Cam/Piston Help

[Zuber187]

I have a 04 honda 400 and recently installed the Ross 10.8.1 stock bore and the XRS Only HRC Copy cam. The bike runs good so I thought untill I raced my buddy and he beats worst than when it was stockand his bike is untouched 04 ex. It does fell like it has better low to mid but doesnt seem to have the pull on top that I was expecting. Could I be tooth off on the cam sprocket? Do think that Copy cam bogus? The bike runs good starts right up, no back firing and all tricks have been done, Ajusted throttle cable, grinded welds, no choke and holes in air box. I am running 160 main with Wb slipon 12 disc 20"razors. PLease help I cant stand losing.

[K_Fulk]

Some bikes just run better then others. Did you hone the cylinder when you put in the piston? What air filter? Did you try gearing higher? Your probly making quite a bit more on the bottom if you move it up you could take more advantage of it.

[Zuber187]

Yes, I rehoned it and and checked all the end gaps and clearances to what ross recomended. I was thinking the same thing with the gearing. I just checked the sprokets and I have 15/39. Does that sound right for stock gearing? I guess I should try going down a couple in the rear or a 16 up front. I am still a little sketchy on that HRC copy cam. Has any one else tried this cam. I am thinking of trying a Hot Cam since they are pretty cheap and see if it improves any.

[K_Fulk]

Stock is 15/38, Try a 36 rear or a 16 front. 36 on the rear would probly be a little better for your setup. 16 on the front might be a little to steep. Keep your eye open for tc cams. They work pretty good but are quite a bit more then hotcams.

[ranger400ex1994]

do you have a pipe? ya something is defently wrong. i have a stock bore 11:1 compression wiseco piston witha stage 2 hot cam with some porting and i have beaten stock 400exs with pipes and Z400s with pipes by like 4 or 5 quad lenghts. i have also beaten about every 416ex i have raced so i would say that there must be something worng. also my jetting is 42 pilot and 160 main jet.

[cals400ex]

i would try 15/36 gearing or so. also, adjust your throttle cable. there shouldn't be a lot of slack in it. make sure there is about 1/4 inch of slack in it and no more. this will make a huge difference if it is wrong.

[Zuber187]

Yes, I have adjusted the throttle which by the way has made the biggest difference so far out of all the Mods I have done. Do you think the cam could be a tooth off. I install it top dead center with the lobes facing down on the compresion stroke. I fiqured the bike would pop and bang or not even run at all if the cam was in wrong. The bike fires right up and and has great throttle response but as far as seat of pants feel, it doesnt feel much different. I have ajusted the valves according to spec card which is same as the stock. I even ran 50/50 110 octane which definetly help out the ping but thats about it.

[cals400ex]

i would take the head cover off and check for timing problems. you need to put the flywheel on the T mark. then look at the cam sprocket. the two horizontal lines must align with the head. with the cam lobes down, the 3rd line will be facing up. if the 3rd line is facing down, rotate the crank one time until the T mark lines up on the flywheel. now make sure both horizontal lines are lined up with the head. if not, the sprocket is offf a tooth.


my guess is that cam is just not aggressive enough. i would look into something more aggressive. the TC mx grind and the stage 2 hotcam rev much much higher than the stock cam.

[Zuber187]

Thanks for the info. Im pretty sure everything is lined up. She seems to be coming around now. I guess everthing was still tight and needing to break in. When I first posted this I only had a couple of hours on the bike. I just jumped to conclusion to fast. The bike really seems to be picking up now and starting to pull away on those damn Z's. Thanks for all the info. What a great site.