Newb doing the top end myself, PLEASE HELP! Lots of pics!


55 replies to this topic
  • Aka.Goose

Posted May 14, 2009 - 02:55 PM

#21

Here's some more pics...The side clearance on the top and second ring were a tight fit .03mm (standard is .03-.065), the side clearance on the oil rings were ridiculous >1mm (no standard, maybe this isn't a measurement normally taken?), the end gaps on all rings were way off, the top was .65 (standard is .20-.30), 2nd was 1.7 (standard .35-.50), and oil rings were 1.4 and 1.7 (standard .20-.50)...So yes the rings were toast especially the oil rings...The only other issue I can see is the crankshaft small end free play is high at about 1.5mm (standard is .4-1.0 with a 2.0 limit) and if the runout limit is the ability of the shaft to move back and forth as if from pushing and pulling from where the flywheel goes, then it must be over, not sure how to measure this exactly but there is a tiny bit of movement, I'd guess somewhere between .2 and .5mm, but the limit is only .05 (which means that it basically shouldn't move at all right?)...And the side of the cylinder wall that the piston was slapping the head does have some very tiny scratches...
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  • TIG88

Posted May 14, 2009 - 03:52 PM

#22

When I opened my 03 about 2 months ago, the factory crosshatching was obvious. I mean my jug looked new. I see no crosshatching on your cylinder wall, except for the very top. Its almost like the Nikasil is worn right off.

You will need a new jug too, and probably a new crank, unless you can rebuild it.

  • grayracer513

Posted May 14, 2009 - 04:01 PM

#23

On page 2-7, there are the specs for crank clearances. Clearance in the rod bearing itself is measured by the rocking measurement, 'F'. Be sure that the rod does not move along 'D' during this measurement. Before you ask (you might know this) the hot spot on the crank belongs there.

Looking at the pictures, there is quite a bit of metal transferred onto the front side of the cylinder wall, and the picture of the exhaust side of the piston shows a lot of wear. That, I would guess, is the source of your trouble. Otherwise, the cylinder looks good; no deep scratches.

Hone the cylinder:

http://www.thumperta...759#post4380759

...then trial fit a new piston and check the clearance. I'll get back to this later with some more recommendations, I'm a little pressed at the moment.

  • grayracer513

Posted May 14, 2009 - 07:29 PM

#24

On the valves...

Obviously, at something like $80 each, you don't want to put them on your list, but just as obviously, there's a major risk involved in not doing so. Here's what I would do.

Remove the valves, or, since it requires a spring compressor, take it to a good M/C machine shop and have it done. Be sure that during the disassembly all parts are labeled in some way so that all of the components (lifters, shims, valves) can be returned to their original locations.

You are going to discard the right side outer, so don't bother with that one, but check the other two intakes by chucking them in a lathe or a valve grinder and running a dial indicator on their faces to see if they are bent. Don't tolerate more than .001" wobble.

  • matt4x4

Posted May 15, 2009 - 03:52 AM

#25

To remove the valves - you can do it the crude way without needing a valve spring compressor (It works surprisingly well):
http://www.thumperta...ad.php?t=769655

By looking at it - I really don't think you need a new jug - do as Grey suggests and clean it up - pistons rarely wear through nikasil since the piston material is much softer.
If your crank moves excessively by pushing and pulling on it - that means there is wear on the crank bearings themselves or the chases they run in allowing the inner chase to have more side to side play than allowed, this will also add to the up/down play of your crank since your gaps between (chase-bearing-chase) are increased.
This is not measured as part of the big end rod play - they are measured completely separate from one another.
The con rod should move side to side within it's allowed specs but should not lift up/down at all, if it does, it can also contribute to piston touching head.

All in all - measure EVERYTHING very carefully and accurately so you know what needs to be replaced to completely eliminate your piston to head issue and give you a reliable machine you don't need to worry about every time you ride.

If it means splitting the cases to do so - it's a pretty easy job and you don't have to start worrying!

  • Aka.Goose

Posted June 01, 2009 - 02:54 PM

#26

Alright, I had to put in some overtime, but the new motor is now on it's way...
What I plan on doing is this:
I'm going to open up the new motor, check to see how much difference there is compared to this one in the crankshaft movement...If this one does actually have too much play, I'm going to take it out and bring it to the shop to have the bearings replaced...I'll also have the cylinder honed, and bring the head in to have the valves and springs replaced...Then I'm going to put the piston and rings from the new motor into this one, close it up and hope it runs well...I'll break it in with a mellow day at the Elsinore vet track...Then tear it all down again...Put the new motor in, using a hi-comp CP piston, and swap out the clutch, water pump, oil filter, etc...Then I'll have a ready to go, broken in, back-up motor that hopefully won't be needed very soon...And cross my fingers the new motor and tranny work out well...

