Ive noticed that on the right side there is a protrusion where the inner clutch cover bolt sits,this could be ground out (breaking through and requiring filling) along with a shorter bolt (there seems to be enough depth).
One thing im not sure on is the oil way/main bearing feed mod,
ive noticed some fill this area just leaving a small hole at the top,my concern is what,
What does this to do to bearing life?
Is there ANY gain (performance wise) in even doing this?
My reason being is,
Ive never come across a purpose built race bike (h***a RS or Yam TZ) that uses this mod,even the Kitted h***a didnt.
All jap mx's ive seen DONT use this mod.
Comparing say a early 90's KX125 intake its obvious thought has been put into this area (more than a KR) but the oil feed is left.
Im not sure if this has an effect or not but due to the KR engine being angled forward when installed,the standard oil feed catch area does just that,any oil/fel mix in this area get caught and directed to the hole.
If you dont have this your relying on fuel thats in suspension finding the now small oil feed hole as the only means of lubricating the mains.
With the stock setup you also have the benefit of oil thats accumulated in this area (oil thats dropped out of suspension) feeding the bearings.
Personally i woud say that providing this area has any edges radiused then thats all thats needed.
Not knocking anyone that does this as i can see why you may think this mod is beneficial,just that after some thought im not sure it will contribute anything to the flow from crankcase to barrel scavange ports,after all if its not used on an out and out racer (not road based) there must be a good reason.
Another mod that i can think of is ,barrel/gasket/crankcase matching,
My thoughts are,providing the step is in the right direction i.e, stepping down from crankcase to barrel then there is no gain in grinding out the case to match the larger barrel area as there is NO hindrance to flow (which would be the case if the step was UP).
Maybe some of these mods are more based on a "feel good" decison rather than it WILL make a difference?
Oh just read the lates classic mag,stan stephens can gain up to 8hp by modding the KR crankcases
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Your thoughts?
Anyone?
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Regards
Dave
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