Greetings all! I have browsed, and enjoyed, this forum for years and it has been very useful. Now it’s time for some payback, so here is info on my recent B&B 351 install; hope it’s useful.

Back in March when the pandemic first became an issue here in Canada and travel plans changed, I thought it would be a good time to do the B&B 351 Big Bore upgrade. Bill sent the kit right away but it got stuck at the Canadian customs for almost a couple of weeks; got charged GST and PST (Canadian taxes) on the full amount.

The bike is a 2009 with about 27k km; main modifications before the big bore installation:

• DynoJet kit 2152, stage 2
• FMF PowerBomb header
• FMF Q4 exhaust
• IMS fuel tank
• TwinAir air filter, snorkel removed

Overall, the installation went fine. I took my time and tried to be as thorough as I could; also took the opportunity to do some other maintenance. Here are a few observations from the installation:

• I was surprised to find all four tappets (valve buckets) worn; the one next to the KACR was the worst. I replaced them all (Kawasaki part #12032-1058).
• The cam journals weren’t perfect either but not too bad; did some very light polishing.
• Removed the KACR. Not really for any reason other than that I like simplification and I don’t think it’s needed.
• Positioned the rings as per the service manual.
• Put the piston with the first circlip in the cylinder before attaching it to the rod; quite easy to this by hand if working on a workbench.
• With the cylinder on the bike and pin in place, getting the second circlip in place was, of course, a pain but with the help of a second pair of hands it worked! Circlips at 12 o’clock.
• Used Permatex Red where the engine case is split as per the service manual.

I decided to be conservative with the jetting and actually didn’t change anything. This might be surprising but I don’t think the bike could run any better than it is with this configuration:

• Dynojet needle DN0228

• E-clip on third needle groove from the top
• 
Two of the small Dynojet washers above the e-clip
• 
Dynojet slide spring DSP027 in place of the stock slide spring
• 
Dynojet #128 main jet

• Kawasaki #35 pilot jet
• 
Moose longer (easier to tune) idle mixture screw set to 2 1/8 turns out. This is actually a leaner setting than I had before the install

Having ridden the bike for now a few months, I’m more than pleased. It has already been said many times here but it’s just amazing what difference those 100 cc’s make! The one thing I had to do, though, was getting stronger clutch springs. Pulling hard in a higher gear the clutch slipped. I guess that says something about the difference the upgrade does :-) I used Barnett’s Clutch Spring Kit 501-25-06043 and replaced all six springs. This resolved the issue without making the clutch overly hard to operate.

Friends were curious about the project so I put together a very short video of the project. If anyone is interested it’s at

That’s it! Thanks for reading.

 

My experience suggests that the BB351 will kill starter motors with the KACR disabled. I removed the KACR spring when I did the MCM? mod. Forgot the name but advanced and retarded cams to boost low RPM torque. Bike started fine. I installed the BB351 with the stock cam timing and after not many miles the bike would not crank, the speedo panel would blink off and trip-meter and clock would reset. Assuming the battery died; I installed a new one but still no crank-no start. Checked everything in the manual. After a local shop refreshed the starter motor, the bike cranked well, but having had this experience, I ordered and installed a new KACR spring. Bike starts quickly with KACR operational whereas I had to crank longer with the stock piston and cam timing. I think that with the larger, higher CR piston of the BB351, the KACR brings the bike's dynamic compression close to the same as the bike had with stock piston, MCM, KACR disabled, based on the way she fires up almost as fast; this definitely helps when the engine is hot, she would barely crank with KACR disabled even with the refreshed starter motor and a newish battery. Make sure to let us know if the starter motor dies in the near future.

 

@LarsF , If you re-set your CVK for lidless running (and pull off your airbox lid of course) , you'll kick yourself for not doing it from the start. Your performance increase will be "impressive"..
Note that you will have to learn throttle discipline with Lidless running - to keep the bike under you instead of on top of you..

You'll need the stock slide spring, a "verified stock" slide lift port (hole), a DJ150 main jet, and duct tape for keeping your hands on the bars..

 

Hello snappster, yes, I knew this could be an issue but decided to do it anyway. For sure, I’ll provide updates on any issues arising. For now, though, the engine seems to turn over easily when starting; cold or hot.

 

Klxster, thanks for your suggestion! I’m done working on the bike for this season; I want to ride it instead :-) but sound like something to consider for the future. Now, how much loader does it make the bike removing the lid? I find the bike rather loud as is and wouldn’t really want to make it even loader.

As for the duct tape, I almost feel like I need it already now…

By the way, I have read many of you posts over the years and really appreciate all the good info and suggestion you provide!

 

It will only add the sound of new biggy horsepower being made !

Thanks for the kudos..

Be safe..