Topic: Lightened Crank and Replacement Case. Which bearings??

[odin836]

After much waiting my CycleX Crankshaft has arrived...

I need to do some more reading up on how to determine which bearings I need...
A Replacement Crank Case and New Crankshaft (well new to me) means the markings on the case and crank are worthless...








Has anyone who has used plastiguage lately to do this?
Some dot points and photos would help greatly if you've got them?
Cheers.

The repair manual is as usual a little confusing for me on this topic.

[Jerry Rxman Griffin aka MuthaF'er]

Did you read the scribbled/engraved markings on the crank before you shipped it off? I'm assuming the "new" case is used? Does it have the markings stamped on it? If you had this information you would have a good starting point for bearing shell sizes.

You would match those 2 sets of letters and get the appropriate bearing shells to start with. Then plastigauge for correct clearance, buy more bearing shells if your squished plastigauge indicates incorrect clearance. I believe some of the guys might even do 1 crank/case journal set at a time without buying a complete set of bearing shells then buy the others once the correct clearances are determined. I would prefer only stretching the crankcase bolts 2 or 3 more times than what they've already been stretched from previous assembly as opposed to measuring each journal with only 1 pair of shells thus tightening/stretching the bolts perhaps 10 more times. I would also prefer to have all the bolts torqued together for the measurements. With this being said I have a new heavy duty stud set to use and it will be the first/only 2 times they get stretched aka torqued by a wrench.

Perhaps a combination of these first 2. If you do not have the crank size engravings then measure the crank and combine with what's on the cases and go from there.

IMO, I think it's smart to plastigauge with both methods as a final check with all bearing shells in place.

Another way would be to buy some possibly expensive calipers/mics and measure the differences to determine starting bearing shells, plastigauge, then possibly buy more correct shells. I won't use this method because I have no prior experience with this type of measuring. Too critical at this point to jack it up.

Another methodology I've encountered is to use the largest clearance bearing shells and call it a day. I do not believe in this method but shoddy shops/mechanics will do this.

At any rate I think there is a good chance you will have extra shells leftover. There's many guys here that will need those so be careful with them and do not cause any damage. We can take them off your hands.

  

[MCRider]

Plastigauge will do the job and is very easy. I've got an episode in my build thread, (see signature) but out of all the pages I couldn't tell you where. About halfway I think.

A stick of Pgauge is about $1.50 at the auto store. Get the Green, it comes in 3 colors for the different ranges of clearances.

Search on PlastiGauge here, or on the internet in general for instructions. Widespread use. Designed so morons could rebuild military vehicles.

Coincidentally, the CB750 will use green shells over all others about 4 to 1. So get a bunch. If they measure too tight or too loose you'll have to get others. There are only 4 possibilities.

Read up and come back for clarification.

[mystic_1]

Another methodology I've encountered is to use the largest clearance bearing shells and call it a day. I do not believe in this method but shoddy shops/mechanics will do this.

Another approach I've heard of is, some people just buy all black shells (tightest) which possible leaves some clearances too small.  They figure that the ones that are too tight will wear a bit faster and then they're clearances will be ok.  Not an approach that I'd use, but there it is.

mystic_1

[odin836]

Thanks, the info above helps alot!

The case (new to me but used) is stamped "BBBBB".
The crankshaft has no markings, and as its not my original crankshaft I have no way of knowing what markings it had originally.

One thing I have nto done is priced the shells, what are they worth each?

MCRider, i'll check out your build thread, thanks a heap.

[mystic_1]

One thing I have nto done is priced the shells, what are they worth each?

One arm, one leg, two front teeth

Seriously though they're fairly steep, Western Hills Honda charges $11.36 per conrod bearing half, and $13.02 per crankshaft bearing half.  You need 8 conrod halves and 10 crankshaft halves, so around (8*11.36)+(10*13.02) = $221.08 for a full set.

mystic_1

[MCRider]

Thanks, the info above helps alot!

The case (new to me but used) is stamped "BBBBB".
The crankshaft has no markings, and as its not my original crankshaft I have no way of knowing what markings it had originally.

One thing I have nto done is priced the shells, what are they worth each?

MCRider, i'll check out your build thread, thanks a heap.

Motogrid.com has shells for about $10 each (takes 2 per jornal, duh.)

Many of us have extras left over from our projects and I think we can help out. I think I have 2 pairs of greens.

So the case is straight that's good. But as you say the crank is an unknown as the codes are removed in the lightening process.

