bluegnu Posted February 2, 2017 Report Share Posted February 2, 2017 HiI'm sure these are familiar problems with older bikes... Recently found an old 2004 Sherco 250 to give a go, it's tatty but mechanically looked serviceable. I've ridden it a couple of times, just getting a feel for it for an hour or so and to begin with it sounded good, deep and throaty and idled nicely. It has however been very temperamental to start, the original kickstart lever snapped to begin with and I'd put the difficulty starting down to a cold, flooded engine. But after a day of unsuccessful kicking with a new lever, lots of backfiring and sever flooding, I thought something must be wrong... I took the carb (Dellorto) off and it looked clean and in good condition, but looking in reed cage I could see that one reed had split and dropped across the cage. So, I replaced the reeds and imagined this would cure the problems starting and improve the performance. Spent another half day of frustrated kicking, adjusting the carb idle/mix and could not get it to run for more than a few seconds. No matter what I did with the mix screw, it would 'bog down' with anything more than a fraction of throttle and not turn over without the choke or 1/8 of accelerator. Finally the kickstart spring bust, so now I'm waiting for the replacement to arrive. From what I can tell, the first place to check is the carb jets aren't blocked, the spark plug is new (cleaned it a couple of times after flooding), compression feels good, tiny side movement in piston from feeling through exhaust, new airfilter. Any advice would be greatly appreciated. It's great to read so much support here. Happy riding! Sam Quote Link to comment Share on other sites More sharing options...
heffergm Posted February 2, 2017 Report Share Posted February 2, 2017 Based on your part of the description that said 'No matter what I did with the mix screw, it would 'bog down' with anything more than a fraction of throttle and not turn over without the choke or 1/8 of accelerator.', I'd say you've got a clogged pilot circuit. Pull the carb apart, blast the internal carb passages (not just the jet) with carb cleaner, and put it back together and see if that makes a difference. Quote Link to comment Share on other sites More sharing options...
bluegnu Posted February 2, 2017 Author Report Share Posted February 2, 2017 Thanks Heffergm - I'll try that again and update. I'd blasted it pretty well when i took it off, but perhaps I'd pushed something in there. It hadn't got an airfilter when I got it! Quote Link to comment Share on other sites More sharing options...
bluegnu Posted February 2, 2017 Author Report Share Posted February 2, 2017 (edited) In the meantime, I'd drained the coolant as I thought it was overheating (there was more than i'd expected to see), but when I drained the oil it was a milky emulsion: So have ordered pump seals and see if that helps. It did seem to be running very hot, fan was intermittent but was coming on and then I got some knocking after a while. Edited February 2, 2017 by bluegnu Quote Link to comment Share on other sites More sharing options...
bluegnu Posted February 2, 2017 Author Report Share Posted February 2, 2017 Also the exhaust has burnt the radiator hose and scorched the cylinder head! Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted February 2, 2017 Report Share Posted February 2, 2017 (edited) I would check the ignition timing while you're at it. Edited February 2, 2017 by 2stroke4stroke Quote Link to comment Share on other sites More sharing options...
heffergm Posted February 2, 2017 Report Share Posted February 2, 2017 If its been run a long time without an air filter, I think you're wasting your time. Unless you want a project, you're better off cutting your losses and getting something that was reasonably looked after so you can actually ride. Quote Link to comment Share on other sites More sharing options...
eyore Posted February 2, 2017 Report Share Posted February 2, 2017 1 hour ago, 2stroke4stroke said: I would check the ignition timing while you're at it. I also have a somewhat cantankerous 2005 Sherco and also broke the kickstart lever! Anyway I found it was much easier to start after retarding the timing. Quote Link to comment Share on other sites More sharing options...
tshock250 Posted February 2, 2017 Report Share Posted February 2, 2017 I would check the stator, well know weak spot on this bike, some people have had several replacements, I had one also failed, bad starting and/or erratic starting are symptoms. As is running for a short while until hot, then stopping and refusing to re-start. Quote Link to comment Share on other sites More sharing options...
copemech Posted February 3, 2017 Report Share Posted February 3, 2017 Use a strand of copper wire to pass through the pilot jet. Quote Link to comment Share on other sites More sharing options...
bluegnu Posted February 3, 2017 Author Report Share Posted February 3, 2017 Thanks for all your feedback guys! I'm hoping it it's not a lost cause, the guy I bought it from said he'd just put it back together after sitting in a garage for 6+ months. I'll give this a go over the weekend: Clean carb thoroughly Change pump seals Gearbox oil (450ml) Coolant to top of fins New iridium spark Check timing (if poss without tools) If the rad hose is burnt through, does anyone know if I can modify 08-09 kits to fit 2004? Such as the SFS silicone set on ebay. I'm guessing the exhaust should not be touching the hose or cylinder. Quote Link to comment Share on other sites More sharing options...
copemech Posted February 4, 2017 Report Share Posted February 4, 2017 The coolant hoses are allways very close. Just get a new one, will last another decade or so. Quote Link to comment Share on other sites More sharing options...
tony27 Posted February 4, 2017 Report Share Posted February 4, 2017 If I remember correctly the hose from the pump isn't quite right as supplied. I suggest you give Chris at Splatshop a call & see what he can suggest, has always been very helpful as a lot of people on this site will agree Quote Link to comment Share on other sites More sharing options...
bluegnu Posted February 8, 2017 Author Report Share Posted February 8, 2017 Argh, it still won't run more than a few seconds! Starting easily on the whole (could be the better spark), but will only tick over for a few seconds before just stopping and won't take any revs. Backfiring pretty badly too. On one occasion I had it idling for perhaps 30 seconds, I noticed the exhaust front pipe got so hot it was glowing red (in the dark), this can't be normal!? Can a dodgy stator cause the engine to severely overheat like this? Flywheel puller and tools are ordered, so I'll check the timing once I can get in there. I guess there's no way of telling if the stator is on the way out without a multimeter(?), any advise on how/what to measure would be greatly appreciated. Thanks again Quote Link to comment Share on other sites More sharing options...
bluegnu Posted February 8, 2017 Author Report Share Posted February 8, 2017 (edited) I'll be praying it is something as small as the woodruff key Oni Nou - would the flywheel be loose on the crank though if that was the case? I'm rereading an old post re stator readings (i've no idea what to look for). Ah, just found full details on SplatShop stator exchange listing Edited February 8, 2017 by bluegnu Quote Link to comment Share on other sites More sharing options...
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