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Splitting A Monty 348 Eng


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all stripped,heres the reason why below:( ,thats 1 down 3 to go,got 4 engines hopeing to make 2 good ones out of the 4 for mine and my mates,got the gasket set on order(millers)ive never had any trouble with monty frames maybe I dont ride them as hard as you lot :lol: any ideas on why the crank went?

BIKEPICS005.jpg

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That looks nice :lol:

The frame used to snap at the front, I think it was only on the early models though as I think they stiffenered up the later ones. I had one of the last ones made (got it cheap when the 349's appeared) it was the best wheelie bike ever but the original opaque rear mudguards were an absolute arm & a leg to replace.

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any ideas on why the crank went?

BIKEPICS005.jpg

What do the magneto cover dowel holes and kickstart shaft look like? If they are bent out of shape it might have been a crash into a solid object that did it.

Otherwise I can't see the fracture surface well enough in the photo to see if it was fatigue failure or not.

Typically 348 frames crack just under the steering head if the bike is ridden very heavily. There was a factory recall that added gussets at the steering head to the early model 348s. Later ones had the gusseting from new. I have three 348 frames and none of them show evidence of cracking or crack repair work there. Apart from that issue I reckon they are a great frame.

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I had an R reg (i think) 348 and it snapped in half just at the top of a step, they snapped at the back of the steering head and the effect was that only the clutch and throttle cable were left holding the front of the bike to the back - as a result the throttle cable stretched putting the bike onto full throttle while the sump crashed into the ground and you were flung over the bars which were by this time on the ground and into the front wheel. - looking back it must have been quite funny but it wasnt at the time.

once you had managed to pull the plug cap off, and had several thousend volts dashing up your arm, the next problem was how to get two halves of a bike home.

I remember it happened on saturday afternoon and i had to take the two halves to my mates house - we chucked it on the ground and electric welded it back together to ride the trial the next day.

traded it in for a new RTL Suzuki shortly after that - those frames never broke !

the other thing 348s did was jump out of first gear without warning - usually half way up a step. - now you see why i dont hold them in very high regard :wacko:

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all stripped,heres the reason why below:( ,thats 1 down 3 to go,got 4 engines hopeing to make 2 good ones out of the 4 for mine and my mates,got the gasket set on order(millers)ive never had any trouble with monty frames maybe I dont ride them as hard as you lot :wacko: any ideas on why the crank went?

Can't give you a define answer why it happened but can suggest somebody having too much fun tighening it up with the airwrench to stop it shearing the wrong size flywheel key they had just fitted in the very very worn keyway maybe? I snapped the crank on a 1 year old GZ125 suzuki last year (wiht no wear on it) that just looked like it was made from cr*p to be honest, it wasn't even particularly tight when it went.

I have a 349 crank thats done the same on the other side....But on the plus side I haven't broken any 348 frames - yet. Didn't the first of the alloy framed bikes have a reputation for breaking in two behind the headstock as well?

Giles

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been busy today stripping the 2nd eng to rob the crank,ive noticed a difference in the cranks to my eng and my mates,my eng number being 51m his 51h(later eng maybe?)has anybody got the procedure to set the timeing up,pics would be nice allso the points gap?another fault ive found is the kickstart shaft has punched a hole in the magneto caseing,I remember this happening on my last monty is there a cure for it? :guinness:

BIKEPICS025.jpg

pic of difference in crank

BIKEPICS029.jpg

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