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Old 04-19-2012, 02:43 PM   #61
FJ_Kevin OP
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Splitting the cases:

As already mentioned, I have quite a variety of motors and cases to work my way through. But before jumping in I thought I would list the serial number prefixes and try and identify the models and years they correspond to.


3R5 = 1980 YZ465G with 5speed gearbox
4V4 = 1981 YZ465H with 5-speed gearbox
5X6 = 1982 YZ490J with 4- speed gearbox
23X = 1983 YZ490K with 4-speed gearbox
26A = 1983 IT490K with 5-speed gearbox
1LV = (?) 1985 YZ490N with 4-speed gearbox
xxx = 1986 YZ490S with 5-speed gearbox


The above listing is my best guess at the moment, please correct me if this is in error. You can see that both 4 and 5 speed transmissions were used across all the models. The 465 only used the 5-speed. The YZ490 used a 4-speed gear box from introduction until 1985 with the N model. The 1986 S model went back to a 5-speed. The 1983/84 IT490 also uses a 5-speed although I believe the design and/or gear ratios differ from the 465 5-speed in some way.

Because of this change in the '86 490 back to five-speed, I was optimistic that I could use the 1LV cases with the 465 5-speed gearbox and this turns out to be true. Another interesting point is the change from side port cylinder to center port cylinder that occurrred in the 1984 490. I found that this change had no impact in the case design. My guess is that cases as new as the WR500 also work in the 465's, not bad!

So my plan going forward is to strip two 465 motors. One being a 3R5 and the other being a 4V4. I plan to use a 5-speed gearbox as original. I have a few different case sets to choose from but have decided to go forward with the 1LV cases from the 1985 490. I found some changes involving the clutch arm and venting that swayed me to go in this direction (I will point these out later).

I should mention that I consulted the factory YZ465 and YZ490 manuals extensively while breaking these down. Reading through them both before starting work is well worth the time. Not being in a rush, I took plenty of time and proceeded cautiously. It is not a difficult job but it is easy to break something if not careful.

I will also mention that an air wrench is handy for removing the sprocket nut, flywheel nut, clutch hub nut and the crank gear nut without having the factory holding tools.

I wont go through every detail as that what the manual is for. Instead, I will just try to point out some traps and differences in the model years as that is what I am most interested in.

Ok, so here we go with the 1st set of photos. The engine covers, cylinder and case screws are already removed and the next task is to remove the flywheel.

After removing the flywheel nut with my air wrench, I attempted to use this nice aftermarket puller to get the darn thing off. Although specified as correct for the YZ465, the puller had an internal shoulder that prevented it from threading far enough into the flywheel. The fix was to chuck it in the lathe and hog it out this area. Had I not noticed this I am sure I would have pulled the threads out of the flywheel and had a real mess on my hands.

After threading the modified puller body fully into the flywheel I then tighten the bolt to press the flywheel off the crank taper. It is not too often that they pop off unless you go overboard on the tightening. But I prefer to avoid tightening too much so as not to distort the flywheel. Instead, I give the bolt head a couple of sharp raps with a hammer and usually the sharp impact is enough to break things loose. Make sure you save the key (replace with new) and examine the keyway slot in both the crank and inside the flywheel. Look for galling or other signs of movement or spinning (shifts or bad fit here can affect ignition timing and balance)



Inside of the puller after some machining to add depth



After removing the clutch assembly, kickstarter shaft assembly, and crank gear, this is what one of the 4v4 motors looks like. One thing to point out is the shift drum near the bottom of the case. In this motor, the selector star is removable from the shift drum via a screw (it is already removed here).



In later 465 and 490 motors the selector star is welded to the shift drum and is not removable. The shift drum bearing resides under the selector star and so is not easily replaceable in this version. When I first saw the welded star I actually thought a previous owner had done that. But in fact, that is a factory Yamaha weld! You can see the welded star in the next photo.


In splitting the cases, you may choose to leave the transmission and crank in either case half. However, you must make sure the welded star (if you have one) is correctly positioned if you plan to separate things such that the drum is removed from the right hand case (this detail is also explained in the manual).

You will need another puller to press the crank through the crank bearing during the splitting process. A steering wheel puller can often do the trick. Mine was not large enough so I whipped up a puller out of some scrap steel.



Here is the 1st motor split with transmission and crank in left hand case


And here is the 2nd motor with transmission in right hand case and crank in left hand case.



The 5-speed transmissions





More to come...

