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Author Topic: First time top end rebuild  (Read 6545 times)

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Offline BLACKBEARD

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First time top end rebuild
« on: July 28, 2013, 03:10:28 AM »
First of all I'm new here. But i just recently got back into the dirt after a lengthy stint with the whole streetbike scene. I got myself a 03 kx100. The cylinder,piston and head will need replaced. I've always done repairs and maintenance on mine and my fellow riders in the past, but never rebuilt a whole top end. I've got the head and cylinder off. What should I be looking for in this process? I guess I should drain the fluids and try to flush the bottom end thorally? Any info at All would be a Big help. Thanks in advance.
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Offline sandblaster

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Re: First time top end rebuild
« Reply #1 on: July 28, 2013, 01:45:05 PM »
Hello BLACKBEARD.
Welcome to the site.
There is a ton of great info and guys on this site.
One of the first things I would recommend you do is buy a Clymer Service manual.
There is more documented info in there then you could write about in a year, specs, pics, tolerances, ect.

Quote from: BLACKBEARD on July 28, 2013, 03:10:28 AM
What should I be looking for in this process? I guess I should drain the fluids and try to flush the bottom end thorally?

That certainly wouldn't hurt.
Since you have the top end off I would measure your connecting rod to crank side play with a feeler gauge.
From there it would all depend on what you find...
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Motorrad

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Re: First time top end rebuild
« Reply #2 on: July 28, 2013, 03:59:45 PM »
Leakedown test BEFORE dissasembly.     
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Offline BLACKBEARD

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Re: First time top end rebuild
« Reply #3 on: July 28, 2013, 04:16:01 PM »
I know nothing about a leakdown test to begin with,or the results I'm testing for. Do I need a tool for that? as far as the disassembly I already have the cylinder head and piston off.
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Offline sandblaster

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Re: First time top end rebuild
« Reply #4 on: July 28, 2013, 04:27:34 PM »
Too late for a leak down.... :lol:
Then again you could reassemble it and do a leak down test...
However, If you measure the rod to crank clearance that will tell us if the crank needs to be replaced.
If it does need to be replaced, then it's time to replace those leaky seals anyway...
« Last Edit: July 28, 2013, 04:34:30 PM by sandblaster »
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline BLACKBEARD

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Re: First time top end rebuild
« Reply #5 on: July 29, 2013, 03:36:03 AM »
Ok rod, crank ,bearings And seals seem to be intact. I think the cylinder is suspect. There is a small groove in a place where the P.O. Replaced one of the studs in the cylinder with an oversized stud. Could I get around buying a new cylinder? Or would it just be more problems down the road? Once again thanks for all and any help.
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Offline sandblaster

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Re: First time top end rebuild
« Reply #6 on: July 29, 2013, 04:10:16 AM »
You can't tell by looking at the crank or seals or feeling them to know if they are good.
The seals can look brand new and leak like a sieve causing a lean burn condition which can smoke your freshly rebuilt engine  :-o
Your crank may "feel" and "Look" good but be completely out of specs which can fly apart and blow your cases and ruin your new top end  :-o
The crank is easy to check with a 3 dollar feeler gauge and 1 minute of time.
Your top end can most likely be repaired and plated but to be sure, send some pics to the plating companies.
You can also get your cylinder sleeved rather then plated.
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline BLACKBEARD

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Re: First time top end rebuild
« Reply #7 on: July 29, 2013, 11:21:35 AM »
Gonna get me a feeler gauge and check the rod to crank play. What measurement or ball park should I be looking for? Is this where manual starts to come into play? Another thing Sandblaster, you got a way of putting things that I don't know, that Make it easy to grasp on. Thanks
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Offline sandblaster

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Re: First time top end rebuild
« Reply #8 on: July 29, 2013, 12:34:44 PM »
Quote from: BLACKBEARD on July 29, 2013, 11:21:35 AM
What measurement or ball park should I be looking for? Is this where manual starts to come into play?

Yep..
Connecting Rod Big End Side Clearance
Standard: 0.40 ∼ 0.50 mm (0.016 ∼ 0.20 in.)
Service Limit: 0.7 mm (0.028 in.)
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Motorrad

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Re: First time top end rebuild
« Reply #9 on: July 29, 2013, 03:53:07 PM »
sandblaster is the man.    knows his sheet. listen to him.    I do...   got me to where I am today.
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Offline sandblaster

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Re: First time top end rebuild
« Reply #10 on: July 29, 2013, 04:27:56 PM »
Don't believe everything you hear...  :wink:
I learned everything good I know about motorcycles from Motorrad (Yodarrad).
Listen to him young Padawan  8-)
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline BLACKBEARD

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Re: First time top end rebuild
« Reply #11 on: July 29, 2013, 11:59:08 PM »
That's good information. I will be doing that tonight,I work full time and I only get a few hours in the evening to "play with my toys" as the wifey says. I would like to do as much as I can without going to a shop. Thanks
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Motorrad

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Re: First time top end rebuild
« Reply #12 on: July 30, 2013, 01:05:03 AM »
Quote from: BLACKBEARD on July 29, 2013, 11:59:08 PM
That's good information. I will be doing that tonight,I work full time and I only get a few hours in the evening to "play with my toys" as the wifey says. I would like to do as much as I can without going to a shop. Thanks

Im watching this thread.      Mr Blaster has a good handle on it.     If somthing is missed. Ill jump in.

Top ends are easy. 

get us some pics of that "fixed" head stud, and "score mark".     
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