Top end rebuild advice?

[Spumoni]

I've got an all original 42 WLC, but I'm not sure with how many miles because the speedo stopped at 14,500. I have a receipt from 1947 showing new pistons and a rebore for a total of $31.98! It's definitely blowing a little oil smoke, and if I look through the spark plug hole you can see a little oil on the top of the piston. Aside from that, the bike runs great, and sounds really quiet. Although I've never rebuilt a motor, I work with a guy who's experienced and would be willing to help. NOS parts are still available, and it doesn't look like an impossible job.

My question is this - what are the chances the bottom end is going to need a rebuild? The book says if there's more than (I think) 1/8" of play, then the entire motor needs to be pulled.

Any advice would be appreciated.

[58flh]

SPUMONI---FOLLOW the SPECS in your OEM MANUAL!---IF the bottom-end falls into accepted specs.-Then a standard top-end job is in order.Use feeler gage to check rod clearence at the crankpin.-If its in spec ,You now check for a BENT ROD!--(get a 1/4-inch steel plate & cut a U in it to clear the rods & sit on the case deck FLAT!.)--You May have to drill the holes for the cylinder bolts.Once on the case for the front rod rotate the motor so the piston bottoms out on the plate!-Use a FEELER GUAGE to check for any BENT RODS!/& Yuo can check your piston-pins for correct fit when at this point.Do the same for rear piston.If they are in spec. on the sideplay for the rod at the crankpin & in spec for the BENT rod check,,Your bottom is good to go!.Your gearcase -(if it were me)-I would replace any bushings & check all cams for correct sideplay.This is all covered on the forum & your MANUAL.Use New cast Pistons & Hastings iron rings-(the black ones)-Assuming no overbore is needed!--If it needs to be bored.USE CAST-PISTONS & HASTINGS RINGS!--This is a GREAT set-up for a daily runner & the rings find a home in the first 100 Miles!.I hope this helps you as THERE is ALOT more that It dont pay to type if you can read-it from the K-BASE!.If you should find one of the rods are bent--(you can fix that using a long piece of steel that fits thru the pin & apply pressure in the direction it has to go.-(I found that Bent rods that are just say .040 out--Its easy to remove the steel plate & bend a little more as it will bend back from the Memory in the steel.On your heads use a soft abrasive when in the beading-tank--I use walnut shells!-& there cheap! & dont EMBED into the matieral being blasted!.---Do your investigative READING & you will see what you can do at home or send out!---RESPECTFULLY----RICHIE

[Spumoni]

Thanks for the advice RICHIE! Now that the weather is turning for the worse (Upstate NY), I will plan on tackling this. I will report back when I do. Hopefully I won't have to go any further than the top end - would you recommend using all NOS parts if possible?

By the way - what's the K-Base???



Thanks again!
Tony

[PanPal]

would you recommend using all NOS parts if possible?

OEM or NOS....The answer is always yes if you can find them.

[RUBONE]

By the way - what's the K-Base???

Look at the top of your page. Note the heading "Knowledge Base". Click on it, and that's it...

[Spumoni]

I finally got the jugs and pistons off. Please keep in mind I'm an amateur, so if my descriptions are off, be patient! I think I'm going to need some opinions on what to do.

The front connecting rod has exactly 1/8 inch side to side play at the very top. There is no up and down play. The rear connecting rod has much less play. However according to the book, at 1/8 or more, they suggest tearing out the motor and rebuilding the bottom end. Should I bother doing this (or more likely finding someone that can) while I have it apart, or is this acceptable?

The pistons are 40 over, but there seems to be very little wear if any in the cylinders. I'm hoping the rings are not oversized. If not, would it be acceptable to use oversized rings and keep the original cylinders? I'm assuming 40 over is max, and I'd really like to use OEM parts only. \

Any advice would be very helpful. Thanks in advance!

[PanPal]

The pistons are 40 over, but there seems to be very little wear if any in the cylinders. I'm hoping the rings are not oversized. If not, would it be acceptable to use oversized rings and keep the original cylinders? I'm assuming 40 over is max, and I'd really like to use OEM parts only.

If your pistons are .040" over this means it has been bored out to clean up the cylinder walls. You rings were likely to be .040" over also to fit the new bore. The next size would be .050". You piston to cylinder wall fit is what you need to make sure is correct. The only time we use rings bigger than the overbore size is to get the ring end gap in tolerance. Hastings says .003 per inch of bore, but you will find .020 or more when installing the 40 overs in a 40 over bore. so a .050 over ring can be file fit to get the ring end gap correct on a .040 over assembly. Your cylinders have room to grow. People bore them 100 over using torque plates while doing the work.

Where did you get the 1/8" side play at the top of the rod tolerance from? Just curious. Cleaning the oil out of the crank pin rod end, then hold the top of the rod up with 2 fingers and smack the end of the rod down with the palm of your other hand. Listen for the sound of up and down play to make sure.

