I am putting the EFI from KMS on in september and have $2000 to spend. The case is split getting the gear fixed and doing some internal mods would labor wise be inexpensive now. I have looked at the 730 big bore kit from HP research 1700$ or the ported head? I like riding the dunes and trails but nothing better than winning the race. What would you guys do to get the most power for the money. Nothing else done to the bike other than pipe.

 

Get high compression piston from MR. Hp, and get some head work and cams. Should be able to do this for less than two grand and you will see a big increase in hp. Look at the dyno numbers of Sandragggen. 65hp with a stock bore ds. Mr. Hp 70hp out a stock ds. Port work was the major difference in the numbers.

 

Would the 730 kit yield more power than head work and stock bore with the high compression piston. I can get the HP research 730 bolt on for 1700$ but no head work or cam.

 

NOt sure because I havent seen the 730 kit run. In my opionion, the high compression motor with cams and headwork should out flow the 730 kit with stock head work and stock cams. The head work and cams help the motor flow more air.

 

I was also hoping to add the turbo to the efi later this year. Would the air flow issue matter more or less with the pressurized air from the turbo?

 

If you are sure you are going to add the turbo don't increase the compression over stock. I do think Big is right though the higher compression stock bore with some porting would be a better choice than the big bore stock head setup...

 

If your going to add the turbo. I would not get a high compression piston. Turbos and super high compression dont tend to work well together. Hopefully, Scooby or Majorecho will chime in. They both are running turbo setups. They will be more helpfull in that department. Scooby is running a stock bore stock stroke Ds with a turbo and 20lbs of boost 120hp. Majorecho is running a 720 Ds with a turbo, Hp ???. (I believe its a 720?)

 

If the case is going to be split, I would stroke it! You will then have a solid foundation for what every you want. You can go with a +8mm Roller crank with stock bore which will give you 715cc. Latter on add a 105.5mm piston and get 796cc. Now were talking!

If you are only planning on spending $2k and never again add more (yeah right!) then a race head would give you more power then just a stroker with a stock head. The fact that you already have the cases split, 90% of the labor is already done to drop in a new crank.

 

My hope is to produce a quick out of the hole reliable machine that is still rider friendly for duning but sticks with most machines when hill climbing and racing. would the 730 with the original stroke and head but adding the turbo set up work best and then do the head work later. In order to increase to the 796cc i would have to go with a higher compression and that would not work well for the turbo. I am stating what I should be puting question marks behind. I am still learning. Keep the info coming I appreciate it.

 

If I were to do it all over again I'd have just left everything stock except the head and EFI Turbo the thing. The stock rod and piston are good for 80-90 hp all day long. There are guys that have 10k in their motors that have to put them on nitrous to get to that power level. EFI = $1500 + turbo $2500 dial your boost and run as little or as much power as you deem prudent.
Head work such as HD valve springs would be wise with some light port work. Kms is running their Turbo DS at about 85hp and it is completely stock. Best bang for the buck IMO.