Suzuki Central Forum banner

1 - 20 of 27 Posts

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #1 ·
I was looking at this chart:
Lift in mm ...(example = 9.1 mm)
Duration in degrees...(example = 238*)

Hotcam- Newstyle Stage 1- ...........9.1 @ 238*both Int and Exh
Hotcam- Newstyle Stage 2..............9.6 @243 Int and 9.1 @ 238* Exh
Hotcam- Oldstyle ............................9.6 @243* both Int and Exh
Yoshi-...............................................9.0 @ 236* Int and 9.3 @242* Exh.
Web Grind# 631/294-.....................8.7 @ 224* Int and 8.17 @ 218* Exh.
Web Grind# 293/536......................9.14 @ 226* Int and 9.6 @ 244* Exh.
Web Grind# 288/293......................9.35 @ 234* Int and 9.15 @ 226* Exh.
Web Grind# 288/540......................9.35 @ 234* Int and 9.75 @ 248* Exh.
Web Grind# 540/539......................9.75 @ 248* Int and 10.16 @ 256* Exh.
Megacycle X510..............................10.85 @ 257* Int and 9.78 @ 252* Exh.
Stock Cams......................................8.92 @ 227* Int ans 9.3 @ 243* Exh.

and I noticed how much more aggressive the stock exhaust cam is over the intake.. would it be possible to mount the exhaust cam where the intake is? like if I were to buy a used one one ebay or something.. Also, Why do these numbers show that the stock exhaust cam is more aggressive than the hot cams exhaust cam? wouldn't it just be better to only upgrade the intake?
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #2 ·
I know that the exhaust cam has the auto-decompression built into it, but there must be some way to remove it or disable it
 

·
Registered
Joined
·
202 Posts
I highly doubt you can adapt it to work on the intake side, cams are relatively cheap anyways.
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #4 ·
Yes cams are cheap but i'm currently broke, saving money for rebuild parts, and I had read a thread about someone that was told by Web (web cams) that you could put the exhaust cam in place of the intake..
I really don't see why it wouldn't work, Both lobes are in the same place, the cams are the same size.. what else would keep it from working?
 

·
Registered
Joined
·
202 Posts
Maybe someone a little more knowledgeable can chime in.
 

·
Premium Member
Joined
·
4,285 Posts
i dont think i ever heard anyone ask this before, and i actually had to look at the specs to see what you were talking about. interesting idea you have, points to you.

i would remove the auto decomp, it shouldnt be hard to drill or grind the pieces off. after that it should bolt right up in the intake slot, you will have to watch the timing because the marks wont be there, but i think you could make it work. maybe someone with stock cams out of the engine can post up pics for us.

i am interested to see how this works out if anyone tries it. i am beyond that point on my own machine, but its still interesting and i want to know what kind of power it makes.
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #7 ·
I got the idea from this:
z400 cam swap???? - ATVConnection.com ATV Enthusiast Community
(different forum, sorry)
I figured that if you could do that with the Web Cam, why couldn't it be done with the stock? the stock exhaust cam has a more aggressive grind than the new style hot cams intake cam, the yoshi intake cam, and even some of the web intake cams.. It would definitely be worth a try if you can do it! and another plus is how cheap you can get a set of used stock cams for!
 

·
Registered
Joined
·
202 Posts
I figured removing the decompression thing would mess with the balance of the cam.
Another thing to think about is piston to valve clearance, since the stock cam is bigger than most of the aftermarket ones.
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #9 ·
I figured removing the decompression thing would mess with the balance of the cam.
Another thing to think about is piston to valve clearance, since the stock cam is bigger than most of the aftermarket ones.
This is very true! Would it be possible to just disable the decompression mechanism? As far as the piston hitting the valves, I don't think this would really apply to the intake side since all the fuel is being pulled into the motor as the piston is going down, then the intake valves close when the piston starts going back up on the compression stroke so no air or fuel can be pushed out.. But turning it over by hand first may be a good idea!
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #10 ·
The timing really shouldn't be too badly effected.. I mean, just by looking at the stock intake and exhaust cams side by side, you can barely notice a difference in size, if at all.. the differences in the profiles are so tiny, that I don't think it would really make a difference other than that little bit of extra fuel and air that's being allowed into the engine
 

·
Premium Member
Joined
·
4,285 Posts
i can tell you that OSHC's in and ex are the exact same part, just marked with paint pen "IN" and "EX". so you can bolt in a 9.6 cam in the intake.

you could open the decomp and tack weld it so it is always open.

claying the engine is always a good idea, that way you know exactly how much clearance at minimum you have on the piston to valves.
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #12 ·
i can tell you that OSHC's in and ex are the exact same part, just marked with paint pen "IN" and "EX". so you can bolt in a 9.6 cam in the intake.

you could open the decomp and tack weld it so it is always open.

claying the engine is always a good idea, that way you know exactly how much clearance at minimum you have on the piston to valves.
I don't have a welder, and I don't know what you mean by "claying"
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #13 ·
What would happen if you left the decomp. on there, still active, and installed the cam in place of the intake cam? I would imagine that it would be a lot easier on the starter.. I don't see why that would at all be a problem?
 

