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Discussion Starter #1 (Edited)
Hey everyone! So I'm collecting parts as you can see! I've got more than that but that's the big stuff. That crank case has everything in it and I paid 159 w/free shipping. I didn't think that was bad at all.
Couple questions... the connecting rod looks color case hardened in spots. Is that normal? It has kinda a rainbowy appearance in places. Indicative of high heat I'm sure but I didn't think if kept properly oiled it would get that hot right there?
Also, looking down into the gears some of them have small spots of surface rust. What can I do to prevent that from getting worse but that won't mix poorly with oil someday when I use it?
And then lastly, how warm should the diff(s) get while operating at speed? Mine get pretty warm, but not hot. I've changed the fluid in both front and rear diff but I still have diff fluid coming out of the breather tube when I'm moving along pretty fast. Thanks for your input on these various things. The ol girl is running like a top!
 

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Hey everyone! So I'm collecting parts as you can see! I've got more than that but that's the big stuff. That crank case has everything in it and I paid 159 w/free shipping. I didn't think that was bad at all.
Smokin' great deal!

Couple questions... the connecting rod looks color case hardened in spots. Is that normal? It has kinda a rainbowy appearance in places. Indicative of high heat I'm sure but I didn't think if kept properly oiled it would get that hot right there?
The discoloration on the rod is from the heat treatment tempering done by the factory when each rod is made. Its normal in appearance, as you suspected...

Also, looking down into the gears some of them have small spots of surface rust. What can I do to prevent that from getting worse but that won't mix poorly with oil someday when I use it?
If the parts are beginning to rust from sitting you can pour a coating of clean oil inside the cases (its messy, drench everything best you can by flipping the cases over so oil will reach all the parts) and put oil or grease on the shaft ends that are sticking out of the cases. For long term storage I generally oil or grease everything well and put parts in cardboard boxes to keep the dust & dirt out of them. Some parts can be put in plastic bags but be careful not to seal them up tight if the storage temperatures will swing from hot to cold to damp etc. I like to put both clean oiled rags & clean dry rags in with oiled parts to help keep them wet with oil and to hopefully absorb any moisture that will accumulate over time. Best to inspect & reoil them on occasion no matter how they are stored.

And then lastly, how warm should the diff(s) get while operating at speed? Mine get pretty warm, but not hot. I've changed the fluid in both front and rear diff but I still have diff fluid coming out of the breather tube when I'm moving along pretty fast. Thanks for your input on these various things. The ol girl is running like a top!
Both diffs should get a bit warm running at speed, but not hot. If the front diff is running quite a bit warmer than the rear is, check the height/diameter of all four of your tires to make sure no big differences exist in tire sizes. They should be within an inch (in diameter) range of each other and air pressures should be maintained. If one or more are worn a lot more than the others, its the front diff clutches slipping that causes that extra heat. If a mismatch in tire sizes is severe enough, the front diff will wear out those clutches pretty quickly at high speeds. If you ever feel or hear those front diff clutches slipping (some may make a snapping noise, others may be quiet) while driving straight down a smooth road, look for a mismatched tire diameter problem (or front end wheel alignment way off?) somewhere on the bike.

Great to hear that that your 350 is running like a top!
 

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As Goober said make sure the diffs aren't overfilled with oil and that its the proper oil that you are using. Some of the cheap, generic branded gear oils on the market can foam up a lot and may get forced out of the vent at very high speeds. Most barely foam up at all though, regardless of speeds.

You didn't mention whether both vent hoses are blowing oil or just one...? If just one end is blowing oil it may have a worn/leaking pinion seal due to a worn/sloppy pinion bearing. If you rule everything else out as being a possible cause of foaming, the pinion seal is the next most likely cause. To check for that ya gotta pull it apart.
 

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Discussion Starter #5
Thanks for your detailed responses! Its the rear diff breather that leaks. But like I said, only once I've been going around 30mph for a few miles. Then, if I slow down down to 25 for a bit it'll stop doing it. Neither are over filled. I'm very happy to hear that the connecting rod is supposed to be that color. My goal is to strip that crank case down and inspect everything really closely and reassemble with new bearings. I am pretty sure that all the bearings on this machine are all original so I bet its a worn bearing getting real hot when going fast. But even still, neither diff is to hot! I can easily put and hold my hand on either one so maybe that isn't the cause. I'll be buying a used rear diff next.
And the tires are all worn evenly and I am a stickler about air pressure... And oil level...and diff fluid...etc. Lol.
One thing I forgot to ask is what does spark knock sound like on one of these?
I have a sound that happens at certain, fairly low, rpms that sound like somebody tapping a wine glass while holding it. So a muted tinking sound.
I guess it could also sound like two hollow aluminum things lightly tapping each other. It definitely sounds like its coming from the head. I'm almost positive its high on the motor. I know you can't be sure because sound travels oddly sometimes. Thanks again guys! I really appreciate it!
 

