Topic: Undercut Trans?

[scottly]

I may be nuts, but my bike don't pop out of gear anymore!

[MattFreeman]

You guys are nuts

LOL

On a similar topic. Its my thread I can jack it.

I called CX today to ask about undercutting and things related. If I send in my F1 trans and get back a K4 (for example) trans in "exchange", am I getting screwed?

I know they're different, is one CB750 trans inherently better than the other? Mr Rieck do you have an opinion?

The reason I'm asking is I have a slightly worn cog (the one with the two different length teeth) and I want to know if I should try to find a good one or exchange it for one of a different era and be happy.

Also, does anyone have an opinion on the Cycle Exchange trans. service? Or their machine services in general?

[Bill/BentON Racing]

We had trouble with ripping the dogs clean out of gears.
Undercutting actually made the problem a lot worse.
We're now using gear sets manufactured by a bloke in Melbourne.
The gears have 4 dogs instead of 3 and are oblong in shape.
No more problems.

Cheers,
Brian

Brian,tell us more.Price and availability?Gears w/no dogs a problem! .Only seen them broken off a couple times.Bill
Mike's right (as usual).

[754]

We are not nuts... we are CB  750 nuts.................

[scottly]

 

[HondaMan]

You guys are nuts

LOL

On a similar topic. Its my thread I can jack it.

I called CX today to ask about undercutting and things related. If I send in my F1 trans and get back a K4 (for example) trans in "exchange", am I getting screwed?

I know they're different, is one CB750 trans inherently better than the other? Mr Rieck do you have an opinion?

The reason I'm asking is I have a slightly worn cog (the one with the two different length teeth) and I want to know if I should try to find a good one or exchange it for one of a different era and be happy.

Also, does anyone have an opinion on the Cycle Exchange trans. service? Or their machine services in general?

The "F" bikes have closer ratios in the lower gears for a more "racy" feel. 
The earlier "K" bikes had a more wide-ratio, general-purpose feel to the gears.

[HondaMan]

Drool. 

[bear]

Brian,tell us more.Price and availability?Gears w/no dogs a problem! .Only seen them broken off a couple times.Bill
Mike's right (as usual).
[/quote]

The last set I brought was $1500 AUD.
We are running a SOHC8V in our historic road race sidecar. The power is transmited through a 61/2" car tyre so the drive train gets a pretty good workout. At one stage we where only getting 2 or 3 meetings out of a gear set before the dogs where so rounded off they just kept jumping out of gear. When we undercut them they would break.
We have been running the current gear sets in the two motors we use for over two full seasons with no problems.
I don't think these gear sets  would be much value to anybody unless your bike is getting up over the 100HP@RW.
They are still available, PM me and I will put you onto the bloke.

Cheers,
Brian

[scottly]

Hmm, I guess I AM nuts: $1500 Vs a hand-full of grinding stones, time, and the application of basic tool-and-die making techniques to keep a 400 lb, maybe 80 HP@RW bike from jumping out of gear. What was I thinking???

[bear]

Hmm, I guess I AM nuts: $1500 Vs a hand-full of grinding stones, time, and the application of basic tool-and-die making techniques to keep a 400 lb, maybe 80 HP@RW bike from jumping out of gear. What was I thinking???

No NO! Your right on the ball.
@ 80HP under cutting's the go.
Our little motor is currently delivering 123HP and with MRiecks shiny new cam winging its way to me as we speak, I'm hoping for a little more(down low at least).
OH & the other thing is $1500 ozzi equates to around a $1.50 American:-)

Cheers,
Brian

[70CB750]

Hmm, I guess I AM nuts: $1500 Vs a hand-full of grinding stones, time, and the application of basic tool-and-die making techniques to keep a 400 lb, maybe 80 HP@RW bike from jumping out of gear. What was I thinking???

I was searching around and found this:

http://www.practicalmachinist.com/vb/general/undercutting-dogs-gears-motorcycle-gearbox-258469/index3.html

there may be some undercutting in my future, the K0 2nd is basically useless.

[MRieck]

That's funny.

[70CB750]

That's funny.

I did not post it as funny, more like inspiration.   

At least he considered angles and positioning and did not try it free hand.

[70CB750]

Well, we dont know what he used to measure angles and setup the grinder.  Better than free hand in my book.

I divide people in those who try, tinker and adapt and do things, and than the smart ones who make fun of them.   

[bwaller]

The issue is positive even engagement of all engagement dogs, difficult without a proper setup. The second issue with our gearboxes is undercutting round dogs & oval receiver slots. I'm all for do it yourself when it's possible, but you can't use simple tools for this job. $300 or so is pretty short money for this work.

[70CB750]

Well I only have masters in Mechanical Engineering, i.e. I lack your imagination, but how exactly would undercutting dogs lock up a transmission  and send me to the light pole? 

The biggest problem here would be that the matching surfaces are off and/or the three dogs do not lock the same, but there are cheap enough jigs out there to take care of that.  Test on assembly and it is important to make sure the load is not carried by shifting forks.

I am not suggesting that every diy out there should give it a shot, but machinist worth his salt should be able to get it done.  For racing by all means, go with professional product, but to bring 2nd gear back to life I am with Scottly - he done it to his bike.

Also not sure if you know any machinists, but using make-shift tools is their second nature, good machinist is very inventive, because he has to get things done with the tooling and machinery available to him.

Off my soap box now 

[bwaller]

Sounds Lin you're up to the task, have at it.I agree real machinists are good thinkers, I have a close friend that fits in this category. Post pic.