locogato11283 Posted January 31, 2013 Report Share Posted January 31, 2013 I don't have illusions, that's you. You want a 100% definitive answer. I doubt you get it. No one is going to guarantee anything in this sport. You don't know if a 10mm will live or not. If you already know a 4DM is producing the numbers and curve you're looking for, then why haven't you built it? Fact is that we don't know one way or the other. Sometimes you've got to be the guinea pig. You think I didn't spend a fuck load of money to be at the top? Sometimes it pays off. I say build the 10 with good components and a good builder and whip people's asses. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 31, 2013 Author Report Share Posted January 31, 2013 No one is going to guarantee anything in this sport. You don't know if a 10mm will live or not. If you already know a 4DM is producing the numbers and curve you're looking for, then why haven't you built it? That's just it, I don't know if the DM could work, that's why I made a post. I never said it would. I was inquiring if I could do some machining to manipulate it and instead it just feels like you are pushing the 10 mil agenda down my throat. I want as much displacement as possible with out going with a big stroke. Again, just because it doesn't fit your agenda doesn't make it a retarted idea. Almost 30 posts in and not one definitive answer. That's why it's not built. The money is there, but I just wanna make sure it gets done in a way that doesn't become a catastrophe. Why is that such a problem? Original post: 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? Just never knew exactley what the power characteristics of the DM were, hence my post. I would rather figure it out from the fellas that have one then just call a builder and waste their time. Never did I say that the DM is for me, I'm just asking if I can make it work with a good builder. All Have confirmed is I'm not making any attempt at a 10 mil build. Quote Link to comment Share on other sites More sharing options...
m671054 Posted January 31, 2013 Report Share Posted January 31, 2013 Do you have any specs from a 4 or 7 dm? Piston part# would be were i would start. Second question is what kinda timing numbers do you think you want. Ill check the 10 mil sheet i got to compare some numbers. Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted January 31, 2013 Report Share Posted January 31, 2013 I can answer that for you. A DM of any stroke is going to have a better curve and make more power than a Cub of the same stroke. Stroke is where it's at in my opinion. I'm not a fan of the huge bore motors. You've been talking about this stuff for months. I remember discussing it in the Shoutbox. Why not just build a 4DM and be done? You're already sure a 10mm will break. I guess I'm not sure what you're wanting to hear at this point. Quote Link to comment Share on other sites More sharing options...
dozer Posted January 31, 2013 Report Share Posted January 31, 2013 Does anyone know what kind of gas andy used on that dyno run. Quote Link to comment Share on other sites More sharing options...
Paulie B Posted January 31, 2013 Report Share Posted January 31, 2013 What you are talking is what I've wanted to do for a few years now. You want ridiculous power everywhere out of a 2 stroke. I think it can be done but at a whole lottah time and money invested. I'm talking totally off my head now but I do have some 'hands on' experience here with my 400 single blaster. I made a trail pipe for it using a DG YZ400 dirtbike pipe. I ended up adding a few inches to the headpipe- just to make it fit the chassis. What I ended up with was a powerband that pulled the wheels up litterly right of idle in the first 4 gears. The problem is it ended at about 5000 rpm. I had the motor re-ported and it still didn't make a difference. The pipe was just all wrong. I picture a 4mil DM having great torque because of it's shear size but then ripping your arms out of socket when the powerband really hits. A powervalve WOULD help a lil but the pipe will aways be holding you back. If you could have an adjustable pipe like the 350cc hydro boat racers use, a powervalve, and a big motor you could prolly get what you want but like I said that would probably never happen. Here's a vid of an adjustable headpipe incase someone is wondering. Here's a vid of my blaster with a too long headpipe Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted January 31, 2013 Report Share Posted January 31, 2013 So basically you want to make like a Super Sized Serval? So these long stroke motors won't hold up to long continues use such as 10+ lap flat track race? As you have stated builders have built motors for flat track that don't live up to expectations? Wise choice to maybe not to totally trust them for an answer as they may just want to sell a job, and if it doesn't work as "expected", they'll say "That's what you told us to do" . Maybe best to contact CP directly to see what they say, jmho. Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted January 31, 2013 Report Share Posted January 31, 2013 So basically you want to make like a Super Sized Serval? So these long stroke motors won't hold up to long continues use such as 10+ lap flat track race? As you have stated builders have built motors for flat track that don't live up to expectations? Wise choice to maybe not to totally trust them for an answer as they may just want to sell a job, and if it doesn't work as "expected", they'll say "That's what you told us to do" . Maybe best to contact CP directly to see what they say, jmho. CP isn't going to know more than the builders do. The builders are the ones that deal with the end customer, not CP. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 31, 2013 Author Report Share Posted January 31, 2013 CP isn't going to know more than the builders do. The builders are the ones that deal with the end customer, not CP. Definitely have to agree on that.The only reason I'm looking in to bore over stroke is because once I was ready to go to a builder for a 10mm serval I briefly spoke with Cam about it and he said he wouldn't be confident in it and reccomended possibly either combination from our previous conversation( decked super cub, or cheetah) Quote Link to comment Share on other sites More sharing options...
