Evo 250 To 200

[spawtydawg]

Hi, has anyone converted a 250 Evo down to a 200? Is it just a case of changing the barrel and the piston? I've noticed that the stroke on the 200, 250 and the 300 is the same at 60.5mm, which would suggest that they use the same crank. I know the carb is different, but, I don't think that this would be an issue. The bike in question is a 2012 model.

Any advice appreciated.

Thanks in advance.

[mcman56]

I went 200 to 250 on a 2008 Rev3. Looking at the manual for the evo, it is pretty much the same engine except that the coolant connection on the head points in a different direction. In addition to the 200 top end, the small end of the rod is bushed down to accept the smaller 200 wrist pin bearing. (that may be gudgeon pin to you) I think trialsandtribulations sells (sold?) a special overside bearing that eliminates the need for the bushing. The carb was the same on the rev3. I have only seen one 125 evo but it had the same PWK28 that the bigger bikes have so the carb may be the same also.

[spawtydawg]

Hi, I've spoken to the Beta importers here in the UK and it's not a cost worthy option.

Yes it can be done but you're looking at almost a complete engine, piston, cylinder, con rod, crank, etc. so you'd be better off buying a new bike. Converting a 250 to a 300 is much easier as they basically are the same apart from the cylinder and piston from what I can gather.

So I'll either soften my 250 or save my pennies and buy a new 200.

[mcman56]

Fasdr - I went from a Sherco 290 to the Beta 200. On the 200, it was harder to do semi vertical wall type obstacles, like 4 feet high or so. On the larger bike, I could chop the throttle at the bottom and the larger engine would continue to pull me up. On the 200, I would have to continue to use throttle to make it to the top. This created another task for my small brain to manage and posed a risk of using too much throttle and flipping over. This was not too bad a sea level but made me pretty uncomfortable at 5500 feet elevation. At around 7500 feet the 200 felt quite weak and I had problems with it bogging when opening the throttle. Even small logs were an issue. I did add a bolt on flywheel weight when going to 250cc so that is part of the equation. As a 250, the Beta was more like my old Sherco. The only negative is that it takes more effort to kick. There was another posting on this issue a while back and someone suggested that 270s had an extra weight.

Spatwydawg - The crank and rod do have different part numbers on the parts list. From what I can tell, the difference is the bronze bush pressed into the rod small end. It is not shown as a separate part on the 200 list. The only economical way is to buy a used top end of the desired size. They show up on ebay but for me shipping UK to US was not cheap. The cylinder I used does not match the year of the bike. I noticed that Beta sold 270 kits for 250s but there were different kits for different year bikes. I never found out what the differences were.