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Old 04-25-2012, 08:54 AM   #62
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FJ Kevin:

Check out this report I made about my YZ 465 and Diamond Don's:

http://www.advrider.com/forums/showthread.php?t=785009
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Old 04-27-2012, 02:11 PM   #63
FJ_Kevin OP
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Alright, before continuing I want to thank WFOPete again for that great Diamond Dons report here...

http://www.advrider.com/forums/showthread.php?t=785009 it's really super!

I have a lot more photos but not much time, lets see how far I can before I have to go!

So far I have a couple of engines apart and have been busy stripping down gearsets and such. The next step for me was close examination and study of the various parts. Recall that I am working with different model year 465's and 490's so I need to pay attention to differences and incompatibilities. I also need to look for damage and flaws.

First up is the gear sets.

I think the only way to really evaluate the gear dogs is to strip them off their shafts. Plus it's a good opportunity to examine the shafts themselves for galling or overheating on the surfaces that the gears run on.

They come apart pretty easily although you will need a good set of snap ring pliers. There is one snap ring, however, that is more difficult to remove as it sits right up against the gear and the dogs of that gear get in the way somewhat.

I found it went much easier if I 1st stood the shaft upwrite in loosely tightend vice jaws. Then, while holding the snap ring open with one hand, I tapped the shaft with a rubber mallot. This forces the gear (resting on the vice jaw) to push the ring past the groove.

This photo shows that ring. You can see it rests against the gear in a recess that makes it less straightforward to remove.



And here is the ring after it has been pushed pass the groove.


Some of the gears on one motor were in rough shape. I found pitting in several gear teeth. There was also damage resulting from engine case material falling into the gear set when the kick start mechanism blew out.

Lets have a look...



Some of the gear dog pockets were pretty beaten up,



Other gears were found to be in great shape





I laid the parts for each gear set on the bench,carefully noting the condition of each part.



uh oh, rats, out of time... sorry, have to run, Ill have to come back to this.
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Old 04-28-2012, 06:59 AM   #64
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Kevin,

PM sent.
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Old 04-28-2012, 10:32 AM   #65
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I am enjoying your thread--and learning quite a bit. I have two '81 IT465s I am combining into one. I have a new top end--piston and freshly bored matched cylinder. I also have some new wiring, new bearings everywhere, new DG exhaust system, new bars, new tires, new cables, new brakes. In short, a nice project ready to put together and try out.

My biggest dilemma with the IT465 is that neither of my cases will work without some repair and maybe machining. The better of the cases has a hole between the tranny and the crankcase.The other case is shattered at the kickstarter shaft (lots of abuse there from energetic POs, I fear). I recognize some of the flaws in your cases as similar to my own,

Your photos and research have shown me my cases are about par for the course and not unusually damaged. I am also learning what to look for as I put everything back together.

My best course of action, though, might be to purchase a set of cases in good condition and bin what I have. I have plenty of tranny gears in good shape so even a worn out gearbox won't be a deal breaker for me.

Thank you for taking the time to document your YZ project
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Old 04-30-2012, 01:57 PM   #66
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Originally Posted by Cordless View Post
I am enjoying your thread--and learning quite a bit. I have two '81 IT465s I am combining into one. I have a new top end--piston and freshly bored matched cylinder. I also have some new wiring, new bearings everywhere, new DG exhaust system, new bars, new tires, new cables, new brakes. In short, a nice project ready to put together and try out.

My biggest dilemma with the IT465 is that neither of my cases will work without some repair and maybe machining. The better of the cases has a hole between the tranny and the crankcase.The other case is shattered at the kickstarter shaft (lots of abuse there from energetic POs, I fear). I recognize some of the flaws in your cases as similar to my own,

Your photos and research have shown me my cases are about par for the course and not unusually damaged. I am also learning what to look for as I put everything back together.

My best course of action, though, might be to purchase a set of cases in good condition and bin what I have. I have plenty of tranny gears in good shape so even a worn out gearbox won't be a deal breaker for me.

Thank you for taking the time to document your YZ project
Thanks cordless. I am glad you are finding this helpful. There are many great projects going on here at ADVR, the site has been a great source of information to me also as I have a couple of airheads I often tinker with.

From your description, it sounds like you are making good progress yourself. Perhaps you can post some pictures?
Have you had your it465 for long? All of the 465's are fine bikes. I am glad to hear you are fixing it.

