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Everything posted by AlanC

  1. Anybody know which way up the shock in a 95 JT 250 should be, or does it even matter. I think when I removed it, the blue damping adjuster was at the top of the shock, and the preload adjuster at the bottom. Is this correct. And has anyone rebuilt one of these, ie. drilled and tapped the body of the shock to replace the oil? Thanks in advance, Alan.
  2. Well thanks everyone for all the help. I got the tyre on properly, did a trial today and the tyre was fine. Turns out the main problem was not using proper tyre soap, beading wax, whatever you want to call it. I bought some, put a ton of it on the tyre inside and out, and it popped at about 60/70 psi I think, with the valve stem removed, after 3 goes of pumping it up. Pity I wasn't good enough today to warrant a new tyre. Ah well, maybe next time. At least it's bedded in now! Thanks Alan
  3. Thanks for all your replies. Made a few calls today, and the general consensus is that I had enough pressure, and just need a ton of proper tyre soap, and a bit of time for the bead to work itself on. Its an old wheel, so more patience will probably help too. Alan
  4. Thank for the replies folks. I was using a proper air line with a big compressor so no shortage of air, and I had the valve core removed too. Thats why I was wondering why it wouldn't pop. But I didn't have the nerve to go to 110 psi. and I didn't try WD40 either. But I did try bouncing the tyre on the ground with 70 psi in it, but it didn't work. Thanks Alan
  5. Hi Folks, Just looking for an easy solution to this problem if there is one. How much pressure is it safe to use to get a new trial tyre onto the rim? Rear tyre, tube fitted due to air leaking at the spokes even though a seal is fitted, lots of soapy water used. Used 70lb of pressure but last bit of the tyre still won't pop onto the rim properly. Tries valve out and in, and tried using the rubbery bead seal thing that should pop out when the tyre is on. Plan B will be to refit the old tyre if I can't figure it out! Thanks Alan
  6. Thanks for the replies folks. Testing the shock with no spring on it would be good idea. But I wouldn't know how much damping it should have in the first place. It's old, and I'm just pottering about on it for fun at the moment. I've did it up a bit, so I'll try it and if it has no grip and can't get up the hills, I'll know its the shock as its the only thing I haven't done.
  7. Hi folks, Can someone tell me this.. Do shocks wear out on a trials bike? Or since the one I have would need to be drilled, are they like a standard road bike and just fade a bit. Or is the damping that important on them. Its an old Gasgas Thanks
  8. AlanC

    2006 Scorpa SY 250

    Your tyre might be rubbing on the bolts because the wheel is not set straight in line. Just coz the rear wheel adjusters are on the same marks doesn't mean the wheel is exactly in line. You could also get a hacksaw and shorten the bolts.
  9. Surely that timing rule is backwards. Would it not be easier to add points if you're over the time limit? Then chances are that nobody will ever get a zero and the maths would be easier. And there would only limited advantage to putting your foot down to speed up, coz you would still be getting points.
  10. AlanC

    Engine removal

    Before I start pulling things apart, is there any particular order I should try to remove a GG engine from the frame to weld a bit on it? Airbox, exhaust and carb already off. Should the bolts come out in any particular order? Its 26 years old now so I don't want to do something silly and break something that I can't replace.
  11. Thanks again folks. I was just checking to see if we were getting value for money or not. Limiting factors will be lack of talent and balance. It will just be for a bit of fun.
  12. Thanks for all the info folks. 280 should be ok power wise. Used to driving big bikes on the road. And I was hoping that a 280 would be under less pressure in general over time than a 250. Not a huge choice of cheap stuff at the moment though.
  13. Thanks for the reply ChrisCH. There seems to be 2021 stock in a few dealers now, so hopefully that will filter down the system soon.
  14. Hi Folks, Any idea what a 20 year old Gasgas 280 is worth now? Assuming everything working on it. Did they have any major problems that would be expensive to fix? Or anything to be looking out for? Just looking for a general idea for a friend looking to get into trials, and don't want him to get ripped off. Thanks in advance
  15. Agreed. I'll have to fork out for new tyres soon. Thats if I can find somewhere to use them soon!
  16. Thanks al orange, you have a point. If you think about something long enough, you will find an excuse other than your own lack of talent 🙂
  17. I would agree with the weight transfer theory Baldilocks. But I was thinking more about the shock working being delayed on acceleration while it waits for the play to be soaked up. I did have a problem with it spinning up before, but it might have been the worn tyre. The edges of the blocks are all worn in one direction. I'll just have to put up with it for now. I'm sure the bike is better than me anyway.
  18. Sorry for the confusion lads. When I was looking at the 10mm of play, I was pulling the rear of the bike off the ground by hand, so not 100% accurate, and so it would include the sag in the shock too. But you can feel the change from one to the other as you lift it up, and feel it on the swingarm with the bike on the home made paddock stand that I have. I think I need to take it apart again to find the root of the problem. Anyway, its an old bike so it won't be perfect anyway. As it is, would it be causing the rear wheel to spin when taking off from a standing start? I'm not worried about dropping off heights or any big stuff. I'm not that good. And I'm only learning all the terms you use to describe all these moves. I'm happy enough to stay on the bike. One of the skills I like the most is learning to find grip where there is none by feeling clutch and throttle biting and using yourself as a counterbalance to shift the weight around. Maybe I'll enter a competition this year, if any go ahead.
  19. Thanks for the reply. I have replaced all linkage bearings bar the swingarm bearings/bushings and one one the suspension bushings because it was out of stock. Everything is moving smoothly, but there still seems to be about 10mm of play at the wheel (no play in wheel). I was thinking, if you try to hop the back wheel, the play will make it really difficult for the wheel to leave the ground at the top of the stroke. I think I found where the play is still there, and I'm wondering if the bolt inside the bushing could have worn down a bit to cause this. Or could the shock bushings wear out too? I'm just wondering because if you had that much play on a road bike, it would be like driving a canoe. Off road stuff is not my field of expertise, as you might have guessed.
  20. Question for the technically minded. What is the effect of play in the rear suspension linkage and the shock mountings? Does it affect grip, or just delay when the power kicks in? Does it matter after the chain has taken up slack? And lastly, what is a normal amount of play with everything working correctly? Thanks in advance.
  21. Looking at a few specs for new bikes, geometry doesn't seem to be something they promote. Maybe it can vary a lot due to soft suspension. I'm just hazarding a guess. Anyway, they're not like a super bike where geometry can make a big difference if its wrong.
  22. AlanC

    Spark plug

    Thanks b40rt, all info appreciated. I did use the choke to start it, but didn't need it on for as long. And I always turn the petrol off when its parked. Bearings, bushings and brakes done, so time to get the cobwebs off me now!
  23. AlanC

    head gasket

    Fan seems to be kicking in a bit more often than I remember on my bike (been a few years). Would this be a sign of a head gasket on the way out? Not boiling or emptying the rad, but the inside of the rad cap looks a bit dirty.
  24. AlanC

    Spark plug

    Update on the spark plug issue. Ran the bike round the yard yesterday evening for a while. No high revs really. Checked the plug (5) this evening when cold. Looks like its burning a lot cleaner than the 6 that I took out. Started easier too. Didn't really need to use the choke at all, and it was cold. Hope this info is of some use to someone else.
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