125-200cc i stuffed up!

seized my 165 yesterday. after an hour of driving got 2 minutes down the road & she locked up. knew straight away so clutched it & rolled to a stop. piston had 32 hours on it so not too bad I guess. leaned rod off too much, ran too hot at cruising speed & game over. spark plug was white! sensitive these lectrons.

thought it felt a little underpowered but assumed it was cos ive been riding 300 lately. anyway ripped it apart last night(learnt to do a 2T top end in quick time!) & cylinder looks pretty good just gotta clean some piston residue off it. no scratches to lining from what I can see/feel so new slug & shel be good to go again. base gasket didn't even rip apart so just whacked new 125 top end back on & she fired first kick this morning(after putting rod back to where it was).

never seized a 2T before & kicking myself for fiddling too much, shoulda left well enough alone! what shits me the most is I drove for 2 hours & missed a good ride! ah well lesson learnt. BTW ms3 rod at 50mm was no good, 49mm seems about the best/safest

Bummer
good job you didn't sell the 125 top end

yeh I was thinking that last night after 8 stubbies swapping top ends over. on a positive note I can do a top end in a coupla hours tops now! I gotta learn to leave well enough alone

If you used the base gasket from the 165 which was .8mm ? it may not run as good as it could
With a stock motor 125 could run. .3mm gasket as long as squish 1mm
Check the squish
Did you use the 125 circlip ?

nah didnt check squish figured itd be sweet with big gasket. 125 piston had 1 circlip in & reused one from the 165 piston

"piston had 32 hours on it so not too bad" 32 is not much, glad you didnt have more damage though. good lesson tho..hope it lasts longer this time!

Man that sucks, was looking forward to riding your 165. Shame about seize but at least you know why it happend gutted about drive and loss of ride but it didnt happen 2 hours into the ride so lucky there i guess.
Good luck getting it sawted shawbagga

Bugger Shawry
That's no good at all bro.
White plug sounds really lean. Check your air boot too mate, mine was warped from the factory and that caused mine to lock up. Do a leak down test on the cylinder also to confirm no air leaks around the cylinder gaskets or bottom end seals.
You can try some diluted acid on a cotton bud on the bore to remove the piston residue and wash it thoroughly before putting it back together
Make sure to do the solder test for squish height to determine base gasket thickness. Machining tolerances vary a bit.
Hope you get it back together soon bro
Give me a bell if you need any more help.

cheers Damo I may well ring you to ask you dumb questions again! nah no airleaks mate just me being a cowboy tard & not understanding how much adjustments effect the carb/engine. went by measurements not turns. went a whole turn leaner to get measurement which was way too much in hindsight(1/4-1/2 max). was trying to get idle adjustment right. started(both my bikes first kick every time I shit you not its awesome! ) & idled sweet but didn't pre run it for feel. got all excited bout going for a ride & forgot to pay attention when I jumped on. anyway its done now & ive been edumacated the harsh way! will take it on board

just realised today when I was sorting new garage/man cave/husky workshop that I forgot to put the fricken seal in for the PV shaft(the one that sits in the cylinder where the shaft slides in through-bout 20mm diameter). was cleaning the 165 cylinder(depressing) & noticed the seal still in that cylinder, thought hey I don't remember the 125 cylinder having one of those, pulled pipe & PV cover & yep-im an idiot! no way to get that bad boy in there short of tearing her apart again from what I can see.

I was only planning on going to 40-50 hours tops justintendo so yeh bit short of where I was planning on pulling it down. im sure they could go 60-70 hours but im a big boy(240lbs+ kitted up) & don't cut that little engine much slack(its a sucker for punishment & makes me feel like a mx champion ). anyway sort of good thing cos now ill whack the spare 0.5mm base gasket I got in there & measure the squish properly for 125. kinda looking forward to riding it as a 125 again, wanna smash it on the mx track & embarrass me bro further on his 500!

all good juicypips ill order a new slug in a coupla weeks & slap her back together in 165 guise before you get here. have all the orings, gaskets ready to go just need the heart donor! when you heading over here again? who we ordering pistons off for 165s someone please?

scotchbrite pads & wd40 clean cylinders yas reckon or go with something harsher(get on the acid man!)?

Wallybeans the man for 165 kit, am over may 23-june19 will get a sim card n use it while im over there as i wont gave internet..

ill bet you get alot more than 50 outta her once you richen it back up!

the scotch brite work well unless you have some alum to remove from your bore

yeh bit of ally to remove, will try scotchbrite first then get some weak acid. what sort of acid we talking bout here?

thank you good sir!

err dumb question but can you damage the cross hatching/nikasil from scrubbing too hard with scotchbrite pads? use wd40 or parts cleaner type gear on it? will track down some muriatic acid if required also. was finally gonna get around to cleaning this cylinder up for 165 time again(yeah im slack but lifes busy!). getting over the 125 a bit now!

No, about the only thing that will scuff the cyl is a diamond hone... I guess besides a catastrophic failure

BTW, PB Blaster works way better than WD-40

I've never hurt a cylinder with a Scotch Brite pad. Don't push for too perfect in 2T carb tuning. The bike was never crisper and pulling harder, is the usual preface to.... and then she seized!

yes yes yes I agree norm. im a little OCD & like to fiddle(sometimes to the point of breaking stuff). lesson learnt. don't even touch the PJ anymore(3/4 from seated for 125 & 300, still good economy but plenty rich enough for endless deep sand we ride sometimes) & have just left the rod at where it was pre seizure for 125. when I re-165 it I will probably leave it there again as it was really running sweet till I 'tinkered'! 1/4-1/2 turn leaner at most

what the hell is pb blaster doug? parts cleaner type spray?

Just scrotch brite the bloody thing, it's only to deglaze the cylinder, you could spend bucks on flex hone to suit the cylinder size ...some people like'em some don't but l use one on my 360 and 250 cylinder and it's bloody easier than a pad!!

Lucky with the lean seizure, l ran my old KX from the track to the car park via road some 5 kms, had it pinned in 5th, backed of a touch and whacked it again only to perform a great long skid