Author Topic: RM 100 T / 125 T BITS  (Read 1005 times)

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Offline rocketfrog

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RM 100 T / 125 T BITS
« on: October 21, 2008, 05:58:39 pm »
Has anyone got a crank and rod assy for a 125T that is surplus to requirements. Failing that perhaps, an RM 100 T barrel and head.
Below is a blog from another thread which i have pasted in for background info. (Note that the 125 barrel I have is last oversize and in pretty poor shape generally, ie; some light scores lower in the bore. Cheers fellas, any help with these bits would be appreciated.


The stroke for the RM100 is 50mm and the bore is 50mm (std). The RM125 has a 54mm bore and 54mm stroke. The RM100 Engine that I have here has been fitted with a 125 barrel, so in essence the stroke has remained the same (actual piston travel measures 50mm), the bore has been increased by 4mm and the squish incorrect because the length of the barrel is correct for the 125 - naturally. So here is the conundrum, do I replace the rod with the standard item to remedy the sloppy bottom end and seek out an RM 100 T Barrel to return the engine to std specs (ie; restore the correct squish) or modify / replace the 100 crank so as to increase the stroke to 54mm and simply convert the 100 into a 125? I suppose the obvious answer is upgrade to 125, but I may be best putting it out there for either a 125 crank or a 100 barrel and head and seeing which comes up cheaper. At the end of the day the cost of the repair and the availability of spares will be the driving factors. After all it is only a fun bike, but preventative maintenance now could be the difference between keeping this little RM going for another 25 years or junking it when it expires because of the repair bill out weighing the practicality of a major repair job.   
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Offline rocketfrog

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Re: RM 100 T / 125 T BITS
« Reply #1 on: October 22, 2008, 07:16:03 am »
Having said all that, the parts I require are - a barrel and head for an RM 100 T
Political correctness is a doctrine,fostered by journalists and politicians, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."