KLX 250 ( 300 ) camshaft mod by Marcelino
#532
Cmott426, grab both charts on my megabomb dyno thread - we will be looking at only the "before megabomb" chart lines in blue - print them full page, draw a line across the HP/AFR chart at the 14:1 mark found on far right. Notice the bike is at or above 14:1 until 8700rpm where it then starts dipping toward 13:1 - notice what happens to the HP starting at that same point ( 8700 ) - it takes a big leap and keeps it until the operator killed the throttle at 9400 rpm - which is too soon if you ask me. Now go look at the HP/TRQ chart and you'll see TRQ start to leap and hold better #'s at that same 8700rpm - the TRQ leap is smaller than the HP because of the calculations that create the HP #'s.... A small jump in TRQ at higher RPM's causes a big jump in HP #'s.....
If your lucky , at your altitude, you'll get the benefit of an AFR that is closer to 13 over the entire RPM range of the engine.... If so, that should be big power increases - the kind that lofts the front wheel on throttle alone.
Good luck !
If your lucky , at your altitude, you'll get the benefit of an AFR that is closer to 13 over the entire RPM range of the engine.... If so, that should be big power increases - the kind that lofts the front wheel on throttle alone.
Good luck !
Last edited by Klxster; 04-10-2014 at 05:59 PM.
#533
I am ready to do the cam work, but I have one question. The comment about the compression release being pressed out and reinserted.
Is the 8mm rotation measured 8mm radially around the OD of the end of the cam shaft? I mark the cam and release, then press it off. Measure 8mm radially, mark the cam, then align the marks with that I made on the cam and press it on, right?
Also looking at the compression release end of the cam, to advance the release would be to rotate it counterclockwise, correct?
Is the 8mm rotation measured 8mm radially around the OD of the end of the cam shaft? I mark the cam and release, then press it off. Measure 8mm radially, mark the cam, then align the marks with that I made on the cam and press it on, right?
Also looking at the compression release end of the cam, to advance the release would be to rotate it counterclockwise, correct?
#536
So I found an interesting thread regarding the ACR here.http://www.thumpertalk.com/topic/766...sues-resolved/
My thought is, if this guy had ground his ACR to increase compression, does it need to be retimed? I'm looking for a way to do this mod without pressing the ACR. Is grinding a possibility? Also I saw mention of 'deactivating' the ACR. Is it possible to leave the ACR totally intact and just remove its functionality. Sorry if this was already covered.
My thought is, if this guy had ground his ACR to increase compression, does it need to be retimed? I'm looking for a way to do this mod without pressing the ACR. Is grinding a possibility? Also I saw mention of 'deactivating' the ACR. Is it possible to leave the ACR totally intact and just remove its functionality. Sorry if this was already covered.
#537
So I found an interesting thread regarding the ACR here.KLX250S starting issues resolved - KLX/KLR 125/140/250/300 - ThumperTalk
My thought is, if this guy had ground his ACR to increase compression, does it need to be retimed? I'm looking for a way to do this mod without pressing the ACR. Is grinding a possibility? Also I saw mention of 'deactivating' the ACR. Is it possible to leave the ACR totally intact and just remove its functionality. Sorry if this was already covered.
My thought is, if this guy had ground his ACR to increase compression, does it need to be retimed? I'm looking for a way to do this mod without pressing the ACR. Is grinding a possibility? Also I saw mention of 'deactivating' the ACR. Is it possible to leave the ACR totally intact and just remove its functionality. Sorry if this was already covered.
Last edited by cmott426; 04-11-2014 at 04:42 PM.
#538
Alht so I did the mod. Not super hard! For sure the best free mod. Ever. Disabling the ACR literally showed no difference in how quickly the starter turns. Though, the bike does start quicker. The tuning has to be dialed in for sure. And this next issue may be related to my tuning. The bike falls off pretty hard at 8k RPM. If this is just how it runs, totally fine, because it pulls harder now at 6k rpm than it did at 8k rpm before. My current setup at 6000' feet is bone stock, snorkel removed, DJ jet kit with 120 main, pilot 2 turns out, and clip on needle second from top. Should I step up a size on the main? Is the power supposed to fall off like this?
#539
If you looked at the dyno charts you'd see it. Even the stock set up has the peak HP at 8200 rpm. Everything from there on is over revving. Marcelino simply timed the cams for the best mid-range and horsepower based on cam timing theory. Kaw had the timing for harder revs at the sacrifice of peak power and performance within the true power band. Thus his comments about cam timing for Ducati rpm - aka 12,000 rpm.
#540
If you looked at the dyno charts you'd see it. Even the stock set up has the peak HP at 8200 rpm. Everything from there on is over revving. Marcelino simply timed the cams for the best mid-range and horsepower based on cam timing theory. Kaw had the timing for harder revs at the sacrifice of peak power and performance within the true power band. Thus his comments about cam timing for Ducati rpm - aka 12,000 rpm.