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...because every day is MotoGP day when you own a CBR 125r...
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PostPosted: Wed Apr 30, 2014 4:45 am 
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Performance Pack

Joined: Tue Mar 25, 2014 3:21 pm
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Regarding your "false neutral": this is more likely to be a mis-shift, probably caused by a rounding of either the selector forks' edges, or the edges of the engaging dogs on the gears themselves.
This wear can be as minute as a polishing - but it's enough to occasionally stop that nice slick engagement. You might overcome it by having the gears undercut - a specialist task for a gear-machining shop. It will make gear-changes more positive, but slightly harder - but you won't be bouncing off the limiter ever time you mis-shift!


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PostPosted: Wed Apr 30, 2014 6:22 pm 
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Racing ECU (!!)
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Location: Parksville, BC, Canada
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Precis wrote:
Regarding your "false neutral": this is more likely to be a mis-shift, probably caused by a rounding of either the selector forks' edges, or the edges of the engaging dogs on the gears themselves.
This wear can be as minute as a polishing - but it's enough to occasionally stop that nice slick engagement. You might overcome it by having the gears undercut - a specialist task for a gear-machining shop. It will make gear-changes more positive, but slightly harder - but you won't be bouncing off the limiter ever time you mis-shift!


Excellent advice Precis - much appreciated. No matter how much I looked at it all I could find was minor intermittent-type wear on the gear in question. So I ordered up two of them (the fourth gear and also the 3rd as it too has a trace of wear on it - pics to follow). I then looked at the countershaft side and said, screw it, let's replace them too after reading your post :biggrin: So I'm replacing all the gears that are related to 4th gear and also 3rd even though it was not problematic. This includes the dogs related to those gears as well as the gears themselves. That should cover everything you mentioned other then the shift forks. I looked at those very closely and they are virtually as new.

Keep in mind, this downshift to 4th 'false neutral' is intermittent. It may happen once a week or twice on a ride. There seems to be no real rhyme or reason to it. Because of that, I felt that the shift forks could probably be ruled out as I would expect them to create a much less intermittent issue.

On the other hand, the gears in question are worn a little in certain areas - perhaps 1/8th of the entire gear is worn. My guess, and it's just a guess, is that perhaps that gives me a 1 in 8 chance of the issue cropping up. Even if I don't understand the actual cause the correlation between the intermittent gear wear and the issue seems apparent. So, we're now covering all the gears in question, their dogs and the slots on the gears that the dogs bite into. I'm about as sure as can be that that will case it.

All the new bearings have been installed. One I'm going to re-do as it seems a bit gritty once installed. I don't know if I damaged it during install or not but second time around I'm going to freeze the bearing and heat the case. Between those two methods I should be able to install it this time with much less force and zero damage. At that point, I can start doing the re-build (probably Friday).

Also, based on your recommendation in the other thread about steel braided brake lines, I picked some up and just finished doing the install. Once the bike's back together I'll be a in a position to more properly discuss their effects based on personal experience :top:

So, all in all, a busy day. The remainder of parts should be here Friday and....I do have a custom camshaft coming to boot. In short order the bike will literally be 'as new' and hopefully even better given that I used the best Jap bearings I could get. I figure in another 20K if the bike starts vibrating again I'll try out SKF's and see how they stand up :top:

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PostPosted: Thu May 01, 2014 4:51 pm 
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All new NTN Bearings installed and loc-tited in place.

Interestingly enough, I had to install a second new countershaft bearing as the first one was a little rough when placed. For the second install I froze the bearing and heated the bore. A little pressure and it more/less popped right into place and the second one turns with no grit. It sucks to install a new bearing twice but it's not worth chancing it. Sure enough, when I popped out the new bearing (the first one) it was gritty. A new counter shaft seal was installed as well as a new shifter seal.


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PostPosted: Fri May 02, 2014 8:22 pm 
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Getting closer....but still waiting for one more gear to arrive...


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PostPosted: Fri May 02, 2014 10:25 pm 
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You're quit correct when it comes to the front turn signals, that was one just one of the reason's why I went with the mirror mounted versions... Adding in the fish-eye LED's into the stalk location just added additional "level" of visibility, while at the same time "filling the remaining holes).

The rear ones I have I'll have to talk another look at, but when I installed them and just sat back a couple of feet away, they seemed to be bright enough. Mind you I know EXACTLY what you mean with regards to the brightness level of some LED's...

One of the first things I tried was LED replacement bulbs and pulled in a number of different type/style of LED bulbs and I found that their brightness level varied greatly from type/model, etc. There are also many different types of replacement LED stalks with larger number of LED's and/or higher output LED's. The ones I went with were on the lower price end and I still may replace them for a higher quality/even brighter output (costing more at the same time of course).

I'll have another peek at my rear turn signal stalks from a greater distance (now that my bike is outside and on the road!!)


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PostPosted: Fri May 02, 2014 11:04 pm 
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I went to test fit the case halves together this afternoon and found that the crank bearing made it very tough to get the other side of case on. I suspect I'll probably have to heat it up before mating them together which makes it a bit of a pain. On the other hand, at least I know that the fit is very tight which is something positive. I can tell already, it's going to be incredibly smooth and if the camshaft work was done properly, and I have no reason not to believe it was, then it's going to be faster then ever given new rings/bearings etc.