If your case is broken in the gasket surface area or in a bearing support then yes, I think I too would look for a replacement set. If it is just a small hole than maybe welding would be fine. One of my motors has a small crack at the back of the kick starter shaft boss where many seem to break. I am going to try welding it up at some point. I can usually weld aluminum pretty well if I can clean the area so it is free of oil and contanminants and if the material is truly aluminum.

I did recently weld a 465 clutch cover which is made of magnesium. That was a tougher process. I think there may have still been oil residue within the crack I was repairing despite efforts to clean it well. The weld did not look too great but it did take and does not leak. Since then I have done some more reading about welding magnesium. There was a nice video on youtube on the topic of welding magnesium. I'll be trying again with another broken cover I have. Practice makes perfect as they say.

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Old 04-30-2012, 02:30 PM   #67
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Once again I am short of time but lets see if I can still get a few things in today.

Continuing with the transmission, the following photo shows the break down of the drive axle. First gear on the drive axle was found to have a chipped tooth. The corresponding gear on the pinion shaft was also bad. As 1st pinion gear is part of the shaft, the shaft is no good either.

.

Eventually I had both transmission apart and lying side by side. I made a table to tabulate the condition of each gear from the two transmissions and to help me keep track of what I was doing! My grading system progressed from bad to excellent using the notation X, check -, check, check +. I was to select check + (excellent) for all gears but I had to settle for a check (good) on the 4 and 5th gears on the clutch axle.



I noticed something else interesting involving the shift drums. These casings are hollowed out for light weight. The 1980 3R5 version appeared to be hogged out more than the 1981 4V4 version. Perhaps Yamaha felt the need for a strengthend part for some reason?

Let's go to the photos... top is 3R5 bottom is 4V4. Again, the 4V4 shift drum has the bearing on it since the selector star is welded rather than screwed on.



Another view...


Both drums appeared to be in fine shape but I will use the 4V4 style in reassembly.

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Old 05-10-2012, 07:15 PM   #68
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I am taking a break from cleaning my work shop to update his thread a bit.

Actually, I have been thinking about a major shop redo for awhile now as stuff is all over the place and I find myself wasting considerable time looking for tools and parts I know I have.

And one thing I am short of is more bench space! To address this issue, I decided to build a new 4x8 bench that I could access from all sides. The bench is on wheels so I can move it around my shop. My plan is to remove two smaller work benches along a wall. I will then move a couple of machine tools in their place in order to free up area in another work bay (for another project?).

While 4x8 sounds like a large surface, haha, I had no problem filling it up with yz/it/465/490 motors!

As you can see my new bench is already pretty well cluttered up as I try to clear the old benches and get them out of the shop. This does even include the motor currently being rebuilt!








Anyway, seeing them all lined up like this remined me to measure the width of the motor mount where the swing arm bolt passes through.



I measured YZ/IT 490 motors and YZ465 motors... and there is a difference! It turns out the width of the 490's, at the mount, are about 10 thousands of an inch less than the 465's. The cases themselves appear to be the same. The difference is in the collars 14 and 9 in the diagram below.




I am still planning to use the 490 cases in my 465.

Ten thousands is not much, but if need be, I will make up for this by using an extra shim (or side thrust washer) in the swing arm bearing assembly. It's nice now to have those spares from the All Balls Kit!


I still need to gather a few pictures of the gear box reassemble, perhaps I will have more tomorrow.

For those who might be interested, here is a few drawings and photos of my new bench. The red part is a sheet metal bender. The bench overhang is to allow my air compressor to tuck under. The grey/blue box is an old multi drawer cabinet I had around. The round tubes are to hold welding rod. Wheels are not shown in drawing but you can see them in pictures.




I am planning to put hardware and carbureto jettting boxes on bottom shelf.


Not finished yet but here is how it is shaping up.





Still have a lot of clean up to do!

I always liked this photo of Kent on his Husky!
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Old 05-11-2012, 05:27 PM   #69
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Kevin,

Where was that shot from; Rio Bravo?
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Old 05-13-2012, 02:49 PM   #70
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So detailed with all of your posts. Thank You so very much for this thread.
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Old 05-15-2012, 01:04 PM   #71
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Originally Posted by wfopete View Post
Kevin,

Where was that shot from; Rio Bravo?
Hi Pete,

Had to go back to the photo file name but it appears to be from Hangtown in 1975. Here is a youtube vid, looks wet alright!

http://www.youtube.com/watch?v=AMJok59MS58
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Old 05-15-2012, 01:05 PM   #72
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So detailed with all of your posts. Thank You so very much for this thread.
You are welcome. Glad you are enjoying it!
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Old 05-15-2012, 02:20 PM   #73
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Ok, I've been a little slow with my updates but the good news is I am way ahead with the project in real life . Even so, I want to continue to post the findings so I dont just forget everything I have learned along the way.


