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Author Topic: modified, aftermarket, or custom. nothing is safe (78 KZ1000)  (Read 34020 times)

Offline Supergyro

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #250 on: Jun 15, 2017, 01:15:27 »
Sick sick beauty!


Offline doc_rot

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #252 on: Jun 19, 2017, 00:48:58 »
I have been slowly sorting out the issues that come with putting a bike on the road. One of the issues that has come up has me puzzled; it is very difficult to down shift coming to a stop or stopped. it simply will not down shift sometimes even with me rocking the bike so I have to slip the crap out of the clutch to get going in 2nd or 3rd. I suspect it may be something to do with the APE heavy duty clutch kit as i have read others have a hard time finding neutral with that. I also have Tarrozi rear-sets and am wondering if the positioning of the throw is making it difficult to shift, but i have tightened everything up to eliminate as much slop as i can. Thoughts?
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'78 KZ1000  Project

'80 KZ750 Twin Project

Offline irk miller

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #253 on: Jun 19, 2017, 01:03:46 »
Can you add length in that shaft to push the clip-on arm back so it's more parallel with the shifter arm?  Believe it or not, your oil can be a factor in all of this too. 

Offline doc_rot

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #254 on: Jun 19, 2017, 01:10:53 »
Yeah i can, I will try that. I'm using "Bikemaster" conventional 10w-40
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'78 KZ1000  Project

'80 KZ750 Twin Project

Offline J-Rod10

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #255 on: Jun 19, 2017, 02:45:33 »
Ideally, you want as close to a 90º angle as you can get with your linkage, to the attachment points on both ends.

Offline jpmobius

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #256 on: Jun 19, 2017, 12:35:05 »
Surprisingly, slop (within reason) in the pedal mechanism has little impact on how well it shifts the transmission.  If the clutch drags even the slightest bit, 1st, 2nd and neutral can be super hard to sort out when the bike is not rolling so investigating that is in order, and I'll second the notion of the oil having a potentially big impact on the clutch.  The angle of the bellcranks, rod and foot lever do make a difference.  You have the pivot on the front crank arm arranged so that there is a limit on the angle it can work through before it binds so make sure that it doesn't if you haven't already.  The whole mechanism is more bendy and deflects a lot more in actual use than you might expect working it by hand so make sure there is an excess of available motion.  As long as there is no binding, I think the way you have the front pivot is fine.  There can also be binding at the pedal pivot as there are side loads in actual operation that you don't tend to notice in hand operation.

Also keep in mind that your foot and ankle orientation, and the angle your ankle has to rotate has a big impact on how hard or easy things seem - not to mention it is easier to push down with your foot than it is to lift up with your toe.

It is challenging to explain the impact of orienting the angles between the crank arms, pedal lever, and rod without some diagrams, but using your photo as a base I'll give it a shot.  Starting with 900 between the elements is always a good idea as J-Rod says, but because the amount of rotation of the cranks is large compared to their lengths, more info is useful.

First though, go back and get the original shifter pedal and compare its length to the new one.  If it is longer, your trans will be noticeably harder to shift with the new shorter pedal assuming the two crank arms on the new mechanism are the same length.  You can restore the original leverage by changing the length of the crank arms.  If your original pedal is 20% longer than your new one, you need the driven crank arm (the one attached to the shift shaft) to be 20% longer than the drive arm.  If this adjustment is not a complete solution, you still have some big tuning capacity in the crank arm angles.

Look at your pic and observe the angle between the drive crank arm and the connecting rod.  The angle is much greater than 900.  Consider the effort required to move the rod in each direction.  When you lift up on the pedal, the angle will increase.  As it does, the mechanical advantage over the rod will increase, so pedal effort needed will decrease the farther it rotates.  This makes the bike easier to upshift force-wise, but you pay for this with longer travel distance of the pedal.  When you down shift, the angle becomes more acute as it comes up to 900, and the force becomes greater, and the pedal distance traveled becomes shorter.