You know, I was thinking about resuming work on the module with a new engineer I met the other day. Then I said to myself, forget it, you've spent too much already. But, for the last few days what's been going through my head is just how much I would like to have nitrous installed. It's something I really, really, really would like for myself. A good 15 shot would be just what this bike needs. I'm pretty certain that would give me a real 30HP. Once I get the bike broken in (again) and if the camshaft does what it should, I'll have to go back for a dyno run and see what the numbers are.

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PostPosted: Sat May 03, 2014 3:48 pm 
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There's lots of areas in this little engine that need assembly lube during re-build. In my case, I soaked and cleaned everything in gasoline which works really well at removing oil and debris from the parts. The problem is that this leaves critical areas bone-dry and during initial startup you really want everything fully lubricated because it will take time for the oil pump to fill all the passages in the engine and build up proper pressure.

So protecting these assemblies and sub-assemblies is crucial and this is the job of assembly lube. It's essentially very thick oil with a great deal of anti-friction modifiers added in such as molybdenum etc.

I found that that best way to lubricate everything with assembly lube was to use a standard syringe such as the kind that come with inkjet refill kits. I took the needle off the end, stuck it in a bottle of assembly lube and pulled as hard as I could (it's thick stuff!).

Once full, the syringe proved ideal to lubricate everything. Just as an example, how do you lubricate the big end of the connecting rod? How do you fill (literally) the camshaft with assembly lube? How about the rocker arms and the rocker shafts? The ball bearings? The transmission splines?

This worked really well for me and the bonus is that you don't end up with a mess all over your desk. The assembly lube is too thick to flow through the needle on it's own :top:

Note the factory heat treatment on the connecting rod....


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PostPosted: Sat May 03, 2014 3:52 pm 
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Any more lift on that cam and we're going to have to hog out the camshaft housing..... :ohmy: :laugh: :top: :cool:

There's nothing like the sound of a Harley at idle....oh wait....that's the 125!! :top:


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PostPosted: Sun May 04, 2014 4:10 am 
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Next time you are at the doctors for any kind of shot, beg him for the syringe, sans needle. Lubricator applicator for nothing. Assembly lube is essential for any internal motor repair.

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PostPosted: Mon May 05, 2014 3:19 pm 
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Well, just ran into an interesting crankshaft bearing issue.....

The OEM parts catalog lists the crankshaft bearing as two different numbers, one that's pressed into the case and one that's pressed onto the crank.

I originally tried to buy them from Honda. Honda says that the crank bearing is not available (discontinued). You can, however buy the crank bearing that's pressed into the case.

Dealer says, don't worry about it as it shows up in the parts listing as a 6207 bearing. So, I go up to the bearing store and special order some quality NTN (Japanese) bearings. I didn't look at them very closely when they came in and pressed one onto the crank and one into the case.

During a trial fit I found out the crank is not sitting deep enough into the bearing. After a lot of head scratching I pulled the 6207 bearing and measured it - it's two millimetres thicker then the stock bearing....

The 6207 bearing, which is what the OEM Honda parts book calls it, is 17mm thick. The Honda 6207 series bearing, for this bike, is 15mm thick......and that explains why the crank won't sit properly....

The OEM bearing is a 6207 series bearing made by NTN. After exhaustive research it seems that this bearing does not exist in the 'real' world - it only exists in the Honda world. This, as it turns out, is because the bearing is specially made for Honda by NTN....so it cannot be sourced anywhere else.

Call up a bearing engineer, give him the dimensions of the Honda 6207 bearing and you will draw a blank. It does not exist.

OK, so we can't go to the aftermarket for this bearing. But, Honda also declares the crank bearing as discontinued. This means you can't go to the aftermarket or to Honda for the crank bearing!

I seem to have lost my bearings.... :rolleyes:

Dimensionally, the crank bearing that is pressed into the case it identical to the crank bearing that is pressed onto the crank... The case bearing is available, the crank bearing is not.

What does this mean? It means if you buy a 2014 CBR125 and cook the crank bearing you are out of luck - at least as far as the dealer and aftermarket is concerned.

Even though both bearings are dimensionally identical the crank bearing carries a different part number. Why is that? I can think of several reasons;

The crank bearing is either a precision bearing or it's a 'loose' bearing or it's a 'tight bearing'. God only knows what the story is on the crank bearing or what makes it 'special' I do know that both bearings are specially heat-treated over and above a standard 6207.

The Honda service manual specifically states that whenever you split the case ALWAYS replace the crank-side bearing. Why is that? Is that particular bearing subjected to more or different load then the crank's case bearing?

What makes the crank bearing special, to the degree that it merits it's own part number and must always be replaced when the case is split? Why does the Honda parts manual designate that bearing is 'special' ?

Aside from that, what is a person to do? If you cannot get the crank-side bearing what do you do? Buy two case-side bearings and install them because they are dimensionally identical? That's the work-around that I'm going ahead with but I don't like not knowing why the crank-side bearing is 'special'.

Either way, I wasted $$ on two 6207 bearings and the time to install them.... :wacko: :angry: only to replace them (again).

What the heck is so special about the crank-side bearing that Honda insists they have to be replaced every time the case is split and that causes them to have a special number?

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...because every day is MotoGP day when you own a CBR 125r...


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