +6" arm and wants to lift the front end at will. Has modified pipes as well. the outlets of the pipes and the stingers are bigger around than any I have seen. Someone has cut off the ends of the pipes and welded the bigger outlets on. I'll post some pics tonight of the head and tops of the cylinders, you guys should be able to tell if they are truly stock or not. I'll measure the stud placement as well, perhaps it will match up with a Super Cub head and I can proceed with my plan. I would guess that this work was all done long before you could get whatever bigger and longer cylinders you wanted, dropped off on your doorstep in a cardboard box.

Stroke is 64mm bore is 72mm. I bought it used after I pulled a plug and measured the stroke. I bought the whole bike for the engine and some other parts. It runs, I knew it was a 10mil, and a good deal. I am in the Portland Oregon area, I would believe the engine was built in the 90s sometime by the style of paint and accessories. PO said it was Chad at Holeshot Racing who did the work. Later on, the crank was replaced with a 10mm twister, shop unknown. I have been riding these things for 20 years, so I know a bit about them. Just haven't come across such a monster motor that looks so close to stock. I am hoping a super cub cool head can fit this thing, so I can put some big domes on and run it on pump gas.

Hi guys, First off, thanks for all the content creators here on BansheeHQ, I have searched, read, and learned so much on this site. By far the best Banshee resource on the net. I have a motor that I want to get more "rideable". It is a 10mil with a 72mm bore that is a bear to kick and has to run on race fuel. I want to lower the compression and run pump gas to make things easier. Compression was about 190 lbs last time I checked it. I have broken the kicker gear, cracked the side cover, lived days with a sore foot, and ran all over hell and gone to buy race fuel. I am over it. I can have just about as much fun or more with my 60HP ported 350. I only ride at the dunes, but I don't drag, show off, or do anything competitive. I just like to climb everything with ease and pull some wheelies. My thought was to put a cool head on it, and run some bigger domes. When I pulled the head, I noticed that the bolt spacing is not the same as the cool head. The bolts are spread out farther for the big pistons. I didn't realize there were 72mm bores in there. The jug actually looks stock , but longer, and the head appears stock to me as well. Any ideas what this thing is, and how I can lower the compression? Spacer plate, gaskets, chamber cutting? Cool head that fits strange bolt spacing? <img></img> <img></img>

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