Clutch spring advice

[J.S.@SMS]

I've been riding my drifter lately and I've noticed that it doesn't seem to have much off the line acceleration. The top end is good and it has pretty good acceleration once the clutch locks up (for a 100% stock predator). But it takes 15-20 feet to lock the clutch. Is there a cheap and easy way to fix this? I was thinking that a slightly stronger spring might help (maybe a green spring). I would like to be able to do peel outs, but I don't think it'll do those without a torque converter, so for now I'd like to get the clutch to lock up quicker.

The kart's a Carter 2575 with a live axle conversion, with 11" slicks and 4.8:1 gearing. And I'm running a max-torque clutch.

 

[JTSpeedDemon]

Hmmmm, that would increase engagement speed by about 350 RPM. That might decrease the time it takes to lock up, but definitely not peel out.
My kart peels out occasionally, with 5.5/1 gearing and 5" wide tires and the same Max Torque SS clutch, but granted it is 1WD and has dry rotted tires.
Even with a TC, it is highly unlikely that you'll get that kart to peel out.
I plan to play with clutch engagement speed in the future, we'll see how that goes.

I know it'll kill the top speed, but if you want better acceleration, it's really still down to gearing. Clutch springs can help, but only to an extent.

 

[J.S.@SMS]

I probably should have specified, the kart gets used for drifting on grass in fields. It'll spin the tires like it's nothing once the clutch locks up. And it does pretty good donuts but they'd be better if it had more steering angle, and I'm still getting used to it (the engine is 3 hours out of the break in). And I might be able to use a 50t sprocket, but a 60t sprocket is too big.

And I think it would peel out with s TC since it has 6" wide slicks.

 

[JTSpeedDemon]

Maybe some narrower slicks would help. That way it would spin the tires a little more readily, making it easier on the clutch.

 

[itsid]

a stronger spring will INcrease the time it takes for a locking clutch, not decrease it!

think about it this way:
the more rpms the engine needs to fully lock a clutch at a fixed gear ratio,
the faster the wheels need to turn in order to fully lock a clutch.

with a fixed amount of power.. more speed means LONGER acceleration
(since quicker acceleration would require more power or a better gear ratio in your case)

So no.. a stiffer spring is NOT what you want..
in fact a weaker spring is also not what you want
since the predator is idling just under
the engagement speed of a clutch (@1800 rpms) and 2200 full lock,
clutches start engaging roughly at 1800 rpms.. (both +/- 150rpms)
so there is no nominal wiggle room I'm afraid.
certainly none for a weaker spring.

Also less engine rpm means less power and you wouldn't gain much in terms of acceleration anyways.

the only option left is a better gear ratio I'm afraid.
(a TC would do that for you quite well.. IIWY I'd get one)

'sid

 

[J.S.@SMS]

I really need to get a cheap tach for out in the garage. I set the idle on my engines to just above the point where they stall, in that sweet spot between having a high idle and having a rough, choppy idle. I think it's somewhere around 1700, but I really need to check it with a tach.

But I'll start planning on adding a TC in the next few months. I actually set up the kart so that I could install a TC by just moving the sprocket a bit, because I wasn't sure how a centrifugal clutch would perform, and I didn't want to spend too much at first. I might try one of the cheapo ebay TCs.

 

[JTSpeedDemon]

Actually 'sid, Max Torque SS's like JS's and mine, engage at 2200, full lock comes later.
Max Torque's website says they engage at 2200 RPM, compared to the 1800 RPM most other clutches engage at. I believe it, because the blue spring is for 1800 RPM. I'm sending an e mail to Max Torque to confirm.

 

[J.S.@SMS]

Let me know what they say.

 

[JTSpeedDemon]

Uhm, WOW, they got back to me really fast!
Here's what he said:

If the spring color is silver you are correct it starts to tick around 2,200 and is LOCKED when it gets to 2,400rpm. There are two stronger springs.

So yes, our clutches engage at 2200 and lock at 2400 RPM.

 

[J.S.@SMS]

I thought that engagement sounded higher than 1800.

 

[JTSpeedDemon]

It's handy for rather temperamental engines like mine, so it's more forgiving to tune and won't launch at idle!

 

[itsid]

Uhm, WOW, they got back to me really fast!
Here's what he said:

Quote: If the spring color is silver you are correct it starts to tick around 2,200 and is LOCKED when it gets to 2,400rpm. There are two stronger springs.

So yes, our clutches engage at 2200 and lock at 2400 RPM.

Thanks for the verification.
Odd, but if Jim says so I must have misunderstood the denomination earlier for what he was explaining..
(or they changed the spring in the last decade to not have to deal with issues on high speed idling engines like the predator)
older Hondas, and essentially all brand engines idle at 1400 rpms
Mine came with a blue spring btw.. (and it was labelled 1800 on the orderform)

Anyways.. while that makes room for a slightly lower engagement speed (weaker) spring;
it certainly wouldn't help with the issue..
the predator idles like crap at low speeds because it doesn't have any power down there..
so acceleration wouldn't improve if the spring woul dengage earlier..
chances are it'd be worse in fact.
But what now is the blue spring still available or not?

a stronger spring is the exact opposite of a faster full locking clutch as explained above.
So swapping springs is still not going to help either way!
Especially if they -as the reply implies- only make two stronger springs now anyways

I mean frankly.. Jim makes you whatever you want.. if you just ask nicely
(that does include indicidually dialed in engagement speeds AND fancy toothcounts as long as they're viable (1" 8T #35 is NOT ))

'sid

PS thinking about it.. if you never have good traction (always on wet grass or loose gravel) maybe a stronger spring would help... since the wheels can break traction with the initial jerk...
but as soon as you got grip you are likely to burn out the clutch at a higher engagement speed before you get up to speed in just a couple of runs.

 

[JTSpeedDemon]

Hmm, didn't know clones idled at 1.4K! Briggs idle around 1750, so I can really use the extra engagement room.

OMBWarehouse sells several springs, listed here in order from weakest to strongest:

1 - Yellow spring(1500 RPM)
2 - Blue spring(1800 RPM)
3 - Standard silver spring(2200 RPM)
4 - Green spring(2550 RPM)
5 - Black spring(3100 RPM)

I really like my Max Torque SS, it holds up to my abuse and launches hard!

 

[J.S.@SMS]

It gets enough traction, but it has the power to spin the rear wheels on demand, just not from a stop. There isn't much gravel around here, and i haven't tried to ride it when it's wet out. So I'll keep the stock spring for now, and get a TC soon.

 

[itsid]

Hmm, didn't know clones idled at 1.4K!

maybe not all but surely the better ones
and yes Flatheads rev a tad higher;

but OHV engines are usually 1400'ish (Briggs in fact 1500)

IIRC that holds true for Ducar Lifan and Loncin at least..

Rato doesn't tell but gives compression ratio for 1400 rpm speed (that suggests idle speed to me tbh)
for both the 196cc R200 true clone and the 212cc R210 (what you call predator)
the predator manual calls for 1800 rpms however

IDK. I don't care too much tbh...

'sid

 

[J.S.@SMS]

Yeah, my minibike (a 196cc Rato) calls for a 1500+- 150. But I was able to idle it down a bit from factory. Though it's now idling a bit higher than stock because, while the engine can idle lower (200-300 rpm by the sound if it), the torque converter lets you know that there's play in the clover hub, by making a sound similar to rod knock (when I first heard it I though the engine was going to need another rebuild).

And I've only seen one max-torque clutch go out. It was on my Manco (the one I'm putting the new jackshaft on), and the po tried running it without the jackshaft (2.7:1 with 145/70-6 tires). Needless to say the clutch was shot.