Author Topic: Engine repair plan  (Read 2937 times)

spldart

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Engine repair plan
« on: October 26, 2013, 02:05:03 PM »
So....
A while back I posted about my 83 losing compression in the rear cylinder and iron filings in the case.... (front cyl measured great)
I now have a donor motor with a grenaded tranny.
How would you suggest I proceed?

Current plan.
1) take a spare starter and stuff it in the donor engine and use jumper cables to turn it over with the compression tester in each spark plug hole and see what I have to work with.
2) tear down donor rear jug assy and examine/clean the parts.
3) drop the motor on the bike and pull the rear jug assy off (taking lots of pics for you guys ;) )
4) put the cyl, piston, rings and head from the donor on the current bike.
5) check all the valves clearances. (is there a good cold clearance number I could go by?)
6) Profit (south park underpants gnome joke)

Do I bother with a hone when I keep a used piston, rings and cylinder together? My thought is not.
Would you proceed differently?
Oh! And a third oil change in the last 1500 miles since I bought it. Don't want crap getting up into the used parts and ending the motor again ;(

Jimustanguitar

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Re: Engine repair plan
« Reply #1 on: October 26, 2013, 02:49:34 PM »
You should always hone. The crosshatch helps keep you from burning oil, and re-seating the rings can help with compression.

Put anything from the spare engine that's shinier on the one you're going to use :)

Re-Vision

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Re: Engine repair plan
« Reply #2 on: October 26, 2013, 04:32:41 PM »
I'm not sure what a grenaded tranny will do to the engine case, I'd inspect both and choose the one that looks the best. I recently left you a message to contact me but never heard back, what I wanted to tell you was I'm in Azle TX and have an 82 bike in my driveway with an 83 engine. Person I bought it from said "engine was good but had a bad 3rd gear."  BDC

spldart

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Re: Engine repair plan
« Reply #3 on: October 26, 2013, 04:44:25 PM »
I'm not sure what a grenaded tranny will do to the engine case, I'd inspect both and choose the one that looks the best. I recently left you a message to contact me but never heard back, what I wanted to tell you was I'm in Azle TX and have an 82 bike in my driveway with an 83 engine. Person I bought it from said "engine was good but had a bad 3rd gear."  BDC

Life has gotten... overly complicated of late. Car accident daughter. Then the rental got hit and run'd. Then I got rear ended in the car fresh out of the body shop and injured. And while they were treating me they found heart disease and my life span got seriously shortened. Any-who. Sorry. I'm using my case and tranny and keeping my front cylinder untouched. Just transplanting the rear. The case of the current bike is VERY low mileage (all things considered). I just need to save it with the rear cylinder transplant :)
I'm also wondering how many gaskets are involved in this... and o-rings..
« Last Edit: October 26, 2013, 05:52:08 PM by spldart »

Rick G

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Re: Engine repair plan
« Reply #4 on: October 26, 2013, 07:36:39 PM »
Honing is mandatory anytime you separate  a cylinder and piston . If you do not , you will regret it!
Rick G
Go soothingly on the grease mud, as there in lurks the skid demon
'82.5 Yamaha XZ550 RJ  Vision,
'90 Suzuki VX800, 1990 Suzuki DR350.
'74  XL350   Honda , 77 XL350 Honda, 78 XL350 Honda, '82 XT 200 Yamaha, '67 Yamaha YG1TK, 80cc trail bike

spldart

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Re: Engine repair plan
« Reply #5 on: October 26, 2013, 09:35:52 PM »
Honing is mandatory anytime you separate  a cylinder and piston . If you do not , you will regret it!

Please confirm...
I will be keeping the union between piston, rings and cylinder.
That is Rear Piston A, Rear Cylinder A and Rear Rings A will come off motor A and get transplanted to Motor B's rear position.
Old trio goes to new case.... (even plan to maintain the ring gap orientation it comes off with)
 
I have done numerous various cycle motors in the past but they were rebuilt 'new' with half millimeter overbore pistons and fresh machined cylinders. I had my fav machine shop do all the machine work on most of the jobs.

I will buy a new hone if you guys say it's necessary to reseat the old rings even though I'm keeping piston, cylinder and rings together where they have lived for miles.

Thank you guys so much for your input 8~)

fret not

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Re: Engine repair plan
« Reply #6 on: October 27, 2013, 01:25:44 AM »
Take your cylinder to the machine shop and have them run a glaze breaker through it.  You just need to lightly scuff the walls of the cylinder so the rings will have some light abrasion to seat them when you put it back together.  Or buy a hone that you will probably not need again.  The cylinders are interchangeable front and rear, but the heads are apparently not as they have different part numbers.
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spldart

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Re: Engine repair plan
« Reply #7 on: October 27, 2013, 04:39:46 AM »
Take your cylinder to the machine shop and have them run a glaze breaker through it.  You just need to lightly scuff the walls of the cylinder so the rings will have some light abrasion to seat them when you put it back together.  Or buy a hone that you will probably not need again.  The cylinders are interchangeable front and rear, but the heads are apparently not as they have different part numbers.

Oh neat! The cylinders are interchangeable?! Are the pistons as well? This offers more options as I transplant parts! Shaweeet!

