I thought I would give my quick review of the Bill Blue 351 kit as far as installation, power improvement, etc. I looked for info before and during the kit install, and saw very few people who installed it on the SF model.

After about a week of off and on tinkering, I finally got the whole thing together. This was my first top end job on a bike, first time actually going into a motor,though I have done pretty much everything else on a bike.

The progression of adjustments I made and the performance from seat of the pants dyno are as follows.

After I bought the bike new: almost turned around and returned it to Kawi dealer. Didn't do my research, assumed it would hit like a 250 dirt bike. Thing was a dog. Could barely get the bike to clutch up wheelie in 1st revving the snot out of it. Felt like a 150cc geared tall.

1st mods: Did the airbox, rejetted the carb, aftermarket pipe, 1 down in the front. This made a huge difference compared to stock. Rode the bike like this for 2500 miles. Was able to easily clutch up bike for wheelies in 1st and 2nd gear, get to balance point no problem. Not bad, but nowhere near where my old DR SM was.

Final mod: installed 351 kit, mikuni tm33 pumper carb from Bill Blue. I just ran the bike down the block and back. It now will wheelie in 1st and 2nd WITHOUT the clutch, and actually feels WAY easier bringing up the front in 2nd without the clutch than my jetted and piped Suzuki DR SM did.

In summary, huge difference between the big bore and the usual upgrades to stock. I will post up if I have any failures, head gasket leaks, etc with the kit. I'll post change in MPG too. I was getting 48mpg average with jetted and piped 250 cylinder.

A KTM or Husqvarna it ain't, but more than a DR SM it might be! Sounds like a proper supermoto now too.

 

Good to hear md.
What pipe did you get, and what series number is on your 351? Just curious how many are out there now.

 

Thanks for the review Dragon. Glad to hear that low-end grunt is improved.

Do you have any observations on the 351 at highway speeds? Specifically 100km/h (60 mph) and up?

I am at a crossroads with my KLX where I am considering either upsizing to the 351, or replacing with a 450 or 650 dual sport.

With my set-up (TBR pipe, Uni filter & jet kit) the 250 is perfect off-road & around town, but I just don’t find it adequate for safe travel highway.

 

go:
I find highway much easier. The 351 gives power to pass. But the bike is still light and more easily tossed around by wind, passing trucks, etc. I much prefer the KLR650 on the 75mph freeway. But on 55 to 65 mph highways, I don't mind taking the KLX at all.

 

Thanks ID, how 'bout engine vibes at higher rpms? Is the larger piston unbalanced at all?

 

+1 ^.... The wind and trucks at freeway speeds will get your heart pumping.

 

I think the 351 in the klx is about the perfect bike. I have ridden many larger cc bikes and smaller. I think the DRZ400 handles like crap. The KLX always amazes me how it just gets traction, yesterday mid hill climb i let off of it almost lost it then got back into it and went right up the hill. Love the way it handles. Very predictible. After having it for 6 years now love it more than ever.

 

I think the larger piston does make the bike vibrate more. I am not sure about being unbalanced, but putting different handlebars and grips seem to help a little with the vibration.

 

I've read of some guys saying they noticed a little more vibration. I don't notice much if any more than before. I think the 351 piston is just a little heavier than stock IIRC.

 

been working too much so haven't had chance to fully break in yet. I accidentally used energy saving oil so my clutch slips, just put in fresh non energy saving oil. Also ordered stiffer clutch springs in case the slipping is more than an oil issue.

Even the 250 did fine on the highway. I don't recommend them for long highway trips, as you'll be revving the snot out of the motor. These bikes are really made for around town riding, not touring. Of course you could ride around the world on a ruckus, but not my idea of fun.

I have.a decent amount of time on bikes, and have not once felt blown around or dangerous highway riding. With my 240 lbs. on it it will still do 93 mph indicated maxed out (250). I imagine the 351 kit might give me another 5 mph top speed.

Will post once i get it broken in and tuned. Look forward to 3rd gear clutch up wheelies.