Topic: Motor Rebuild? Who's with me?

[wrenchmuch]

I suggest you get two sets(4 pieces) of greens to start. With these you can use plastigauge and check the clearances directly across the crank . I've done this 3 times and each time I found the clearance was a little big when doing it by the book. The first time I did it I ended up with 3 sets I couldn't use. These got used up the next 2 times I fitted cranks. I have found that the journals on either side of the crank sprockets were one or two steps away from what the book procedure called for. I did my k1 2 years ago. By the book the center journal called for green but actually needed black. Journals closer to the ends were closer to what the book called for. The idea is to get the five journals matched in clearance as closely as possible so that oil supply is balanced across the crank. Tighter main bearing clearances will supply more oil to the rod bearings. If you haven't already, clean the oil passages in the crank really well.

[Ephesmax]

Thanks. For the advice I'll order em up

[Ephesmax]

ok fellas heres the results when i clearenced my green shell beaings in my journals.in inches from left to right

 .0015, .0015, .0020, .0025, .0020.

 I was told that i want those clearenced  as close as possible in comparison to each other. but i know the high limit is like .0028in but i dont know the low limit im thinking .0005? Either i got this right or backwards i think i need
 
 green  green  yellow  yellow  yellow

please correct me if im wrong  thanks.

[Ephesmax]

ok fellas,

  So without further ado i wound up using 2 greens and 3 yellow shells on my main journal bearings giving me .0015 clearance across the five journals. Now im moving on to fitting the  connecting rods which i plan on fitting the same way. I can get the new rod bolts no problem from Honda but the nuts seem to be discontinued any suggestions?

[super pasty white guy]

Try looking for bolts/nuts for the F2.  I just bought for my F0, about 6 months ago.

Stronger and they should be interchangeable (I think).  Others with a similar year to yours can confirm.

spwg

[Ephesmax]

I rechecked the codes on the crank for the con rods to be 4444



they are kind of faint I wish they were stamped but ull be able to see them when ur looking at a crank

The rods are all stamped D on one side and 2 on the other.


Does any one know what the D is for?


Then i plug both numbers into the table



This gives me green code bearings all the way across the rods. So ill order two shells to check that i dont need a tighter set then order the rest.

Here's the hook though two of my rods have some surface rust on the small end





I cant seem to find anything in the manual about inspection of the small end so if anyone wants to kick in some thoughts im open to suggestion.
Still looking for con rod cap bolts and nuts too. Pasty suggested F2 nuts he wasnt positive if theyd work for my application 

[Ephesmax]

or i could put a set of these in i have 836 bore already? Does anyone know any thing about these rods for a street application?

http://www.ebay.com/itm/Honda-CB750-A-F-K-69-78-Set-Forged-Connecting-Rods-NEW-/200817199455?pt=Motorcycles_Parts_Accessories&hash=item2ec1a3495f&vxp=mtr

[MCRider]

or i could put a set of these in i have 836 bore already? Does anyone know any thing about these rods for a street application?

http://www.ebay.com/itm/Honda-CB750-A-F-K-69-78-Set-Forged-Connecting-Rods-NEW-/200817199455?pt=Motorcycles_Parts_Accessories&hash=item2ec1a3495f&vxp=mtr

Those rods have been kicking around for years. i had a set, sold em. Don't know any one who ever installed them. Note, The big end cap has a locating dowel. You'll need to drill the bearing shell to install. There is a slip of paper in the box explaining this. But its a step I didn't want to pursue.

In your case i'd stick with OEM and get the later bolts.

[Ephesmax]

thanx for the help once again mcrider. anyone know if i can use those rods with the surface rust on em?

[MCRider]

thanx for the help once again mcrider. anyone know if i can use those rods with the surface rust on em?

New pins? You can take the rod to a machinist to hone the small end to fit the pin. You need to do that anyway if new pins, and that will remove any rust contacting the pin. Use some EvapRust or other phosphate based rust remover to stabilize the rust. Wipe it around with finger in a rag.

Not ideal but practical approach I think. (Ideal being no rust in the first place.)

[Ephesmax]

i have some other rods from the old crank can i just use those in lieu of the rods with the surface rust?

[MCRider]

i have some other rods from the old crank can i just use those in lieu of the rods with the surface rust?

OK by me, you have my permission.

[Ephesmax]

thats what i fig'd thanks again mcrider lol

[Ephesmax]

Sorry everyone for the delay since I last posted my wife and I started looking for houses and finally moved in and got settled so its back to work.

 I'm un able to source rod nuts for this year motor. I've read I can use a better set out of a Honda f2 the only f2 I know of is a cbR600f2 made from 91 - 94 is this the f2 that has been referred to. Thank in advance

[lucky]

another option is a used motor - worth thinking through anyway - lots of parts bikes out there with locked motors from the cylinders rusting slightly - easier and cheaper to deal with that compared to a frozen crankshaft, if that's what you have.

Not a good option at all.

You just get another used engine with the same or more problems.
Then you just have an engine that does not have the correct serial numbers and it could cost you more than what you have now.

A real waste of time and money.

Did your bike seize because it had pods and performance exhaust without being rejetted ,needle position changed on the slide?

You cannot just change the main jet. The bike operates on the slide needle 90% of the time.

[MRieck]

Sorry everyone for the delay since I last posted my wife and I started looking for houses and finally moved in and got settled so its back to work.

 I'm un able to source rod nuts for this year motor. I've read I can use a better set out of a Honda f2 the only f2 I know of is a cbR600f2 made from 91 - 94 is this the f2 that has been referred to. Thank in advance

Bolt Part# 13213-KVO-000  Nut 13214-410-003   Replace both....the newer bolt is stronger

[cabrala]

another option is a used motor - worth thinking through anyway - lots of parts bikes out there with locked motors from the cylinders rusting slightly - easier and cheaper to deal with that compared to a frozen crankshaft, if that's what you have.

Not a good option at all.

You just get another used engine with the same or more problems.
Then you just have an engine that does not have the correct serial numbers and it could cost you more than what you have now.

A real waste of time and money.

Did your bike seize because it had pods and performance exhaust without being rejetted ,needle position changed on the slide?

You cannot just change the main jet. The bike operates on the slide needle 90% of the time.

^ Is this real life??

Lucky, the motor is apart and he is going forward with the rebuild of his original powerplant.

Ephesmax, the "F2" is referring to the 1977 CB750F Super Sport.
'75 was F0, '76 was F1, so on and so forth; well until '78...

Hope that helps clear up your question. Follow Mike's lead on those part numbers and replace them as he recommends.

[Ephesmax]

Just got all the Conrad parts in. Spec'd them all in. I was wondering how important replacing the head studs with some arp's would be and a recomondation on a gasket set. Primary chains and timing chains
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[Ephesmax]

bump