m671054 Posted January 31, 2013 Report Share Posted January 31, 2013 2 things. First i think your both wrong about cp. They are the ones with the most info on these cylinders as they designed them. Second ive been looking over my dimensions sheet on the 10 dm and comparing it to other cp cylinder specs i have compiled. It seems that if you deck the bottom of the cylinder your going to either have to tall of an exh port leading to high durations or at bdc the crown will be above the exh and transfer port floors. Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted January 31, 2013 Report Share Posted January 31, 2013 2 things. First i think your both wrong about cp. They are the ones with the most info on these cylinders as they designed them. Second ive been looking over my dimensions sheet on the 10 dm and comparing it to other cp cylinder specs i have compiled. It seems that if you deck the bottom of the cylinder your going to either have to tall of an exh port leading to high durations or at bdc the crown will be above the exh and transfer port floors. You're delusional if you think Calvin knows what motors are being used where. The BUILDERS are the ones setting up and selling the motors to the end users, the CUSTOMERS.. The customers aren't calling CP and telling them what they're using the motors for. So, you're wrong. Quote Link to comment Share on other sites More sharing options...
lms1977 Posted January 31, 2013 Report Share Posted January 31, 2013 I wonder if a big wheel crank and better rods "bigger pin" maybe even a longer rod would hold up? Down side is big$$$$ for crank amd cases. Good luck with it.. the builder who built your current motor which you love what does he say about the dm cyl? Quote Link to comment Share on other sites More sharing options...
RZBansheeMan Posted January 31, 2013 Report Share Posted January 31, 2013 Have ya considered a 4 or 7 mm "super serval", massaged into the port timings you want, or are they not producing very good numbers.. ? Or maybe in the case of a 10 mm serval / super serval.. if they make that much more torque then what you have, couldn't you pull more gear and keep the revs down a lil bit.. ? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 31, 2013 Author Report Share Posted January 31, 2013 I wonder if a big wheel crank and better rods "bigger pin" maybe even a longer rod would hold up? Down side is big$$$$ for crank amd cases.Good luck with it.. the builder who built your current motor which you love what does he say about the dm cyl?Jim seems to think the DM could work and we talked about the heat issue which seems like it could definitely be addressed. Just a bit more cash ; )I Havnt spoke to my other builder of choice yet but he is very familiar with machining cylinders this way to get a better curve. Yeah it gives up a little bit up top but with a motor that big it's no big deal. I just would like to know if the added machine work would make the difference in the way the power just slams you. I know anything that big will have torque like a sum' bitch but when it gets to moving heat and really comes alive I need it to not be the light switch. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted January 31, 2013 Author Report Share Posted January 31, 2013 Have ya considered a 4 or 7 mm "super serval", massaged into the port timings you want, or are they not producing very good numbers.. ? Or maybe in the case of a 10 mm serval / super serval.. if they make that much more torque then what you have, couldn't you pull more gear and keep the revs down a lil bit.. ? That's the only solution to the big stroke is the gearing. Hoping I can make the other idea work, but if it won't then I'll bite the bullet and do a 10mm. Just really trying to avoid that. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.