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Old 07-25-2012, 07:31 PM   #1
cruzy OP
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Pissed xr500rd crank

hi all, firstly gaday from australia, hope someone can help me , im rebuilding my bottom end on a 1983 xr500rd due to a conrod issue. i have purchased a seconhand crank and when fitting crank , i noticed 2 differences between cranks.
1. threaded end of crank is larger nut that holds oil pump drive , original nut is to small , i found that nut size is same as clutch basket

2. balancer alignment marks wont align

the seller assures me that it is a xr500rd crank , has anyone else come across this difference .

the different nut size is not a problem, but the balancer alignment has me concerned . i thought of just counting teeth on original crank and matching up with replacement crank . the crank fits in every other way . hope someone can share some advice

xrs rock

cruzy
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Old 07-25-2012, 09:47 PM   #2
Ghost_Mutant
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Cruzy,

I have both an 83 500RD and an 84 500RE (plus a spare parts 84 XR5). All three of my 500 cranks looked the same to me when doing my rebuilds awhile ago. I did not notice the differences you are describing between my 83 and 84.

Taking a quick look at the parts fiche, it appears that the crank drive retaining nut is the same part as the clutch retaining nut for both D and E XR5s. Here is the diagram, and its part number 15:


Sounds to me as if one of your cranks is not a stock 500? The one with the different thread size from the transmission input shaft? Any signs that it has been rebuilt in the past? I'm in the USA and I do believe there are some minor differences between our non-street legal XRs and what the rest of the world has. And I've been wrong in the past regarding part interchange between the big bore RFVC engines

Note that 500 RFVC engines have different left side crank bearing and different connecting rod small end diameter as compared to early 600 RFVC engines. Ivan from Russia is rebuilding his XR500 and he may know what it is you are describing. His rebuild thread is here:
http://www.advrider.com/forums/showt...ghlight=xr500r

The balancer being misaligned would probably not be good for engine vibrations, best case. Here is the best photo I have of my spare 84 crank if that helps.
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Old 07-25-2012, 10:23 PM   #3
cruzy OP
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xr crank

thanks mate for the reply , well engine had top end off when i bought it, just compareing ur pic to mine , on original crank same alignment mark but smaller end nut not the same as clutch, replacement crank i have is similar has same size nut as clutch but alignment mark is in a different position and will not align with balancer as balancer lobe hits crank lobe w.t.f. , fits in case sweet and piston pin fits perfect (brand new orig honda piston and pin , i have fitted balancer in same position as orig crank seems ok but ????? i wondered if maybe cog on crank has slipped

cheers
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Old 07-26-2012, 12:05 AM   #4
Ivanych
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HI, CRUZY!
Welcome to the XR500R club:http://www.advrider.com/forums/showthread.php?t=713048
My collection of nuts crankshaft consists of : XR500re (1984-85 Germany), XBR500, Xr600, Xr650l. All of these nuts are the same! I have the shaft balancing XBR500 (1985) - this is another shaft (I can't use xbr500 shaft in my XR500re). I think was of poor quality (bad) repair Your crankshaft.
Publish photos for joint thinking.
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Old 07-26-2012, 08:56 AM   #5
Ghost_Mutant
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So:

1) the crank that came with the engine had stripped threads at one point and the previous owner machined the shaft for a smaller thread? And this crank has the bad con-rod? Is there anything else wrong with the end of this crank? Because that is where the oil feed goes, and you don't want any leaks there.

2) New/used crank has a rotated balancer gear? No doubt it was aligned properly when it left Honda in the early 80s Is there any sign of damage from a colliding balancer on this crank?

I wouldn't run either crank as is

What can you do? Here is my list:

1) return/exchange the new/used crank for one that has both a good con-rod and proper balancer gear position.
2) get another used crank. I see them on ebay every once in awhile.
3) rebuild.........move good con-rod over to the crank with the good gear, which would cost more than an ebay crank.

Perhaps there is a way to re-certify the balancer gear so you know it won't move in the running engine? I haven't rebuilt any cranks, so I don't know the answer to that.
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Old 07-26-2012, 10:53 PM   #6
cruzy OP
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cr500 crank

hi guys how do i upload some pics

cheers
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Old 07-26-2012, 11:30 PM   #7
Ivanych
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Quote:
Originally Posted by cruzy View Post
hi guys how do i upload some pics

cheers
You must use Internet repository for photos and paste the link to a photo of the store in the line opens after clicking the "insert image" in the message.


Take a look here:
http://www.advrider.com/forums/showthread.php?t=919
good luck
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Old 07-27-2012, 01:38 AM   #8
cruzy OP
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xr500rd crank


ok guys this is pic of original crank , the nut size on crank is 16mm


this is replacement crank , nut size is 18mm which is correct size i believe , but note balancer alignment marks, i did a tooth count and in pic 2 u can see crank is now in same position as pic1 , there is no damage to replacment crank or balancer cog at all . cog does not seem loose , but i guess if previous owner sie ,zed engine maybe cog moved but its very tight now, im reasonablely sure this should work what do u all think

cheers

cruzy screwed with this post 07-27-2012 at 02:31 AM Reason: pics
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Old 07-27-2012, 01:56 AM   #9
Ivanych
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Quote:
Originally Posted by cruzy View Post
[/IMG]
ok guys this is pic of original crank , the nut size on crank is 16mm

[/IMG]
this is replacement crank , nut size is 18mm which is correct size i believe , but note balancer alignment marks, i did a tooth count and in pic 2 u can see crank is now in same position as pic1 , there is no damage to replacment crank or balancer cog at all . im reasonablely sure this should work what do u all think

cheers

Sorry, photos are not visible.
You can not insert pictures from your computer directly.
You can insert pictures from the inernet - photo storage. (fotobuket, Web Albums Picasa ....)

Ivanych screwed with this post 07-27-2012 at 02:08 AM
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Old 07-27-2012, 08:31 AM   #10
Ghost_Mutant
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Cruzy,

I think you need someone with prior crank rebuilding experience to comment on this, and I'm not that guy.

The best I can do is point you to this thread on crank rebuilding:
http://www.thumpertalk.com/topic/627617-crank-rebuild/

Note post #14
In particular, note comment about being timed perfectly. I don't know how important that is for proper balancer operation, but what do you think the odds are that your offset gear is perfect? How close to perfect in degrees does it have to be?

It would seem that your new/used crank has been worked on before and its odd that the gear was not put back on in the proper orientation. If true, what does that say about the crank rebuilder?

The only other explanation I can think of is that the gear moved in a running engine, but how could it be that far off without a collision and obvious damage?

If it did move in the running engine, it will probably move again if you use it as is.

At the very least, I would try to figure out a way to check the alignment of the crank/gear without splitting the cases for future checking. I can't remember if the gear edge can be observed through a hole from the right side. But if there is a spot to observe through the case half, then I would suggest putting some witness marks on both the crank and gear so that you can check it later if you decide to use this crank.
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Old 07-27-2012, 06:47 PM   #11
cruzy OP
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xr crank

thanks for ur input ghost . its a strange one , sad part is the crank is in perfect condition with not a mark on it , big end and little end r near perfect, i counted teeth from original crank from edge of crank lobe and set replacement in same position , in theroy this should work providing cog does not move mmmm paid 150 bucks for it from usa bought it a year ago only just getting around to fitting it ,

cheers
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