So the 351 from Bill Blue is a steel sleeved cylinder and the 331 is a nickelsil cylinder. Which would be the better choice? I like the idea of the extra cc's but sleeved cylinder is old technology which isn't used in production engines. Nickelsil has its advantages, long lasting and good heat dispersion. There is quite a bit of material removed to get to the 331cc displacement, would this result in a weakened cylinder wall?

 

The Bill Blue kits are sleeves, 351 and 331.
The Kustom Kraft 330 kit is a big bore 300 cylinder with nicasil plating.
The 351 is a wet sleeve, it's so big it goes in the space use for water cooling.
I didn't want to limit the water cooling, that's why I personnaly chose à 330 kit.
I like to keep my bike for a long time, so I chose the nicasil plating because it's really tough on the long run, yes it's expensive, but still way less than changing bike.
There's already a lot of treads here talking about that, you should look at that to help you make your choice.

 

I had a 351 kitted bike that was stolen, I now have another 351 kitted bike. My friend has a 351 kitted bike.

There's a guy on the ADV forum that has 300,000 KM on his KLX351. This guy lives in the tropics too. So, worries about overheating are misplaced.

+/- 100,000KM on the original 250cc engine.
+/- 130,000KM on the first Bill Blue 351cc BB along with lots of other freshening up.
+/- 60,000KM on the 351cc BB rebuild. At that time I redid a lot of things - bearings, cam chains, wiring harness, ignition in addition to the rebuild.

Whatever theoretical ideas anyone may have about the 351 not being a totally bulletproof build are just that, theoretical.

Tons of people here have done the 351 kit and I am not seeing any remorse.

The depth of tuning info for the 351 is deep. When you go to set up the carb, change the carb, put on a pipe or change the airbox there will be people that already worked out the jetting for the 351, for the 330, not so much.

Go 351.

 

What Taxonomy said 👆

 

It boils down to what you are comfortable with. I went conservative and went 331. I liked the extra sealing area for the head gasket and that the 331 is a dry liner with no intrusion into the cooling jackets. Get either one, they both have good results.

 

Sleeving may be old technology in your mind, Guzzi has plated surfaces for the last several decades, my 75 had chromed bores. Kawasaki started Nikasil in I think the 70s as well, so not so new.

Key thing, you can ruin a liner, push or bore it out and replace it with a new one, starting all over at std bore. You can't with a plated bore if damaged bad enough.

Plated bores have a bit of an advantage in heat transfer since I believe aluminum dissipates heat a bit faster than steel and the plating probably makes little difference there. It is also a bit lighter than the steel lined cylinder.

I would see if Bill Blue does overbore pistons for his kit in case it is needed. If not then it's a push. If he has overbores for clean up the linered cylinder is the better choice. I don't see any issue with a wet liner vs dry other than possibly a shorter path to cooling with the wet liner.

 

Thanks, decision made.

 

Yup, 351, find a TM36-68 pumper carb (I got mine new off eBay for 220$) and you'll be hanging off the bars. Makes it a completely different machine.

 

I was thinking of using the tm36-38 but there was threads about grinding half the throttle actuator off and only running just the pull cable. Seemed a little redneck to me so I thought about going with the TM34.

 

I didn't have to do anything with the 36... and I use both push pull... might be different with a bigger tank but stock fits well