Rambunctious
New member
I havr been chasing high rpm on top end
current setup
2000 srx
8dn20s'
4.5 heel. and 5.5 bolts tip
54/42
www prim.
red sec at 70
pulls good down low at 8500. but still hits 8700 on top end
and starting to feel a little sluggish in the backshift ( due to high tip wieght?)
question:1
if I put a green secondary in. it should backshift better right?,
but I think the stiffer spring will make top end struggle even more to shift fullout right???
ie. stiffer secondary inproves backshift at the expense of ( please fill in blank)
question: 2
if I stay with red, but put my 47 (stock helix in) the steeper finish shoudl let it shiftout more easily right ?, ( but may loose some low end upshift that the 54 gave me) right?
just want to check my theories. not much time to test before heading on a trip
Ramb
current setup
2000 srx
8dn20s'
4.5 heel. and 5.5 bolts tip
54/42
www prim.
red sec at 70
pulls good down low at 8500. but still hits 8700 on top end
and starting to feel a little sluggish in the backshift ( due to high tip wieght?)
question:1
if I put a green secondary in. it should backshift better right?,
but I think the stiffer spring will make top end struggle even more to shift fullout right???
ie. stiffer secondary inproves backshift at the expense of ( please fill in blank)
question: 2
if I stay with red, but put my 47 (stock helix in) the steeper finish shoudl let it shiftout more easily right ?, ( but may loose some low end upshift that the 54 gave me) right?
just want to check my theories. not much time to test before heading on a trip
Ramb
1.) the green is a stiffer secondary spring ,it will raise your rpms on top, the backshift can be better with it as its more powerfull then the red.
2.) the helix your using is too low in the finish angle, this is why your over revving on top, the 54/42 needs to be somewhere near a 43-45 finish angle, each helix brand is differnt somewhat, they can be differnt shift rpms.
3.) whats going to happen when you run the straight 47 now is your gonna be ok down lower, it will upshift SLOWER with a smaller angle but the clutch will keep a constant upshft rate from the straight angle but youll now under rev on topend because the 47 finish angle will be too steep for the amount of tip weight you have in, the higher your finish angle the more your loading the engine via the secondary clutch..
I see 2 possible fixes very easily, swap out the helix for something like a 51/43, 50/45, or install smaller 15mm rollers with what you currently have.
2.) the helix your using is too low in the finish angle, this is why your over revving on top, the 54/42 needs to be somewhere near a 43-45 finish angle, each helix brand is differnt somewhat, they can be differnt shift rpms.
3.) whats going to happen when you run the straight 47 now is your gonna be ok down lower, it will upshift SLOWER with a smaller angle but the clutch will keep a constant upshft rate from the straight angle but youll now under rev on topend because the 47 finish angle will be too steep for the amount of tip weight you have in, the higher your finish angle the more your loading the engine via the secondary clutch..
I see 2 possible fixes very easily, swap out the helix for something like a 51/43, 50/45, or install smaller 15mm rollers with what you currently have.
Rambunctious
New member
thanks mrv
50/45 sounds the best, keeping some pull from the 50 but close to the 47 on the finish. This confirms my understanding
seems a 54/47 would be perfect if such a thing is made. do they exist?
the smaller rollers sound good too. they let the swing weights act earlier in the rpm range right?
are they a stock yami part?
I jsut added new helix buttons that I bought last spring thinking that maybe the clutch is hanging up a little.
I also bought the green secondary. and 4.5 rivits again
I have 5g bolts too
have not yet tried anything this season.
so I could go back to 4.5 tip weight with 47. that could at least confirm the finish angle needed. then try to find a 51/45 or something
jsut seems the more tip weight I added, the more sluggiest it seems on the back shift. I like your theory of the less overall squeeze on the belt the better ( clutches not overpinching to compensate for each other) . seems intuitive that it will shift easier each way
Ramb
50/45 sounds the best, keeping some pull from the 50 but close to the 47 on the finish. This confirms my understanding
seems a 54/47 would be perfect if such a thing is made. do they exist?
the smaller rollers sound good too. they let the swing weights act earlier in the rpm range right?
are they a stock yami part?
I jsut added new helix buttons that I bought last spring thinking that maybe the clutch is hanging up a little.
I also bought the green secondary. and 4.5 rivits again
I have 5g bolts too
have not yet tried anything this season.
so I could go back to 4.5 tip weight with 47. that could at least confirm the finish angle needed. then try to find a 51/45 or something
jsut seems the more tip weight I added, the more sluggiest it seems on the back shift. I like your theory of the less overall squeeze on the belt the better ( clutches not overpinching to compensate for each other) . seems intuitive that it will shift easier each way
Ramb
well... your a little off in your theory, let me try to explain this to you, if you were to install a 54/47, what would happen is the sled would upshift rapidly from a dead stop /start, and with the steep finish angle continue to upshift rapidly and overload the engine, there would be no slowing down of the shift much and the secondary would get ahead of the primary clutch and they will basicly miss a gear this way.