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Discussion Starter #6
I thought of one more thing... I can't believe I forgot to ask you all about it!
I CANNOT bleed the brakes! Aaagghhhh! I rebuilt the master cylinder but I must've screwed up because I've bled them till my hands almost fell off.
I re-assembled the master cylinder exactly as it came apart. The seals are all facing the right directing and all o that. Also the shoes are in okay shape and they are adjusted properly.
Does anyone have any suggestions for me? What did I miss!!!???
 

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The rear may have a worn pinion bearing and seal that is sucking air into the housing where it can be whipped into the gear oil then... but no way to know unless its taken off the swingarm to check it. I hadn't thought about it earlier, but a worn out rear driveshaft u-joint could also add some slop in that pinion seal if its allowing the yoke to wobble, since that pinion seal rides on the outer diameter of the driveshaft yoke. I would suspect one of those... but wouldn't spend any money on it without checking them out first.

If the noise comes only while the bike is in too high of gear at low RPMs, pulling hard, causing some backlash noise in the transmission or drivetrain, just downshift and it will cease. Any noise you hear at low RPMs under load could be a slight spark knock if it happens only while its hot and you are using low-octane fuel, but thats rare with a stock motor. A worn piston skirt/cylinder bore clearance issue will be quieter when its hot and noisiest when its first started up cold... Or it could be a slight exhaust leak at one of the two exhaust pipe joints where they seal to the head? Those have copper crush ring gaskets between the two pipe flanges and the exhaust ports in the head. If one of those header pipes is not centered in the head port it can leak a bit, 'cause those copper rings are quite narrow. If thats the case you can take the header pipes off and bend them by hand until they match both of the head ports perfectly. I spread and refitted mine by hand before putting them back on the bike after I refinished them. I probably didn't have to... but I noticed those narrow copper gaskets might not seal up the pipe flange on one side if I didn't center them both..? I'm too fussy I know... :)

Listen for the noise at all operating temps for a while to help you narrow down where it could be coming from. In the end you may find out its a normal behavior though.
 

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Those front brakes can be a bugger to bleed! If you minimize your pumping losses, seal the bleeder screw threads and use a clamp for a check valve to get the master empty of air and the fluid flow started, then it goes pretty quickly. I may (or may not) have a couple useful tips for ya... in no particular order, here is how I do it on Motorcycles/ATVs.

First thing I do on all bikes is remove all of the bleeder screws and wrap all of those threads with 5-8 wraps of Teflon tape. Then screw each bleeder back in by hand until they are about 3/4 of the way threaded back into the wheel cylinder (or caliper). Stop there and put a clear vinyl hose on each bleeder and drop the ends into a small can, jar, or bottle container. Route and support your clear vinyl hoses so that each hose has a loop in it, suspended just above its bleeder, where brake fluid can be held (the looped vinyl hose functions as a small reservoir for fluid that will be drawn back into the wheel cylinder) and escaping air will be directed up to the top of that loop away from the bleeder. All of the excess brake fluid drains into its container from the tops of those hose loops. Before beginning the bleeding process, make sure the teflon tape is fully sealing each of the bleeder threads. If not, snug them up 1/2 turn more, each...

When I bled my 350D out I took the small, round rubber check valve out of the bottom of the brake fluid reservoir until I was almost done, then put it back in place before the final bleeding strokes of the lever. This allows the air in the master cylinder bore to escape back into the reservoir at a much faster rate, than if that rubber restriction is left installed while you are bleeding.

To help minimize pumping stroke losses, I tightened all four of the brake shoe adjusters all the way out tight, so none of the bleeding strokes are being wasted on pushing those four wheel cylinder pistons out against the brake shoe return springs. After the system is bled, just back those four adjusters out three clicks where they belong and you'll be all grins over your cleverness. :)

Use a clamp on the brake hose right near the top of it, real close to the reservoir for a restrictor/check valve until you get all of the air out of the master cylinder bore and are getting full fluid flows coming out of the bleeder screws. Then quit using the clamp on the hose cause it isn't needed or helpful anymore, once a full fluid flow is established at the bleeders. How do you clamp that hose safely...? Wrap a rag around the hose and clamp it with vise grips or a C-clamp adjusted just tightly enough to nearly pinch off the hose completely.... but not quite all the way crushed. Just put the clamp on snuggly and leave it alone until its not needed then take it off. It won't hurt that hose unless its way overdone, so no worries.

