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Old 05-02-2011, 08:18 PM   #31
Ghost_Mutant
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Location: border of granite & flats
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I'm sorry to read about the condition of your engine. I never liked opening things up and seeing this type of work.

It looks like you need to replace a bunch of parts. I purchased some new stainless steel valves from a guy in Israel to fix up my spare head:
http://cgi.ebay.com/ebaymotors/HONDA...mZ220760776408
These were the cheapest I've found, but I haven't used them yet.

My XR500s currently have Kibble White Black diamond valves.

I don't know what kind of piston you have. Except for the valves and gaskets, I used Honda OEM parts in my rebuilds. You should measure the cylinder bore to see if it really is 92.5mm.

I don't understand why your engine needed the spacer between the case and cylinder. Perhaps you should look at the crank to be sure it's the stock XR500 assembly with the 75mm stroke.

I couldn't afford to replace all the parts you need in my rebuilds with new. Perhaps now is the time to look for a donor engine, but I understand these machines are hard to find in your location.


Quote:
Originally Posted by Ivanych View Post
I had one free day and I spent it with my bike.
This day was difficult for me.
I checked Cylindercompression. It was hard. 30 minutes of jumping but the device showed only 8 kg / cm 2, it is not enough.
I am very upset.

I took the engine out of the frame (it was easy to do) and opened it.
When I saw the engine in, I became very angry !!!!!!

I want to tear hands mechanics, who collected the engine in front of me.

It's horrible, it wanted to kill this engine !!!!!
1. Part of the fastener head cover, cylinder head and lost and replaced by strangers. I'm surprised! Where native bolts (hardware)??
2. Single bolt cylinder head was not screwed in (only by hand). The mechanic had no memory??
Mounting bolt cylinder is shortened. Why??
3. Everywhere (everywhere) snot on the sealant.
3. The ends of the release valves were shortened ??????
4. ARM EX.SUB ROCK - has a great point wear !!!!! (A bad valve adjustment!)
5. Chain tensioner received many blows with a hammer !!!!!
6.Piston and the cylinder has a large scratches, but the rings are good. Why??
Small gap between the piston and the cylinder (the error in grinding??)?? or is it mud sand) in the assembly??
7. Piston clean without soot but has traces of blow valves!
Who can identify this piston? This WISECO??
Now I am left to disassemble the cylinder head and I'll have a lot of questions in this forum that I should do next.


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Old 05-03-2011, 07:37 AM   #32
Ivanych OP
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I think I need to replace the piston, cylinder, and have a lot of new parts for the cylinder head.
I want to get displancement - 600ss in my engine with the repairs. (if possible)
Can I use parts (cylinder, piston, crankshaft, BALANCER) of XL600 or XR600R85-87 with CRANKCASE and cylinder head on my bike XR500R?
How can I get displancement = 600ss in my engine?
Which ideas are the professionals?
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Old 05-03-2011, 09:39 PM   #33
Ghost_Mutant
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If I wanted to make my RFVC 500 into a 600, I would just buy another engine from a XL600 which I think will swap in using the existing brackets. The XL600 has the same 75mm stroke but with a larger 100mm cylinder bore.

However, the newer XR600 cylinder is taller, and I think custom brackets for the valve cover upper engine mount might be needed to fit into the 500 frame. But I'm not 100% sure of that. Someone has probably done this swap before.

If you could find such a 600 engine in good condition, that is usually the cheapest way.

I don't think I would spend money to buy the XL600 parts separately. Most of the dealer prices I see are too high for my bike building budgets to do that kind of swapping. Only you know what prices are like in your location.

It would be cheaper around here to just buy another bike

But part swapping to make a 500 into a 600 is possible if you were willing to track down all the differences.

The 500 has a different clutch basket than the 600. The buffer springs in the 500 basket are slightly weaker. Also, the primary drive gear on the crank is different between the two engines. Or I should say it is on my 84 XR500R........... but I'm not sure about your XR500.
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Old 05-04-2011, 05:46 AM   #34
jub jub
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I was just wondering, when you were checking compression, did you disable the decompression valve and hold the throttle wide open. That would make a difference I would think. Also, the piston appears to be at least 11 or 12 to 1 considering the dome and relief pockets for the valves. You should have way better compression than what you mentioned.
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Old 05-04-2011, 11:05 AM   #35
Ivanych OP
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Riddle of the appearance of an aluminum strip under my engine cylinder is solved !!!!!
This is a high piston !!!!!
He does not fit in the cylinder!!
I don `t know who came up to put it into the motor.
This is a photo without the aluminum gasket. (post # 19)
Attached Images
 

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Old 05-04-2011, 11:13 AM   #36
Ivanych OP
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Quote:
Originally Posted by jub jub View Post
I was just wondering, when you were checking compression, did you disable the decompression valve and hold the throttle wide open. That would make a difference I would think. Also, the piston appears to be at least 11 or 12 to 1 considering the dome and relief pockets for the valves. You should have way better compression than what you mentioned.
Yes, I did everything as you say!
But the valve motor did not hold air (non-watertight).
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Old 05-04-2011, 12:14 PM   #37
ChrisC
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Quote:
Originally Posted by Ivanych View Post
Circumcision valve
I thought only KTMs had circumcision valves?
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Old 05-04-2011, 03:31 PM   #38
GR0NK
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Yes that is a Wiseco piston, apparently not the right one for the application. But appearances can be deceiving. Run the numbers to verify. Pray it is the wrong piston.