[Spumoni]

Thanks for the info Panpal!!!

I got the info from the 45" service manual - that little orange book. Here's how it reads:

"When appreciable up and down play is found and either or both rods have 1/8 inch or more side shake at extreme upper end, the connecting rod roller bearing should be refitted"

I can't feel any up and down play, but the front rod does have side to side play - about 1/8 inches to be exact. However, the motor was very quiet before I took it apart, and I don't want to open up a pandora's box unless I really need to. The entire reason I took the heads off was because it's blowing smoke. The cylinders and pistons look great by the way, I'm almost thinking I can just get away with rings. But now that it's apart, I want to do the right thing. This bike is all original, and I plan on keeping it for a long time... Not sure if I should mess with the bottom end or not..??

[indianut]

If you have 1/8 on the male rod and you truly plan on keeping it a Long time then it should be a no brainer. Do the bottom and it will most likely be good to go for the rest of your use of it and you will know what you've got. Just choose your re-builder carefully!

[Spumoni]

I'm taking your advice and rebuilding the bottom end as well. With the help of someone more experienced, we have the motor completely out. The pistons are .040 over, and just slightly out of spec (about .0035 clearance the book says should be between .0015-.0025) I'm hoping all I'll need are new .040 pistons and that should get me in spec. I'll keep checking eBay for NOS .040 pistons.

As for the bottom end, we are in the process of splitting the case now.

Any suggestions of who I can send the crank to? I'm assuming we can tackle everything else.

[58flh]

SPUMONI!--STOP,--Do not buy pistons until you ACTUALLY use a SNAP-GAGE & MIC to Measure ,or a bore gage!--It May NEED to be bored!/I have put just pistons on previously bored jugs in the past,BUT THE NEW PISTONS FELL INTO CORRECT SPEC-AFTER a Light-honing!/-You have to consider this!/Honing will remove some matieral!--IF you are at .0035 already -(YOU NEDD TO BORE!)-Dont let this freak you out!--HINT-(GET THE .050 pistons first!-& let the rebuilder fit THEM ACCURATELY!).-Its the correct way & YOU will be very PLEASED you did!--(cast slugs are not much & a Bore & hone to fit is NOT MUCH $$$$ either.).Just for your INFO--I have heard of guys KNURLING the slugs & fitting new rings!--If its suggested FIND ANOTHER MACHINIST & MOTOR BUILDER!.It works for about 500-miles then it becomes a cropduster again!.KEEP ASKING QUESTIONS you are doing the right thing!---Respectfully---Richie

[Kurt]

I run .0045 to .005" clearance on my 45's.........0015 to .0025 is too tight, I always had seizing problems.

Kurt

[58flh]

KURT--I understand they run hotter!-But .005-Is a Slappin Motor.-With cast slugs ..002 & finish hone at .003 is a nice # to go by.My inistial post of .0015-was my Panhead thinkin AGAIN!.At any rate -The bore needs to be checked for out of round-I wouldnt buy slugs until I was sure of the #s.What do you other guys run when you set-up your tops??/The last 45 I did is still running regularly after a 12yrs.(One of my best friends)-It was set .0015 more then my pan.So .003 & I was skeptical!-But After all this time & countless mileage!-The heads were removed for 2-valve-jobs in all that time!--45s are TUFF no doubt!,Theres a reason there the most produced twin out there.---Respectfully---Richie

[58flh]

GUYS---I called my buddy with the 45--As I am not in my garage today being its Thanksgiving & All that stuff.However all my previous motor jobs I keep logs on!--I asked him if he had his copy for the cylinder to piston fitment?--He did & my previous # of .003 was off the top of my head & wrong again-(For this I APOLOGIZE to ALL!)-The Final Clearences on both cyl.--WERE .0023!---Its hard remembering things when you do alot of work over the yrs..The bike starts easy/I just did the linkert this summer!--Had Venturi shrinkage.But anyway its a 1-hot kicker with 2primer kicks! & she NEVER had SEIZURE PROBLEMS!--I also Went with .002 on the valve-guide clearence for both In & Ex./He said I hi-lighted in his manual that OEM specs. were WAY TO LOOSE!.-I believe We all run tighter clearences here due to Valve & guide Technology in Matierals is of better quality.He said his manual called for .006/& That was not going to fly!.Anyway This is the Piston to wall #s I used & She RUNS strong after ALOT of MILAGE!---Respectfully---RICHIE

[indianut]

I set up all Flatheads with .005- on both the piston to bore and the guide to stem. I build a lot of Flatheads and believe me when I say you can NOT Hear a piston slap at .005. I have set up Wall Bikes at .008 and still you can not hear any piston noise. I think a lot of the clearance you decide to run depends on your climate as well. I am in Florida and if you set a Pan or Shovel valve guide to the low side of the spec it will hang!