[turbobobby]

i milled the head and now need to degree the cams. i am looking for the specs - degrees @ .050 for both intake and exhaust and the lobe centers on the intake and exhaust.

 

[red121572]

Thats a really good question and it deserves a really good answer. Hmmmm......

Its not in the service manual. :/

OH! Ask whats his face...Ummmm...Gary from the Superbike Shop, he'll know.

 

[turbobobby]

opps....forgot i posted this question here. well i didn't find anything out on the forums i normally use so i called web cams. there is a gal, lori, boy she rally knows her stuff when it comes to cams! she got me all lined out.

i had a problem with my predator a small while back. 4th gear decided to go out. well while waiting for parts to arrive i had the head ported and the pipe ceramic coated and the piston and combustion chamber poly-ceramic coated. o-yea and the head milled .025 to up my compression. after i got my bike back from the dealer it was slower than it was stock! i was very unhappy about losing performance. i decided to go inside the engine to find out why it was running bad. i though maybe milling the head caused the cams to be out of spec. so i learned how to use a degree wheel. next i found these cam specs from web cams. i then degreed my cams. come to find out the dealer installed my cams - both of them - 16 degrees advanced!!! that would be exactly 1 tooth off!. after i put them back where they are supposed to be the bike runs like a champ! once again a very happy predator owner!
believe me they will run and idle fine when the cams are off one tooth. i couldn't believe it but it is true!
BTW milling the head .025 retarded the cams by 2 degrees. good for high rpm power.....perfect for duning in the sand!

it pulls 13 37 in second gear with padla bratt 9 paddle tires launching



intake
opens @ 8 degrees BTDC
closes @ 49.5 degrees ABDC
exhaust
opens @ 39.5 degrees BBDC
closes @15 degrees ATDC

BTDC - before top dead center
ABDC - after bottom dead center
BBDC - before bottom dead center
ATDC - after top dead center

lobe centers intake 111 exhaust is 103

duration is almost identicle at around 236 degrees. from what i found this # is a little conservative.

lobe separation between intake and exhaust is 108


there it is not sure on the checking method like at .050 lift.

 

[powerslider]

Any lift #'s TB? The duration is very conservative. Just for comparison sake the 400EX stock cam is;

lift intake;316 exhaust; 302,
[email protected] .050 lift is intake 234, exhaust 238

The HRC upgrade for this using a 11:1 comp ratio is
.350 .339 254 256

 

[turbobobby]

the lift is .409 for both intake and exhaust.

i would like to try some cams with around 280 degrees duration. that ought to really wake up the mid and top end for the sand. o-yea need a 13-1 comp piston to keep the bottom end grunt. i do all my riding in the sand so i really like it to rev.

 

[powerslider]

Thanks, that's better lift than I expected, that explains the quick rev characteristics of this motor. It'll be interesting to see what the aftermarket comes up with for cams. Maybe Web will whip up some .479ish 280ish combo's, scary thought ehh????