Here's the official site with how to: http://www.plastigaugeusa.com/how.html

But if you Google it, you'll get all you'll ever need to know.    http://www.dansmc.com/bush_plain_bearings.htm

The deal with our cases is you ahve to set up all 5 journals with shells and plastigage, gently set the bottom case on and torque it down. Then remove it carefully. Some of th PGage will stick to the shell some to the crankshaft. No problem just be sure to have room to set the case down carefully and don't turn the crank during this process.

[754]

Are you sure the code is removed from the crank?

 Even if they did that they could remark it.

 There has been quite a few times on here people could just not see it.. ( they are not looking hard)

[mick7504]

The best way to work out the crank letter code (if it is unreadable or gone) is to measure each journal with a micrometer.
Effectively it is working backwards.
For example: If one of the main bearing journals has a diameter of say 35.991mm (1.417") it would fall into the "B" letter code for the journal as per the bearing selection chart.
Your cases are marked "BBBBB" which means that that the case letter code "B" crossed on the bearing selection chart with journal code "B" = bearing colour code Green.
Plastigauge or ACL Flexigauge Type AG1 (The green one) is the way to go for final clearance checking.
You should get this at Repco being in Melbourne and it is not expensive.
Working out the codes to determine the right clearance bearing shells is the safest way to get it right the first time.
The Plastigauge/Flexigauge checking will confirm everything.
You probably won't have to worry about the conrod journals as I would assume that they would have been done by Cyclex when they fitted the rods.
As far as I know the only place to get bearing shells is through Honda.
They are not terribly cheap but if you keep clean oil and filters in the motor, they should last for many years.
The only other advise that I can think of is not to have a fan switched on while you are using the Plastigauge/Flexigauge.
It blows around like a feather as is evident on my workshop floor. 

[bucky katt]

call and ask ken, i have a set of the sohc f2 rods that they used to do, with the huge arp studs and nuts on them and i had to call and ask about that.

[Terry in Australia]

Are you sure the code is removed from the crank?

 Even if they did that they could remark it.

 There has been quite a few times on here people could just not see it.. ( they are not looking hard)

Pffft! Best of luck Frank, APE lightened and balanced my crank, and machined the numbers off in the process. Cheers, Terry.

[wrenchmuch]

Bryan in the UK swears buy going all black and going easy on the engine for a while till they get worn in . I plastigaged using greens to start and found that the markings on case and crank didn't match with what the plasigage was telling me . Ended up with greens on the ends , brown between 2 and 3 and blacks on either side of the primary and cam drives . I have greens aplenty  The two 750,s I,ve done so far have both been like this . All black may be the way to go if you want to avoid having to buy more than one set of shells .
Good Luck
Mike

[MRieck]

Are you sure the code is removed from the crank?

 Even if they did that they could remark it.

 There has been quite a few times on here people could just not see it.. ( they are not looking hard)

Pffft! Best of luck Frank, APE lightened and balanced my crank, and machined the numbers off in the process. Cheers, Terry.

Sam and I were looking at an APE crank yesterday and they had marked the codes on a counterweight. They also supply a paper with all the info. That being said there was a time when that didn't happen.

[754]

Either way..
 a good engine buiding pactice would be;

 Measure each journal in at least 2 spots.

 This checks for out of round and whether the code is still correct. Then you can change the code, or remark if it has been removed.

 In addition to this you should note your sizes in the notes you make on your engine build, even if it is on the crank. That way you can reorder shells (if crank is good) before splitting your cases.

 FWIW

[Jerry Rxman Griffin aka MuthaF'er]

Mike,

When was that crank done? Mine only has APE stamped and 3174 engraved/etched. No paperwork either.

That sure would be a nice thing for Jay to do, hint hint Jay, considering many of the guys here have never built an engine before and may not have the fine tools or experience using them.

[nippon]

Our cutomer crank came back from APE with all infos on a paper.
Of course, we wrote down the infos before we gave them out of the house.

nippon

[MCRider]

Our cutomer crank came back from APE with all infos on a paper.
Of course, we wrote down the infos before we gave them out of the house.

nippon

My APE crank was already lightened years ago, so the codes were long gone. I asked them to check the journals for out of round for me, since it had 50k+ miles on it, before lightening and balancing it again. I assume they did so, they said the crank was fine. Did their work (said they were able to balance it better than it already was), so improvement.

I'm perfectly happy with them checking the roundness, and me using Plastigauge for the bearings.

There are options, and I don't need to overthink it. Truth be told, 90% of 750 engines will be fine just throwing in a full set of one color and running it. Like wrenchmuch/brian says.

[MRieck]

Mike,

When was that crank done? Mine only has APE stamped and 3174 engraved/etched. No paperwork either.

That sure would be a nice thing for Jay to do, hint hint Jay, considering many of the guys here have never built an engine before and may not have the fine tools or experience using them.

