Big Bore for MX

[JoePA]

I know this question has been asked a million times but how much difference in power between the 330 and 350 with similar port match from ESR. Is it worth going all out for the Big bore, say a 370 or will the smaller 330 get the job done? Whats the trade off? Is there a trade off?

[Tbone07]

I'll just give you the reason I opted for my LED 350 over a smaller bore engine...

I'm around 240-245lbs and ride/race XC. Larger the engine the more torque, and as a heavier rider I need all the engine I can get. With the big-bore I can carry a higher gear and lug through sections of track without shifting as frequently. I can't see how having a larger engine would be harmful for XC or MX. I hear some guys say that large of an engine is too much to handle, but I think the opposite is true. It's not arm-ripping power, it's gobs of smooth controllable torque.

If I had to do it again I'd go even larger and get LED's stock stroke 370

[rablack21]

For the small amount of money difference, the 350 is worth the extra. You still have to bore the cases and do all the same work. With that said, obviously the bigger the engine the more it will wear stuff out. With that said, 20cc is not a huge difference in the grand picture of wear/power/longevity. So then it comes back to money. As you move up in size, you will get more vibration though. My 310pv has noticeably less vibration than my 363. Just keep it in mind.

[havinnoj]

Agree with the comments on going for a bigger motor as long as it’s setup for your needs.  More torque isn’t going to hurt.  Vibration may be something you notice but at 350cc I never noticed much. 

[Burns363R]

honestly i havent ridden a small bore 250r in so long i have forgotten what its like.  I dont feel like i have any vibration, but I would probably need to get back on a small bore and back that up.  Im probably just more used to it.

As far as hp and MX.  I dont think I would want my XC 370 for my MX bike, I think it woudl be to much.  The nice thing is Im not every at wide open on the XC bike, except for the straight aways.   On the MX track Im wide open alot more and that will really wear you out when your man handling that much power.   I know its backwards thinking but for XC its nice to have all that power in reserve and barley use the power in the woods.  Click up a gear and just modulate the throttle, smooth power!

[Tbone07]

honestly i havent ridden a small bore 250r in so long i have forgotten what its like.  I dont feel like i have any vibration, but I would probably need to get back on a small bore and back that up.  Im probably just more used to it.

As far as hp and MX.  I dont think I would want my XC 370 for my MX bike, I think it woudl be to much.  The nice thing is Im not every at wide open on the XC bike, except for the straight aways.   On the MX track Im wide open alot more and that will really wear you out when your man handling that much power.   I know its backwards thinking but for XC its nice to have all that power in reserve and barley use the power in the woods.  Click up a gear and just modulate the throttle, smooth power!

How would you compare the difference in power between the +4 363 and stock stroke 370? Seems to me like they'd be pretty close

[Burns363R]

I feel the 370 has a much broader power band that comes in earlier.