October 17, 200718 yr I am wondering if the new 250 fi is going to go to trials, I think it might if it proves reliable. I believe the 5 valve engine to be a good design, I have a WR400F and like it. But four valves are probably enough. I haven't seen the new 250 and don't know the weight comparison between the two. What do ya'll think/know? Neil King
October 17, 200718 yr I am wondering if the new 250 fi is going to go to trials, I think it might if it proves reliable. I believe the 5 valve engine to be a good design, I have a WR400F and like it. But four valves are probably enough. I haven't seen the new 250 and don't know the weight comparison between the two. What do ya'll think/know? Neil King The new WR250X and WR250R from Yamaha with EFI run the same 4-valve motor. Personally, I'd like to see a sidevalve two-valve trials motor, as it would lower the center of gravity of the bike. We certainly don't need twin cams and four valves given the rev range of a trials bike.
October 17, 200718 yr Author I am wondering if the new 250 fi is going to go to trials, I think it might if it proves reliable. I believe the 5 valve engine to be a good design, I have a WR400F and like it. But four valves are probably enough. I haven't seen the new 250 and don't know the weight comparison between the two. What do ya'll think/know? Neil King The new WR250X and WR250R from Yamaha with EFI run the same 4-valve motor. Personally, I'd like to see a sidevalve two-valve trials motor, as it would lower the center of gravity of the bike. We certainly don't need twin cams and four valves given the rev range of a trials bike. Isn't that what the gasgas 4t is supposed to be? I think that 4 overhead valves was a great advancement for a single cylinder engine, and multiple cylinder engines for that matter. Kind of like the reed valve for 2 strokes.
October 23, 200718 yr This is an interesting subject. Although I am pretty happy with the two units I have with five valve heads I think the writing is on the wall and this configuration
October 24, 200718 yr Isn't that what the gasgas 4t is supposed to be? I think that 4 overhead valves was a great advancement for a single cylinder engine, and multiple cylinder engines for that matter. Kind of like the reed valve for 2 strokes. The pics I've seen of the GG indicate that. The 4 OHV configuration for four-strokes is great, if you need a high/quick revving engine. The questions is this: Do the advantages of a 4 OHV design outweigh (no pun intended) the disadvantages of the higher center of gravity and taller motor?
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