BB kit for $143
Member
Joined: Sep 2017
Posts: 36
From: Nanaimo BC
1st Gear Member
Really impressed with this kit so far. If you are on the fence, I say go for it. If I had deeper pockets I would opt for the BB351 for max torque, but this one pulls pretty hard mid to redline with very little vibration.
I seem to have pretty closely nailed the tuning with this kit first go around. I may go next size up on main jet, but thats about it. This bike now has the engine to match the chassis. Very fun street bike , in fact may swap out the 244's for some quieter Michelin Pilot Streets as I do little off roading , which is why I chose the SF.
I seem to have pretty closely nailed the tuning with this kit first go around. I may go next size up on main jet, but thats about it. This bike now has the engine to match the chassis. Very fun street bike , in fact may swap out the 244's for some quieter Michelin Pilot Streets as I do little off roading , which is why I chose the SF.
Member
Joined: Sep 2017
Posts: 36
From: Nanaimo BC
1st Gear Member
Update
Hello members, just an update and some info for anyone thinking of this kit. Firstly, I like it, should come stock with this. I have about 2500 km on it now and runs great, especially after finally getting the carb set up right. This is what I had it at initially, note I am mostly at sea level. Dynojet 2182, 132 main, 40 pilot, Idle screw out 2 1/2, needle clip at 4th notch down, spring included with kit, uni filter, snorkel removed P4 slip on . Ran ok but smelled rich and idled all over the place. BTW, I initially drilled the starter jet from .015 inch stock, to .018 and the bike starts hot or cold, first turn over. Fuel mileage, 4.76 lt / 100 km or 49.4 MPG US A friends Mazda 3 does better!
Here is what I have now , Pretty much as DJ recommends, DOH! for the 250. Dynojet 2182 , 128 main, 38 pilot, needle clip at 3rd notch down, everything else same.
Runs way better, from idle to redline. Almost power wheelies in first. Fuel mileage, 4.00 lt / 100 km or 58.8 MPG US, pretty much where I figure it should be. Reason I pulled the carb again was fueling up with a ride with a friend with a crf250l, he got double the first mileage. Hope this info can save some time for yas
Here is what I have now , Pretty much as DJ recommends, DOH! for the 250. Dynojet 2182 , 128 main, 38 pilot, needle clip at 3rd notch down, everything else same.
Runs way better, from idle to redline. Almost power wheelies in first. Fuel mileage, 4.00 lt / 100 km or 58.8 MPG US, pretty much where I figure it should be. Reason I pulled the carb again was fueling up with a ride with a friend with a crf250l, he got double the first mileage. Hope this info can save some time for yas
Senior Member
Joined: Mar 2016
Posts: 157
From: Texada Island, BC
1st Gear Member
Appreciate the update.
I have my kit sitting here, going to drop it off at the machine shop to get the jug milled down to increase compression to 11.7:1.
Interesting that you had to lean out the pilot circuit also, seen a few other say they had to go down one on the main jet so that's not a suprise.
I'm hoping my current main jet will work as I'm going to upgrade the headpipe also which would typically require 1 size bigger main.
I have my kit sitting here, going to drop it off at the machine shop to get the jug milled down to increase compression to 11.7:1.
Interesting that you had to lean out the pilot circuit also, seen a few other say they had to go down one on the main jet so that's not a suprise.
I'm hoping my current main jet will work as I'm going to upgrade the headpipe also which would typically require 1 size bigger main.
Member
Joined: Sep 2017
Posts: 36
From: Nanaimo BC
1st Gear Member
Yes the 38 pilot gives a nice part throttle response, however this is seat of the pants, have not been on a dyno to see actual mixture. So interested in the milling. How did you determine the CR of this kit and what are they removing from the head to arrive at 11.7 ? Brilliant idea, you may pick up 1/2 hp or so with that. Did that once with a Triumph spitfire with great results except with a pushrod engine I had rocker arm geometry to deal with
Senior Member
Joined: Mar 2016
Posts: 157
From: Texada Island, BC
1st Gear Member
OK SO I have yet to tear into the motor and take all the measurements I need to figure out how much I will need to get milled to get the the 11.7:1
I had found a few posts years ago referencing a magazine article where they had milled 0.4mm from the bottom of a klx300 jug to get the 11.7:1
Also looked up the specs on the loncin engine the kit is made for and it's listed at 11:1 the same as the KLX300.
