Mech

When thermostats have been in service, and then the coolant gets drained and they remain empty long enough for the thermostat to dry, the thermostat can jamb closed sometimes. I've seen it plenty of times. Even brand new ones can stick on their first run. Once they have opened though they seem to come right. Mostly if you are watch them and be ready to take some sort of action like drive or cool the radiator with a hose, they will come right after they get to a higher temp than they are meant to open at. It seems like it takes time more than temperature, but then once they have opened and got over the dryness they are ok.. That said, thermostats are a part I reckon should be changed every few years as a preventative bit of maintenance. They are too cheap, and critical, and can cause so much damage for the small cost of a thermostat, that it's best to change them before they play up. The manufacturers these dayssay after two years, but I reckon up to four years.. Or when the coolant's being changed.

It it's a carby model then the first thing I'd do would be use the drain screw on the bottom of the carb and catch what comes out looking for water, then I'd turn the tap on and make sure plenty of fuel was getting right through the tap and filters and into the carby at a good rate. If you have a timing light you could connect it to the bike and watch it when the bike falters looking to see the spark wasn't dying out. If you don't have one then... If draining the fuel and checking the flow didn't change things then I'd take the carby off and strip it right down, entirely, and clean every jet and passageway, and then check the seals where it fits onto the engine as I was putting it back together. It will probably be right after that.

ALL ?... TRIED ?...

You'd be right about that Krominator.. Machinery doesn't like being idle..

Manuals are up the top of the page in "More", then "service manuals", then when you get to the new page you go halfway down the page and on the right you choose your make. You have to make ten posts before you can download though.. which is no great hardship.. You're up to 2 already.

If your bike's only stalling at idle Dpd, then it will be an air leak or the idle mixture isn't right.. as Dave says. It's possible the idle jet is dirty, or the float level a little low. If it's only at idle though it won't be the emulsion tube that Dave mentions(the brass tube with small holes in the side), or the slide needle setting, those two only effect the mixture from about 1/4 to 7/8 throttle open running. The first and simplest thing to try is adjusting the mixture screw. If it adjusts from a bit rich to a bit lean in about a half a turn then things are probably ok inside the carby and that's all you need to do. If you can turn the screw more than about a full turn in either direction without it having the desired/expected effect then the carby needs cleaning or the air leak finding.. It's also possible to get that symptom though if the carby breather is blocked.. probably a good idea to check that first up even though it's a rare problem. In general though, to people that are cleaning their carbies for bad running, especially bad running under power, it is essential to fully strip the carb and take that emulsion tube out and clean it. If we only do a half the job of cleaning the carb, and things don't come right, then we don't know whether it is the carb or something else.. If we clean the carb really thoroughly and check the rubber manifold for splits, or damaged O ring or warpage if it's an aluminum bolt on type manifold, then we know we have eliminated that as the problem and we can start looking at the fuel tap or pump or electrics or mechanical faults. If we can't diagnose problems absolutely, then being thorough and eliminating the possibilities one at a time is the next best thing.

Have you done a tune up on it ? That would be the first thing to try. Check the air and fuel filters, drain the carby looking for water, check small hoses are on and not split or blocked, check the fuel tank breather, check the spark-plug condition and the valve clearances. Check the choke is working, and going right off properly. Adjust the idle mixture. If you have a timing light you could check the ignition timing. Then, is it smoking badly ? Is the smoke black or grey/blue ? Try and ascertain when it's playing up whether the exhaust is still flowing.. A piece of rusted metal in the exhaust could be blocking things temporarily.

At least it wasn't engine oil !!

