I didn't read or see any comments, everything I've seen on here is pretty good. I was talking to a very reputable machine shop and he said not to get the 351, but get the 331 instead. His reason was that the 351 doesn't have enough cooling capacity because of the amount of material that was removed for the extra 101cc. So far I've gathered that there is no cooling issues regardless of what is done to this engine because it's so over built. Any 351 owners to confirm this? Before the tear down I did 25k miles in less than a year. I'll ride rain, shine, snow, or whatever. I ride every day, mostly on the road. Even 25 degree weather in January

 

I have yet to hear the radiator fan operate on my 351, which suggests passive cooling through the rads is sufficient.

When I installed the 351, I also did a full coolant system flush and filled-up with "Engine Ice".

Prior to the 351 and Engine Ice, I only ever noticed the rad fan during a particularly hot and humid Ontario summer's day while axle-deep in muck.

POWERSPORT INDUSTRY?S #1 ENGINE COOLANT - Engine Ice

 

Well that's good news to me. And thank you for reminding me about the coolant, I was gonna use the Evans waterless coolant. I'm sure that will be plenty sufficient. I think I have gathered all the info I need too make my decision. Thank you all for the very good and useful info. Can't wait to ride again!

 

There is Ricky over in Thailand that has over 100,000 miles on a 351 kit.

 

I like to chime in on the subject of overheating as a differing point of view. Though I will say from the start that you don't need an oil cooler.

I'm sure I'm part of an extreme minority. But my klx does/did overheat when riding. I've burned the B&B Cycle sticker off the side. The reason, I'm putting a lot of stress on the engine. I'm heavy, at about 250 pounds. I load it up with a lot of gear. I ride up mountains at steep grades that could take 20 min at least to get to the top, if not a lot longer, (usually a lot longer!) switchback after switchback....gassing the hell out of it the whole way. And all this in a hot and humid climate with little airflow while going up. I used to have the overheating light come on almost guaranteed in these situations. Installed a manual fan switch and haven't had it come on (much) since then. Basically just leave it on the whole time. And I'm using distilled water and Water Wetter now.

In normal riding I haven't had a problem though. Maybe a few times in traffic (hot and humid, surrounded by a plethora of scooters producing more heat at stop lights waiting for a minute or so) but only in the summer.

Again, I'm a rare case from what seems to be a very cool engine. Listen to what the other guys are saying. They know. Just throwing my experience out there.

(and I'm running the 331, EFI)

 

Nope you're not alone. I'm 260lbs with the 351 kit and my light comes on more than it should. I've changed thermostat, rad cap, both sensors, manual fan switch, etc and in the woods on a hot day the light is almost guaranteed.

I've since went to engine ice, and done the rad cap and water sensor since last fall, so have not been able to test out these things (too damn cold here now).

I've contacted Bill Blue and he has suggested a few things that I will try. He doesn't believe it can be a gasket.

anyways, I'll keep ya posted, but it will be 2 months before it gets warm enough to ride