The grinding on the valve stems suggest that there was no more adjustment left in the tappet so they ground it down to "create" adjustment? Scary stuff. You run out of adjustment as the valve wears into the valve seat. Running out of adjustment is your final warning before the motor drops a valve.

You need to pull the crank out because if the Wiseco piston is correct for that motor, then the connecting rod is not.



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Old 05-04-2011, 06:06 PM   #39
Ghost_Mutant
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Quote:
Originally Posted by GR0NK View Post
You need to pull the crank out because if the Wiseco piston is correct for that motor, then the connecting rod is not.
I'm guessing that the crank is not stock, and therefore the stroke is not 75mm.

Check the case serial number to determine if the bottom end is from a more recent Honda XR with 80mm stroke.

If I recall correctly, all the big bore RFVC engines have the same length connecting rod. Somebody please correct me if I'm wrong on that one.
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Old 05-04-2011, 11:07 PM   #40
Ivanych OP
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hi!
Mystique continues!
I spent the measure:
stroke = 75 mm
piston pin = Ф 22 mm.
This KRANKSHAFT belongs XR500R (I think so)

What is the height of the body CYLINDERS? (height shirts?)
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Old 05-05-2011, 06:28 AM   #41
GR0NK
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If the stroke is correct that only means the crank is correct. The connecting rod might not be. Measure the length of the connecting rod. The rod for an 80mm stroke crank would be longer for the same cylinder height. Maybe the crank was rebuilt with the wrong rod?


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Old 05-05-2011, 09:43 AM   #42
Ghost_Mutant
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75mm stroke and 22mm pin diameter are correct for the RFVC XR500.

I think it's really unlikely that the rod is non-stock since the other big bore RFVC engines have a larger piston pin diameter of 24mm. I found that out during my rebuilds and here is a link to the discussion in the XL600 forum:
http://www.advrider.com/forums/showt...45878&page=149
(starting with post #2227)

I also think it is unlikely that the cylinder has been made shorter. I will measure my spare cylinder for you later. It is in my attic which is blocked right now, so I can't easily get to it.

However, I do have my original stock Honda XR500 piston handy, so lets compare dimensions with your piston.

Stock XR500 piston dimensions:
piston diameter measured at skirt = 91.9mm
pin diameter = 22.0mm
Top edge of piston to center of piston pin = 33.0mm
height of piston, bottom to top = 67mm
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Old 05-05-2011, 11:54 AM   #43
Ivanych OP
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Ghost_Mutant Thanks for the info on the piston.
But I can make their measurements only on Sunday.
I also think that all problemma due to the piston.
I read the manual (XL600, XR600R, XR500R, XBR500) about the piston pin.
Dimensions piston pin:
XL600 - 24 mm
XR600R - 24 mm
XBR500 - 24 mm
only XR500r - 22mm
I think the standard rod (XR500r)

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Old 05-09-2011, 01:53 AM   #44
Ivanych OP
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Here are my measurements the piston and cylinder:
piston diameter measured at skirt = 92.5mm
pin diameter = 22.0mm
Top edge of piston to center of piston pin = 33.0mm (until the protrusion 37)
height of piston, bottom to top = 67mm (up to protrusion 71)
Hull length of the cylinder = 100.5
Long sleeves = 133
I think that the piston is Correct and all probleemy in the cylinder.
Ghost_Mutant very interesting to know the dimensions (length) of your cylinder (or cylinder of XL600)
Here is my scribble:
Attached Images
 
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Old 05-09-2011, 08:18 AM   #45
Ghost_Mutant
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My spare cylinder measurements:

sleeve length = 143.2 mm

bottom of sleeve to case/base gasket surface = 38.6 mm

Subtracting to get cylinder casting/hull length = 104.6 mm


So we have a difference, does this explain the spacer? What is the dimensions of the spacer? Is the spacer a homemade job?

Looking at your close up photo on the last page, it looks like some of the aluminum has been machined off the bottom of your cylinder. I see more aluminum below the 498cm3 on my spare cylinder. I guess the previous owners of the bike were trying to adjust the compression ratio.

eBay listings for 84 cylinder and piston (won't ship outside of US):
http://cgi.ebay.com/ebaymotors/ws/eB...=270746892668&
http://cgi.ebay.com/ebaymotors/1984-...-/270717998716

By the way, this eBay seller also has a head for sale and it has the reed valve. Ivan's head shown in this thread is the only one I've seen that didn't have the reed valve. Which makes me wonder if it's really a XR500 head?

Photos of my spare cylinder:


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