lee harris Posted September 21, 2009 Report Share Posted September 21, 2009 Hi Gents, I just picked up a good 300 barrel with no fin damage. It has no cut out for the bigger flywheel so came off a 300 The bore is 72mm meaning it came from france. The 300 was sold there with 240 instead of 249 cc for insurance reasons. It needs a new piston so I will get it bored to 74mm and 249. My question is on porting. The 300s all had a so called low port motor, later 249s where high port motors. I think it refers to the exhaust port, I can compared to a 303 barrel I have but do I want to change the exhaust or other port timing? Info please!!! Lee Quote Link to comment Share on other sites More sharing options...
furse Posted October 1, 2009 Report Share Posted October 1, 2009 If its any help, I have a Montesa barrel that was ported for James Lampkin, Its main re-porting has been done on the exhaust port only, she rev's like a darling! Quote Link to comment Share on other sites More sharing options...
axulsuv Posted October 8, 2009 Report Share Posted October 8, 2009 Lee , on the 240 barrel I've got that has the major porting changes to the known stock one I've got , most of the port work was done on the exhaust and transfers ... And just a bit on the intake side . But with Chris's OKO and the iridium plug , K&N airfilter and The new stator and coil , it will idle slow enough that you can almost count the rpm and still go wide open without any hesitation . All without a sharp edge anywhere in the powerband ... When I have it apart to get it replated for the forged piston I've got waiting to go in , I'll send you some scaled comparison photos . But it may be awhile as I've not noticed a drop in compression yet ... Ask Classic what he does to the early 300's to stop the spark knock ... Glenn Quote Link to comment Share on other sites More sharing options...
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