701SJ - FP Exhasut Question

[j'ray]

HI,

So I've had this old beater 1991 SJ for a long time. I've swapped a 61x 701 motor in it. Its been a while, but I have a factory pipe bolted up to it and it runs pretty good. I have a 650 chamber installed right now, but I've been toying with buying a real 701 b pipe to replace the old 650 chamber.

Is the header pipe and manifold that I have bolted up right now (that came with the 650 camber) any different than the header pipe / manifold that come with the 701? Obviously it bolted up to the 701 motor fine, but I'm wondering if buying a proper 701 bpipe chamber will result in a big enough performance gain to justify buying spending $300 on a new chamber? Big camping trip coming up in a month, so I don't have a ton of time or patience to wait for a second hand chamber to come up.

If you were in my situation, would you go for limited or mod chamber? I'm all about bottom end snap for freeride/freestyle

I've heard a little about port matching. I just bolted the mani and head pipe on. I'd like to keep it bolted and just change out the chambers for easy quick install, but what is advised here? Will it make a big difference? How bad could the alignment be?

Also, would I need to replace the coupler or elbow into the waterbox? I seem to remember using some old rubber tubing and fabbing my own elbow... Seems to work so far!

Other motor mods:
- Pro-tec high comp head
- Flow control valve
- Tornado spark arrestor

thanks!

 

[Mdavies_02]

I believe just porting out the FP Manifold and Headpipe will achieve the same end result, however, I doubt you would see noticeable gains going from a 650 FP to a 701 FP. I'd rather spend the money on an A/M CDI, or Impeller, or save for a mag etc.

That said, I've never run a 650 FP, just my thoughts on the matter.

 

[j'ray]

Thanks I appreciate your input. I do have a 9/15 hooker prop, stubby pump cone, ride plate, and intake grate.

Just looking for the next best motor mod for the money. I wonder if anyone has any experience running a limited bpipe with a 650 head/mani.

After doing some more research, from what I can tell you are correct. a 701 chamber will make some, but not a lot of difference. I'd be better off opening up the manifold. Guess I'll pass on the chamber for now.