The MCM Mod thread has some good data on head volume and valve clearence
If the squish measurement is accurate I may get 0.3mm milled of and see where that gets me. Should also retard the cam timing a smidge which is not a bad thing in this motor. May have to get
Ultimately i want to go with a bigger cam
Got a few big projects around the house to finish before I can dig into this motor build.
I had found a few posts years ago referencing a magazine article where they had milled 0.4mm from the bottom of a klx300 jug to get the 11.7:1
Also looked up the specs on the loncin engine the kit is made for and it's listed at 11:1 the same as the KLX300.
The MCM Mod thread has some good data on head volume and valve clearence
I have the data that was missing from the original post .
The piston to valve clearance is 3.2 mm for the intake and 2.6 mm for the exhaust . These values are with the cam mod . With the original timing the values are 3.4 and 2.8 . These values are a whole lot higher than the minimal clearance required wich are 1.5 - 2 mm . This renders the argument of dangerously close valve to piston clearance mute .
On a different topic I have some other numbers for those who may wish to know :
The squish on the KLX is 1 mm . For those seeking more compression , let me remind you that you should not go under 0.7 mm under no circumstance !
The displacement of the combustion chamber in the head is 18 cc and it's the same for KLX 250 and KLX 300 .
The displacement in the squish volume is 4 cc . This makes the total for the combustion chamber on a 250 equal to 22 cc . 250 / 11 = 22.-something .
The 300 piston has a big shallow recess with a capacity of 5 cc .This makes the combustion chamber of a 300 reach 27 cc . 300 / 11 = 27.- something .
When measuring volumes one cannot get to under 1 cc accuracy without fancy lab equipment so please take all the volume measurements with a +/- 0.5 cc tolerance .
The piston valve recesses have the exact same depth in the 250 and the 300 pistons ( the original Kawasaki ones ) . The 300 recesses may seem smaller due to the big central recess that adds 5 cc to the combustion chamber .
I will update the original post with the valve to piston clearence data shortly .
The piston to valve clearance is 3.2 mm for the intake and 2.6 mm for the exhaust . These values are with the cam mod . With the original timing the values are 3.4 and 2.8 . These values are a whole lot higher than the minimal clearance required wich are 1.5 - 2 mm . This renders the argument of dangerously close valve to piston clearance mute .
On a different topic I have some other numbers for those who may wish to know :
The squish on the KLX is 1 mm . For those seeking more compression , let me remind you that you should not go under 0.7 mm under no circumstance !
The displacement of the combustion chamber in the head is 18 cc and it's the same for KLX 250 and KLX 300 .
The displacement in the squish volume is 4 cc . This makes the total for the combustion chamber on a 250 equal to 22 cc . 250 / 11 = 22.-something .
The 300 piston has a big shallow recess with a capacity of 5 cc .This makes the combustion chamber of a 300 reach 27 cc . 300 / 11 = 27.- something .
When measuring volumes one cannot get to under 1 cc accuracy without fancy lab equipment so please take all the volume measurements with a +/- 0.5 cc tolerance .
The piston valve recesses have the exact same depth in the 250 and the 300 pistons ( the original Kawasaki ones ) . The 300 recesses may seem smaller due to the big central recess that adds 5 cc to the combustion chamber .
I will update the original post with the valve to piston clearence data shortly .
Ultimately i want to go with a bigger cam
Got a few big projects around the house to finish before I can dig into this motor build.
Member
Joined: Sep 2017
Posts: 36
From: Nanaimo BC
1st Gear Member
Ok great thanks for that. Interesting goal worth considering. I'm good with the performance at this stage but its clear this motor is capable of more without reliability issues. Going to enjoy as is for local on and off road rides. Have my eye on the new Ninja 400 for highway
Senior Member
Joined: Jun 2013
Posts: 3,315
From: North Texas
1st Gear Member
Ahh, with a proper CVK set up on a lidless airbox, and with a performance slipon, a 250 power wheelies in 1st gear.. My KLX300R power wheelies in 1st, 2nd, and even 3rd ( with a tug on the bars).. If you want to try out the lidless setup, I'd be happy to share the info..
