Big Bore Kit Questions
#51
02-29-2012, 04:25 AM
Join Date: Apr 2011
Location: Fort Atkinson, WI
Posts: 349
My bike is coming up on 1 year old and I’m pondering a big bore kit. I’m leaning towards the 330 to 340cc increase. B&B has the 331 and 340cc with a marginal difference in price while Kustom Kraft has the 330cc for $789.00. Do any of you have feedback on either one of these? I know the saying – you get what you pay for, but $290 to $300 difference in price…
#52
02-29-2012, 02:39 PM
Join Date: Oct 2009
Location: Sonoran Desert, Arizona
Posts: 262
The 351 just won't work in the desert. It also won't work for long distance rides. If you put a Thermo-Bob on one it will probably blow up. 
Ron
Ron
#54
02-29-2012, 11:33 PM
Join Date: Feb 2011
Location: Northern Kettle Moraine
Posts: 628
I found a dyno sheet on KK website for a 330 with stock pipe and carb. As luck would have it Bill Blue's site has a dyno sheet for a 351 with stock pipe and carb.
KK 330 has 21.75 hp at 8K and 16.5 ft-lbs at 6.5k
BB 351 has 22.24 hp at 6.5K and 18.6 ft-lbs at 5.4k
.49 hp difference and 2.1 ft-lbs
The delivery is the biggest difference, 330 is like stock delivery just more of everything. Tq peaks at 8k.
351 peaks at 6.5k both hp and tq dip after 6.5k
A drag race would be interesting! From dyno sheets alone I like the 331 from a power delivery standpoint and it really compares pretty well to the 351 on peak numbers.
KK 330 has 21.75 hp at 8K and 16.5 ft-lbs at 6.5k
BB 351 has 22.24 hp at 6.5K and 18.6 ft-lbs at 5.4k
.49 hp difference and 2.1 ft-lbs
The delivery is the biggest difference, 330 is like stock delivery just more of everything. Tq peaks at 8k.
351 peaks at 6.5k both hp and tq dip after 6.5k
A drag race would be interesting! From dyno sheets alone I like the 331 from a power delivery standpoint and it really compares pretty well to the 351 on peak numbers.
Last edited by 2veedubs; 03-01-2012 at 03:33 AM.
#55
03-01-2012, 03:44 AM
Join Date: Feb 2011
Location: Northern Kettle Moraine
Posts: 628
I had to edit the torque peak rpm's above. The layover from stock/ modified mixed me up.
Further comparison shows 331 holds 20 hp or more from 6400-8900 a span of 2500 rpm.
And torque on 14/16 ft-lbs from 4-8k a span of 4k rpm.
The 351 holds 20 or more hp from 5700-7500 a span of 1800 rpm. And torque of 16/18 ft-lbs from 3400-7000 a span of 3600 rpm.
The 351 is king by the numbers, the 331 spreads what it has over a wider range. I would think the 340 would fall in the middle.
Further comparison shows 331 holds 20 hp or more from 6400-8900 a span of 2500 rpm.
And torque on 14/16 ft-lbs from 4-8k a span of 4k rpm.
The 351 holds 20 or more hp from 5700-7500 a span of 1800 rpm. And torque of 16/18 ft-lbs from 3400-7000 a span of 3600 rpm.
The 351 is king by the numbers, the 331 spreads what it has over a wider range. I would think the 340 would fall in the middle.
Last edited by 2veedubs; 03-01-2012 at 03:50 AM. Reason: Dyno info
#57
03-01-2012, 01:37 PM
Good stuff 2veedubs. Thanks.
Can you post up any of the Bill Blue curves you have? I recall at least one on his old site, but can't find any on the new site. If I ever get a chance to dyno my 351, it would be good to have Bill's as a reference point.
Here's the one from KK that I found - KLX250S 330 Big Bore Kit - are you using same?
http://kustom-kraft.com/files/KLX250...rt_6_22_11.pdf
Can you post up any of the Bill Blue curves you have? I recall at least one on his old site, but can't find any on the new site. If I ever get a chance to dyno my 351, it would be good to have Bill's as a reference point.
Here's the one from KK that I found - KLX250S 330 Big Bore Kit - are you using same?
http://kustom-kraft.com/files/KLX250...rt_6_22_11.pdf
#58
03-01-2012, 01:48 PM
Join Date: Oct 2009
Location: Sonoran Desert, Arizona
Posts: 262
Nobody bit, huh?
Ron
#59
03-01-2012, 02:01 PM
When I can't improve on a sarcastic comment, I just let it bask in it's own glory! Sure got a chuckle out of me...