2006 klx250s with a 331bb kit going in....my questions are:
1. is port and polish worth it/noticeable? ($250)
2.cams..are they really over $400 for this bike? (webcams).
not interested in doing the free cam mod with big bore kit.
3. 331kit only and be happy?

 

Big bore and pumper I think is the best bang for your buck

 

If you want the BEST gains port work is needed, with larger valves. The cams aren't quite as necessary.

 

The big bore totally transforms the bike. Worth every penny IMO.


*edit* that reminds me that i need to take some time and install my lighter flywheel... if it ever stops snowing.

 

I'm with Matt on this one, mathematically the valves (with head porting) are the most critical for power gains after the big bore.

 

At some point you have to step back and question whether it's worth the investment to add all of the hop up parts vs. buying a machine that's engineered from the factory to give you the power you want. After all of the mods I have done to my KLX it is definitely not the same machine I rolled off of the showroom floor but it still pales in comparison to a KTM or the like.
My list-
1. Big bore-best return/$
2. Pumper carb
3. Exhaust-slip on would suffice.
4. toss up between cams and head work. This is where returns vs. cost are diminishing. I cleaned up the ports and chamber on my head since I've had considerable experience porting automotive heads so it was no cost for me. Spending $ to get it done vs. power gains= not worth it(see explanation above). Adding cams did improve performance with the 351 kit and made the most gains above 8K when the stock cams would sign off. Still hard to justify spending the money( especially since WebCam bumped the price again).

Bottom line-it's your money so spend it as you wish...

 

@GBauto has a great point. To be honest, porting/valves is very expensive compared to power gains. Plus the webcams only show improvement above 8k, which isn't really practical usage.

To be honest, if I weren't running a motovlog and trying to prove a point, I would've probably never done porting or valves. Anyhow, cost per estimated horsepower:

351= $50:1bhp
Valves/Porting: $220:1bhp
Slip-On Exhaust: $80:1bhp
Webcams: $200:1bhp? (I haven't looked too much into these)
TM-36-68: $70:1bhp (The TM34 is more expensive)
Filter: $70:1bhp

That's pretty much about it, other than a few questionable free mods. I've done all but the webcams, and I can say my bike has become more expensive than my father's 2014 KTM350ECF. We'll see how it compares in terms of functionality once I get my bike running again...

 

the reason im semi willing to spend on things in addition to the BB kit is because i had a bigger bike,DRZ400. i was fine with the power stock but disliked everything else about the bike.(height,weight,top heavy,5 speed). KTM is too pricey for me, and too much maintenance. the klx was only $2100 and the right physical size. sounds like for the money 331 kit,pipe, rejet is it........makes me wonder if the money for cams/port/polish would be better spent on a better carb....also the age old question..331 vs 351? thought i read they make the same power without the worries of wet sleeve on the 331?

 

I think you got that backwards. It's a 4V motor with relatively large valve area and extremely mild cams.

 

Just do the kit. I would have done and have done the 351 kit. The bike will be amazing compared to the old 250. Then, in a year or so decide if you need or want more power. It's not an all or nothing deal.

Who is doing port and polish for $250?

Part of the attraction of the KLX is you can mod or not. You can build the bike over a long time. Adding a new part once in a while makes the bike exciting again.

Once the 351 kit is in I would look at your suspension, be sure it's sprung right, especially up front. Getting spring rate right is worth more than any post big bore power gains you'll get from a pumper or cams.