The crank was done about 3 months ago Jerry

[odin836]

Sounds to me like half of the work would have been done if I received papers with the crank when it arrived from CycleX.

I'll have one last look at the crank for markings of some kind, although since its so clean I think I would have already seen them if it had some.

My last question is, what shellls do you think I should start with?
Given a trip to my local Honda dealer is not something I can do easily on a daily basis...

As mentioned the case shows (BBBBB), is this a gooda place as any to start using the plastiguage method?

[Terry in Australia]

Are you sure the code is removed from the crank?

 Even if they did that they could remark it.

 There has been quite a few times on here people could just not see it.. ( they are not looking hard)

Pffft! Best of luck Frank, APE lightened and balanced my crank, and machined the numbers off in the process. Cheers, Terry.

Sam and I were looking at an APE crank yesterday and they had marked the codes on a counterweight. They also supply a paper with all the info. That being said there was a time when that didn't happen.

I've still got the crank in the box that APE sent it to me in, (I'm still waiting for a reply from some guy called JMR about whether or not he's still got a spare billet cylinder block to sell me, but I think he's ignoring me.....) so I'll go check it again, but I'm sure I looked at it pretty good when I received it. Not too big an issue, I bought the crank off a member here (he was kind enough to send it to APE for me) and he sent me the numbers as we both assumed that they'd be machined off. Cheers, Terry.   

[754]

BBBBB is the outside of the bearing size, now you need the inside size..

 Why guess at it, measure it;
 A ..to see if it is round

 B... to determine your bearing size

 Cant think of any reason to do it improperly, if you do it wrong, its going to be money thrown away, and possible downtime..

your choice.. BTW it is fairly easy to mesure the crank, use a micrometer.

[bryanj]

Use a mic, chances are you will measure it smaller than Honda did with air gauges so the shells you get will be too tight a tolerance.

Having said that i have built several with all black shells(including my 500 in my avatar) and not had any back---most of them were 25 years ago mind!!!

The story goes that Honda built the engines with clearances as if they had run 5,000 miles so all they needed was a bit of bedding in and you were good to go Hence using tightest shells and GENTLY running in (copious oil changing as well) ended up with the same result

[MCRider]

Use a mic, chances are you will measure it smaller than Honda did with air gauges so the shells you get will be too tight a tolerance.

Having said that i have built several with all black shells(including my 500 in my avatar) and not had any back---most of them were 25 years ago mind!!!

The story goes that Honda built the engines with clearances as if they had run 5,000 miles so all they needed was a bit of bedding in and you were good to go Hence using tightest shells and GENTLY running in (copious oil changing as well) ended up with the same result

I worked in a shop where we built mostly 1970s style choppers (extended fronts, no rake and king and queen seats, and 16" wheels, yuk) to pay for the owners drag racing habit. He had several records on various types of CB750 set ups. He knew Russ Collins personally and we wemt for a visit and had dinner, I was 20.

Anyway we'd always thrash Friday and saturday to get ready for Sunday. Engine teardown and rebuilds from crank up. He'd have cranks from god knows where and cases from likewise unknown sources. He had boxes of the loosest color shells and he'd just throw those in and run it. That way he never worried about breaking it in, so he said. Never had a crank or rod failure while I was there.

Now that's just not right I know. But I'm just saying...   

[MCRider]

Using a mic is a learned skill. Everyone has a diferent "hand". In training, you'd have to mic 10 different journals, then compare your results to the trainers, then mic them again and see if you get the same results. Rinse and repeat until you know what you are doing.

Mosy of us will only have the need once or twice in our lifetime, not near enough experience to pretend that we'd be good at it.

It's easy for someone who's good at it to tell someoone else that's what they should do. But some people will never have the "hand" for it, no matter how much they try.
I know.

[754]

I dont find anything wrong with running loosest shells, to gp racing without breakin time..

 But these motors, can and will run for decades/50K + miles,  put together properly. So proper setup can result in a very long life.

 Everything is open, everything is clean, it takes minutes to measure it correctly.

 Now it will take longer if, you are not experienced at this, but you have a few options.
 A, take it to whoever is doing your boring. valve work/resurfacing...pay them a few bux to measure it and write it down.

 B,  buy someone, that can measure and has the tools, a six pack & get them to walk you through it and show you..then have the six pack..

 C, get a micrometer with FRICTION  or RATCHET THIMBLE , and take the time to work thru it yourself.

 To make this a little less dunting, I should mention, it is not nearly as difficullt as measuring the case bore (use the letter cide), and I would not be suggesting folks that are inexperienced try this, if it were not for micrometers with friction or ratchet thimbles..

 Its a skill worth knowing...doing it right.. priceless..