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Discussion Starter · #1 ·
calling sto, basically, cuz im sure he has lots of knowledge on these things(and of course antibody els whos knos about cams)

heres the deal, my stage 2 HC broke, so ima haft get another cam, yes i liked the power band pretty good, but how much bottom end will i loose by going to a stage three? also will much top end be gained from a stage three on my set-up?- im running a trail ported head, 11:1 piston, stock carbs with open element filter, and barkers....

i still need to pull off the head and check the valves and piston, and i most likely will stay on pump gas

i have researched stage2 vs stage 3, and have read diff opinions, jsut wanting a bit more insight........

-also, are the x3 and/or the web 685 cams worth looking into? and how would they compare to the stage 2 or 3 HC?.....

thanks guys
 

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Webcam 3, not alot of guys run them but with the right supporting mods and headwork they seem make obnoxious torque on the bottom end, my setup has a real nice climb in hp and it holds it there solid for a good 2500 rpm. Dyno #s really dont mean much but the guy who dyno tuned mine said that it was the best hp and torque curve hes seen. Maybe the build fits itself just right too, ive rode several builds some higher hp and some lower but mine seems to make power sobmuvh differently. You can lug it hard in 3rd 4th and 5th and as soon as you stab the throttle it starts getting wild almost instantly.
 

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That's alot of cams but I do my best.
- on a 673 dyno I gave up 2 ftlbs or torque in the midrange but gained 2 HP in the upper rpms between the stage 2 and stage 3 cams, swapped cams right there on the dyno.
- megacycle x3 is a good all around cam but would be pretty tough on the valvetrain if you really put alot of hours on it, i would place it between the web 685/686 and the x4
-the 685 is a good midrange cam, I only know 1 person who ever actually bought and ran one because the HC stage 2 is close to the same and quite a bit cheaper

I have a ton of cams which I have aquired over the years, if you're willing to send a deposit and pay for shipping them, I'll send you some to try.
 

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Discussion Starter · #4 ·
i liked the stage 2, i was just getting that thing running descent, i changed my jetting some and the thing seemed to have alot of midrange, with descent top end (for me), i would get into fifth gear pretty quick in a strait away-with 14/40 gearing on 18 in. tires-.....i was just thinking if i had to get another cam, usually the stage 3s go cheaper, i might just try that, but i still have to pull the head off and check my valves and piston(i broke both exhaust rocker arms-do u have any of those sto???)-il pm u..
 

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You've got a larger problem if you broke both exhaust rockers, lucky the valves didn't break and trash the top end. It would have to have jumped time for that to happen and I'd suspect either a severly worn timing chain, failed auto tensioner or the crank timing chain wheel spun on the crank.
When you say that your cam broke, can you explain what happened to it?
 

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Discussion Starter · #6 ·
ok, heres the deal. i was doing some carb stuff, and i was like, hey, il check my vlaves, and apparently i didnt tighten the one intake adjuster nut came loose, as well as the little"bolt" that u adjust (or it just worked loose, im sure i would have tightened it)... but i can see it ran that way for a bit, because of wear on the spring retainer. the nut and lil bolt are missing, i guess in the motor somewhere in the bottom. did this interfere with the cam in some way?? i dont kno for sure.. but the cam broke right were thecam gear bolts on, so the cam is just a cam with out that flange, the decomp mech. just kept in on ther spinning free, the cam must have been spinning fast enough to open thos exhaust valves to cause the carnage. this cam had low hrs on it as well, Dog 86 can verify that(at least im pretty sure it does, lol). and the cam chain was just replaced, and still looks good,.(il be pulling the head off this eve prolly)
 

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So the cam didn't break on two pieces, just cracked? Otherwise, how did the the gear stay on top of the head since the cam is all that holds it in place.
Yeah, pulling the head to check is the right thing to do but I would do a leakdown test first so you can tell if the valves are bent, otherwise, I'd replace both exhaust valves, springs and retainers along with a valve job on all 5.
 

