Cams

[400exrules]

I want to get a cam to give me some more power. I drag race in 300ft. dirt. All i have now is a filter, jets, and a slipon (mods in sig)...but i want to get a cam and a sparks full system. What stage and brand of cam should i get? do drop in cams give less power then non-drop in cams? And will i need to rejet with a cam?

thanks!

[DaleJrFan]

i dont know the difference between the drop in and non-drop in but i installed a stg 2 hot cam and i am really satisfied with it.

[DaleJrFan]

i forgot, i didnt have to re-jet, hope this helps.

[greg_gorrell]

alright to make this simple, the drop-in cams, like the hot cams, dont require you to do anything else, you can just drop them in and ride. this is because the metal used to make the cam is the same hardness as the stock cam and the rocker arms. The other cams, where you have to send your core out like tc racing, they take the old cam and grind off the lobes, and then put new ones on. They metal they use for those is harder than the rocker arms and other parts where they will meet. so you will need hardened rocker arms which will require you to harden a few other things. cams have no effect on the air to gas ratio so you will not have to do any jetting with just the cam. when you get the sparks full system, then you will have to worry about jetting.

[DaleJrFan]

so they will take the stock cam, grind off the lobes, and at that point, do they weld some blob on and grind into shape or what?

[mikeboone]

Originally posted by DaleJrFan
so they will take the stock cam, grind off the lobes, and at that point, do they weld some blob on and grind into shape or what?

They dont grind the stock lobes off. they just weld to them and regrind to their specs. They can not only adjust the height (lift) of the lobes but how steep they are.

[DaleJrFan]

makes sense, thanks.

[400exrules]

ok cool!

couple more questions

1. what are some good drop in cam makers
2. what stage cam should i get for 300ft. dirt drag racing
3. will the full system sparks respond much better with the cam then my hmf slip-on would?


thx for the info:D

[mikeboone]

Originally posted by 400exrules
ok cool!

couple more questions

1. what are some good drop in cam makers
2. what stage cam should i get for 300ft. dirt drag racing
3. will the full system sparks respond much better with the cam then my hmf slip-on would?


thx for the info:D

For 300ft dirt I would get the Stage 1 Hotcam. You are only gonna get through 3rd gear likely and need good hit off the line. I would set gearing where it is hella low where you can slip the clutch and leave in 2nd eliminating one gear shift. For mild motors the slip on is best. Chassis etup will play more part in winning than overall HP.

Pump froint tires up twice normal for less drag.

Remove any non essential weight

Back off the preload on rear shock a little so you get good weight transfer over rear tires.

The Stock 400ex rear tires work good but the Maxxis 4 snow tires are what I run (plan to) on dirt. Around the house they hook great! Get spare set of rear rims and mount them and see which works best. Tires are only about $45/each

[mikeboone]

Just read your sig--forget about the Maxxis since you have the best tires for the job.

:)

Lowering kit would help keep front down if you have wheelying probs.,

[400exrider707]

I have a stage 1 cam for sale, PM me if interested.:cool:

[mikeboone]

Hotcams could make any lift and duration cam they wanted. A drop in cam CAN be made just as good as a hardwelded one. Once you get around .350 lift on a 400ex the tappet on rocker arm is very close to smashing into the valve guide which sticks up about 3/8" above the head surface. If Hotcams wanted they could manf. short valve guides & HD springs like WEB does and make high lift cams.

For the average rider the Drop ins are the most bang for the buck. The WEB 451 has very little more lift over the Stage 3 Hotcams and requires nearly $300 more for rocker hardfacing plus HD spring costs.

[400exrules]

Originally posted by mikeboone
Just read your sig--forget about the Maxxis since you have the best tires for the job.

:)

Lowering kit would help keep front down if you have wheelying probs.,

i met a guy at the dragstrip, that sold his sons 400ex and got a yfz, so he's gonna bring his wheelie bar next weekend and im gonna try it out, i might buy it from him instead of me and my dad making one. I grew up around this drag strip and thats out i got my interest in fourwheelers....and ive been trail ridin for awhile, but started racing their about a month or 2 ago, and let me tell you, its addicting lol.