Oh dear..... CT110 seized, running but not healthy

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Those new looking bolts on the end of the cam arent bigger than the originals are they? Maybe they're just catching on the cover. If not maybe try putting washer between the cam cover and the head at each bolt and see if the noise goes away, it'll leak a bit of oil, but thats a good thing as you'll know your top end is getting lubricated. Also check your timing marks are spot on, one tooth out it'll idle fine but start carrying on higher in the rev range.
 
timing is spot on
Bolts are originals

I've pulled the head off again, I really can't see anything wrong with how the cam sits, it doesn't even have bearings it just rides in the head. I've also turned the little black rubber wheel around, maybe it's pushing it to 1 side a bit

Did notice 2 things that look a little offputting though...
1st why does my exhaust valve look like this? i presume i'm running way lean on the pilot/needle? would somewhat make sense as the original rings were trashed and letting a lot of oil into the combustion chamber and likely i had to jet lean to compensate. Will rejet
P.S. I filled the head with WD40 30 minutes ago, it's still all there so no major leak. Would take hours to leak through
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The 2nd is this
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They're very small and I had to look fairly close and also get the light just right to see them. But that doesn't look right to me, vertical scratches? especially on a cylinder with <1 hour use.
Does this look like a botched rebore with too much clearance causing the piston to skew and scratch the barrel? that would explain the knocking sound

edit: there are absolutely no nicks on the top of the piston, valves/plug have not been contacting it
 
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from where i sit that is a really **** hone, and no I don't believe there sould be verticle scratches either. Then theres the matter of the pitting of the bore... Hmmm not a good look :(
 
as long as the sleve is around 3mm 2mm i would call low..
i would say use the bore if it is not the issue
to tell if its been slapping take the piston out and if there is no scratching on the center of the skirt then its most likley that
 
If I take the piston out won't that screw up the 'break in' since the rings will be at a different angle?
And don't you mean if there 'are' scratches on the skirt its piston slap?
 
might be a stupid question but are you sure the top ends getting oil? `What was the oil pump sprocket like? Did you make sure the timing chain is running over the oil pump sprocket? If it has worn teeth it'll pump at low revs and but slip when revved hard.
 
RangaBlitzFanga said:
If I take the piston out won't that screw up the 'break in' since the rings will be at a different angle?
And don't you mean if there 'are' scratches on the skirt its piston slap?
Click to expand...

nah, on the end and top of the skirt then slap..

maybe the bore is not round or to small... it wouldnt explain the knock though
 
Totally forgot to check the piston before reassembling it again

Good news though finally sorted the scratching problem. I believe it was the camchain being too tight and wanting to pull it into the casing. I also noticed the seal was worn on 1 side which reinforces that theory. I also applied liquid gasket in addition to the stock gasket to help give it a touch more clearance. Either way it's sorted it

I also polished the head while I was at it. Seems to have made it run smoother especially at constant rev, no more of that mysterious jolting at >60kph. I'm gonna put some distance on it and then recheck the piston/bore down the track

1 mysterious issue though is it sometimes seems really low on compression when cold. I can turn it over with 1 hand, when it heats up it regains compression. This problem was there before the initial seizure and I blamed it on worn rings, but that's surely not the case now. Any idea why? I left the head sitting with WD40 in it since last night, it was half gone almost 24 hours later. It didn't move at all after 1 hour so I highly doubt its a bent valve. Both valves also in spec at 0.05mm. Doesn't make sense
 
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Here's a thought regarding the knock/rattle.... Could it be the little end of the crankshaft? After all the original gudgeon pin is discoloured from heat buildup, maybe it expanded the hole causing a very slight clearance which of course the piston would slam harder against as more throttle is applied, which is exactly what happens
 
RangaBlitzFanga said:
Here's a thought regarding the knock/rattle.... Could it be the little end of the crankshaft? After all the original gudgeon pin is discoloured from heat buildup, maybe it expanded the hole causing a very slight clearance which of course the piston would slam harder against as more throttle is applied, which is exactly what happens
Click to expand...
ARE YOU NUTS?
of cause you have to replace the gudeon pin it would have got as hot as the piston.....
pull apart and inspect and hope that was it...
(if it was it then before you take the piston off feel to see if there is any slop in there)
 
Yes I replaced the gudgeon pin, god I hate engine part names

Not crankshaft, conrod. The little end of the conrod could have expanded? making the new gudgeon pin slightly smaller
 
RangaBlitzFanga said:
Yes I replaced the gudgeon pin, god I hate engine part names

Not crankshaft, conrod. The little end of the conrod could have expanded? making the new gudgeon pin slightly smaller
Click to expand...

when you have the bore off, see if there is any play..also rotate the crank and make sure those bearings arnt screwed... (the crank bearings)
 
checked them ages ago. There's no in/out movement on the crank, slight side to side movement (video posted earlier in the thread showing how much). But I didn't check gudgeon pin clearance
 
RangaBlitzFanga said:
checked them ages ago. There's no in/out movement on the crank, slight side to side movement (video posted earlier in the thread showing how much). But I didn't check gudgeon pin clearance
Click to expand...

check it, you should have anyway.. well now you will remember whenever you pull the engine down lol
 
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