Please help me!!!

gerbal · L Plate Warrior Joined: 19 May 2004 Karma :

right where to start......
right i have a old honda mt5 and i've owned it for like 3 year and its been fine but a about a year a it lost compression so it was rebored form 49cc to 50cc and it was fine but that night i was riding it and it locked up doing a bout 35mph.....complete lock and it ground to a halt but it restarted and run fine me home......so i was very weary of it afterwards......and the other day i was riding it up a hill doing about 30 and it locked again and mate nearly crashed right into the back of me so my question is this what the hell is going on with my bike??? i am now scared to ride it on the road incase it locks and i get hit .... can i be fixed cheaply as i've just spent 200 quid on it and its only worth about 200 or would it be cheaper to sell it to my mate as a off roader and buy a cheap 125 ???? many thanks James

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

First, are you sure there's enough 2 stroke getting to it?

After that I'd be taking the head off and checking that the bore/piston is ok.

Had a similar thing on our minimoto when we realised we were using the wrong ratio of 2 stroke.

Robby · Dirty Old Man Joined: 16 May 2002 Karma :

When you say you were doing 35 that night - do you mean you were doing 35 directly after the rebuild with no running in.

If its just been rebored and its on a on oversized piston, possibly a pattern one, it needs some running in.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

You weren't using a pattern piston were you? If so throw it away and buy an original Honda one.

What has probably happened is the bike has seized as the engine has warmed up and the piston has expanded. Piston are not round, being slightly oval to take account of the rate of expansion in different directions.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

Ninja · Caption Abuser Joined: 22 Apr 2004 Karma :

what keith said - sounds like it's simply overheated - a heat seizure will still leave marks on the rings/ bores and will need 'cleaning' up at the very least.

If it's having a tendency to 'nip-up' I'd suggest the motor may in fact be running on the lean side.

Before you go checking mixture and settings etc make sure you've simply not run out of oil?
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James
4 wheels transport the Body ... 2 wheels transport the SOUL