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Post by Down&Out on Nov 7, 2011 19:01:01 GMT
Hello there,
Got a gp100 that ive had for ages, and its only probably been working and on the road for a week in total, and even then it was misbehaving.
Im just trying to get it running so i can get it back together, and possibly sell it. I like bikes, but i dont trust the thing not to cut out and i'd rather get a honda!
Ive changed the stator, points, coil and condenser, which has got me the spark back. Ive also gapped the points, and its getting fuel and two stroke but its not starting at all. Showing no signs of doing so anytime soon either. Spark appears good and blue, so im not sure.
Any ideas? even easy start isnt working!
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Post by dungbug on Nov 7, 2011 19:54:46 GMT
Hey Jono, did you do a compression test? If you've got a good spark & fuel it should fire if the compression is good.
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Post by Down&Out on Nov 7, 2011 20:14:40 GMT
I havent done no, i assume i have to buy something to do that?
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Post by TerraRoot on Nov 7, 2011 20:35:57 GMT
pop the exhaust off and have a look at the piston ring/piston if there all melty... theres your problem! you do have the airbox on? bugger to start unless it's all there.
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Post by Down&Out on Nov 7, 2011 20:43:06 GMT
I do have the airbox on yeah, i'll check the piston though, its a good idea!
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Post by jawathemutt on Nov 8, 2011 14:22:50 GMT
timing may be out, turn it over to tdc look at the cam lobe that operates the points should be just be before the the pointy bit of the lobe,,on the compression issue put your thumb over the plug hole press down to seal it and kick it over should blow your thumb away
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Post by Down&Out on Nov 13, 2011 17:02:01 GMT
Right, been faffing with this today and im sure i can hear a compression leak, Had the exhaust off and on compression stroke it appears to leak, though im really not sure. Whats the best plan of action, new rings and head gasket and see if that sorts things?
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Post by TerraRoot on Nov 13, 2011 20:15:43 GMT
if the piston looks like this: www.slipstreamperformance.com.au/store/images/pistonblowby_234.jpgi.e. the black above the rings is as black as the black below the rings, well thats new rings time. if there okay go back to checking earths. then try if the air side of the crank seal is actually sealing, bugger to detect, try a bit of thick oil on it to temporally seal it up. the oil side seal is easy to diagnose, it should smoke like crazy when running and your gearbox oil will disappear. try diluted washing up liquid around the out side, around near the head gasket, base gasket, crank case, should bubble up if there is air escaping as the engine is being turned over. this guide is useful, even though it's for more performace motocrossers. www.slipstreamperformance.com.au/store/index.php?cPath=4_567
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Post by Down&Out on Nov 13, 2011 20:39:29 GMT
I must admit, the piston did look a bit like that. Piston and rings set is actually cheaper than just new rings on ebay, might just get hold of that and change the lot, Worth a go?
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Post by TerraRoot on Nov 13, 2011 20:51:27 GMT
can you get a decent all round picture? loath to tell someone over the internet to spend money where they might not have to. Has the disc valve been messed with at any point? it could be out 180 which would bugger things up. I assume the spark is timed up right yeah? if it's a light brown under the rings don't worry, thats not a huge problem.
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Post by Down&Out on Nov 14, 2011 0:26:59 GMT
Funnily enough my dad said "could it be 180 degrees out?" not sure what a disc valve is though.
Piston did look black in places, might see if i can get a picture. Ive timed it yeah, whether its right i dont know but i know that i did it a few times and when it sparked best, i left it.
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Post by TerraRoot on Nov 14, 2011 8:27:40 GMT
part 21 here is the disc valve www.cmsnl.com/suzuki-gp100-1978-c_model13378/partslist/FIG-04.htmlif its out a lot, it won't run, if its out a bit it'll run very badly. not sure if this will work but i'd try, taking the snorkle/airbox off the carb and put your hand over the mouth of the carb. Get someone to give it a few kicks over (3-4) if you palm gets wet with fuel and you feel some suction then the disc is probably ok. If it still won't start even with easy start that leaves the crank seals and the spark timing. and mostly it should start with the crank seal busted anyway, just dangerously lean.
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Post by dungbug on Nov 25, 2011 15:16:21 GMT
Any joy with this chap?
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stueyt
Retro Apprentice
Posts: 12
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Post by stueyt on Nov 25, 2011 17:29:55 GMT
Just a thought you said you have had the bike a while and only used for approx 2 weeks, have you changed the fuel on it as it does go off really quickly, I found this out on a VFR400 I once owned, I changed everything and spent a small fortune, when all it should have cost was £5 for fresh fuel.
Cheers,
Stu.
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Post by Down&Out on Nov 28, 2011 15:00:39 GMT
No luck with this yet, dont see how a simple two stroke that used to work, can be so much trouble. The fuel was ok, i drained the tank recently and used it in my melody to get to the petrol station and it was fine, but i'll put fresh in and see where that gets me.
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