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Discussion Starter · #9 ·
the cam broke, in halve, completely, lol. the part of the decomp that goes from the gear into the cam like 2 in. is what kept it "together", letting the cam spin free from the gear, which i guess the cam had enough inertia to open the exhaust valves yet. I ddi pull the head last eve and the exhaust valves kissed the piston, marks on the valves and slight ones on the piston. ima get new exhaust ones, intakes look fin. the valves in this head has very low hours on them as well,and look good. they are the Vesrah brand i believe, dont kno much about them......


i think the nut or lil bolt got between the cam flange(part the the gear bolts to) and the head, as there is a little mark on the head there, causing it to snap. il try to post up some pics..
 

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Discussion Starter · #10 ·
@ dog86- i kno right, lol...stupid badluk.......i cant believe i wouldn't have tightened that sucker down. but maybe i ddnt, either way, its another lesson learned i guess
 

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Discussion Starter · #11 ·
some pics



and u cant c it the best, but there is a little nick thet would be between teh cam flange there and the head
 

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That looks like quite a bit more than a single contact or two on those exhaust valves. They appear to have some fairly deep wear patterns in them which wouldn't occur with a just a few smacks. Obviously replace them, then clay the piston to check the piston/valve clearance when you go to put it back together.
 

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Discussion Starter · #13 ·
the piston looks fine from what i have seen so far, barley can see were the valves hit on the piston..im not scared to use it, but i might go with more comp and a stage 3 HC...............idk yet tho lol
 

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Is there a place that I can go on the web to find out how to install a stage2 hot cam in my 660? do I need to skip a tooth on the timing chain to set the timing up correct? or how is the best way to do it?
 

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Discussion Starter · #15 ·
well pulled the piston off the crank and noticed a small crack on both sides of the skirts, on BOTH skirts. total of 4 small cracks. not clean cracks, just cracks that have started. IDK if its from the jolt of the valves hitting the piston, or if it had some slap from lugging the motor.............

any way, im thinking about a stage 3 cam and some comp..... maybe a piston other than wiseco. this is the second one i have had skirt probs with(my first one was a std. bore that im sure had some slap, i should have bored it back then. i blame that broken skirt on piston slap from an egged out cylinder)-so maybe il try a diff. brand... hows the cp 12.5 do? i would think it would be strong with a stage 3..
 

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yeah, that'd be a strong combo but be prepared to at least mix fuel.

Just as a suggestion...do you have a bore dial indicator to check the machine shops work? Were both cylinders bored at the same place? I only know of 1 660 torque plate for boring cylinders but you should be able to get by with a quality bore on a recreational use motor. Problem is, you can not see the potential issues with the naked eye. 3 or 4 thou out of square is going to be major problems but that would look good to the naked eye. I'd make the machine shop show me the bore dial.

It really sounds to me like you have machine shop problems, not piston problems...remember when I said those exhaust valve wear patterns weren't from a single or few piston to valve contacts? That wear pattern is because your piston is rocking in the bore at TDC either due to an egg shaped bore or too large piston to wall clearance.
 

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Discussion Starter · #17 · (Edited)
the first time around, it wasnt bored, just honed and put a piston in. i dont blame the piston on that incident...

i got the local yamaha dealer to bore it second time around.... maybe il check into someplace els....

pretty sure i can get VP race fuel like 5 min. away from here, lol...any idea what mix? bout 96 or so?
idk yet what il do...i dont ride as much as i used to, might just go ahead and run some comp and stage three for a decently strong set-up and just ride when im going to RIDE... lol not every day to and fro etc..
 

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Discussion Starter · #18 ·
yeah, that'd be a strong combo but be prepared to at least mix fuel.

Just as a suggestion...do you have a bore dial indicator to check the machine shops work? Were both cylinders bored at the same place? I only know of 1 660 torque plate for boring cylinders but you should be able to get by with a quality bore on a recreational use motor. Problem is, you can not see the potential issues with the naked eye. 3 or 4 thou out of square is going to be major problems but that would look good to the naked eye. I'd make the machine shop show me the bore dial.

It really sounds to me like you have machine shop problems, not piston problems...remember when I said those exhaust valve wear patterns weren't from a single or few piston to valve contacts? That wear pattern is because your piston is rocking in the bore at TDC either due to an egg shaped bore or too large piston to wall clearance.
so u think my valves were hitting for a wile before this happened??? cam chain was very new...i guess like u said the piston may have been rocking..
 

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I'd just stick with the 12.5. If you can find some C16 you can mix that 2/3rds premium pump and 1/3 C16 and be fine.
 
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