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Cam Timing How Too

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Turbo11T

Well-known member
Nov 26, 2007
3,062
751
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Lake Crystal, MN
I figured since I just did it I would do a write up on it. If there is something i miss or need correction on please feel free to point it out.

I am going to start assuming that you have the valve cover off. Also please reference the service manual for cam removal and torque specs and sequeances. If you dont have one you can find them on ebay or online for $5 for the cd of the service manual. It is very worth having.

Pic of the tools needed.

SDC10524.jpg


1. Mount the degree wheel on the clutch(vector and nytro).
2. Fab a pointer off a rigid point on the motor. That goes to the degree wheel.
3. Set the motor at TDC on the cylinder closest to the cam chain. Do this by lining up the timing mark on the flywheel and the mag cover.
4. Set the degree wheel to 0 degrees TDC.
5. Loosen the cam chain tensioner with small straight screwdriver. I removed it from the engine.
6. !!!!!VERY IMPORTANT!!!!! Do NOT turn the engine over after this step until the the tensioner has been reinstalled.
7. You can either remove the cams now and remove the gears to slot them or you can just remove the gears and slot them. ****be careful to not drop the bolts into the crankcase.
8. Keep good track of which gears go to the intake and exhaust as you do not want to get this screwed up. It would be best to mark them with a tag or a sharpie.
9. When looking at the gears, slot from the side with the stamped writing. Slot the Holes on the exhaust cam clockwise about half way to the next hole in the gear. Slot the intake gear counterclockwise aprox half way to the next gear. Use care when doing this.
10. Reinstall gears. Reinstall cams if you removed them.
11. follow service manual for reinstalling cam chain, tensioner, etc.
12. Now you should be able to turn the engine over again. Do so with care, and very slowly for the first couple rotations. Do not force it past any resesitance. Also watch to see that the timing chain has not jumped a tooth.
13. Install tdc stop in the end spark plug hole. I used a bolt i got at the hardware store that matched the spark plug threads I think it was a m10x1.00 and was 50mm long.
14. Now turn the motor over slowly backwards until the piston stops on the stop. Now note the reading of the pointer on the degree wheel. Write it down. Then turn the motor over the corect direction slowly till it stops at the stop again. Note the reading on the degree wheel. A good example would be the first measurement was 104 degrees and the second was 140 degrees. You need to split the number. Mine was closer than that from setting the degree wheel at tdc earlier. Either way what you want to do is split the number. You would get 18 degrees.
15. Loosen and rotate the degree wheel(not the motor) to 0 TDC and then remove the piston stop. Now rotate the motor to 18 degrees. Stop loosen the degree wheel again using care to not rotate the motor and set the degree wheel to 0 TDC once again.
16.Now setup a mag base and dial indicator like shown below. On the intake cam.
SDC10525.jpg

SDC10526.jpg

SDC10530.jpg

17. Set the dial indicator to 0.
NOTE:do not rotate the engine backwards if you go past just rotate forward. this needs to be done to keep the timing chain tension correct int he next steps.
18. Now rotate the engine until the dial indicator reads .040 of valve lift. Write down the reading from the degree wheel. An example would be that i had 5 degrees.
19. Now continue rotating the crank until the dial indicator indicates .040 before closing. EXample I got 46 degrees
20. Now for the math.

Intake cam

OPEN 5 degrees
close 46 degress
add =51
add 180
= 231/2
=115.5
- 5
= 110.5

This gives me 110.5 lobe centers.

Now repeat the exhaust side. Always subract the smaller of the opening and closing numbers as seen above.

After having the cams where i wanted them I removed the degree wheel and reinstalled everything again and checked my work once again, I did this 3 times to be sure of my work. It was the same every time. Then I was confident I had done it correct. It was good for peace of mind.

Again, I am no expert I am just trying to help those out there trying to do this themselves. Really it was not that bad to do.

It is also best to set your cams to what your turbo manufacture reccommends. I set mine at 110.5 and 113.5. AS powderlites told me that anything over 110 is really good on the vector motor.
 
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Turbo11T

Well-known member
Nov 26, 2007
3,062
751
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Lake Crystal, MN
GEars

are you using megacycle gears or moded OE stuff to make adjustments??

I slotted my stock gears. You can get slotted gears from Hurricane Performance in canada or others as well. The cost is not bad on them but I had the tools to slot my own so it was much cheaper.
 
