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  • Fl400 top end on 250r lower?

    Saw a guy selling a set of cases stating that they were machined to fit an fl400 top end. How is this possible what has to be done to make this combo work he also states that they are machined for a 7mil crank can you use a stock lower? What pipe and carb combo would you use and would frame mods have to be done to make it fit?

  • #2
    I've seen it done on a TRX before from Dennis Packard racing. Its a setup that he specialized in, maybe give him a call for more details.

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    • #3
      You know Dennis? He is in my shop once a month at LEAST! My boss actually built all the pipes and some of dennis' pilot motors believe it or not, we used to dyno all of his stuff till recently when he bought one!

      You have to weld on the case to make enough of it to move the studs out. You have to machine the cases for the sleeve to fit, and you have to machine for the crank. They will run with stock cranks or strokers. If the cylinder is set up for a stroker, you'll have to remove the spacer or if it is ported for a stroker, you have to run one or your durations will be WAY OFF! A polaris 400 top end it MUCH easier to put on and a lot less work. A rotax 800 top end will also go right on but they are little more "pipey". All of these motors are capable of 100+rwhp. We have a puma top end on a STOCK BOTTOM END making 92rwhp on 91oct! Those 250R's are about the best you can get! A stock crank and tranny that will handle 100 hp. (although I would recommend billet gears in the tranny, crank is fine!)

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      • #4
        plz tell me more about the polaris and rotax top ends, what has to be done to run them and how much are where to buy the parts to do it?

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        • #5
          You have to split the cases and machine them to except the larger sleeve. Pull the studs, fill with aluminum bolts, cut of, relocate studs, drill, tap, check your porting to make sure the durations are correct, (if you need a spacer or not) Use the head from the new cylinder.

          Really if you want this power with alot more ease, Calvin Pollet Ind. makes a whole bunch of different top ends for the 250R that BOLT ON, and only require minimal machining to clear the sleeve. They have different port arrangment for top, mid, or bottom, plus you can port them your way when you get them. I dont know the price but I know you get the cylinder, piston, intake, head, and reeds. The puma I spoke of earlier is a 400cc with a 4mil stroke. They build up to 540cc with a 6mm stroke. Capable of 140hp!

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          • #6
            Polandas as founder Dave Moore calls them or Hondalaris as Pete From Hybrid Engineering calls them.

            From what I know about them. Fl400 Cylinder. Yz250 piston or Rod cant remember exactly! They have nothing but problems from what ive heard! Youd be better off building a ESR 350 Cyl with a 4 or 5 mill crank!

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            • #7
              Here's a JDI Racing's rotax(471) vs Hybrid Engineering's saber(500) for ya...
              http://www.youtube.com/watch?v=jNdafCKOuOk
              Last edited by jadleybray; 03-27-2009, 11:30 AM.

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              • #8
                Originally posted by BigTBones
                Polandas as founder Dave Moore calls them or Hondalaris as Pete From Hybrid Engineering calls them.

                From what I know about them. Fl400 Cylinder. Yz250 piston or Rod cant remember exactly! They have nothing but problems from what ive heard! Youd be better off building a ESR 350 Cyl with a 4 or 5 mill crank!

                You use the STOCK pilot piston, and the STOCK 250R crank. If you want, use a stroker. The only problem with them is all the welding you have to do to the case's. It makes them weak around the edges but they still run and I've seen them run for years. They ROCK up sand mountain! The polaris and rotax dont require the welding, only moving the studs out. They are a very reliable setup.

                If you want 60-70hp, get an ESR. Then you have to order parts directly from them, and are at thier total mercy. If you want some realy power, dont spend all your money making someone rich for not much gain. I have NEVER seen an ESR motor do any good up Sand mountain. On the flats they may rock, but the "flat aint where its at" It take REAL power to pull up the mountain! A stock 250R cylinder, bored to 74 and a 4mm stroke (327cc) will do damn near 80 on alky! Why spend more for less?

                And it is the CP cylinders that use the YZ250 intake ONLY! No pistons or rods!

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                • #9
                  Jadleybray,

                  Video link did not work.. Sent me to a front page..

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                  • #10
                    iam with 3wheelergod on this one... the pilot-brid is a hell of a engine, but is very "one off", i would go with a puma or sphyix (sp?), i ran a pro-x cylinder for years and loved it, i was waiting for the puma to come out before I got out of bikes for awhile. a 400cc puma will be cheaper in my personal opinion... and alot easier to pull power out of

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                    • #11
                      Fixed the link for you guys

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