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About stew79

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  1. stew79

    XT500 no spark

    if the points are clean and have the right gap, but the timing is out, you will get a weak spark or none at all. if the timing is in the right place but the condenser is faulty its the same. replace with a new one for piece of mind. (they dont last for ever) stew
  2. stew79

    I have to ask... CRF250L vs. CRF250X

    i cant find the 305 thread ? (went back 10 pages) have you any experience with the older bikes ? or carbs ? i think its good to compare old with new just to see if the modern teck is any better than the past. once again i am very disappointed with efi, although your bike will give better mpg than mine, thats not even on the list of important things. how it rides and accelerates, wheelies etc and beats bigger bikes is what gets me interested. i just wish i had dynod it after it was bored out to 330 as it must have been well over 30 but had more so much more bottom end pull. (reg plate avg315w) stew
  3. stew79

    I have to ask... CRF250L vs. CRF250X

    can you show a print out for the 26 bhp figure on the 305 ? stew
  4. just a 78/79 xl engine in a yz bike (with IT swing arm) normal inertia dyno operated by very good engineers. they have an enormous data base of bikes they have tested, and predicted about 20 bhp (as the bike has std piston, crank, valves, rs250 road bike cam,) as for reliability, i owned the bike for nearly 20 years (well the engine, it had been in 2 other frames) not many weak spots. (some more pics on here in honda)
  5. looking at the dyno pictures is quite disappointing, i thought modern teck would make things so much better than old fashion carbs. the last time my old 250 was dynoed (about 2003) it was 27 bhp. i havent got the print out but its on the computer system at BDK race engineering in england. thats on petrol with a 32mm mikuni carb, home made ex pipe, basic porting and refining of jetting, timing etc. it was a road reg play bike with lights and used every day as a run around. tuned to be an all rounder, not just set up for racing at over 7000 rpm. stew
  6. stew79

    XT 600 cam timing

    if you take the side cover and rotor off, you will loose the timing marks. just look through the window for "t"
  7. stew79

    Big Bore Stroker 325

    i suppose if the efi could be perfectly mapped it would possibly make the same power as with a good carb, but with better mpg, less emissions. etc. if you get it on a dyno, perhaps 35 bhp would be a safe figure to aim for, but with more bottom end and mid range pull than a std 250. my 330 would wheely at will off the throttle in second at about 30 (only 5 gears, geared for 90 mph) but just ping the clutch in 3rd or 4th at speed and it was a wheely monster. (with very basic 1970,s tech) stew
  8. stew79

    Big Bore Stroker 325

    how much re programing can yo do to the original map ? can you "plug it in" to a pc to look at all the parameters ? some bikes no what gear you are in and adjust the power available to "protect the rider" but not on a 250 ? without enough experience in knowing what you need to adjust, and at what throttle position, rpm, load etc you could spend years fiddling about with this and get no where ! stew ps if you put a mukuni carb on it i could give you good jetting suggestions (but you would still need to no what the ig timing is doing)
  9. stew79

    Big Bore Stroker 325

    hi from england, i have looked into and read about efi for many years, but never had anything with it (apart from mercedes sprinter van, but thats common rail diesel and not likely to ever be tuned up) i would have thought ex gas temperature would be more useful in trying to get the maximum performance from a tuned up engine ? 02 measure is not going to help there, unless it can work at really rich mixtures, but that only works with the right timing. why go for max economy ? its not meant to save the planet, its meant to have fun riding on it. but for road use you could keep below what the max out put could be, to allow a safety margin. but you would perhaps need to see how far you could push the engine to no what its capable of. stew
  10. stew79

    Big Bore Stroker 325

    great news that its back together and running, never had a bike with a chrome/ nikasil or what ever bore, so dont no how much running in it takes ? (i,m still back in the stone age with cast iron, but if done right it only takes 5 miles or so in stages with 2 or 3 complete cool downs and start again) what can the fuel mix meter go down to ? still cant see how it helps with performance ? can feel, experiment, and years of practice be put in a program for a computer ? and what ignition timing do you have ? stew
  11. stew79

    Big Bore Stroker 325

    as i only no about carbs, porting, timing, and basic stuff, i cant imagine how to adjust or tune with efi. but after 3000 rpm or so, is the ignition timing fixed or dose it alter ? if you have a gas analyzer in the ex pipe, how will that help for max acceleration and power? under those conditions its it usually out of the loop, relying on a pre programed amount of fuel ? (thats the norm in "car world") when i have played around with a bike and got it to run as best as i can, i then sometimes put it on a dyno. they all like to put a probe in the pipe to see whats going on. "its too rich off the scale, but i cant believe how much power its making" is the common reply, but the scale only goes down to about 9 or 10. if i wanted to cruse along at a steady 50 mph all day, i would like a higher reading (14-1 or so) but not for racing. max acceleration with my old carb technology is probably about 7 or 8 to 1. if the ignition and plug can handle it, the extra fuel helps to cool the engine a bit. (all air cooled bikes) the hard part is to get the jetting right so you still have smooth slow speed running. it is possible, but there you must have an advantage with eli. stew
  12. stew79

    Big Bore Stroker 325

    this looks very good, what power did the original make ? what power do you think it will make when finished ? i no its not about the numbers it more the feel but numbers do help to compare things. i only wish i could have kept my bored out 250 and dynoed the thing, 330cc felt so much better. stew
  13. stew79

    two carbs ?

    the std ignition wouldnt advance once the engine got warm (common problem, quite dear to fix) but it dosnt advance fast enough, or far enough, and its hard to alter (cant move the max adv pick up very far, and the the speed is stuck in the electronics, but the fly wheel is way too heavy anyway) i have made cdi ignitions for many bikes, timed from the cam, so that was the easiest option. lighter honda rotors can be made to fit the crank, but still use the yam coils. (the rotors can be lightened even further depending on what you want) so with totally adjustable timing, better carbs, porting, etc, you can wear out the soft yam gear box even quicker ! stew ps home made ignition on the sp370 in the suzuki section under dr
  14. great simple bike, just my kind of thing. back in the 80,s i found a good way of getting one of my hondas to handle, stop etc better. put the engine in a zy !
  15. stew79

    Crf250x 2005 crank/conrod rebuild

    to split and re assemble a crank is a bit specialized, needing the right equipment. as an engineer with my own business its a service i supply. you may have damaged or distorted the crank wheels. but put the crank between running centers (thasts centers that have bearings in them) on a lathe, (very little pressure) and record the run out with a good clock. (mark with a felt pen) take out and hold in one hand. it is possible to hit one half of the crank wheel with a copper mallet, to bring it into alignment. with wedges and a press its possible to true up the faces. keep returning to the lathe and re clocking up what you have done. if you are lucky you may get it right. or take it to a machine shop. stew