keli vari + 1.5K= nasty shudder at launch. Aero help.

[akskoot]

So my Keli vari and 1.5K torque spring finally arrived($63 shipped-Daywot) for my 1985 Aero Nb50. Stoked. I spent the day installing, then the test drive. I picked up 4 mph for a solid 42mph on flat with a really crisp and solid midrange throttle response. Then there's the launch. At WOT from a stop there is just a massive bog and lurchy shudder. Once I get rolling it's great.
Now the helpful details:
The vari and 9g rollers are bone dry with the o-ring and grease cover omitted(the one with 3 7mm bolts). Running dry had mixed results on my stock vari.
In an attempt to effectively make the clutch springs stronger, I lightened the stock, heavy clutch by drilling 3 symmetrical holes through the 3 symmetrical holes on the clutch plate:
I don't think this is the problem. Can anyone point me in the right direction to remedy this * poor launch?

[burnt_toast]

maybe needs new/stiffer clutch springs too

odd to see shudder from those mods alone, can you describe it bit more?

[Arnadanoob]

Sounds like the clutch engagement point is too soon. What other mods do you have? Does the problem occur all the time or after the bike's been warmed up?

[Wheelman-111]

Greetings:

Is there perchance a spot of grease on the drive belt? Hope so, because you're not gonna like the following, in order of increasing PITA:

Warped clutch bell. I suppose this can be diagnosed (and fixed) by turning in a lathe, if you can find a machine shop that has a suitable method of chucking it in.

Driven pulley bent out of true by over-zealous compression when you disassembled the clutch.

Stripped splines somewhere on the big (and expensive) tranny parts.

Ditto on the crank splines. You didn't just stuff the outer pulley sheave on and whack it with an air impact tool, didja?

I suggest you disassemble again, clean the belt with a fresh rag and mild solvent - dry it quickly - and the pulley sheaves with brake cleaner. Look at the crank splines critically. Reassemble with care.

Before you reinstall the belt, give everything a spin and check for wobble.

Good luck!

[akskoot]

Sounds like the clutch engagement point is too soon. What other mods do you have? Does the problem occur all the time or after the bike's been warmed up?

It does feel like the clutch is grabbing right away, at the slightest throttle. No other mods, happens at every launch now.

[akskoot]

maybe needs new/stiffer clutch springs too

odd to see shudder from those mods alone, can you describe it bit more?

The clutch engages so soon, I feel like you may be right. describe more...hmm: I start to turn the throttle and no matter how much I do the first thing that happens is a low rumbly bog. Right then there is a shaking lurchy engagement of drive train. Soon after I get rolling, like 5 feet, it kicks in and takes off nice, smooth, and fast.

[wiguy05]

1. Drilling thos holes sounds like a bad idea. It is probably out of balance, no matter how good you eyeballed the holes.

2. I would skip the 1.5k spring all together. I ran a Keli Vari on a de-restricted stock motor with the 9g rollers and it was very, very nice.

[akskoot]

Sounds like the clutch engagement point is too soon. What other mods do you have? Does the problem occur all the time or after the bike's been warmed up?

Interesting discovery today, the day after install. I removed the belt cover and inspected. All looks good. Then I ran it on the stand while watching vari movement and applying light brake to simulate load. Everything was spinning very true and no shudder. I take her for a spin. Launching and shifting like a champ. It was great....then after 10 mins the shudder started to creap in on the launch then progressively got worse and worse, but only on the launch. Mid and top were still great. Is it my clutch springs or more likely my clutch drilling experiment?

[scooterwerx]

harbor freight sells a digital scale for 15$ or so, as long as the clutch pads are all the same weight its OK. i think this sounds like its the clutch springs, if it heats up and then starts acting up....

[burnt_toast]

Sounds like the clutch engagement point is too soon. What other mods do you have? Does the problem occur all the time or after the bike's been warmed up?

Interesting discovery today, the day after install. I removed the belt cover and inspected. All looks good. Then I ran it on the stand while watching vari movement and applying light brake to simulate load. Everything was spinning very true and no shudder. I take her for a spin. Launching and shifting like a champ. It was great....then after 10 mins the shudder started to creap in on the launch then progressively got worse and worse, but only on the launch. Mid and top were still great. Is it my clutch springs or more likely my clutch drilling experiment?

It is your springs.

They are working fine cold, then getting heat soaked after 10min ride and engaging too soon giving you boggy launch. Swap to aftermarket, Yamaha Jog style 2k grab springs would be good for you and cost only $5 or so on ebay, they are not as aggressive as actual dio springs and good for street tune.

I think your clutch drilling should be okay for most part and done right should improve launch some, doubt its your main problem.

[Arnadanoob]

Toast seems to have installed mind-reading parts on his bike, lol.

What he said. ^^

[akskoot]

Ha thanx so much for the help guys, hopefully that puts this problem to bed. Wheelman, thanx for scaring the sh** out of me!

[Wheelman-111]

Greetings:

Sorry dawg! Guess I just didn't get "lurchy"... It sounded to me like when you have warped brake rotors - only reversed - and the clutch engages with a succession of tac tac tac tac tac

In retrospect I understand you meant you could feel each combustion stroke through the drivetrain. These things don't produce much thrust at 2000 RPM.

[maddog]

stiffer clutch springs, yes you can also drill out the pads and you can add a spacer to the center spring also, thats a custom dialed in trans, go for it!

[akskoot]

Yes, today I took off each individual clutch shoe and measured it out to 137.4 g with a digital scale(don't ask ). Then I learned a very important lesson. Don't EVER run a clutch without the clutch bellhousing on. I figured I would quickly check the expansion action of the clutch shoes before I bolted her all back up. Well they expand alright, expand the sh** out of the clutch springs that is. Hopefully someone else will learn from my "noobiness".