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250x cam

7006 Views 7 Replies 4 Participants Last post by  Billy250X
i know this has all been discussed many times. but what i am looking at is this. i recently put a 80mm big bore kit in my 250x. it still has the stock cam. i had a nice newer model 300ex carb which is a 32mm, so i put it on and rejetted. problem is, i don't think that it is getting enough gas. i have a 400ex carb on its way from gdh racing so this should help. i know i need a bigger cam with more duration but i really don't want to change valve springs and rockers. i don't have so much of a problem with getting the hard weld rockers as i do running those stiff a** springs. i have seen what they do to the valve tips, not to mention the extra stress on the timing chain parts. i guess what i am asking is; will the hotcams stage one be enough to make my big bore kit run good? if not, what cam do i need to buy and can i even get a cam that would make this engine run well without having to change the valve springs. i don't need to squeeze every ounce of power out of it, but i do know that my current cam and carb set up is not enough. my big bore kit is rated at 11.5 to 1 compression. i put new valves, guides, etc. in the head. i have a 400ex carb coming and i am running a fmf megamax 2 exhaust. my sprockets are still stock 13/38 with 20 inch rear tires. any help or tips much appreciated.
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well, according to the instructions with the kit i could leave the slow jet stock or go up one size, it is a 38. they recommended going up at least 4 sizes on the main, which i did and eventually went two more. so the main wound up at a 140 and i also raised the needle one notch. there is no hesitation and it runs good with the plug burning a light brown color at wide open. this is with the 32mm 300ex carb. it runs good, but i cannot tell that it has much more than the stock engine that i had in it. the only thing i have to compare it to is the old fords i use to have. you can tell when a engine is not getting enough fuel.
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