RB head mod w/o carb mod: KDX220 riding impressions
Posted: 03:41 pm May 17 2007
I just got back from an hour + riding session on my bike which was just fitted with an RB modified head.
The bike is low time with a strong running engine. See my bike profile below to check out what I've done other than stock.
I installed the head with no other changes; including making no changes to jetting the stock carb.
The familiar loop I took was pretty tough, with several rutted, steep hill climbs (including the obligatory root barriers), traction was lousy - mostly hard pack with a thin layer of sandy crap that made hooking up nearly impossible most places. I threw in a few miles of fire roads too but mostly a lot of single track. Thankfully, I have a stealhy flywheel weight which helps a lot, even so, my bike was doing its best crab-walk impression up some of the more technical hills.
Right off, I noticed the irritating boggy thing right off idle was gone. I had worked with this issue on this bike and on a previous 220, and short of changing needles I was never able to completely get rid of it. Well, the head mod got rid of it without any jet changes - hot dang! Wheelies are easier to initiate now as you might expect....
It was hard to tell if the hit right off bottom is now softer because the thing now carburetes so cleanly. Overall, I'd have to rate it better now, because the low rpms now transition to higher in a linear, more controllable manner.
I did have issues with fanning the clutch more than usual, but that is soley due to the fact that I was hitting some tricky hill climb spots at one gear higher than before.
I was using noticeably less throttle to hold the same speeds as I am used to on the fire roads. I wonder if that will translate to better mileage?
I could not find any negatives power-wise. This mod seems to be a major improvement everywhere, every bit as significant as an aftermarket pipe IMO.
One reason I decided to go with this head mod was due to the 220's tendency to overheat -I felt that higher compression might help with that issue. I couldn't draw any conclusions today because it was only in the upper 70's, but things look promising - I'll update this thread on this subject after I get some serious hot-temp time on the bike.
I've read here where some folks noticed the higher compression while kick-starting - however, I couldn't tell any difference.
Good stuff for 45 bucks - indeed.
The bike is low time with a strong running engine. See my bike profile below to check out what I've done other than stock.
I installed the head with no other changes; including making no changes to jetting the stock carb.
The familiar loop I took was pretty tough, with several rutted, steep hill climbs (including the obligatory root barriers), traction was lousy - mostly hard pack with a thin layer of sandy crap that made hooking up nearly impossible most places. I threw in a few miles of fire roads too but mostly a lot of single track. Thankfully, I have a stealhy flywheel weight which helps a lot, even so, my bike was doing its best crab-walk impression up some of the more technical hills.
Right off, I noticed the irritating boggy thing right off idle was gone. I had worked with this issue on this bike and on a previous 220, and short of changing needles I was never able to completely get rid of it. Well, the head mod got rid of it without any jet changes - hot dang! Wheelies are easier to initiate now as you might expect....
It was hard to tell if the hit right off bottom is now softer because the thing now carburetes so cleanly. Overall, I'd have to rate it better now, because the low rpms now transition to higher in a linear, more controllable manner.
I did have issues with fanning the clutch more than usual, but that is soley due to the fact that I was hitting some tricky hill climb spots at one gear higher than before.
I was using noticeably less throttle to hold the same speeds as I am used to on the fire roads. I wonder if that will translate to better mileage?
I could not find any negatives power-wise. This mod seems to be a major improvement everywhere, every bit as significant as an aftermarket pipe IMO.
One reason I decided to go with this head mod was due to the 220's tendency to overheat -I felt that higher compression might help with that issue. I couldn't draw any conclusions today because it was only in the upper 70's, but things look promising - I'll update this thread on this subject after I get some serious hot-temp time on the bike.
I've read here where some folks noticed the higher compression while kick-starting - however, I couldn't tell any difference.
Good stuff for 45 bucks - indeed.