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Cheng's Across - tales of woe.

Discussion in 'Technical and Troubleshooting Torque' started by Loz, Jul 17, 2006.

  1. I thought I'd pop a thread up b/c there's been a lot of folks helping diagnose the weird engine and handling difficulties we've been having with this little fella.

    1) Pissweak engine

    OK so the engine has been tuned up and is running beautifully smooth, but it's still well down on power from other Acrosses. JohnnyO and Grobby pointed me towards the throttle slide holders, little plastic pieces that wear out with time and gradually cause an engine to lose power. See here for photos etc:

    So I opened up the carbs and pulled out all 4 slide holders to take a look. They're definately not stuffed like the ones in the photos on the ozcross page there - but there's a bit of 'play' in them, they can wobble back and forth and in and out just a bit so I thought I'd replace the lot anyway at $20 or whatever (plus $1.90 for the bastarding screw I dropped somewhere down into the feckin' darkness.)

    I don't think this is the answer. Talking further to Charlie at Turn One, he reckons this one's an import, and that the Japanese GSX250F has different pistons and other engine characteristics which simply make for a weaker engine.

    It's OK - here's the plan. The new throttle slide holders will go in whenever I get them and then we'll drill the baffles out of the exhaust, which should at least give it a touch more power and a nicer sound. At the end of the day, a lack of power might be annoying but it won't get Cheng into trouble and it won't stop her riding the thing. We can live with it.

    2) "Wandering" steering

    Even with the steering head loosened right back, the bike has a tendency (after being ridden for a while) to sort of wander to the left or right at random intervals. You can feel it through the 'bars, kind of steering itself. this is a real issue, when you're banked over a bit and it decides to make a steering change for you it's bloody scary. Noot a situation I want Cheng dealing with, it'll scare her off the thing foor good.

    It sounds exactly like what this bloke found:
    The steering head bearings are f*cked.

    So I'll pick up some new bearings, and have a punt at chucking them in myself with the workshop manual in hand, if I can find the bastard. Anyone who I've ever seen clutching a spanner can expect a telephone call when this operation gets underway.

    So yeah, that's where we're at. The engine may be permanently underpowered but we can live with that. The handling *must* be corrected and I'll have a crack at sorting it out.

    Over n out
  2. well just ask. may be a 'lets fix a dodgy bike day' as for steering dont under estimate the crappy effect of wrong tyre preseure or 'squared off' tyres
  3. Yeah Woodsy we just replaced the front tyre and the rear, while not perfect, has plenty left in it.
  4. ok, i'll let you off ths time :) just thought i'd mention it cause i've been caught before with a squared off tyre. weird feeling
  5. Sounds like steering head bearings to me. Hardest part of the job is getting the old bearing cups out of the frame. With a workshop manual you'll be fine.
    Be sure to tighten the new bearings right up when you first install them, turn the handlebars full lock quite a few times and then reset the bearing tension. You do this to help seat the new bearings. You will also have to readjust them after say 500 kms. The bearings should provide a light drag at the handlebars, most manuals have you adjust them a little too loose, but tapered bearings can handle preload.
    ALso check your front wheel bearings for wander issues, especially in corners. Bad front bearings can cause a weird feeling on initial turn in on a corner, and weirdness on bumps in corners. The worn bearings allow the wheel to slide sideways on the axle, which is a barrel of fun!

    Regards, Andrew.
  6. Loz - if you haven't done so already, whack a post up at this Across forum. I reckon you'll get some useful info quicksmart.
  7. Have you done a leakdown pressure test or a compression test? Maybe the engine is just severely worn?
  8. Loz.
    What are Cheng's thoughts on NOS! :LOL: :LOL:
    Sorry, just had to. :wink:

    Did you get the carb's balanced?
  9. Loz,

    Don't discount the throttle sliders as the cause of the bikes sluggishness...you remember how I was saying that Shans bike was shockingly slow and had fcuk all go low in the rev range?...well I did the 4 sliders on friday and while they did not look bad I thought buger it it 's only a few bucks so I did all four...it feels like the bike has another 50cc...no bullshit it feels like a totally different bike, idles alot better, more torque at low revs and is just more perky everywhere.

    Do these first before you drop more money/effort on the thing...and try not to spend more than $100 on repairs...after all you don't wanna spend more on an Across than they are worth :p
  10. check that the arrow on your air box intake is pointing forward and the air box is securerly sealed to the carbis or you could have a big lack in performance.
  11. Mmmmmmmmm don't think so. It's only 25k old, and looks clean throughout.
  12. NOS indeed. She's giggling at the mere thought of it. Or that could just be from inhaling it...

    I don't think he balanced tha carbs... But the engine's running beautifully smoothly - it's just power-free.
  13. Yeah I've got new slide holders on order, I'll do 'em for the hell of it but I don't expect a massive improvement. They're just not rooted enough. Still, we'll see, maybe it'll do something.
  14. Yep that was the first thing Grobby wanted to check... So we pulled the tank off under the streetlights at Firday coffee so he could have a perve... All good.
  15. I haven't heard anything about grey-import Acrosses having less power than Suzuki Oz imports.

    But as I said, see what the guys on the Across forum have to contribute, because Greg (in particular) is a bloody guru on the things.

    Good luck. :)
  16. OK Gromit I've signed up and once my posting privs are sorted I'll pop something up there.
  17. Loz you have got to compression test this sucker.Thats going to automatically illiminate rings and/or valves.I have a compression tester your welcome to borrow or come to my place and use.PM me and we can work something out this weekend if you want?As for the steering,have you raised the forks of the ground,put the equivalent of a dial indicator on the front wheel,and see if youre front wheels tracking true?
  18. Righto Ken I'll take you up on that compression test - not sure when will be good but my people will call your people.

    I'm reasonably sure about the steering head bearings, the symptoms are exactly the same as what I've heard others describe, and Charlie at Turn One had the same thing to say. It's a corrosion issue I think, happens to a lot of grey imports in sea transit.
  19. Veeeerrrrrryyyyy cheeeeeky.