1989 K75 reanimation

[daveson]

Good one thanks I'll be keeping an eye out.

That thingy's a biggy.

[koshak]

[koshak]

Engine is ready for treatment



Lapping valves

[koshak]

my conrod bolts are on the way, as well as other spares.
So before i broke anything better ask - is there any trick (apart from hammering) to remove old conrod bolt?
The heavier hammer the better?
And then on refit new bolt - hammer it back?

[Laitch]

If you haven't tried heating the bolts with a heat gun, applying a penetrant like Liquid Wrench, waiting a few minutes then using a socket on a breaker bar or impact wrench, you might try that.

[koshak]

to heat bolt? Will not it expand and be even more tight than now? 

[koshak]

Question, I'm curious, could you measure or post a photo of the width of the tangs and grooves on the balance shaft gear to the balance shaft? I'm thinking from other threads that the gap might be excessive on later models, compared to the earlier ones, like yours.

I was asked to make some measurements. Here it is.

[koshak]

Filter wrench was adopted for the available opening by lathe.
Now should fit well.

[Laitch]

to heat bolt? Will not it expand and be even more tight than now? 

I wouldn't have recommended it if I hadn't used the method successfully numerous times. You're heating the bolt head and nut; a heat gun isn't precise. Heating the bolt can crack up corrosion and helps conduct the penetrant down the shaft into the threads. You let it cool then you loosen it.

[koshak]

Laitch, did you use this method on conrod bolts? They are not screwed in, they are tight pressed as i understand.

[Laitch]

Laitch, did you use this method on conrod bolts? They are not screwed in, they are tight pressed as i understand.

No, but I wouldn't be shy about using this method on con rod bolts. The principle is the same. The flanges of both the nut and bolt might be seized to the rod so you're not only try to break corrosion on the threads beneath the nut but also on the nut flange and the bolt head.

[koshak]

The flanges of both the nut and bolt might be seized to the rod so you're not only try to break corrosion on the threads beneath the nut but also on the nut flange and the bolt head.

ok, seems we are talking about different bolts.

[Laitch]

ok, seems we are talking about different bolts.

We aren't. With your depth of experience rebuilding motorcycles, I was surprised you even asked the question, but I answered. I'm not invested in your compliance with the suggestion. I'm sure you'll get it done one way or the other.

Once penetrating oil has been used, a deadblow hammer can be used to drive out the bolt. After the bolt bores have been cleaned and lubricated, the replacement bolts shouldn't pose a problem during insertion.

[The Mighty Gryphon]

I was asked to make some measurements. Here it is.

Hmmm, that looks exactly like the gap in my engine as well.  Makes me think it's designed in.

Now the question is WHY???  All I can see it do is make the engine clank like a can of scrap metal when it's coming off idle.

Here's a photo of mine:


DSCN1758.JPG (46.82 kB . 768x576 - viewed 410 times)

[daveson]

Thanks Koshak, that's really surprising, I felt sure it was going to be less. Maybe it's too small a sample, but the handful of times I've read about the problem have all been about 1993 models. Now I'm wondering if it might be reduced tension in the output shaft circlip that could cause a noise.

P. S. I'm wrong, I've since read about earlier models with the problem.

[The Mighty Gryphon]

Daveson, that tension has nothing to do with the output shaft clank. 

It's not a circlip, but a spring that preloads the anti-lash gear.  It has nothing to do with the tab in that slot.  As far as I can tell, it's free to bang around all it wants as the engine runs.  Any unevenness in rotation speed from cylinder to cylinder at low rpm is going to make that tab bang around like crazy. 

That effect of imbalance is the reason I work hard to have valve gaps as uniform from cylinder to cylinder as possible, and balance throttle bodies frequently.

My engine had a perfect spring and still clanked like someone was hammering on the insides of the engine.  While gear lash can probably make the clanking worse, eliminating the lash won't make it go away. 

I was able to get temporary relief from the noise by cleaning all the oil from the faces of the clutch basket and the balance shaft and torquing the clutch nut to a few pounds above the spec.  Got rid of the noise for maybe 3-4,000 miles or about half of my riding season.

The only thing that prevents that tab banging around in the slot is the friction between the clutch hub and the balance shaft which isn't very much because both surfaces have pretty smooth surfaces.

It's a pretty shiity design.

[daveson]

Agree about the clutch basket and anti lash gear comments. I wasn't meaning to point to the anti lash. Realise I'm reaching a bit. Was surprised the gap was the same. Did your tabs have marks consistent with banging? It's about time I got familiar with suppliers catalogs and part numbers,  then I might be able to find a difference around 1993.

On mine (a k100, but same deal I think) the circlip (the castellated type) ties the bearing with the gear.

I better leave it at that, I feel I've thread jacked this a bit.

[The Mighty Gryphon]

The K100 doesn't have a balance shaft or that tab-in-slot thingie, thus the clank is part of the K75's unique charm. 

As far as any wear or distortion, there was none visible on my parts.  The gap was made at the factory when the parts were machined.  Like I said, shiity design.

[daveson]

Yep the K100 is way different, was referring to the circlip, which seems to be the same.

The circlip on mine was also cone shaped so acted as a spring too. Strange to also act as a spring, since it's open ended. That makes me wonder how it could be tested for reduced tension.

If yours was the castellated type, the concave side should have been facing the bearing.

[koshak]

critical spares did not arrive yet, but there is still a lot to do. so, slowly progressing with assembly.

[koshak]

when installing output shaft, make sure marks on crankshaft and output shaft are aligned.

[koshak]

cannot continue with the crankcase until spares arrive (some gaskets, oil sight glass, conrod bolts), so wrapped it in plastic and placed aside.

will play with other stuff.

rusty stand assembly. why not to bring it in better order now?
as i told earlier, originally here is self-folding side stand.
such confusing construction, and i found it inconvenient for me.


so already replaced to the "non-self folding type". Also have parts to connect it to the clutch gear, but did not decide yet if will do this connection. May be do test after final assembly and then decide.

[koshak]

now nice clean and shiny.

[koshak]

cleaning starter

[daveson]

Hi Koshak,

Would you be able to do me one more favour, if your engine is still in pieces?

If you remove the output shaft from the gear and rotate it 180 degrees, do the tabs prevent it from re-engaging  with the gear? If so, maybe that's their purpose.

Unless somebody else already knows the answer?