trickedcarbine Posted January 25, 2013 Report Share Posted January 25, 2013 Ok so up till the last few recent years guys would buy a Cub cylinder with say a 7mm stroker lay out and then deck them down to work with a 4mm crank effectively trading some top for an impressive low end. Basically which is now the serval style cylinder. My question is does the same theory apply to the bigger CP Industries cylinders like the DM? Can I buy a taller cylinder and take it down and get some low end out of it. I had ZERO interest in a 10 mm serval before people go posting that it is my better option. I have had builders question whether or not a 10mm crank would survive the sustained RPM's of my type of riding so it's just out of the question. I'd like to do something custom with a DM if possible and I don't really care how cost effective it may or not be. I want the maximum amount of displacement for a 4mm with out it being Drag only type of power. Is this possible with the DM or only in the regular cub series of cylinders? Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted January 25, 2013 Report Share Posted January 25, 2013 Have you ever ridden a DM? They make a fuck load more power from top to bottom than any other motor I've owned. I think before you go trying to do something silly, you need to ride one. The power my 18DM makes off the bottom is fucking ridiculous compared to my old 10mm Cub. Same with the 10DM I had.. Tons of power everywhere. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 25, 2013 Author Report Share Posted January 25, 2013 Alrighty, any one in Michigan got a 4mm DM I can rip? Quote Link to comment Share on other sites More sharing options...
m671054 Posted January 25, 2013 Report Share Posted January 25, 2013 It would be more than decking anyway as the oring grooves are on the cyl not the head. Could probably get a twister setup built like you want Quote Link to comment Share on other sites More sharing options...
Finch Posted January 25, 2013 Report Share Posted January 25, 2013 think youd be fine with just a dm. no decking i know brandons is a torquey sob Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 25, 2013 Author Report Share Posted January 25, 2013 It would be more than decking anyway as the oring grooves are on the cyl not the head. Could probably get a twister setup built like you want The process I'm referring to is when builders take the cylinder and remove material from the base of the jug so that the timing is lower. It was a sort of common practice before the servals were out. Builders would do it to 7mm cubs and configure them to work with a 4mm crank. It would effectively give the the motor more torque by lowering the timings. Although a decked 4mm cub would usually come in around 80-85 HP at peak it would have a solid 50 ft lbs. of torque with a very usable curve and that's on gas. This is how some of the winning Pikes Peak Super Cubs were done as well. I have just never actually rode a DM and I thought that they were pretty much a drag style port format that would not come out of the hole. I have. Even searching for Un ported 4mm DM dyno graphs with no success. So if any one happens to have one please let me know. Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted January 26, 2013 Report Share Posted January 26, 2013 Small block mini twister Quote Link to comment Share on other sites More sharing options...
dozer Posted January 26, 2013 Report Share Posted January 26, 2013 Me and a friend were talking about this today. I was wondering if you could get a better torque curve out of a 10 cub or a 4 dm. Quote Link to comment Share on other sites More sharing options...
camatv Posted January 26, 2013 Report Share Posted January 26, 2013 tylers GAS dm rips out of the hole... and umm yea a large CC motor BETTER have more power everywhere. kinda hard to compare a 400cc motor to a 700-800cc motor thats 2 TIMES the displacement. should feel like a 4 cyl cub... does that bring any light to the massiveness of these engines?? seems that the alky ones are the finiky ones... not sure why.. might also look into sustained running and what kind of heat capacity the dm's have.... Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 26, 2013 Author Report Share Posted January 26, 2013 Nay on the Twister. I'm literally looking to mimic the curves of a 10mm serv out of a 4mm. And a 4mm DM with lower port timing seems to be the best way to do so. The heat thing is the only thing hat worries me. Is it possible to open the water jackets up on these things at all. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 30, 2013 Author Report Share Posted January 30, 2013 Bump, One last time before I start calling builders. I just like having all the ducks in a row before I waste people's time Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted January 30, 2013 Report Share Posted January 30, 2013 Bump, One last time before I start calling builders. I just like having all the ducks in a row before I waste people's time I think you're going to be wasting their time anyway. If you want a 10mm curve then build a 10mm. Are you just scared of a 10mm motor? Quote Link to comment Share on other sites More sharing options...
frog Posted January 30, 2013 Report Share Posted January 30, 2013 The cooling seems to be a issue with the DM cylinders but there has to be a way to cool them down. I want to build a DM dune bike to drive. Some one please help. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 30, 2013 Author Report Share Posted January 30, 2013 I think you're going to be wasting their time anyway. If you want a 10mm curve then build a 10mm. Are you just scared of a 10mm motor? Once again..... No! However I have had several builders tell me it WILL NOT live under sustained RPM. Trails and dunes and drag racing are find but I just don't think you get the issues that are associated with the heat soak in Ice racing. You can hot lap a drag bike how many times before you have to shut it down? Then there is the riding I do where you literally hot lap the motor 20 laps and on a nice half mile track that is equivelant to 40 WFO 600' passes with barely any throttle chop to set up for the turn. You guys all seem to think that drag racing or hill climbing is the only test of a motor. When Cam, Dan Hull, John Stallworth, Mat Shearer, and Jim all say they doubt a 10 mm would last half a season in my bike, then I definitely don't think I have any business putting a 10mm together. There is one bike that runs a 10mm cub, but it doesn't have nearly the time on it like mine would and it is massively de tuned. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted January 30, 2013 Report Share Posted January 30, 2013 Small-block twister. Louie can machine it with whatever port timing you want, just call him. There are plenty of ways around the cooling problems... Quote Link to comment Share on other sites More sharing options...
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