It would be the same as starting off in 1st gear in a stick shift car, rev the engine dump the clutch and smoke the tires, then when the engine hits redline hit 2nd gear, car is still going good and spinning tires then again hit reline and shift to 5th gear, bypassing 3rd and 4th, now the car bogs and drops rpm, loses speed and power. It will recover from this but it will take a great distance to recover the power and rpm from the overshift. The sled clutch will be doing the same thing, because the shift never slowed down, and the clutchs get ahead of the engines power curve, the engine doesnt keep revving up the same constant rate. The shift has to match the power curve of the engine or the engine will not produce the power curve from lugging the engine.
((YOU WROTE)) ("I like your theory of the less overall squeeze on the belt the better ( clutches not overpinching to compensate for each other) . seems intuitive that it will shift easier each way")-
This part I dont have any idea where your getting this concept from what I wrote or understand what your saying, but you dont want less belt squeeze ever, and I am not sure how the clutchs can overpinch the belt and compensate each other?? youll have to explain your thinking to me.
what i suggested was a 51/43 helix and with your extra tip weight would be about perfect with the rest of your combo, if you went to the 50/45 helix it would also work well but would be a tad yet lower in the upper rpm, even though its only 2 degrees smaller on the finish then the 47 is the backshift will be improved because the helix is shallower then a 47 is and will pinch the belt more because of the smaller angle, it requires LESS secondary spring to apply the same amount of belt pressure in the secondary and this way you gain more topend speed.
As for the 15mm rollers, they will lower your rpms down by applying more belt pressure from the weights, it makes the weights act heavier then they are, this LOWERS the engagement speed and LOWERS shift speed rpm. You might want to read this as well to help.
http://www.totallyamaha.net/forums/showthread.php?t=32944
It would be the same as starting off in 1st gear in a stick shift car, rev the engine dump the clutch and smoke the tires, then when the engine hits redline hit 2nd gear, car is still going good and spinning tires then again hit reline and shift to 5th gear, bypassing 3rd and 4th, now the car bogs and drops rpm, loses speed and power. It will recover from this but it will take a great distance to recover the power and rpm from the overshift. The sled clutch will be doing the same thing, because the shift never slowed down, and the clutchs get ahead of the engines power curve, the engine doesnt keep revving up the same constant rate. The shift has to match the power curve of the engine or the engine will not produce the power curve from lugging the engine.
((YOU WROTE)) ("I like your theory of the less overall squeeze on the belt the better ( clutches not overpinching to compensate for each other) . seems intuitive that it will shift easier each way")-
This part I dont have any idea where your getting this concept from what I wrote or understand what your saying, but you dont want less belt squeeze ever, and I am not sure how the clutchs can overpinch the belt and compensate each other?? youll have to explain your thinking to me.
what i suggested was a 51/43 helix and with your extra tip weight would be about perfect with the rest of your combo, if you went to the 50/45 helix it would also work well but would be a tad yet lower in the upper rpm, even though its only 2 degrees smaller on the finish then the 47 is the backshift will be improved because the helix is shallower then a 47 is and will pinch the belt more because of the smaller angle, it requires LESS secondary spring to apply the same amount of belt pressure in the secondary and this way you gain more topend speed.
As for the 15mm rollers, they will lower your rpms down by applying more belt pressure from the weights, it makes the weights act heavier then they are, this LOWERS the engagement speed and LOWERS shift speed rpm. You might want to read this as well to help.
http://www.totallyamaha.net/forums/showthread.php?t=32944
Last edited:
Rambunctious
New member
sorry for the confusion. the comment was from previous comments you made
bottom line. I need to try these combos
I have everythign but a 51/43 or a 50/45
if I can pull the 50/45 in top end ok, then I will have some room left for when I hit my nitrous ( that's problem is step 2. I hit 9000 when I do that)
too many choices, just too many choices
so who has a true 50/45
and who has a 51/43
off to the waated section
)
Ramb
bottom line. I need to try these combos
I have everythign but a 51/43 or a 50/45
if I can pull the 50/45 in top end ok, then I will have some room left for when I hit my nitrous ( that's problem is step 2. I hit 9000 when I do that)
too many choices, just too many choices
so who has a true 50/45
and who has a 51/43
off to the waated section
)Ramb
hang in there youll get it....lol
Rambunctious
New member
thanks mr v
its fun to see i'm not the only one who try to learn how it work lolll..........
Yamanewf
New member
I have a 51/45 if you are interested.
yamaholic22
Active member
A 51/45 will work very well with that setup. I have used it with good results.
Rambunctious
New member
yamanewf: I call dibs
look for a pm, thanks
modsrx, my burden.... I'm an engineer. I Need to know why something works, not just that it does.
now if my buddies have enough patients to let me switch out helixes and springs at our favorite stop and race spot, I'll be good to go.
Ramb
look for a pm, thanks
modsrx, my burden.... I'm an engineer. I Need to know why something works, not just that it does.
now if my buddies have enough patients to let me switch out helixes and springs at our favorite stop and race spot, I'll be good to go.
Ramb