So the gearset went together without any drama. Surprisingly, all the shift forks were in fine condition. No deep groves or anything to indicate a bent fork. The posts that ride in the shift drum grooves were nice and round with no squaring whats so ever.

Here is a photo of the gear set ready to be installed. From the top are the shift drum, the drive axle (counter shaft sprocet goes on right) and the pinion shaft (clutch goes on left). Once installed, the counter shaft spocket nut will pull the shaft against the counter shaft bearing in the case.

Likewise, the pinion shaft will be pulled against a bearing via the clutch hub nut.



Before closing things up we will have a look at some differences I noticed in the 465/490 engine cases.

Here we are comparing a left side engine case for and 81 YZ465 and a 85 YZ490. The left photos show the outside while the right photos show the inside. Key differences include a modification of the clutch arm area and some beefing up of the 490 case around the transmission bearing. The volume of the crank case was measured to be the same. This makes sense as the crank fly wheels also measure the same and the cranks are in fact interchangable.

A


Ah another interruption I am afraid... but I am back now!

Here is a little more info on the changes to the clutch arm area. It turns out the clutch arm for 1980 through 1984 models is the same. But then a change occured in 1985 where the shaft of the clutch arm is extended and goes further into the case. The extended casting for the clutch arm is shown in the lower left of the above photo.

The next photo compares the 1980-81 465, the 82-84 490 and 1985 490 and later style cases in the clutch arm area. Side and top vies are shown. The 80-81 case has the short casting. Looking from the top, the bore from for the clutch arm shaft is centered in the casting circle.

The '82 thru '83 (maybe 84?) still has the short casting but adds a screw hole for the countershaft sprocket cover. However, the top view shows
the bore for the clutch shaft is machined off center from the casting circle.

And finally, the 1985 and later case with the extended casting as shown.



Here is a comparison of the early and late style clutch arm clearly showing the difference in shaft length. It is important to use the clutch arm style that matches the case. I later found that the offset clutch arm style (all 490 cases) also requires use of the 490 clutch pressure plate. this late plate has a longer adjuster to make up for the increased distance due to the shaft offset. I will return to this point later in the assembly of my 465 using 490 cases.



The was also minor differences discovered in the shifter shaft where the later shaft was machine down in the middle (weight savings). And finally, the lower picture shows the later vent hole location. The YZ465 case has the vent near the kick starter.


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Old 05-16-2012, 06:20 AM   #74
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Wink Excuse me while I jump in here.

Hey Kevin,

I finally got around to timing my 465G. On the bike's maiden voyage, the motor ran fine down low but once in the midrange or higher it rattled and clanked something awful. It also, required 20+ kicks to get fired up hot or cold. So I really didn’t know if I had a jetting, timing or a possible vacuum leak problem. For those of you not familiar with timing this beast, it’s a bit different than most other bikes. Most bikes of that era had the timing set statically. Wouldn't you know it; starting with the 465's, Yamaha specifies that the timing be set dynamically (engine running, using a timing light and tachometer). Yamaha recommends 16 degrees BTDC at 2000 rpm. This requires using a 12V battery to power the timing light. The Yamaha timing marks are not like the big “T” and “F” found on the flywheel of Hondas. The marks are relatively small and likely covered with a little grime. Also, there are three areas where you will need to locate timing marks; the flywheel, the crankcase and the stator plate. I marked the flywheel and crankcase timing marks in red color so they would show up better. Big thanks to Kevin for his assistance in the location of the procedure of this whole mess. First, I set the static timing at factory specs (2.0mm BTDC) using a dial indicator. This required the partial removal of the engine as the frame interfered with my dial indictor. Of course you get to pull the flywheel each time you need to make an adjustment too. I had removed the stator plate for cleaning so I can’t tell you what the original timing was set at but I believe it was too far retarded, which is as bad as having the timing too far advanced. Guess what? The bike started great, like 4th kick after sitting for a month.

