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About MXCRacingGreg

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  1. MXCRacingGreg

    Running 87 gas in bike. Can it cause...

    Apparently it can. You ought to trust the professional mechanic who told you it could.
  2. MXCRacingGreg

    06 kx450f hard to kick problem

    I would expect a broken piston. unfortunately there has been an issue with some of the 06 KXF450s (if you look you may find some old posts about this issue) we run 3 06 KXF450's and I only had 1 break a piston. Jumping timing is unlikely on these bikes. The issue had to do with a weakness in the stock piston casting allowing it to crack. A compression test may reveal a badly broken piston but ours still made ok compression it just ran and sounded bad.
  3. MXCRacingGreg

    Turning issues

    The SAG on the 06 KXF450 is very critical. if the rider sag is too much it will turn poorly and feel like it richochets off every bump. Run the sag around 105mm and it will effectively "shorten" the wheelbase and steepen the head angle giving a quicker more accurate turn. I also run the Pro Circuit link and feel it improves the turn even more, but it won't improve anything with too much sag. We have been racing 3 06 KXF450s for the past 2 years. 2 riders are fast intermediates and I am an over 45 Vet. we all like the PC link but the sag was the most urgent fix.
  4. MXCRacingGreg

    I need to cool this beast down

    We have had good luck with "Engine Ice" coolant. You must completely drain and blow out your cooling system before changing to it. Also it is not an anti-freeze so that may be a problem up there unless you change over for the winter or store the bike in a heated area. Greg
  5. MXCRacingGreg

    New owner

    We have 4 KX450s in our program, so we have a fair sample. I agree that the stock suspension needs a little break in time to loosen up but the clickers are there to be used. First the 450 is the most sensitive to correct sag, since your weight is average the stock springs should be fine. Set the race sag at 105mm in riding position. Second the rear shock seems to blow through the stroke, so set the slow speed compression to 6-8clicks out. I know it seems odd to add compression to control harshness but we found the harshness to come from the shock riding to low in the stroke. next rear rebound a little tighter than stock until it doesent kick off jumps. Some experimentation should get settings you like. sliding the fork tubes up will just give more head shake, make sure the fork stem is not loose in the head and that the triple clamps are not torqued over 14ftlbs. also check for smoothness in the rear end, you may need to grease the swing arm and shock/linkage bushings. Our riders range from a 160 lb beginner, 170lb intermediate, 190lb intermediate, 225lb vet. I last rode an 05 CRF450. I liked the suspension ok, Then had my suspension guy completely re-work it which gave a tremendous improvement over stock...I like the KX450 suspension better stock than my fully modified CRF450 suspension. But, it did take some time and experimentation to get it right. Good luck, Greg
  6. MXCRacingGreg

    Valve Clearance

    Remember that the valve clearance gets smaller as the valves wear, so tight valves are what you don't want. When the valves give problems it is usually because they lose the gap between the valve stem and the cam lobe (not directly of course, the bucket and shim are there too). This gap exists so that when the valve heats up and the stem lengthens the valve will still close completely. The valve must close completely and with enough pressure on the seat that the heat built up in the valve will be disipated to the head. if the valve cannot dispurse the heat it will fail. Also overly "tight" (littel or no clearance) valves will cause a loss of compression in the cylinder. The correct size feeler guage should slide smoothly through the gap between the bucket and cam lobe with slight drag. Since the surfaces of the cam and bucket are very hard and smooth and the feeler guage is usually very hard as well it is possible to force a guage between the surfaces and open the valve slightly giving a false gap reading. Hope this helps. Greg
  7. MXCRacingGreg

    Racing Gas?

    The KX450F runs 12:1 compression stock. Even though you may not notice the effect of race gas when you ride, it is good insurance against detonation. Detonation is easy to miss on these loud bikes and the effect can be costly-premature piston and rod failure. I run VP Ultimate4 mixed 50/50 with good 93 octane pump fuel for practice and straight Ultimate4 for races. 50/50 mix works out to about $7/gal (that's what they pay in europe for pump gas). considering the relatively small amount of fuel they burn and the high cost of engine failure, I take the high road. Just my $00.02 worth.
  8. MXCRacingGreg

    o ring chain?

    Needed to change chain and only had an EK SRX520 X ring chain. It hit the 3 small nubs on case so I ground them down with a die grinder. Worked fine. I would have run a narrower chain if I had one, but I didn't. Good luck
  9. MXCRacingGreg

    What Oil Do You Guys Use?

    Castrol R4 when it gets here. In the mean time we have been running Castrol SYNTEC 5W/50 and it has been doing just fine. cool motor, good clutch feel, (no slipping) we are running it in 3 KX450Fs - Vet Novice to Intermediate level.
  10. MXCRacingGreg

    About Ti Headers/Pipes...

    Its folks like you that screw up this whole medium of communication. According to your profile you ride a dozen year old Honda tank (not a bad bike in its time) and a Yamaha. Why in the heck are you cruisin around the KX450F forum? I am guessing that you are just looking to talk shiot someplace where you won't get beat down. Go to a Honda or Yamaha forum or better yet go ride and get off the internet. As for the KX450F we have 4 of them racing currently and we have not had any problems. They are racing bikes so there may be problems down the road but thats just part of it. We ride 5 days a week on average. Currently I have 14 bikes 01 through 06 Yamis, Kawis, Hondas, Zooks even a Ktoom, so I am familiar with them all.....06 KX450F best by far. Stock suspension on the Kawi is better than my full mod 05 CRF450. And the 05 CRF450 mod suspension was a huge improvement over stock. KXF power is much better than the 05 CRF was.