Rick G

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Re: Engine repair plan
« Reply #8 on: October 27, 2013, 05:57:40 PM »
Pay attention! If you separate  a piston from the bore to reinstall the piston and cylinder  on the same engine  or another engine, with the old rings OR new rings you MUST hone the cylinder  with a glaze breaker  hone . This type of hone only  removes a microscopic  amount of metal  , but creates a cross hatch  pattern in the bore  , that seats or reseats the rings (as the case may be) This pattern should be at 90 deg  to  the other pattern , to be most effective,  One pattern is lay-ed down on the forward stroke and the other on the return stroke.  A variable speed drill  at a very slow sped is best . Add a but of solvent of  an ample squirt of WD 40 to float the debris from the honing to the surface  and to lubricate the hone. Glaze breaking hones are not expensive  and you may find it useful  in the future. I
I bought a genuine Yamaha hone in 1957  and still use it  even though I had a couple of others.
Rick G
Go soothingly on the grease mud, as there in lurks the skid demon
'82.5 Yamaha XZ550 RJ  Vision,
'90 Suzuki VX800, 1990 Suzuki DR350.
'74  XL350   Honda , 77 XL350 Honda, 78 XL350 Honda, '82 XT 200 Yamaha, '67 Yamaha YG1TK, 80cc trail bike

spldart

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Re: Engine repair plan
« Reply #9 on: October 27, 2013, 06:37:26 PM »
ok.. dumbed down to much. But still appreciated. I do have some engine build experience ;) Oki doke... used parts will get a proper hone job before reinstall... Again... Pics forethcoming


spldart

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Re: Engine repair plan
« Reply #10 on: October 27, 2013, 06:40:21 PM »
And TONS of thanks :)

fret not

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Re: Engine repair plan
« Reply #11 on: October 28, 2013, 12:09:39 AM »
It helps to become familiar with the parts fiches at the various websites that sell Yamaha parts.  If a part number is the same then the parts are the same.  There are lots of parts this applies to, pistons for one.  Not all sites have all the information, as some has been deleted by Yamaha, usually meaning the parts are no longer available from the factory.  But the numbers are still a good method of identifying parts.  I really like Ron Ayers site as he has a reverse look up feature where you enter the part number and it comes up with all the applications, as year and model where used.  There are some parts that fit a LOT of other models and may well still be in current use.  For example, the swing arm pivot and bearings for the XZ are used on a bunch of other Yamahas and some are late models, so will be available from a dealer.
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fret not

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Re: Engine repair plan
« Reply #12 on: October 28, 2013, 12:44:08 AM »
I just visited the Ron Ayers site and the part number reverse look up feature is no longer there.  Sad to say. 
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

Prophet Of Doom

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Re: Engine repair plan
« Reply #13 on: October 28, 2013, 01:25:32 AM »
Fret Nut, you can do a reverse parts lookup simply by entering the part number in the SEARCH box on boats.net

This is me searching for a swingarm bearing using the number on the fiche

Rikugun

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Re: Engine repair plan
« Reply #14 on: October 28, 2013, 08:00:40 AM »
Pay attention! If you separate  a piston from the bore to reinstall the piston and cylinder  on the same engine  or another engine, with the old rings OR new rings you MUST hone the cylinder  with a glaze breaker  hone .

I worked with a guy who NEVER did this when replacing the piston in a bore it came from and he never had a come-back.  Note this applies to NO new parts and no machining. A typical scenario was replacing leaking base and head gaskets under warranty. The bores still had a crosshatch (as any serviceable top end will) therefore the cylinders were re-installed over the same piston/rings with no glaze breaking. The engine did not blow smoke prior to disassembly and the rings had long since seated. What bad voodoo has occurred during disassembly re-assembly to change that? As I recall he didn't even pay attention to where the (4 cycle) ring gaps were positioned. The horror!  :o  :D

I was taught, as I'm sure Rick was, that running a glaze breaker through the bore is a good practice. The correct drill RPM and stroke speed is used to produce the correct angle finish. This mechanic in question had no formal training so was blissfully unaware of the "rules".  ;) Eventually I brought it to his attention but he refused to change his ways stating it was a waste of time. His results backed up his flat rate mechanic inspired response and I had not a leg to stand on to argue with. You just can't argue with results.  ;D  I continued to use the flex stone like the good little rule follower I was trained to be. We both got the same results so who was right!?  :)
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

Jimustanguitar

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Re: Engine repair plan
« Reply #15 on: October 28, 2013, 08:13:42 AM »
Or buy a hone that you will probably not need again.

I thought that, and I've used the same hone dozens of times. Plus they're not that expensive anyway.

fret not

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Re: Engine repair plan
« Reply #16 on: October 29, 2013, 12:34:22 AM »
Yes, the glaze breaker hones are fairly inexpensive and can be useful if you are going to be taking motors apart.

Update on the Ron Ayers reverse look up feature, they responded that it should be up again next May or so.  In the mean time I am very pleased that PoD has brought to our attention the similar feature on the Boats.com site.
Retired, on the downhill slide. . . . . . . . still feels like going uphill!