NorazDad

NorazDad
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A lovely Sunday ride ended in disaster when I blew my engine. I took the engine out and proceeded to dismantle the top end. When I got to the core, I found I had holed a piston and snapped the head off an exhaust valve and cracked the cylinder sleeve. I found the pieces in the crank case.
So I started making a list: new valves, mikes new piston, ring and jug kit, valve stem seals, gaskets, cam chain, cam chain guide, etc.
So, I'm fixing to clean up the combustion chamber, lap the valves, etc. what solvent do you guys recommend, oven cleaner, paint stripper, what?
My next big question right now is, will I need to hone the cylinders before I install the new pistons and rings?
I've got pics to add to this thread which I will add from my main computer.
I've read much of everything posted on rebuilding the top end, but I am open to any early advice and I hope some of you gurus will chime in along the way.
Thanks in advance.
 
HooBoy, 'sploded engine!

Add to yer list:

Split the cases and sterilize in there.
Of course, the sump and side filters, oil pump.
Check the conrod ends for damage.
Check the crank, bearings and for runout...
 
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IMG_0143.JPG
Well, thanks 2M for the nudge to open the sump and oil filter
Here's what spilled out
And here is the devastation
I believe parts is parts and the bottom end now relieved of effluence will be fine
Answer to the honing question is no need. There's a fine cross hatch on the cylinder sleeves
As for carbon cleaning...I'm going to try everything till it's clean and if I'm still not satisfied, I'll get someone to soda or vapor blast it
I think another engine would be nice, but I'll try to fix the one I got...but I'll keep my eyes open for a spare
I know I have my work cut out for me, but I have all of you to help out
And if you can do it, so can I
Thanks for the input
Let's commence with the rebuild
 
Have a critical look at the exhaust valve guide.

If you're happy with the conrod small ends, and their "rocking" limit, you could try an impromptu runout test. You'll want the clutch basket removed, to isolate and see the primary drive gear. Grab the conrod tops and go up/down, rotating the crank. Feel/listen for rough bearings. Watch the crank ends, primary and rotor, looking for runout. Assuming, of course, your eyecrometers are calibrated.

GggGary has a really good video of end runout on a twisted crank...
 
I know you stated no honing, but I would have a machine shop double check the new pistons to bore. Check the end gap on the new rings too. With the amount of poorly manufactured crap quality that I have come across with Mikes stuff, I would double check.

I got my latest pistons, rings, clips and pins from CruzinImage on ebay for $100 total for the set. They look and feel better than the Mike's pistons I have. Very happy with them. A couple people on here have many miles on those pistons too.


.....
 
Thanks for the input, guys. I'll look for the run out test video. RG, you are absolutely right. Timing is everything. I think the register pin on the cam shaft had fallen out during a stressful time installing the Pamco and e-Advance. At some point I over torqued the advance rod and the nut on the sensor end snapped off which caused me to have to have to replace the rod. I could have missed the register pin on replacement which caused the timing to be way off...even though it ran great until it exploded. I don't know how that worked out.
I will have the pistons and jugs looked at. As to Mike's quality, I'm not getting on that bandwagon. Everything looks good so far and I will proceed with the parts I have purchased.
One step at a time.
 
I got my latest pistons, rings, clips and pins from CruzinImage on ebay for $100 total for the set. They look and feel better than the Mike's pistons I have. Very happy with them. A couple people on here have many miles on those pistons too.
I got my rings from him. Half the typical price and nothing but good reviews that I could find. The spacer ring looks possibly slightly less robust than stock, but it seems to be working fine.
 
Paint stripper works really well for carbon and old gasket removal. It usually requires several applications. After the carbon removal, a little chrome polish will have the combustion chambers looking like new .....

CleanHead.jpg
 
Thanks for the response 5T
Valves lapped and installed
Not happy with the gap in the collets
Polished up nicely
Lapping was fun
Test was done and I passed
On to the pistons and rings
Notice change in cam chain tensioner
Thanks all
 

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Well, I cleaned and checked the bottom end as best I could. I did not flush with kerosene, but I may change my oil a few times much sooner than normal.
I snaked the new cam chain and then proceeded to do the pistons.
I ringed the pistons. I thought the oil rings and the expansion ring would never fit together in that groove...but then it did. So I did the other one and it went together fine. I arranged the gaps, dropped them in the jug, connected them to the arms and then on to the cam. So I used the peen method as described by many here and my peens look better than the factory. Needed to take one side of the bearings off to get the chain on and then started to button her up and took a quick look at the manual and realized that I had the cam in backward. So, off with the bearings. Slip the cam out under the chain. Get it all back to TDC and the marks facing up and I got it in without having to break my link. I did have to sort of move tooth by tooth to get the orientation correct on the cam and remain at TDC. Tricky and slow, but I'm sure you've all done it. So the head is back together. Need to torque it and install the REGISTER PIN, advance rod...etc, clean up the frame a bit, polish the exhausts, drop her back into the frame, reconnect all of the components and pump some oil in it and start her up.
Wish me luck. I will report soon.
 
So, I have a speculation as to what may have happened to make me blow a piston and snap a valve. The advance locating pin was nowhere to be found...not that I was looking for it when I did the tear down. It is possible that the pin slipped out and stopped registering and made the timing go why out of whack. That is despite the fact that the bike was running great prior to the break down. So I don't really know. But, I did have to trim the Pamco timing plate to get the bike to run and to time it where it showed full advance at 3500 rpms or so. Now my timing mark was a bit of a guess/mystery due to the PMA lacking true connection or indicator between the crank and the cam, etc. with a woodruff key. I never did the wheel test or the piston stop thing. But I know where TDC is now and I know how to feel, hear it and see it so that should no longer be a problem.
However, moving forward, I did make a new advance locating pin out of a drill bit and I made sure to locktite it and made sure the brass bushing for the advance rod was directly under it so it wouldn't fall through the hole. I was under the impression that the pin was somewhat tapered so it would stay in the hole, but when I tried the one I bought it fell right through. So I made a new one and I think it will be happy in its new position.
Lastly, I am going to kick pump some oil through the system and then drain it before I put it back in the bike. Hopefully it will rinse out any unwanted bits of debris. OK, That's it for now. It all looks like it should be a fine running bike tomorrow.
Peace All!
 
You can guess pretty well for TDC but you can't guess for the ignition timing mark. It's about 15° before TDC. The full advance is determined by your advance unit. When new, it is made to advance the timing exactly 25°, but as it wears and loosens up, that amount grows. So, even if you have the idle timing correctly set, you can still be over advancing. You need a second timing mark, one for full advance, to check it against.
 
You would be wise to take the time now, to find the exact TDC, This is not the time to be in a rush to get the engine back together.
I'm not sure if you mean you have a woodruff or you don't. Why would you not use a woodruff key??
 
:twocents: A timing problem usually holes a piston, but doesn't bust a valve. My take is that the exhaust valve hung open, the piston hammered on it til it broke the head off, that holed the piston. You got by pretty easy, I have sure seen a lot worse damage when a valve let go on an XS But Yes the con rod and small end get beat pretty hard as it comes to a halt.
 
You can guess pretty well for TDC but you can't guess for the ignition timing mark. It's about 15° before TDC. The full advance is determined by your advance unit. When new, it is made to advance the timing exactly 25°, but as it wears and loosens up, that amount grows. So, even if you have the idle timing correctly set, you can still be over advancing. You need a second timing mark, one for full advance, to check it against.
I have Hugh's PMA and the sticker that marks the timing. The real problem is marking the rotor so it clearly and accurately displays the timing mark so it can be read. I will use a grease pen and hope it is accurate enough.
 
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