Then, with the engine runnng, I checked for any seal/gasket leaks by spraying WD40 around the ignition side crank seal, base gasket, carb intake and reed gasket areas. A spray bottle of water works well here too. I didn’t get any indication of a leak. Then I put the timing light on and had a look at the marks (kinda takes a knack the first time or two doing this); hmmm, not far off. I shut the bike down and restarted while it was hot and it started in three kicks. Adjusted the idle and the air screw and ended up advancing the timing just a wee bit more. Then I took the 465 out for a ride on a long steep uphill gravel road. Power was smooth on the bottom then started coming on hard at about 1/3 of the way through the RPM range. I’m using a 3.5 slide in the carburetor that probably helps smooth the low-end power. Found a flat hard packed section and the front and came up easily in fourth gear (I didn’t try fifth). The engine noise that I experienced on a MX track at Diamond Don's was gone. Plug was tan/brown. This is one of the cleanest running big bores I’ve ever seen. I’m running Maxima Castor 927 at 40:1; back in the day Yamaha recommended 20:1. So I think I’m in the ballpark. There will be more adjusting & fine-tuning needed. For one thing I’m not happy about it’s cold starting, as it seems to be a bit of a moving target. This could be my technique or a mechanical issue, for one I probably will bump my PJ from a 40 to a 45 but until I can get it out on a track for a more extended eval, I'm calling it good.
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Old 05-17-2012, 11:43 AM   #75
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Quote:
Originally Posted by wfopete View Post
Hey Kevin,

I finally got around to timing my 465G. On the bike's maiden voyage, the motor ran fine down low but once in the midrange or higher it rattled and clanked something awful. It also, required 20+ kicks to get fired up hot or cold. So I really didnít know if I had a jetting, timing or a possible vacuum leak problem. For those of you not familiar with timing this beast, itís a bit different than most other bikes. Most bikes of that era had the timing set statically. Wouldn't you know it; starting with the 465's, Yamaha specifies that the timing be set dynamically (engine running, using a timing light and tachometer). Yamaha recommends 16 degrees BTDC at 2000 rpm. This requires using a 12V battery to power the timing light. The Yamaha timing marks are not like the big ďTĒ and ďFĒ found on the flywheel of Hondas. The marks are relatively small and likely covered with a little grime. Also, there are three areas where you will need to locate timing marks; the flywheel, the crankcase and the stator plate. I marked the flywheel and crankcase timing marks in red color so they would show up better. Big thanks to Kevin for his assistance in the location of the procedure of this whole mess. First, I set the static timing at factory specs (2.0mm BTDC) using a dial indicator. This required the partial removal of the engine as the frame interfered with my dial indictor. Of course you get to pull the flywheel each time you need to make an adjustment too. I had removed the stator plate for cleaning so I canít tell you what the original timing was set at but I believe it was too far retarded, which is as bad as having the timing too far advanced. Guess what? The bike started great, like 4th kick after sitting for a month.

Then, with the engine runnng, I checked for any seal/gasket leaks by spraying WD40 around the ignition side crank seal, base gasket, carb intake and reed gasket areas. A spray bottle of water works well here too. I didnít get any indication of a leak. Then I put the timing light on and had a look at the marks (kinda takes a knack the first time or two doing this); hmmm, not far off. I shut the bike down and restarted while it was hot and it started in three kicks. Adjusted the idle and the air screw and ended up advancing the timing just a wee bit more. Then I took the 465 out for a ride on a long steep uphill gravel road. Power was smooth on the bottom then started coming on hard at about 1/3 of the way through the RPM range. Iím using a 3.5 slide in the carburetor that probably helps smooth the low-end power. Found a flat hard packed section and the front and came up easily in fourth gear (I didnít try fifth). The engine noise that I experienced on a MX track at Diamond Don's was gone. Plug was tan/brown. This is one of the cleanest running big bores Iíve ever seen. Iím running Maxima Castor 927 at 40:1; back in the day Yamaha recommended 20:1. So I think Iím in the ballpark. There will be more adjusting & fine-tuning needed. For one thing Iím not happy about itís cold starting, as it seems to be a bit of a moving target. This could be my technique or a mechanical issue, for one I probably will bump my PJ from a 40 to a 45 but until I can get it out on a track for a more extended eval, I'm calling it good.
Pete,

Thanks for the very nice writeup on setting ignition timing using a timing light. Always nice to get someone's 1st hand experience.

And great that your bike starts so easily now. I am sure it will be much more enjoyable. With all the energy you will be saving from not kicking so much you will probably move up a couple of positions in your next race .

As I mentioned to you, last weekend my IT490 started in 3 kicks cold after sitting for 3 months, then just 1 kick when hot. Who says these are hard starting bikes???

Thanks again, this Mikkola is for you!

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