  • grayracer513

Posted June 01, 2009 - 03:32 PM

#27

...Then I'm going to put the piston and rings from the new motor into this one, close it up and hope it runs well...

If you do this, be sure you use the piston, rings AND CYLINDER all together as a set. DO NOT run a used piston and/or rings in a different cylinder than the one they ran in before.

  • Aka.Goose

Posted June 01, 2009 - 10:01 PM

#28

Gray, this is a 0 hour brand new motor I'd be taking the piston out of in order to use in the honed cylinder (which will end up being the backup motor), then using the CP piston in the new cylinder...
I realize getting one running, then swapping it out for a new one is a bit unconventional, but seems like a good idea...I like the thought of having a broken in, ready to run motor at all times, while able to take my time fixing whatever issue the downed motor has...
Seem like a good plan?

  • rufusz

Posted June 02, 2009 - 02:06 AM

#29

Hone the cylinder:

http://www.thumperta...759#post4380759


I've found several flexhone products on ebay with grits : 180,240,320,480. The finer the better? Or what should be used and when?

  • grayracer513

Posted June 02, 2009 - 09:56 AM

#30

Gray, this is a 0 hour brand new motor I'd be taking the piston out of in order to use in the honed cylinder (which will end up being the backup motor),

That's different. In that situation, you could go ahead and use it, and it should be fine.

I've found several flexhone products on ebay with grits : 180,240,320,480. The finer the better? Or what should be used and when?

240 would be my first choice. 180 2nd, 320 3rd. Note in the post on honing that you run the tool very briefly.

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  • Aka.Goose

Posted June 02, 2009 - 10:41 PM

#31

Well...Slight change of plans...I'm just going to use the new motor as is (while transferring my carb, clutch, waterpump)...
I threw down some money on 24mm Applied factory clamps with the Scott's submount plate today...Ordering new tires, chain, sprockets tomorrow...All my overtime dough is used up, so the downed motor will have to wait a bit...Especially since I plan on also getting a Scotts damper, and suspension work...
:crazy:

  • NortonMoto

Posted June 03, 2009 - 12:19 AM

#32

What oil did you use also what brand of gas did you run in bike before rebuild ?

  • Aka.Goose

Posted June 03, 2009 - 12:30 AM

#33

Amsoil 10-40w
Chevron supreme...please don't tell me I should be running race gas, I have way too many friends with long running engines on 91...
and I'm not racing...maybe if I were I'd consider 50/50...

  • Beaz

Posted June 04, 2009 - 05:56 PM

#34

How many hours were on the motor?

  • Aka.Goose

Posted June 04, 2009 - 06:01 PM

#35

How many hours were on the motor?


There was only about 20 hours on the motor...

  • NortonMoto

Posted June 04, 2009 - 11:53 PM

#36

I'm surprised to see so much build up in motor,I use amsoil and would hope to see my motor cleaner And I have 75 hours on mine.

  • Aka.Goose

Posted June 04, 2009 - 11:55 PM

#37

Transition day...waiting for parts...so hard to see the bike like this:
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  • Aka.Goose

Posted June 04, 2009 - 11:57 PM

#38

Also, Ive been stalling pulling out the clutch...I hate using the generic clutch holding tool on it for fear of damaging teeth...Any tips/tricks???

  • matt4x4

Posted June 05, 2009 - 04:11 AM

#39

Never ever used a clutch tool in my life, a penny between the gears and an impact gun is all I use, you can bend a lot of pennies before equaling the cost of a clutch tool.

On small bikes, you can usually just hold the clutch in a gloved hand to spin off the nut.

  • grayracer513

Posted June 05, 2009 - 06:26 AM

#40

I'm surprised to see so much build up in motor,I use amsoil and would hope to see my motor cleaner And I have 75 hours on mine.

His engine was burning oil due to the piston damage. That's why the build up.

Also, Ive been stalling pulling out the clutch...I hate using the generic clutch holding tool on it for fear of damaging teeth...Any tips/tricks???

An impact wrench. I almost never use anything other than my hands (with rags or gloves) to hold, but the cut boss can be a little tricky. Either pad the jaws of a big pair of pliers and reach in and grab one side of it like it was a coffee can, or stack up some of the clutch plates and hold pressure on them with pliers, so that the basket holds the boss.

If you're going to wedge gears as Matt suggests, use wood, not metal, whenever possible.





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