250hp for a Gen I Build, Which Way to Go?

[krex]

I'd like to hear some ideas on building a 250hp na motor. I'm not sure whether to go 1507 or 1600ccs. Same price just not sure of the drawbacks of the longer stroke. I'm thinking a good stock valve(I think?) ported head, 84mm,  big cams(not sure how big to go), billet rods, studs. Not sure about compression ratio but will run whatever gas is necessary. Sound like I'm in the ball park? What else? This is for a run what ya brung drag bike.

[Stainless1]

Contact Steve Knecum

[RansomT]

To get to 250 HP, a 1507 isn't going to get there.  If it was me, I would build a 1635 (10mm stroke). 

[speedduck]

I dont know what size is the best for that kind of dragbike, but for the power, go big, 1600+ and .425" or .445" cams,
I am really interested to see how it turns out, using stock size valves, and what fuel , keep us posted.
 

[knecum]

You can reach 250 no problem with a 5 or 6 1/4 stroker and up to 285 with 9-10 mill x 84 mm bores, stock valve heads.  Contact me if you  need assistance.

[Ali123]

lol... guy must have thought he could do this for 4 grand or so...... lotta dreams out there

[6 inch over]

Steve

What size cams for that 250 HP build?

[Ali123]

u wanna buy some cams from him... or just free information

[6 inch over]

 

I have a Bob 1397,425-415 webs
  just asking
Wanting to change the crank and rods

[firemanjim]

I had a 1507, made 260 at the wheel, but it was a Forstall/ Knecum bike---sweet sounding ride, went to Stainless.

[RansomT]

I had a 1507, made 260 at the wheel, but it was a Forstall/ Knecum bike---sweet sounding ride, went to Stainless.

Not doubting....but I've never seen a 1507 make north of 250 on my dyno.  But my LSR 1340 does make 240 (so it should be possible).  Truthfully, I've had a hard time keeping that 1340 together.  Compression high as heck and top end clearances crazy tight.

[Stainless1]

I had a 1507, made 260 at the wheel, but it was a Forstall/ Knecum bike---sweet sounding ride, went to Stainless.

Jim, that one is a 1630... "Steve 1" stroker must have 24v to spin.

[firemanjim]

OOPS, my bad, and both batteries better be topped off as it would spin over but not fire---

[Ali123]

for what its worth.. I had starting issues with a big turbo bike... I went through 3 batteries... finally found a 720cca 12.3aH lithium battery for a hayabusa…. make by full spectrum... it works GREAT... and if it gets low.. the battery simply shuts down... NO POWER can be produced.. and u hit a button on the battery and it saves enough energy to start the bike.. amazing... and I HATE lithium batteries.. but this battery works GREAT.

[Nosgsx1300]

OOPS, my bad, and both batteries better be topped off as it would spin over but not fire---

Voltmeter on the coils WHILE CRANKING
I even had the only 24v 9-1 turbo bike and still hard starting
I ended up running a 12v switched to feed the coils and now she fires immediately

[Thomas]

OOPS, my bad, and both batteries better be topped off as it would spin over but not fire---

Voltmeter on the coils WHILE CRANKING
I even had the only 24v 9-1 turbo bike and still hard starting
I ended up running a 12v switched to feed the coils and now she fires immediately

FWIW I vouch for this advice, I checked that with a scope.
http://www.suzukihayabusa.org/forum/index.php?topic=166279.msg1595188#msg1595188
I ended up with:
1. Dedicated relay located close to the battery to feed both coils and fuel pump (that is, it's a relay with two normally open contact pairs, of a 350z, was controlling cooling fans, one contact pair + fuse for fuel pump, one conctact pair + fuse for IG coils; fuel pump has dedicated ground wire, OEM ground wrie isn't used).
2. Beefing up starter motor positive and negative leads. I think I run 2 GA for negative/ground lead, and two 4 GA in parallel for + lead. "Superflex" wires make routing super easy.

I beefed up starter motor leads because I found there was quite high voltage drop, don't remember the exact value though. OEM wires are ca. 15-16mm2 or ~ 5 GA.