This principle works in reverse at the other end of the push/pull rod.  In your pic,  the angle is less than 900 and as the rod pushes the crank, the angle becomes more acute and the force required to rotate the crank increases.  As you pull on the rod, the force needed decreases until 900 is reached, and then the force required will increase as the angle gets farther away from perpendicular.

The effect of the angle between the rod and crank arm is opposite depending on if it is the drive arm or driven arm.  A bit hard to tell from your pic due to lens distortion, but it looks like the two crank arm are pretty close to parallel.  This has the effect of canceling each other out.  When the drive arm has greater mechanical advantage when pushing the rod due to angle, (or less when pulling) the driven arm has less advantage when being pushed (or more when pulling) and the force on the shift shaft is the same as the pedal shaft - it's a wash.

This only works for fairly small deviations from 900.  Consider the crank on the shift shaft.  If you rotated it counterclockwise a bit, it would have a 900 angle with the rod.  Consider pushing on the rod.  At 900, 10 lbs of force will displace the crank against the spring a certain distance.  If you re-index the crank clockwise, the force required to achieve the same displacement against the same spring pressure will go up.  As the rotation goes up, the force needed goes up very rapidly.  In fact, imagine having to rotate the crank a full 900 - as the crank arm comes up to 900, the force needed to rotate it goes to infinity.  So fairly small deviations from the 900 relationship between the various parts can have a very noticeable effect.

So work on the easy and obvious stuff first.  Check the mechanism for binding, and fix any pedal length issue.  Try some new oil - you probably want to change oil on a new motor anyway.  If your still not happy, you can make a big difference by fooling around with the crank angles.
Mobius


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Offline doc_rot

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #257 on: Jun 20, 2017, 01:54:55 »
Wow, big improvement from adjusting the crank angles. Thanks for the replies guys! Its still a bit tricky to get it into first, but much more rideable. I think with a little more adjustment it will be even better. However i have noticed that it doesnt really "pop" into first gear like i seem to remember it doing, but it has been 7 years ::) could this be a symptom of the clutch not disengaging fully?

I'm loving the evening rides when i get home from work even if they are short, like today. The sound of the flat-slides clacking when you roll on the throttle sounds so mean!
« Last Edit: Jun 20, 2017, 01:59:22 by doc_rot »
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'78 KZ1000  Project

'80 KZ750 Twin Project

Offline doc_rot

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #258 on: Jun 21, 2017, 02:06:33 »
getting the jetting dialed in.  Doing full throttle plug chops gets the ol' adrenaline going, it rips to 100mph pretty fast. I'm still having issues with it shifting but it is better. The APE clutch pack comes with an extra fiber and steel disk, I'm going to pull them to see if that makes a difference.
« Last Edit: Jun 21, 2017, 02:08:55 by doc_rot »
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'78 KZ1000  Project

'80 KZ750 Twin Project

Offline doc_rot

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Re: modified, aftermarket, or custom. nothing is safe (78 KZ1000)
« Reply #259 on: Jun 21, 2017, 04:09:15 »
I pulled off the clutch cover to remove some plates and this circlip falls out. Feck. This is my worst nightmare, so much so that after reading a post about the need to orientate the piston pin circlip openings I tore apart the top end of my motor to check. The  circlips I couldn't move to the correct position I replaced. Fearing the worst after finding that clip I tore the top end off the motor to find out that I'm an idiot. All the pistons have their circlips installed still. My only thought is I accidentally dropped one of the old circlips in the motor and when I was replacing them out of paranoia and didn't realize it. Now that has come back to bite me in the ass. The good news is there is no damage and the motor looks like its breaking in very nicely. ::) Once i have a new base gasket and head gasket this thing will be back together in a couple of hours, I have gotten real good at tearing this shit down and putting it back together again. 5th times a charm. D'OH!
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'78 KZ1000  Project

'80 KZ750 Twin Project