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My GSX250 project

Discussion in 'Your 250cc Projects' started by geesex66, Nov 24, 2013.

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  1. Th3_Huntsman

    Th3_Huntsman Senior Member Contributing Member

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    Sounds silly have you tried choke and start ya bastard? without the airbox you're tune will be all wrong

    Have you checked if the engine is making compression after putting it back together? there is a handy new guide in tech tips
     
    Last edited: Mar 26, 2014
    Th3_Huntsman, Mar 26, 2014
    #41
  2. geesex66

    geesex66 Active Member

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    Yeah choke I've tried a few different settings. Before I rebuilt it it was completely fused in one place anyway...

    Sure yes, without airbox and with new pods and new silencer I would expect less than optimal tuning. But it should start, no..?!

    No, haven't tried start ya bastard yet. But that's just butane right? More designed for the case where an engine turning over a few times <might> temporarily mask other issues preventing an engine from operating normally.

    Thanks for compression tip, will check that next
     
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    geesex66, Mar 27, 2014
    #42
  3. Ben Mulligan

    Ben Mulligan Well-Known Member Premium Member Contributing Member

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    Well technically yes it should start, unless the pilot screw is wrong. Did you reset the carbs by the book? They say not to mess with the pilot screws, but I reset mine to the standard(ish) 2 1/2 turns and that helped. The only jets I changed were main jets which don't help with starting the bike.

    Mine did the same thing, what I did was put my hand over the intake (fingers spread a touch) on the carb and that amount of negative pressure actually started the bike. Admittedly the choke was all the way out and I had to fiddle with the idle adjuster on the carb but it worked.

    Have you checked that the spark plug is wet? Maybe the fuel isnt getting into the chamber?
     
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    Ben Mulligan, Mar 27, 2014
    #43
  4. kiffsta

    kiffsta Senior Member

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    Post from geesex66

    set the pilot screws at two turns out. I think its only for US models you're not supposed to mess with them.

    With a bit more persistence, and with choke fully opened, it started.

    Two problems: if I hold my hand in front of the left hand exhaust port, I can feel air pressure. So that means there' s a leak between the cylinder had and the left hand exhaust. I might be able to tighten the nuts more if I get an extended socket of the right size. The right one seems OK.

    Second problem is there is quite a lot of oil leaking from between the crankcase and the cylinder block around the front left corner, see picture. I'm dreading having to take the cylinder head off again. Wondering if I may be able to get away with some liquid sealant around the area. That would mean just edging the cylinder block up away from the crankcase for a bit, and hopefully not having to let the pistons out of their bores.

    Anyone have any tips on liquid gasket fixer or similar issues?
    gsx_gasket_leak.png
     
    kiffsta, Mar 30, 2014
    #44
  5. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    I have done similar using Permatex. Be sure to wash with petrol or thinners between gasket faces before applying.
     
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    Murdo, Mar 30, 2014
    #45
  6. geesex66

    geesex66 Active Member

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    I am an idiot. Once again.

    So I stripped the top end down again. I took the cylinder head right off, but not the block. I raised the cylinder block off the crankcase a few centimetres, and could see the problem straight away. Where the oil leak was I had left a bit of old gasket on the crankcase mating surface. Tiny, just a millimetre or two in size. Cleaned it up and put it all back together. No permatex. No leak any more.

    For the exhaust leak I put a little copper permatex around the port. Also was a bit more careful with tightening the bolts at the front end. Also no leak any more.
     
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    geesex66, Apr 4, 2014
    #46
  7. geesex66

    geesex66 Active Member

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    Once again apologies for the delay in updating my project. Sadly I've had to leave Sydney, now back in the UK. I gave the bike to a friend, and he's going to continue the journey. He's been riding a lot longer than me, and already has two (much newer) bikes, but doesn't have much experience with maintenance and mechanics. But he's up for the challenge ;)

    So the bike looked ok in the end. I didn't get a chance to update the bars, headlight or meters, but I was reasonably happy with the tank, seat, exhaust, indicators, rear brake light etc. Will all be better second time around :cool: And considering my workshop was a mosquito ridden underground car park, and a balcony - I think I did ok. Learned a lot and had a lot of fun, despite a few moments of intense frustration!

    I never really solved the issue with the carbs/pods. I managed to ride around the block a few times, but it would always die pretty quickly. In a panic towards the end of my time in Sydney I tried to find an experienced mechanic who could help me. I was lucky - I came across Paul at Drifter Bikes:

    http://www.drifterbikes.com/

    Paul couldn't help me directly, he's a busy guy (understandably). However he's very kind and answered all my questions and gave some great advice. He's done the airbox to pod conversion thing many, many times. He offered some great ideas, tips and tricks. The most important thing he said, and I haven't seen anyone else mention this anywhere, is this:
    • Be prepared to go larger and smaller on jet sizes
    It sounds counter-intuitive - the normal logic is that you must go larger to counteract the less restrictive pods. However Paul found that on some bikes running would get smoother and smoother by reducing the jet size. He offered to lend me his collection of jets so that I could try them out on my bike. Which I did - but in the end he only had one size of main jet that fitted the carbs on the GSX, and that one didn't help. And he had no pilot jets at all, and my problems were starting and idling.

    He also said that it may not be always possible to get the same level of performance out of a podded engine. Sometimes you have to be prepared to have to accept 90% or so.

    So goodbye from me, and my GSX. It was very sad to see it leave on the trailer. Thanks everyone for your advice, support and encouragement. Best of luck with your bikes, and ride safe.

    IMG_4314.jpg
    IMG_4195.jpg IMG_4196.jpg IMG_4197.jpg
     
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    geesex66, Jun 11, 2014
    #47
  8. risky

    risky risky

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    looks good and hope you stay on the site and continue your interest in bikes.
     
    risky, Jun 11, 2014
    #48
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    I have often fitted smaller jets to carbs. I do not see anything counter intuitive about it at all. As the intake and exhaust are tuned to match the camshaft timing, the engine becomes more efficient at the required rpm. Rather than just blowing unburnt fuel out of the exhaust port or spitting it back along the inlet tract. In fact I consider it a technique of tuning. However, I am loathe to post this sort of thing on forums as the general consensus is "bigger is better". Much like the bigger bore is better line of thinking.
    cheers
     
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    maelstrom, Sep 10, 2014
    #49
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