Inspecting Crankcases - What are the thresholds?

Puffie40 wrote:I have been cleaning a second lot of cox engines and I notice that these motors have a bit more wear on them.

I think a couple of bores are somewhat rough-looking, and another pair seem to have lips worn into the the front where the driveplate rubs (Electric starters? Pusher props? The result of the spring starter?)

So, what are some guidelines on deeming a crankcase fit for continued service?

These engines are super tough! If the crank has no noticeable play when installed in the case then run it. Even if it has a little play I wouldn't worry to much either. I have a couple well worn engines and the cases/cranks are still fine.

If you are building a high RPM engine then you may want to be a little more picky.

Edit: the cranks and cases are cheap and plentiful so if you have any doubt just grab a new one.

BTW is that a Hodaka your sitting on?

Recommend the use of Cox wrenches for disassembly/assembly. Using commom pliers can very often cause damage and cause "tool marks"..

Study the information provided by Cox International on their site. We have excellent parts support from our several vendors. Most everything is available and at nominal prices.

Thanks for the input so far guys. I'll take a long hard look at them once they come out of the alcohol.

BTW is that a Hodaka your sitting on?

Yep - 1972 Wombat 125, just finished restoring it last summer. I'm a little too big for it, but it was a fun project!

Good Job!

I had a '74 Super Combat. Great bikes! The first Hodaka I ever rode was an Ace 90. Looks like it fits you just fine. They were all small........

Enjoy it!

What are you working on Te Dee or babe bee? There are phonelic shims and prop washers available for each even if it cameth not stock on your engine you may consider that if's too sloppy sendeth pics if you can....

What exactly were the phenolic washer's for? They come on all the TD's from the get go from .049-.15. The .010 and .020 don't have them. I assume it is to prevent damage to the driveplate? Not sure.

cribbs74 wrote:What exactly were the phenolic washer's for? They come on all the TD's from the get go from .049-.15. The .010 and .020 don't have them. I assume it is to prevent damage to the driveplate? Not sure.

That's what they do. Pushers might need them, or an engine with too much crank end play.

RknRusty wrote:That's what they do. Pushers might need them, or an engine with too much crank end play.

Yup.

If you are inclined to use an electric starter, a drop or two of fuel behind the driveplate can add a little lube and reduce driveplate/case nose wear.

But, the crank endplay Rusty mentioned can have some effects that may be detrimental. Generally, the thrust bearing, the mating surface on the front of the crankshaft web and the case surface at the back of the crankcase journal, stays well lubed and has enough area not to wear excessively. So, the end play usually is due to wearing at the case nose and back of the drive plate. Failure fully seat the driveplate after repair can also lead to endplay.

If the crank moves forward, it's not too bad, but when the crank moves back, the crank pin can wear on the reed carrier for reedies or on the backplate of the TD's. It can also alter the geometry of the conrod and pin. As the crank pushes back, the conrod/pin angle may no longer be 90 degrees and the bottom end of the rod may show premature wear.

So, check your endplay and shim if necessary.

I occasionally check for contact, especially after a reassembly. I push the driveplate towards the rear, turn and listen, as well as feel for anything that indicates the crank pin is touching anything. Always inspect the reed housing for scrape marks. Or the backplate on a TD/Medallion.

cribbs74 wrote:What exactly were the phenolic washer's for? They come on all the TD's from the get go from .049-.15. The .010 and .020 don't have them. I assume it is to prevent damage to the driveplate? Not sure.

Don't forget Queen Bees have a strange size SmaSmellic shim too


COUGH, I mean

Puffie40 wrote:Thanks for the input so far guys. I'll take a long hard look at them once they come out of the alcohol.

BTW is that a Hodaka your sitting on?

Yep - 1972 Wombat 125, just finished restoring it last summer. I'm a little too big for it, but it was a fun project!

awesome bike man, wish i had a dirt bike of my own

Alcohol.... Another thing you should know. Sodium hydroxide (NaOH) based cleaners, Purple Dragon, Purple power. VERY fast effective cleaner Much better and faster than Alcohol. Don't leave the parts in for long or will blacken the aluminum but it is SOOOO fast. Also Hard on the hands use gloves.

Another thing I do when i have greasy especially dirt under nails I spray my hands w/purple power and put gloves on 3 min later you`re ready for date night. I'm probably gonna end up w skin cancer LOL

Not my pic below

Alcohol.... Another thing you should know. Sodium hydroxide (NaOH) based cleaners, Purple Dragon, Purple power. VERY fast effective cleaner Much better and faster than Alcohol. Don't leave the parts in for long or will blacken the aluminum but it is SOOOO fast. Also Hard on the hands use gloves.

That's really good to know! I'll start using it when I work on some motors back home - it can't be any more nasty than the "Crock pot of antifreeze" I've heard of other hobbyists using. I'm using 99% isopropyl alcohol right now because its easier to dispose of and contain in the apartment I have.

