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st-st-st-st-stuttering problem on the XJR400

Discussion in 'Technical and Troubleshooting Torque' started by Coconuts, Nov 25, 2005.

  1. I'm at a loss with this little bugger. i never rode it much further than my street until my zx7 recently clapped out on me, and i always just figured its cutting out at around 60 was due to it being a wee bike. but on closer inspection on a longer ride, it turned out that the thing was hitting about 7000 rpm and just not going any further. there is obviously room for improvement here as the redline is at about 12000.

    so clever me thought "kewl, i'll give the carbs a clean" and proceeded to pull them out and apart. they were filthy inside, probably due to there not being a fuel or air filter in it while the previous owner had it :roll: big chunks of dirt and sediment in the bowls and nice black soot up around the needles.

    so all cleaned and put back together, i stuck them back in the bike. oh shit says i! the thing now only revs to 5000 :LOL: i had a flash of inspiration last night and thought this might have a lot to do with the fact that i hadn't hooked it back up to the airbox and is thus getting some kind of vaccum issue, i'll try this tonight. its a long shot, but i'm fresh out of other ideas :?

    does anyone have an idea or two to throw at me? my basic understanding of carbs is that idle jets takes care of the mixture till about 4-5000, the needle height is responsible for the midrange mixture and the main jets are for the top end. i have tried raising the needles a notch with zero results :?

    so yeah, ideas please. if anyone has any? i never liked carbs, and now i like them even less :LOL:

  2. for anyone that was interseted, it was the airbox not being hooked up. put it back together and she runs better than before, as it damn well should with the clean i gave it :LOL:

    and i got the ZX7 going again too..... oooooh coco's on a high tonight :D
  3. hmmmm, so how come my 1986 xjr400z can hit 215-220 with my big fat arse on it :LOL:

    one word of caution, take VERY good care of the carbs as they have a tendancy to go pear shaped very quickly, riding mine every day i ended up cleaning the carbies once a month or the thing would run like shite.

    admitedly i was doing an average of 8-10,000 a month as a courier so you could probably go 3-4 months between maintenance.

    other than that, it is one of the most fun bikes i have ever owned and the only one i have ever managed to scrape the side stand on o left hander (atmitedly a slack side stand spring didnt help much :LOL: :LOL: )
  4. i meant topping out at 60 in first :oops:

    the fact that it had no fuel or air filter and was filthy inside but still running ok leads me to beleive that its a fairly solid bike. carbs aint meant to run with big chunks like that in them, its a wonder it was still going i reckon :shock:

    but yeah, awesome fun little bike. i still much prefer my zx7, but i'm glad i've got a missus that decided the XJR was the go for her :D its great fun to get out and actually rev a bike a little, cos you just cant do that on most bigger bikes.... and keep your licence :LOL: