Mikunioz! Townsville.
Mikunioz! Townsville.
The air filters are K&N's.Nice bike, something is wrong it should rev higher than that with stock gearing. Try a run without those air filters. Some filters that look like the ones in the photo are known to cause problems. The problem is with the mounting flange blocking air circuits. Better air filters are K&N or Uni pods. Unipods are ok but not as free flowing as K & N.
Does your mates dyno have a fuel air meter, you will be able quickly see what needs to be adjusted.
Beautiful bike, Manny. If I were you, I would forget looking at brassware until I had fully assured myself that everything was right; compression/leakdown (as gggGary and Grizld1 have suggested), throttle opening (full lift of the slides), fuel flow, air flow, etc... Is it possible that the cam timing is off by a tooth? There has to be something really wrong with the basics if it won't pull past 4500 rpm. Good luck!Thanks for all the info guys. Much appreciated. I did a mains change as a quick stab, to see if it made a difference on full throttle. I'm not too clued up with carbs. The motor was professionally rebuilt, big bored and rephased 1500 miles ago by Daryl Hutcheon in Oz, who made a living doing this to XS650s. I acquired the bike with only a handful.of miles on the clock. Now it's pretty much run in its disappointing to find it's so gutless. It has a Probe electronic ignition and my timing light suggests idle and 3500rpm up timing is about right. On my mate's rolling road it pulled through to 7000rpm no problem but yesterday on a ride with a few mates it wouldn't pull more than 4500 in top gear, and it took its time to get there. I so wanted to to get off and kick it's ass. I shall read through the techy info in the links and investigate what other brassware \needle info i can pull from my carbs and report back here for your views. Ive always thought setting up carbs a bit of a dark art tbh and have never been able to understand it like id like to. A pic of the bike is attached. I love it, but not the way it's performing, which is a shame after I've done so much to it.
There, I think, lies a major clue: "....according to him he does a "mild grind" of the cam after rephrasing it." You may have a cam that is in some way bad... not correctly timed, not correctly rephased, or correctly ground. In terms of valve clearances, the fact that the cam doesn't have the original profile doesn't dramatically alter valve lash.The air filters are K&N's.
Discussing my issues with my mate who has the rolling road, I think.i need first to double check my valve clearances (not been checked since engine was rebuilt), check accuracy of the TDC and timing marks on the Sparx stator, check the the timing thereafter before going further.
My engine was rephased and fitted with the MikesXs 750big bore kit, by Daryl Hutcheon in Oz. He's done many of these conversions to xs650's and according to him he does a "mild grind" of the cam after rephrasing it. My problem is that I do not know what the valve clearances should be for the reworked cam. Has anyone out there got one of his reworked engines and can tell me what clearances I need?
Agreed grizld1, but as a start, you could check valve timing one cylinder relative to the other, to see if they match. Secondly, you could check the rephased cam's valve timing against stock valve timing and see how that compares. I would expect that the "mild regrind" has a little more lift, and a little more duration, with earlier opening and later closing of the valves. If the cam timings were plotted (resembling bell curves) and overlaid, the mild regrind should basically be simply a higher and broader bell. During the regrind process, an error could also have been introduced in the lobe centerline angle, dramatically altering the behavior of the camAh, the mystery cam. Can't check valve timing if you don't have the specs. Be a shame to replace it with an expensive but known rephased cam and have the same grief afterward. I know you're in Britain and the wizard is in Oz, but unless the business is defunct it shouldn't be hard to get the specs from them. Gotta be an email addie somewhere. Or have you tried and gotten crickets? Feeling your pain, as Slick Willie used to say....
gggGary, recent experience with a "ran when parked" XR250 R that may inspire further checking... engine would not start despite presence of fuel and flame...compression seemed good through the kickstart, but was actually very low. Disassembly of the top end revealed rings firmly stuck in their grooves. Work with PB Blaster and a dental pick freed them up. Engine was reassembled with the now-freed rings and fired on second kick. Runs like a champ to date!Can't be too far off setting valve lash at .003" and .006"
I'd check vavles and cam chain lash then check compression. You should be over 150PSI
Physician heal thy self? Been wasting way to much time trying to start a "ran when parked" XL500S, pretty sure now the motor's FUBAR, going to go check compression, but a bad valve seems REAL likely. D-OH
The cam rephasing has to match the crank for sure!Also, my rephase is a true 270 degrees, not the usual 277 degrees afforded by the Yam 13 spline cranking. So I'm assuming that a different rephased cam will not be right for my motor in any event. Correct??
They are k&n filters and not sure what my mates rolling road has. Will ask him.Nice bike, something is wrong it should rev higher than that with stock gearing. Try a run without those air filters. Some filters that look like the ones in the photo are known to cause problems. The problem is with the mounting flange blocking air circuits. Better air filters are K&N or Uni pods. Unipods are ok but not as free flowing as K & N.
Does your mates dyno have a fuel air meter, you will be able quickly see what needs to be adjusted.