·
Registered
Joined
·
113 Posts
I thin you should try it. If the are the same size etc. Just be careful checking you clearence
 

·
Premium Member
Joined
·
4,285 Posts
you would be pushing intake charge back out the intake, it will probably cause excessive fuel to run out of the carb and act almost like a stuck enrichment circuit (choke).

im sure someone would wled it for almost nothing. also, the cams aren't balanced so i wouldnt worry about taking it off.
 

·
Premium Member
Joined
·
4,285 Posts
claying is when you put clay on the piston around the valve pockets, and assemble and crank the engine over a few times, then you measure the thickness of the clay at the valve pockets and see how close they come to hitting.
 

·
Registered
Joined
·
433 Posts
for the timing you could put your old IN sprocket on an use its marks
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #18 ·
for the timing you could put your old IN sprocket on an use its marks
Thats exactly what i was thinking.. But i was wondering if maybe it should be retarded a tooth or something because it's a good bit bigger than the stock intake is (going by specs.. By eye they look pretty much the same lol)
 

·
Administrator
Joined
·
7,896 Posts
You can not put an exhaust cam on the intake side without removing the auto decomp. A little thing that nobody probably knows is, even if you were to remove the auto decomp, re-install the sprocket AT THE CORRECT TIMING which you wont be able to do in one try, even after that, a stock exhaust cam will not work on the intake side unless you modify either the cam or the head. The surface where the decomp sits is larger in diameter than the bearing jornal, and on the exhaust side it will interfere. when you tighten the cam jornal cap, the cam will be locked up.

It is possible to machine the head, by hand even if you are good, to accept stock or stock re-grind exhaust cams on the intake side. I have done this in my own engine so I could use a web exhaust cam on my intake side. Webs and megacycles, and most other cams are stock re-grind cams so they play by the same rules. The OSHC's were the only exception that I know of, because both cams were made from scratch and were identical.


Now, let's say, knowing what you now know, you still wanted to use 2 stock exhaust cams. First, you are going to need to know how to degree cams. Im not going to take the time to explain how right now. Most people can't do this. You would have to press the sprocket off of the cam you plan to use on the intake side, and remove the auto decomp. Then press the sprocket back on and hope to god you got lucky and can get the timing right as it is. If not, you have to press the sprocket off and back on until you get it right which I wouldn't even have the patience for.

What I did with mine was I sacrificed a set of hot cams and stole the adjustable sprockets, and put them on my web cams. The press fit is not tight, so I had to peen the sprockets first, and then weld the sprocket hubs to the cams when I got it all set how I wanted it. This also is very tedious, but if you are looking to adjust cam timing, it is necessary.


Now if all of that wasn't bad enough, you also need to realize that there are different methods of measuring cams which have a HUGE effect on how they look on paper. Lift is lift in this case, BUT, advertized duration is measured in crank shaft degrees (at zero lash) from when the valve leaves the seat, to when it returns to the seat. This is a very tricky measurment, and a lot of variables can throw it off, so to be more accurate, you measure at something like 0.050" off the seat to when it returns to 0.050" off the seat. This is the most accurate way to check cam specs. BUT just to be a pain in the ass (I assume) Cam manufacturers don't all use the same lift point.

Hot cams for example are measured at 1mm lift, which is virtually the same as 0.040") Megacycle cams are at 0.040"
Webs are at 0.050"

I dont know what figure was used on the stock cams in this chart, but I believe it was 0.040" What I DO know, is back in the OSHC days, you could do just the intake swap for stage 1 which did run harder than stock, or you could do both cams for stage 2 and stage 2 ran much better. I credit this to the cam's timing more than anything else.
 

·
Registered
Joined
·
1,410 Posts
Discussion Starter · #20 ·
Alright. Well, that ends that! May be in the market to buy a larger intake cam for my rebuild once i have the money
 
1 - 20 of 27 Posts
Top