On the subject of mounting drive plates - what some alternative methods of pressing the drive plate on? Screwing a propeller on does not seem to push it as far as I would like it. I may wind up buying an arbor press!

Also, what is an acceptable clearance between the driveplate and crankcase?

[quote="Puffie40"]

Also, what is an acceptable clearance between the driveplate and crankcase?

I don't know the max, but the Paul Gibeault racing article says .015" or less is best. I've had a Black Widow run fine with .022" but it looked like the crank pin had touched the (plastic type) reed housing. In any case, .022" is on the verge of sloppy. If I ever use that case again I'll use a spacer. It doesn't have to be phenolic, stainless steel should work fine. Or aluminum, which you could make.

Use a vice, find a pusher 1/4 drill bit or something that will sit as flat as possible A flat top bolt works really well SHORT so it dosen`t go off to the side on the crank and flat against squeeze till its down. I always used a 2 axis vice from harbor freight for 30 40$ but thats cuz i used to mill cox cut aways and such and stuff and stuff http://www.harborfreight.com/catalogsearch/result?q=vice Any vice'll do

Additional tip. You can find somehting like a plastic tip cap for the bolt u use for the crank that will avoid damage but its hardened steel I suggest grinding it flat and using metal to metal i never caused any damage in mine and used both methods.

At spot number 1 cut the blades off a propeller and use that as a pusher or drill a place for the nipple to go into wood anyhting will do but don't mar up the metal flat prop spinner use some wood.

Puffie40 wrote:

Alcohol.... Another thing you should know. Sodium hydroxide (NaOH) based cleaners, Purple Dragon, Purple power. VERY fast effective cleaner Much better and faster than Alcohol. Don't leave the parts in for long or will blacken the aluminum but it is SOOOO fast. Also Hard on the hands use gloves.

That's really good to know! I'll start using it when I work on some motors back home - it can't be any more nasty than the "Crock pot of antifreeze" I've heard of other hobbyists using. I'm using 99% isopropyl alcohol right now because its easier to dispose of and contain in the apartment I have.

On the subject of mounting drive plates - what some alternative methods of pressing the drive plate on? Screwing a propeller on does not seem to push it as far as I would like it. I may wind up buying an arbor press!

Also, what is an acceptable clearance between the driveplate and crankcase?

Also Ideally you want an ultrasonic parts bath with TC (thermal control) Don't even thing about using a crock pot that's only for yummy production!
P.S spend more than $50 on a ultrasonic bath BTW the others you will buy are not real ultrasonic baths they are BS and they will break and are just an electro motor with a vibrator Not real ultrasonic THIS one really is real. P.SS I have real experience with buying some BS http://www.harborfreight.com/25-liter-ultrasonic-cleaner-95563.html is exactly what I have its AMAZING!!!!!!!!!!

you might be tempted to buy something like this http://www.ebay.com/itm/Ultrasonic-Ultravibra-Wave-EyeGlasses-Jewelry-Coins-Watch-Washing-Cleaner-Washer-/160760423948?pt=LH_DefaultDomain_0&hash=item256e11660c DONT DO IT ITS JUNK

engine049 wrote:Use a vice, find a pusher 1/4 drill bit or something that will sit as flat as possible A flat top bolt works really well SHORT so it dosen`t go off to the side on the crank and flat against squeeze till its down. I always used a 2 axis vice from harbor freight for 30 40$ but thats cuz i used to mill cox cut aways and such and stuff and stuff http://www.harborfreight.com/catalogsearch/result?q=vice Any vice'll do

Additional tip. You can find somehting like a plastic tip cap for the bolt u use for the crank that will avoid damage but its hardened steel I suggest grinding it flat and using metal to metal i never caused any damage in mine and used both methods.

At spot number 1 cut the blades off a propeller and use that as a pusher or drill a place for the nipple to go into wood anyhting will do but don't mar up the metal flat prop spinner use some wood.

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Sorry, Tom, but I don't understand what you're doing here. Unfortunately I don't have a machinist background like you do. What is this procedure accomplishing?

engine049 wrote:

RknRusty wrote:Sorry, Tom, but I don't understand what you're doing here. Unfortunately I don't have a machinist background like you do. What is this procedure accomplishing?

On the subject of mounting drive plates - what some alternative methods of pressing the drive plate on? Screwing a propeller on does not seem to push it as far as I would like it. I may wind up buying an arbor press!

Okay pretend my fingers are the vice that's how to put the prop drive plate on it is accomplishing busing the cranlshaft against the drive plate to drive the Crank into the drive plate

Before

SQUISH

AFTER

Using medallion crank and TD 09 drive plate for instructional purposes only

Oh, okay, I wasn't sure what you were getting at. Got it now, thanks