honda cg - blew piston / replace engine

[Smiley]

hi i blew my piston on my honda cg br (1986) a few weeks ago! i excepted this as wear and tear! so i replaced it and cleaned up my engine but in under 10miles it blew up again! it only blew a hole in the top of my piston! the sides and bottom looks intact! what could be causing this?

but also if the problem cannot be fixed would it be worth replacing the engine? and what would fit bigger than a 125 in a honda cg brazil frame (1986)?
i have heard that you can put a cb250rs engine into it but i have not heard of anyone attually doing this! and the problems which you would occur!

Cheers
Smiley

[BigGeeking]

to blow a hole in a piston that fast fook man

must be super lean
____________________
Bendy "Flip front. I can filter down the M4 while shoving a Twix in my face."
honda CG 125 2001 SOLD-- current Bandit 400--SOLD. current SV650s 2000
MOD 1 ON 20/7/2011**passed** MOD 2 ON 17/10/2011***passed***,,

[BigGeeking]

what plug have you got in and what is the plug like if its not melted

____________________
Bendy "Flip front. I can filter down the M4 while shoving a Twix in my face."
honda CG 125 2001 SOLD-- current Bandit 400--SOLD. current SV650s 2000
MOD 1 ON 20/7/2011**passed** MOD 2 ON 17/10/2011***passed***,,

[Smiley]

im not sure on the plug! but the plug was fine it was mainly melted to the valves (made a right good job of them!). the plug hasnt been changed since i bought the bike and it was riding fine for months! the only thing which has been changed mech is the tappit clearance, but that was done to the haynes manual! (that was done about a month and a half before blowing up). the piston its self looks like its blown down wards due to how the hole is coned!

[Smiley]

and 2 answer your question im 16 stone on a honda cg plodder!!!
it is comical riding with my family while there on there sports bikes and massive tourers!

[BigGeeking]

[Smiley]

i love doing 40 over speed bumps you always get a back end kick from the springs being compressed permantly! so much fun! plus the cg's are awesome for fields! me and my cousins crossing a field
-honda cg
-honda dt - crosser
-yamaha yzr - sports bike
watching them struggle was so funny! as i cruise by! plus the crosser fell over! not because of the crosser due to the rider hes jst cr*p

[iooi]

[Smiley]

well ive been have a chat with my mechanic n he says theres a possibility that its the big ends (warped) but i carn't understand if its that how the piston haas blown from the top downwards! but it ran fine 4 the 1st 4 months!!! with no problem!!!

[unitynotsocri...]

I think IOOI is right about the valve timing gear,make sure the head and barrel havnt been swapped for some china crap cd clone,or ,the timing gear/pushrods might have been swapped.The big ends would have to be so warped that the engine woul'nt turn to cause that amount of damage.Although the 86 cg br model uses points instead of cdi I doubt that timing/points misadjustment could do that amount of damage.
____________________
nearly a normal tax paying tosser.......with ferrileness suzi100,cg125,cb125scb100n,cb175,cd100,cj250t,kh250,c15,125 bantam,super 6,rickman gs750,xt500,250rs,dt175,lifan125,dolomite1850,metro,Morris220ld,morrisfg,leyland princess,range rover,corsa,vw camper .now struggling with legs. MORE ORDER = MORE CHAOS

[N cee thirty]

i'd fuck the points engine off and get a cdi engine and new loom

they all fit in the same
____________________
'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[unitynotsocri...]

Thats the best thing to do except it won't be a 'classic' anymore and you can't adjust the timing for different riding conditions,i.e.bit like me, retarded round town.
____________________
nearly a normal tax paying tosser.......with ferrileness suzi100,cg125,cb125scb100n,cb175,cd100,cj250t,kh250,c15,125 bantam,super 6,rickman gs750,xt500,250rs,dt175,lifan125,dolomite1850,metro,Morris220ld,morrisfg,leyland princess,range rover,corsa,vw camper .now struggling with legs. MORE ORDER = MORE CHAOS