I just ordered a BB 351 kit last week and I was wondering what kind of horsepower and torque numbers I can expect? Can't seem to find this information on the forum for the way I plan on setting up my bike?

This is the set up I will have: BB 351 Kit, stock carb jetted, KDX snorkel, Uni Filter and FMF Q4 slip-on. Also, I might add cams and port and polishing later too, not sure how much that will add also? Thanks

 

From the dyno charts i've seen posted here and other places the BB with stock carb and full exhaust is putting down about ~28+ hp. If the header does make a difference (IMO it would) a safe bet would be around ~26-27 hp with your setup.

Cams should add about another 2-3 from what i've seen (maybe 4) so guess about 30hp.

Porting, no idea as i think that WildWill is the only person i've seen with that done. His bike is putting down 33+hp last i knew.

Keep in mind all dyno's will read a little different (some higher or lower) so a direct comparison is not really possible and all the above mentioned numbers are pure conjecture from various observations. For instance Will's bike could show 33 and change on one dyno and 35+ on another.

Hope that helps.

 

Yeah, wildcard is right, a big bore will put you right around 26-28 hp.

the big thing though is torque. The 351 will put you over 20 lbs ft of torque. This number is what allows you to keep up with the big bikes. I run with an older KTM 400 and his bike doesn't have much on mine.

 

Thanks Wildcard, I was thinking in the 25 to 26 hp area. On Bill Blue's website it shows the BB 351 kit has just little over 22 hp without the bike being uncorked and all the other dyno results showed the kit with cams and other mods being over 28 hp. Just never seen the results that split the differences between not modded and heavily modded.

 

You will have miles of smiles! Years ago I did a 331 kit, fcr pumper and a full exhaust- bike was unbelievable, compared to stock. Enjoy!

 

Thanks Dave, I hope that it lives up to the hype! Mr. Blue said I should have the kit delivered tomorrow.

 

I spoke with Bill Blue and he has a local shop that will port the head (the valves more specifically) for an extra $400... this will let the motor spin to redline, which it won't otherwise (9k is about all she's got from what I've heard). I'm thinking of doing this when I finally get around to ordering mine.

Rob

 

I don't have a problem getting my 351 to 10K rpm, but then again I see little need for it. I rarely take it above 8500. It's a tractor with great low end torque. IMO, if you need to spend a lot of time at high rpms, gear that bike up.

Here's some charts for ya'll. Ya, I know, comparing different bikes on different dynos on different days is a waste of time. But it was my wasted time.











Another member here, ZRexRich, shared these with me. From this thread https://www.kawasakiforums.com/forum...lx351sf-29316/








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+1

I have no problem bouncing my bike off the rev limiter in the first 3 gears. Never tried it in 4th or 5th (almost no bike with hit it in sixth unless its REALLY geared low or ridiculously powerful).

I wouldn't worry about the porting honestly, if it was a race bike and you were looking at every tiny bit of top end maybe, but i would put that $400 towards something else (webcams, pumper carb, etc).

On another note in regards to porting i've heard from some that polishing the intake tract is a waste of time on an NA engine and that you only really benefit from smoother exhaust ports (something to do with intake velocity and air turbulence making fuel atomization more efficient with a rough intake tract).

I'm not well versed in the subject so maybe i'm remembering wrong or those guys were full of it... ?

 

IMO a pumper carb would be better than porting- I did the fcr pumper before the big bore, The difference in throttle response was unbelievable. Now I do not think the pumper helped the total hp- but when you hit the throttle the front wheel would now come up! (2 &3 gear) After the 331 big bore I rode in the lower rpm range 90% of the time- it was a night and day difference.

Great dyno charts,