Once you are getting full fluid flows out of both of the bleeders (and just before taking the clamp off from the brake hose) grab a screwdriver with a hard plastic handle and use the plastic handle to tap on the steel brake lines every couple inches or so along their lengths, beginning at the wheel cylinders and working your way back toward the proportioning valve mounted on the swingarm. Once you reach that valve tap on it several times while pumping the master cylinder lever a few times to move those tiny dislodged air bubbles toward the bleeder screw hoses where they can escape. After this step you can remove the clamp from the hose.

By this point you will probably be seeing only very, very tiny air bubbles escaping up through the fluid loops in the clear hoses, sorta like carbonation bubbles rising from the sides of the glass of your fav cold adult beverage. If so, put the rubber check valve back in the master cylinder reservoir and give each bleeder screw another 1/4-1/2 turn tighter to make sure their threads are still sealing. Then pump the lever a few more times and then stop... holding it fully depressed (you can wrap the lever with something to hold it depressed or use a big rubber o-ring slipped over the end of the handlebar and lever) while you snug up each bleeder screw.

Almost done now... pull the lever back once and hold it while you loosen and quickly retighten the bleeder on the left side, furthest away from the master. Release the lever. Repeat again until no air escapes. Then repeat these final bleeding steps on the other bleeder on the right side of the bike.

Finally, pull the lever once to make sure its hard, then top off the fluid and put the reservoir lid back on. Back off the brake shoe adjusters 3 clicks (back them off 2 clicks if you have new OEM brake shoes installed) where they belong and ride it.

EDIT:
I forgot to make a mention about leveling the brake master cylinder so that air has an upward path to escape from the master cylinder bore. You can turn the handlebar a bit to help level the master and you may have to loosen the handlebar clamp screws and twist the master a bit to get it just right. Doing this helps speed things along and saves on brake fluid waste. Put the master back where it belongs on the alignment punch mark on the bars when you are done.
 

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Discussion Starter #9
Thank you for your replies. I've been working a lot lately and haven't been able to get the plastic tubing and try that method yet. I'll post back as soon as I've made progress! (Hopefully). I'm starting to doubt whether or not I rebuilt the master correctly. Anyhow thanks again. Have a great day!
 

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Well I got it done! I already had them bled and didn't know it. I had been turning the wheel cylinders the wrong way... So I installed the new shoes and immediately had pressure on the first squeeze! I bled them a bit more, got the wheeler in the air and put it in 3rd and kept breaking at the same time to wear em in, made my final adjustments and voila! Front brakes! I kept tapping the lines while holding pressure before bleeding like retro suggested and I think that's why I got it. I'm really pumped! I didn't end up using a vacuum pump, tubing or anything! I just bled and bled and tapped and tapped!! Thank you guys yet again!
And that tinking noise in the head is there, at the same rpm's and whether hot or cold. Its stayed very consistent and hasn't gotten worse so I think I'll chock it up to normal old four wheeler noise...
Have a great evening everyone! Really appreciate your time.
 

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Awesome! You are a master! I like your bike an awful lot too! :)

Edit:
Been talking about the decomp cable/lever adjustment as a possible topend noise maker in a different thread here tonight. If you haven't already... double check that your decomp cable has about 1/8" freeplay per the FSM.

Celebrate! Have fun!
 

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Good deal, thanks for the update , and for turning the adjusters the wrong way haha, we all have made little mistakes from forgetting to turn on the petcock, to turning the key n hitting the start button and forgetting to check the kill switch, lol
 

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Can you post a pic of the rear dif ? Including the vent ....
 

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Good deal, thanks for the update , and for turning the adjusters the wrong way haha, we all have made little mistakes from forgetting to turn on the petcock, to turning the key n hitting the start button and forgetting to check the kill switch, lol
Yep ... Kill switch got me once. Felt like an idiot.
 

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.....we all have made little mistakes from forgetting to turn on the petcock, to turning the key on hitting the start button and forgetting to check the kill switch ...
Kill switch got me once. Felt like an idiot.
Kill switch fix ..... small hole drilled, with cotter pin.
 

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