ok i understand 3/4ths of it. but the dynamic and static comprestion. i wanna no what each one means.and witch on is the one that makes u have to run race gas or not.
ok i understand 3/4ths of it. but the dynamic and static comprestion. i wanna no what each one means.and witch on is the one that makes u have to run race gas or not.
2000 400ex
11:1 wiseco piston
stg2 cam
fmf slip on
douglas wheels around
gbc race rex tires
ac nerf bars.
maiger plastic
pro taper s/e bars
swinger skid plate
450r fronts
Simple explanation. First off, we're not talking about compression readings, we're talking about the actual calculations.Originally posted by 250rforlife
ok i understand 3/4ths of it. but the dynamic and static comprestion. i wanna no what each one means.and witch on is the one that makes u have to run race gas or not.
The compression ratio as you normally see it, like 9.4:1, is the STATIC compression ratio. Let's make up easy numbers. The "size" of the engine is the actually volume the piston moves, let's say it's 360cc. Let's also pretend this engine has a 40cc combustion chamber (the volume of space when the piston is at Top Dead Center, the volume when you're actually burning). The compression ratio is calculated as the TOTAL (360cc+40cc=400cc) divided by the combustion chamber (40cc). This engine would have a 10:1 compression ratio.
However, the valves don't actually close when the piston is at absolute bottom, believe it or not, the air is still moving into the cylinder. The valve actually closes a little later, the piston has already started it's upward travel on the compression stroke. This is the Dynamic Compression. It's not when the piston is at the bottom, but the compression ratio when the valve actually closes.
Let's pretend, in our same 360cc engine, that the piston has started to move up and takes up 20cc of that space before the valve closes. Now we have 380cc (340cc plus the 40cc combustion chamber) divided by our 40cc combustion chamber volume.
380/40=9.5
This is a far cry from our static of 10:1.
As you can see, the static compression is based on the engine design alone. You can change it with pistons that take up more of the combustion chamber, but the dynamic compression actually changes based on the camshaft specifications, because different camshafts close the valves at different times.
Duncan Racing 340PV, +2 A-arms, +4 LSR axle, and a host of other goodies.
XR400.............. .326, .321, 240, 244
HRC................. .350, .339, 254, 256
GT Thunder....... .350, .345, 256, 256
WB Track.......... .350, .345, 256, 256
WB All Around.... .345, .335, 240, 248
WEB 450/451..... .350, .345, 256, 256
WEB 479........... .378, .378, 250, 250
WEB 463/9i....... .385, .370, 272, 270
Hotcams stg 1... .354, .354, 246, 246------Intake centerline 106, Exhaust centerline 107
Hotcams stg 2... .354, .350, 254, 248.5----Intake centerline 106, Exhaust centerline 104.25
HC stg 2 (old).... .348, .349, 254, 254------Intake centerline 106, Exhaust centerline 107
Hotcams stroker. .358, .354, 262, 257------Intake centerline 110.5, Exhaust centerline 104.5
Megacycle x1..... .346, .346, 246, 246
Megacycle X2..... .378, .378, 254, 254
Megacycle X6..... .402, .385, 270, 262
I have a magnum cam and the #'s listed are the same as the gt thunder, wb track and web 450/451 not sure if there are any other specs to take into account hoping it was not a waste of money for a 416 mx build. I was wondering if a port job or should i go +1 valves and if 11-1 or 12-1 compression piston? Thanks
How many guys are running the Part#1043-2 stage 2 HC on their (stock) 400ex's? I purchased one thinking it would be a good cam to have for my 4wheeler, but I have been reading that a stage 1 might be better suited. I have no desire to build the motor as I already have two other projects in the works.
I'm just looking for a bolt and go operation for some weekend fun(trail riding). Would you guys recommend I sale the stage 2 and get a stage 1, or keep the stage 2? I will be running a LEXX muffler on a stock header with the tube welds dremeled out for a little better air flow.
-mr34-
04 400ex - Weekend Warrior
93 SE-R - 2.3L big bore in progress
01 G20T - Automatic tour ride
I posed this question to Steve, and mentioned a possible addition of the +6 key with a stage 2 cam, on the stock bore. surprisingly to me, the responce/opinion was quite different than I would have figured it.
(I'll leave his exact responce out of it, in case HE would like to weigh in on it here).
I'd really like to hear from both GPracer2500, and Wheelie,
to see what their opinions on this would be comparatively...
How would a 400EX stock piston/bore with a stage 2 hot cam, and a +6, timing key perform,...
vs.
a 400EX stock piston/bore with a stage 1 hot cam, and stock, (OR,... +6) timing key ?
(Keep in mind, this question/comparison is for a STOCK Bore, STOCK Compression 400EX)
GPracer, and Wheelie,..... would you guys mind weighing in on this ???
Steve ??? Pipeless ??? Beags ??? Nacsmxer ??? ZRpilot??? wilkin250r???
Thanks
i will post my individual experiences with the keys, though it seems to be a bit different than some others.
I feel that the keys help out top end with more advance.
so a 6 degree with a stage 2 would result in more top end than a stage 2 with a stock key with the same setups for comparison. the low end falls off as a result of this timing advance also.
i dont have any numbers or anything to back this up though, which is why i have issues with anything on the subject.
just my experiences, thoughts?
steve
2019 Maverick X3 XDS Turbo R
2003 TRX 400EX
2016 HONDA RANCHER
speaking from experience, stage two cam on a stock motor makes it lazy and the power was not impressive at all.
2003 400ex
-namura 440 big bore kit
-stage 2 hotcam
-debaffled shorty stock exhaust
-168 main jet
-itp holeshots
-outerwears shock covers
-high bend bars
-tether
I have Read trough this all and I cant make since of anything...
I have a 100% Stock 01400EX with a slip on, what Cam and Piston should I run If I wanted to up mid - high but not really loose bottom end? If that if even possible...
Lance
on a stock bore, stock compression piston,...Originally posted by DirtyBirdRacing
I have Read trough this all and I cant make since of anything...
I have a 100% Stock 01400EX with a slip on, what Cam and Piston should I run If I wanted to up mid - high but not really loose bottom end? If that if even possible...
You'd probably be quite pleased with a HC stage 1.
the stock compression does not really support the flow of a stage 2,....
without sacrificing bottom end.
Add to that, a Uni air filter, outerwears lid, +6 timing key, and a '04-'05 450r carb. (PROPERLY RE-JETTED of course)
You will then be at 32 - 33 Whp,... (as compared to your 26-28 Whp now).
See my carb comparison thread, ( in the stickies ).
and before you even ask,.....
NO,.... you will NOT gain anything with a aftermarket CDI, or coil. They are a complete waste of money, ESPECIALLY on a stock piston configuration.
but before you do ANY of that,...
You will be far better served,...
With a pair of good front shocks.
Would it matter if I ran a K&N filter? sorry for got to mention that I was running that before
Thanks for the help.
Originally posted by tri5ron
on a stock bore, stock compression piston,...
You'd probably be quite pleased with a HC stage 1.
the stock compression does not really support the flow of a stage 2,....
without sacrificing bottom end.
Add to that, a Uni air filter, outerwears lid, +6 timing key, and a '04-'05 450r carb. (PROPERLY RE-JETTED of course)
You will then be at 32 - 33 Whp,... (as compared to your 26-28 Whp now).
See my carb comparison thread, ( in the stickies ).
and before you even ask,.....
NO,.... you will NOT gain anything with a aftermarket CDI, or coil. They are a complete waste of money, ESPECIALLY on a stock piston configuration.
but before you do ANY of that,...
You will be far better served,...
With a pair of good front shocks.
Lance