Big End Bearing Replacement

[tevie54]

Ladies please lets all just calm down, there's no need for personal insults, we don't all have to agree with each other, this is a forum, we all have a common interest. You seem to think I am besmirching your beloved motorbikes but I'm really not, I love NCs, I loved mine and will soon be in position to get another one, after I swapped the crank on mine I did several trackdays and met Rick Oliver at one of them and swapped a couple of tuning ideas and was often the fastest 400 on the track thanks to a Rick Oliver induction kit and a tankfull of AVGAS.
I joined in with this link to give LukeVan some advice like everyone else but he's probably lost interest now, just because you don't agree with my advice doesn't make it wrong, I haven't told anyone their advice is wrong.
Some of you seem to be confusing engine building with mass produced engine assembly but if you don't agree with that that's fine, I'm not going to lose sleep over it, but lets not start being rude, we're all on the same side.

[vfrman]

WHY doesn't this forum have a "like" or "thumbs up" button!?

Seems you have got some work to do

Nope. I'm a moderator, not admin.

[L.Svedberg]

Ladies please lets all just calm down, there's no need for personal insults, we don't all have to agree with each other, this is a forum, we all have a common interest. You seem to think I am besmirching your beloved motorbikes but I'm really not, I love NCs, I loved mine and will soon be in position to get another one, after I swapped the crank on mine I did several trackdays and met Rick Oliver at one of them and swapped a couple of tuning ideas and was often the fastest 400 on the track thanks to a Rick Oliver induction kit and a tankfull of AVGAS.
I joined in with this link to give LukeVan some advice like everyone else but he's probably lost interest now, just because you don't agree with my advice doesn't make it wrong, I haven't told anyone their advice is wrong.
Some of you seem to be confusing engine building with mass produced engine assembly but if you don't agree with that that's fine, I'm not going to lose sleep over it, but lets not start being rude, we're all on the same side.

All good, mate. Sorry about the harsh words. I guess we tend to be a bit anal about these little engines, since one must sink a lot of hard earned cash into a rebuild, at least I feel it's absolutely imperative to be as thorough and professional about it as humanly possible. I'd kill myself if my just rebuilt engine would grenade itself for whatever reason.

Cheers/

Lasse

[tevie54]

I still have the set of four con rods for the NC, do you think it's worth putting them on Ebay

[vfrman]

Ladies please lets all just calm down, there's no need for personal insults, we don't all have to agree with each other, this is a forum, we all have a common interest. You seem to think I am besmirching your beloved motorbikes but I'm really not, I love NCs, I loved mine and will soon be in position to get another one, after I swapped the crank on mine I did several trackdays and met Rick Oliver at one of them and swapped a couple of tuning ideas and was often the fastest 400 on the track thanks to a Rick Oliver induction kit and a tankfull of AVGAS.
I joined in with this link to give LukeVan some advice like everyone else but he's probably lost interest now, just because you don't agree with my advice doesn't make it wrong, I haven't told anyone their advice is wrong.
Some of you seem to be confusing engine building with mass produced engine assembly but if you don't agree with that that's fine, I'm not going to lose sleep over it, but lets not start being rude, we're all on the same side.

All good, mate. Sorry about the harsh words. I guess we tend to be a bit anal about these little engines, since one must sink a lot of hard earned cash into a rebuild, at least I feel it's absolutely imperative to be as thorough and professional about it as humanly possible. I'd kill myself if my just rebuilt engine would grenade itself for whatever reason.

Cheers/

Lasse

Yeah, that happened to me once. The machine shop that turned my cylinders bored them to over double the service limit and I didn't verify before I built up the motor.

[Neosophist]

just because you don't agree with my advice doesn't make it wrong, I haven't told anyone their advice is wrong.Some of you seem to be confusing engine building with mass produced engine assembly but if you don't agree with that that's fine.

It doesn't make your advice right either though.

I haven't been keeping track of this thread very much as I've been super busy recently but I assume you are making reference that measuring bearing shell sizes is not necessary, even though Honda make several sizes?

Not even because I am a forum moderator and as such want to try and protect the interests of the users, i'd still make the same post either way but this is just negligent advice.

It is very easy to do and is documented in the service book.

I think it's impossible to make a blanket statement that you will never have any problems. Even though you might not have had any issues thus-far are you confident enough to say that everyone who follows your advice will also not have any problems?

You are giving advice here to people who may not have any money to replace and engine after it destroys itself from improper advice, all for the sake of just measuring the clearances and checking that the gap is appropriate for the engine.

It's like saying "I drive drunk all the while without consequence ergo it's safe to drive drunk" but this isn't the case for everybody.

I think if you at least acknowledge the fact that skipping measuring clearances can ruin your engine then it is up to people who follow your advice to check or not.

If its too tight youll spin a bearinging and over-heat things, too loose and youll loose oil too quickly.

http://www.hotrod.com/how-to/engine/ctr ... ce-basics/

I think this article sums it up best.

One of the abilities that separates the experienced engine builders from the novices is properly fitting the bearing clearances for both the crank and rod journals

But hey, I'm done with pointing out the flaw in your advice. Let other people make their own minds up. For me personally i'd never leave bearing clearnaces unchecked.

[hunter]

just because you don't agree with my advice doesn't make it wrong, I haven't told anyone their advice is wrong.Some of you seem to be confusing engine building with mass produced engine assembly but if you don't agree with that that's fine.

It doesn't make your advice right either though.

I haven't been keeping track of this thread very much as I've been super busy recently but I assume you are making reference that measuring bearing shell sizes is not necessary, even though Honda make several sizes?

Not even because I am a forum moderator and as such want to try and protect the interests of the users, i'd still make the same post either way but this is just negligent advice.

It is very easy to do and is documented in the service book.

I think it's impossible to make a blanket statement that you will never have any problems. Even though you might not have had any issues thus-far are you confident enough to say that everyone who follows your advice will also not have any problems?

You are giving advice here to people who may not have any money to replace and engine after it destroys itself from improper advice, all for the sake of just measuring the clearances and checking that the gap is appropriate for the engine.

It's like saying "I drive drunk all the while without consequence ergo it's safe to drive drunk" but this isn't the case for everybody.

I think if you at least acknowledge the fact that skipping measuring clearances can ruin your engine then it is up to people who follow your advice to check or not.

If its too tight youll spin a bearinging and over-heat things, too loose and youll loose oil too quickly.

http://www.hotrod.com/how-to/engine/ctr ... ce-basics/

I think this article sums it up best.

One of the abilities that separates the experienced engine builders from the novices is properly fitting the bearing clearances for both the crank and rod journals

But hey, I'm done with pointing out the flaw in your advice. Let other people make their own minds up. For me personally i'd never leave bearing clearnaces unchecked.

My thoughts exactly.

[SevenThreeSeven]

There is a common engineering term for the issue being argued here: Tolerance Stack-Up

The crankshaft of an internal combustion engine, with its multitude of machined surfaces, is a tolerance stack-up just waiting to happen.

[tevie54]

You are not reading my posts correctly, Lukevan has knackered a big end bearing, if he has damaged the journal then measuring the bearings and buying the 'correct' size will make no difference, you cant put new bearing shells on a worn crankshaft.
If it is true that you cant regrind NC cranks and get oversize bearings then buying another crank is the only option, that was my advice.

[krisztian_andre]

I have only ever seen one engine with all the main bearing the same colour code,
The code lettering is stamped on the casing behind the clutch,
It will be something like ABBB or BABB or another combination.
And as vfrman said no black. just Green Brown or Yellow.

Here's my AAAA:
http://s18.postimg.org/mk1wybavr/s_l1600.jpg