So me and my dad just did a rebuild on my crf250r and its very hard to start even though it shouldn't be. We sent the head off to fastheads, so we are sure it isnt the valves. We got the OEM piston and replaced all the bearings and seals we could without splitting the case. The bike takes 15-20 kicks to get it started and I am not sure what it is. The spark plug has not been changed, but it has spark (we tested it). Many people said to reset the Cam Chain Tensioner, which we did. Could it be the jetting? even before the rebuild it was a pain too start, but we assumed it was the valves. The carb was sent off to TokyoMods several years back and we are not sure if we need to redo the jetting or not. Thanks!