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Tortrons GN


tortron

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Just now, Guypie said:

A wise man named @Geophy once told me the break in process for a new lifan 125 is a 4th gear burnout.

Pretty sure the man is a mechanical genius.

Yeah you have to do that, it's the only way to get enough oil flow to wash out the large amount of swarf they come packed with for shipping.

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54 minutes ago, tortron said:

a new engine has all the gears and bearings wearing in yes

 

you dont repeat the whole process for new rings and pistons. no one does an additional 1000km break in process

No but piston and rings still need to bed in over 150 kms or so, just keep doing what your doing it seems to be working well for you 

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anyways, i ran the piston over a stone, dingleballed the cylinder
actually measured the cylinder and piston by digging out my dusty bore gauges
and its now slighlty over the minimum clearance, so its self clearanced nicely (gn125 clearance being 0.03-0.051 to 0.12 max dr200 being 0.04-0.05 to 0.12 max) i measure 0.055

 

going to chuck it back in and go do some 11000rpm shifts

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Yeah there's two trains of thought, one is the old school slow break in method, the other is GIVE IT Heaps so that the rings wear in properly before the cross hatching has gone. Most people who know anything now seem to go with the GIVE IT Heaps method. 

Anyway, richen it up a bit to keep things cooler maybe? 

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I just remember those cbr250 and fzr250 gsxr250 would sometime be totaly fucked after under 20,000 kms. When I was doing my apprenticeship my job was to put the 1st 5 kms on the new bikes and I was threatened with death if I blew them up

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1 hour ago, SOHC said:

I just remember those cbr250 and fzr250 gsxr250 would sometime be totaly fucked after under 20,000 kms. When I was doing my apprenticeship my job was to put the 1st 5 kms on the new bikes and I was threatened with death if I blew them up

Its not about rpm so much as piston speed.

4age @8000rpm -616,000mm/min

GN125 @11000rpm -536,800mm/min

CBR250 @18000rpm -608,400mm/min

the slowest revving engine of those 3 has the highest piston speed. Also spends the lease amount of time doing that speed in all fairness. Bearings and whatnot are a different story but I really don't think the revs are going to hurt the gn

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tou gotta put conrod length in there too

 

but forget all that and look at the engine being in dirt bikes, the redline being 10000rpm 

doing 10000rpm is fine, itl do it all day long. Infact i have several times as a 125 and its the piston and bore is fine

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