Sophomore Rider
Currently Offline
Posts: 201
Likes: 1
Joined: Feb 27, 2013 2:23:40 GMT -5
|
Post by CopperDeer on Feb 19, 2014 22:01:53 GMT -5
I've already decided I'm going to get a BBK for my Derbi GP1 but I like the reliability and sound of the stock intake/exhaust and performance carbs are very expensive for this motor. Because I do not plan to modify or replace the intake or exhaust I am not expecting major speed gains, but would like to realize some extra torque. Will I still see a benefit with a 70cc or even 90cc BBK with just rejetting the carb? Would I be "starving" the engine of air and potentially hurting anything?
|
|
|
|
Post by carasdad on Feb 20, 2014 9:25:08 GMT -5
I've already decided I'm going to get a BBK for my Derbi GP1 but I like the reliability and sound of the stock intake/exhaust and performance carbs are very expensive for this motor. Because I do not plan to modify or replace the intake or exhaust I am not expecting major speed gains, but would like to realize some extra torque. Will I still see a benefit with a 70cc or even 90cc BBK with just rejetting the carb? Would I be "starving" the engine of air and potentially hurting anything? I run a stock carb and airbox on mine..and just recently upgraded to a performance pipe. It ran great all stock expect the BBK. Just make sure you upjet!! Or it WILL run too lean. You will notice a definite performance gain..but if you later add a pipe..the BBK will really turn on the speed and power..  P.s. a Stock 19mm carb is more than plenty for even a mid to high grade BBK. Those that use larger carbs are typically building an all out race type machine.. |
|
Sophomore Rider
Currently Offline
Posts: 201
Likes: 1
Joined: Feb 27, 2013 2:23:40 GMT -5
|
Post by CopperDeer on Feb 20, 2014 18:47:06 GMT -5
Awesome, that is what I figured but I wanted to be sure before I defile my rare & near mint 10 year old Derbi!!! I read somewhere there is a way to derestrict the stock pipe so I'll probably get adventurous with an angle grinder and drill some day. Really appreciate the 2T advice carasdad.
|
|
|
|
Post by carasdad on Feb 20, 2014 20:38:03 GMT -5
Awesome, that is what I figured but I wanted to be sure before I defile my rare & near mint 10 year old Derbi!!! I read somewhere there is a way to derestrict the stock pipe so I'll probably get adventurous with an angle grinder and drill some day. Really appreciate the 2T advice carasdad. Same here..did not want to mess up my Adly..now sold by Lambretta. So i did 'hidden' performance mods so it looks stock..but still rocks! hey 56mph GPS is not too shabby I don't think.. Cruising at 45-50 is easy and comfy and tach shows just below 8k..right at 7.5k so my engine is not screaming away like a chainsaw..  |
|
|
|
Post by skuttadawg on Feb 28, 2014 0:34:26 GMT -5
I have a 19mm carb on my BBK and it runs great . Some come with a 17.5mm or smaller . The 2T power kits often have a 21mm but 19 works fine . You can bolt on a 70 BBK very easy and will have to upjet and test out a few sizes . To go 90cc you have to get the case bored to fit a  piston and the crank and will cost a fortune at a machine shop not to mention having to split the case apart . A BBK will have more power and tuning the CVT alone like changing the weights and clutch springs can do wonders even on a stock engine |
|
Sophomore Rider
Currently Offline
Posts: 201
Likes: 1
Joined: Feb 27, 2013 2:23:40 GMT -5
|
Post by CopperDeer on Mar 5, 2014 1:34:47 GMT -5
Yeah through more research I've realized 90cc is much more intense an upgrade than the many 100cc (83cc) kits I've done on 4Ts. I'm going to stick to a 70cc and maybe try to modify my intake and exhaust at some point to increase flow.
|
|
piston and the crank and will cost a fortune at a machine shop not to mention having to split the case apart . A BBK will have more power and tuning the CVT alone like changing the weights and clutch springs can do wonders even on a stock engine