Newb doing the top end myself, PLEASE HELP! Lots of pics!
Posted May 14, 2009 - 02:55 PM
Posted May 14, 2009 - 03:52 PM
You will need a new jug too, and probably a new crank, unless you can rebuild it.
Posted May 14, 2009 - 04:01 PM
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:
...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.
Posted May 14, 2009 - 07:29 PM
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.
Posted May 15, 2009 - 03:52 AM
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!
Posted June 01, 2009 - 02:54 PM
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...
Posted June 01, 2009 - 03:32 PM
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.
...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...
Posted June 01, 2009 - 10:01 PM
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?
Posted June 02, 2009 - 09:56 AM
That's different. In that situation, you could go ahead and use it, and it should be fine.
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),
240 would be my first choice. 180 2nd, 320 3rd. Note in the post on honing that you run the tool very briefly.
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?
Posted June 02, 2009 - 10:41 PM
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...
Posted June 03, 2009 - 12:19 AM
Posted June 03, 2009 - 12:30 AM
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...
Posted June 04, 2009 - 06:01 PM
How many hours were on the motor?
There was only about 20 hours on the motor...
Posted June 04, 2009 - 11:53 PM
Posted June 04, 2009 - 11:55 PM
Posted June 04, 2009 - 11:57 PM
Posted June 05, 2009 - 04:11 AM
On small bikes, you can usually just hold the clutch in a gloved hand to spin off the nut.
Posted June 05, 2009 - 06:26 AM
His engine was burning oil due to the piston damage. That's why the build up.
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.
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.
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???
If you're going to wedge gears as Matt suggests, use wood, not metal, whenever possible.
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