The following is from a post I did on kawasakiforums.com during the 2020 pandemic
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, KDX200/220 snorkel (Kawasaki part number 14073-1577)
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.
And, just for fun I created a very short video of the project.