neil king Posted October 17, 2007 Report Share Posted October 17, 2007 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 Quote Link to comment Share on other sites More sharing options...
malibudon Posted October 17, 2007 Report Share Posted October 17, 2007 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. Quote Link to comment Share on other sites More sharing options...
neil king Posted October 17, 2007 Author Report Share Posted October 17, 2007 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. Quote Link to comment Share on other sites More sharing options...
ahamayfrank Posted October 23, 2007 Report Share Posted October 23, 2007 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 Quote Link to comment Share on other sites More sharing options...
malibudon Posted October 24, 2007 Report Share Posted October 24, 2007 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? Quote Link to comment Share on other sites More sharing options...
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