Hi all Have recently fitted a dyno jet 2 kit to my m600 1995. Wanted to have an open air box and K&N filter, but have left air box on and removed trumpets (idea from Arquebus ). My problem is that at lower speeds/gears the revs don't immediately die down when the throttle is shut off - eg when gear changing. Is most annoying and disconcerting when riding about town. At higher speed - it goes like a stabbed rat!! I have assumed that the mixture is running lean, so I have backed off the pilot screw to approx 4 1/2 turns - and still she's doing it. Have also noticed a popping from the exhausts on downshifting. When revs do settle at stand still she ticks over fine. Any thoughts about the erratic revs will be gratefully received. Cheers
Back off the 'tickover' screw........these BDST38 type carbs are a pain to set right, so you may have to re-balance and re-adjust the pilot screws. The pilot screw is really a pilot metering 'needle' and provides the fuel for lower revs running........it is also affected by fuel level / float height.........Its not until higher revs are reached that the main jet / needle come into action. Have you got the main needle on notch 3? Mine was a s*d to set up but finally got the pilot screws at 4.25 turns out..............but regardless of 'what the books say', it could mean that 3 turns out for one bike, is actually 5 turns on another.........and not the same on both carbs either. Don't forget, the two valve SS and Monster engines can run like sh*te at anything below 2500 revs.........so tickover can vary considerably from bike to bike...........Mine is at say 1050-1100 rpm, paulk563's is about 1200 and Lumbux's is at about 1400!! Without the Dyno gear, it can take a long time to get them running anywhere near right..........so, back off the tickover/ idle screw and then try the pilot screws in any direction to see if the revs rise........it's a fine balance between tickover and pilot adjustment.
Well, I've been tinkering with idle screw and pilot screws. Thought I had it sorted this pm - went out, didn't over rev in neutral, and pulled nicely all round. Though I'd finally take her out for a ride (as it was a beautiful evening) - and she ran like a pig. Sounded lumpy all through rev range, over revved between gears and then stalled when throttle shut off! Gutted. I'm fresh out of ideas now. My next thought is to take carbs off and thoroughly inspect; and replace all jets etc (except DJ one) with those from the old carb (where the bike ran like a peach). And then start all over again...
apart from idle circuit blocked/maladjusted (or even non-carburretor problems which could cause similar symptoms) - has anyone touched your balance screw as your symptoms closely concur with incorrect balance between carbs. If you are at home with adjusting slow running and balance screws* I can p.m. you with a fairly simple test you can do to confirm. * some people get these mixed up causing the imbalance inadvertently.
Hi - I have tried to balance the carbs using my vacuum gauges - but it was very difficult to get an exact balance. If you can pm me with any way to check, I'd be hugely grateful. Cheers
I had a similar issue........After having cleaned the carbs and replaced lots of parts that were defective, I eventually got the bike running somewhere near right; then suddenly it played up and would not drop the revs quickly.......... .........because I had been moving the bike around in the workshop a lot, the twistgrip rubber had pushed up against the cable housing and was dragging so it wouldn't close easily. However, regardless of the above, any bit of cr*p in these carbs will cause all manner of problems..........even a tiny bit of lint from a cloth will sod up the pilot circuit.....and the pilot circuit is a sod in itself to get clean.......there is a reservoir in the circuit with a non-removable plug in it and petrol can dry out and leave deposits in there, which break off and block the pilot jet and other related holes.
Hi all - success!! After relentless tinkering with idle screw, balancing and mixture screws - all to no avail - I decided to remove the carbs and check then over. I first dismantled my old carbs (which worked fine) and removed the pilot and start up jets. All were clean and clear. Removed carbs from the bike and checked needles and diaphragms; then removed the float bowls. Main jet fine (as it should be, as is new DJ jet) but the start and pilot jets were awful. Both blocked and corroded. Removed them and sprayed carb cleaner all over, round and through and hole I could see!! Removed pilot screws and suddenly realised they were both without the rubber o-ring and little washer! (I did inspect the inside of the carb - and they were definitely not in there). I added spares to the existing screws, and fitted them. Carbs balance on the bench by eye - carefully looking a distance between bottom of butterfly valve on one side, and then turning the screw until the other was the same. All put back together and she ran a peach - had realised she was misfiring before! Now sounded perfect and ticked over a treat. Took her out - and damn , didn't she perform well. Pulled strongly through all gears and no over revving!! Job done!! Would Like to say a massive thanks to all who have helped me and shared their thoughts and advice. Safe riding Danny
A happy customer, then............. .........are you sure the little washer and o rings weren't stuck in the carbs? It's a helluva job to tell because the washer hides the o ring and the washer itself looks like the pilot screw seat........ ...........still, if it's working well, leave it alone now.............
I did wonder if they were stuck in there - took a long time inspecting them, and they really did look like they were missing. Took her out today, and ran like a peach - very pleased Have an intermittent problem with a 'floppy' gear selector when down shifting to 2nd and 1st (will start a new thread for that though)
