bike locks when in motion, able to change gears with clutch

[abbey8k]

today on my way home my xt 125-16 which is a copy of a Honda cg 125 died whilest in gear.
after pulling over I tried to kick start the bike
(because the electric start wouldn't work)
only to find that i couldnt and that it was solid and would not kick down.
i tried to get it going by bumping it down a hill but the second i put the bike into any gear (i tried them all)
the back wheel would instantly lock.

anybody got a rough idea without gong into to much detail on what the problem could be.
am i right on thinking that its a gearbox problem maybe it could be the crankshaft

thanks chris

[N cee thirty]

sounds like it could have seized

is there any oil in it ?

did it make any noise when you stopped
____________________
'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

[stinkwheel]

Yes. sounds like a seized engine. The kickstart is attached to the engine. If the kickstart is solid in neutral, it's the engine rather than the gearbox.

Could be one of a variety or causes, all of which are going to require a fair bit of repairing (or may be beyond economic repair compared to the price of a second hand engine that runs).

First off, drain the oil through an old pair of tights. See if there was enough oil in it and if any big lumps of engine come out with the oil. Once the oil has settled, look for a sheen of metallic particles on the surface

Next I'd be taking off the engine side cover and trying to turn the crank directly with a spanner. If it turns, there may be something up with the starter mechanism

If it's still locked solid, remove the rocker cover and inspect the valvegear and rocker assembly (looking for a dropped valve or anything broken/detached such as a snapped rocker, a bent pushrod, a loose nut jammed under a rocker and so-on).

Those parts are simple and quick. If you find nothing and it's still locked solid, you'll need to take the head off and see if the piston has hit any valves (this would usually be pretty obvious due to severe mangling of said parts).

If that checks out ok, try turning the crank again anyway. If it still doesn't turn, whip off the barrel and check to see if there is any scoring on the barrel or piston indicating a heat-seizure (where the piston had expanded too far and gripped the inside of the barrel). It is possible the barrel wont come off if the piston is seized in it. A good soaking in hot oil followed by hammering a block of wood on top of it will sometimes free it off.

If the barrel looks ok and the crank still wont turn, the crank is screwed. Most likely main bearings or big-end.

Could be a combination of several of those things.

A 4-stroke engine seizure is usually catastrophic in nature and trashes several componants in a fraction of a second so don't get your hopes up and be pleasantly surprised if it's something simple like a thrown pushrod.

You tend to find something along the lines of this:
https://i48.photobucket.com/albums/f216/stinkwheel/305/Image074.jpg
https://i48.photobucket.com/albums/f216/stinkwheel/305/Image076.jpg
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[abbey8k]

it does have oil in the bike. the level is full.
i've got my old boy picking the engine up today for a closer inspection as he is a mechanic, so i will keep you all posted.

thanks for the help

thanks for the info stinkwheel, lets hope its not as surveyor as that