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SPOOLED

Active member
Dec 4, 2007
186
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28
northern bc
nice write the only thing i can see that you should have done to get proper readings is to remove the valve lash so at your 040 you will get a proper measurement on the dial indicator. you will get a more accurate reading.
 

summitboy

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Premium Member
Nov 26, 2007
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I may be no expert in this but is the dial indicator really necessary ? If you have the number 3 piston at TDC with the flywheel mark at the I mark and the cams aligned with the cap mark arrows how can you mess it up ? Sure once you slot the gears you need to make sure the cam marks align once again but you can see what .85mm looks like on the arrow. Maybe this is a Powderlites thing. I believe they go a tooth advanced or something like that on either the Ex or Int, not quite sure. This seems to complicate things in my mind, but heh enlighten me LOL
 
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Turbo11T

Well-known member
Nov 26, 2007
3,062
751
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Lake Crystal, MN
I may be no expert in this but is the dial indicator really necessary ? If you have the number 3 piston at TDC with the flywheel mark at the I mark and the cams aligned with the cap mark arrows how can you mess it up ? Sure once you slot the gears you need to make sure the cam marks align once again but you can see what .85mm looks like on the arrow. Maybe this is a Powderlites thing. I believe they go a tooth advanced or something like that on either the Ex or Int, not quite sure. This seems to complicate things in my mind, but heh enlighten me LOL

This is for cam timing for changing the lobe centers from stock. Not for setting the stock cam timing, though it could be used to check the stock timing as well to be absolutely sure you have it set right.
 
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Menace1

Well-known member
Oct 23, 2008
299
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Calgary
cam timing

Just wondering what the consensus is for cam timing on turbo nytros. Should you advance both intake and exhaust cam timing or just exhaust or any other way with the head shim installed, thanks.
 
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powderlites

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Nov 26, 2007
638
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Sicamous, BC Canada
www.powderlites.com
Cam timing

Well great to see someone helping educate sledders on this topic.
For Nytro, Apex and 1200 SkiDoo we have cam timing jigs to take away the guess work.
Stock vectors and Nytro motors seen to be all around 98 degree lobe centers. Apex can be way off from what i have seen.
68 to 72 degrees of overlap is just not great for boosted motor.
Lower your boost and get more throttle response by degreeing cams has been around for many years.
On Motorcycle cams we would run for drag racing anround 110 lobe centers on non boosted motors.
Have seen using cams from Yosh and stock exhaust etc.
Really had good luck with Webcams. Please don't put head on bench and install camshafts like in the picture as you could bend valves. Support head so valves clear any time cams are put back into head. Two customers have brought me leaking valves that are bent!!
If you are setting up TDC should be with piston stop to center degree wheel.
A way to check you are doing it right is change from .040 to .060 and lobe centers should be the same.
Doesn't matter about valve lash as we are only concern with lobe centers.
I don't care when valves are opening and closing like old school auto car guys.
Do you think at 10,000 RPM it matters? No not tooo much.
These cams are not meant for boost but Dave at Hurricane has got turbo boost cams that make about 20 HP at 20 PSI boost over stock.
Been doing this for over 23 years on bikes and it works no matter what some yahoo says. How can a same psi boost motor make more power? start with cam timing and everything in a well balanced setup.
302 turbo SB ford with a drop of 3 psi boost still with make more power with proper cam installed.
Rememberr on Apex the dots move to the outside and on Vector and nytro dots move to inside because motor run backwards compared to each other.
Vector we have run a total of 32 degrees more lobe seperation then stock.
yup jump one tooth because of head spacer.
 
T

Turbo11T

Well-known member
Nov 26, 2007
3,062
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Lake Crystal, MN
Bench

Please don't put head on bench and install camshafts like in the picture as you could bend valves. Support head so valves clear any time cams are put back into head. Two customers have brought me leaking valves that are bent!! QUOTE said:
Yep the head on the bench was just to show how to set up the dial indicator, and is a spare and the cams are not tightened down on this head. I would not reccommend setting the head on valves either.

Thanks for pointing this out.
 
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AKSNOWRIDER

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Dec 25, 2007
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coming from an auto racing back ground..I will say this cam/cam timing and ports are the key to making power..doesnt matter the induction..someone who spends the time to dial a motor in right will always make more power then a stock/throw togeather motor....and cam lift/duration/lobe center is critical to getting the most out of a 4 stroke..and the closer it matches the induction needs..the better and more power it will make...normally with forced induction you spend more time on the exhaust side trying to help it keep up with the pressurized intake...good thread....
 
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powderlites

Well-known member
Nov 26, 2007
638
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Sicamous, BC Canada
www.powderlites.com
Cam timing

I see powderlite mentioned jumping a gear tooth with a head shim...? I bought a 60 thousandth head shim and wondering which gear needs to jump a tooth and which way?

Just buy our Cam timing jig and then setup to top dead center with bolts in cams and align jig to top of head and install sprockets. once timing is done rotate in the right direction and recheck by setting cam jig over bolts.
Easy way to do cam timing and we have in stock for Nytro, Apex and Skidoo 1200.
powderlites.com
250-836-4422
 

Rattman

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Oct 7, 2013
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Saskabush
I slotted my stock gears. You can get slotted gears from Hurricane Performance in canada or others as well. The cost is not bad on them but I had the tools to slot my own so it was much cheaper.


Have you got any info or how too's on gear slotting?
 
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