That solenoid might be running on/at a duty cycle, so it's voltage is being constantly switched on and off. Digital gauges aren't very good at detecting that. That might be why you were getting varying voltages at it. The chart near the beginning of the diagnosis section shows the causes of one, two or both clutches having low hydraulic pressure. I'm not sure what sort of insights you are after about that but if you are a bit more specific about any theories you may have I will try to figure out if they are possibilities. The 1st orifice control valve they mention as a possibility for low pressure to the second clutch is a shuttle valve in the hydraulic valve body. Shuttle valves have to be worn right out, or rather the aluminum housing they slide in has to be worn right out, before they cause low pressure.. Normally they don't move because they are jammed by crap, or they break a spring and move one way and stay there.. In your case it's most likely that a sealing ring either in the piston that applies the clutch, or on the shaft that supplies/feeds the pressure, will be worn or broken, or, the clutch is so worn that it's piston is moving to far and allowing it's seal to get almost out of it's bore, or, the pipe has a split in it which could allow a loss of pressure down to a certain level. There is a centrifugal clutch for taking off, and if that was worn it would cause the high revs take off. The two actual clutches are used for shifting gears and since it seems to work right, with no slip once the bikes going, it would seem they do grip well enough despite the low pressure to No2 clutch. When it goes into a gear at idle and stopped, one of the shift clutches lock up to engage a gear and then doesn't get slipped again till it's time to change gears. If one of the two clutches was so worn, or had such low pressure to allow slipping, I'd expect that slipping to be at gear change and under power. I haven't had one of those apart but I've had the older models with a centrifugal and manual shift clutch apart and they are easy to work on. The only complication with this one is that it has some hydraulic hoses going onto the cover. The cover's easy to get at though so it should be an easy job. I'd definitly be pulling that front cover off and inspecting the centrifugal clutch as the main suspect, but I'd check the pipe and the other two clutches at the time.. and their sealing rings.

If the cam thingy the cables attach to has a reasonably strong spring you could run it with only one cable. In the two cable setups they have a cable to return the throttle to idle. It's a safety feature, usually on competition bikes that get used at full throttle a lot. Some though have a slightly weaker return spring than the normal one cable carbs and you need to be sure your cable is in good condition and routed correctly, and that your kill switch works..haha. There is a good chance though that that carby isn't really going to be suitable for your bike. I'd consider returning it and trying for the right carby for your bike. That been said though, almost every after-market carb is tuned in a generic sort of way that doesn't suit any particular bike or market and they always seem to take a bit of retuning.. So.. why don't you just repair your old carburetor.. Most of the time they just need a complete strip down and thorough clean out.

Yes Gw, it is always best to try the simplest things first .. before we make things complicated and confusing by fiddling around.. haha. I don't know how many times I've seen problems caused by "mechanics"..

Haha... You must be near there now..

Simplest thing to try, and which often cures the problem, is to tap the side of the carby with a screwdriver handle.. A few sharp taps often jiggle the float free and once it's up and working it will be fine till the carby empties again. If that doesn't work, use the drain screw and empty the float chamber, then turn the fuel on and start the tapping. If it still doesn't cure the problem then it's probably got dirt under the float needle, or a leak between the needle seat and the carb body, or a holed float(rare these days though).

No. It might have an adjustment though..

Have you checked the wheel bearings ? You could have a seizing wheel bearing, or, it could have play in it allowing the 4wd hub to engage somehow.. I'd jack it up and grab the wheel top and bottom and try to rock it in and out from the bike top and bottom.. That's push the wheel in at the top while pulling at the bottom, then pull at the top and push at the bottom. Then rotate it while putting twisting load on the bearing using the same sort of technique and see if it feels rough, then give it a fast spin and listen for any rough noises.

Have you looked for a service manual in this site ? Up the top in the "more" link you will find manuals.. Go to manuals and then halfway down the page on the right you choose your make.

What Tiha says is generally right.. most aftermarket carbs do need re tuning. But.. you say it's "just started" running bad, so the question has to be.. how long has the chinese carby been on there, and did it use to run alright with the chinese carb.. or have you just fitted it and now it's running bad ?

Have you read the service manual ? Is the dash flashing ? Have you tried getting the trouble codes out of the dash ? Are you sure the new battery is good, and fully charged ? Have you checked the charging is charging, and regulating ? Are you sure you didn't momentarily connect the battery up backwards, or try to jump start it but connect the jumpers backwards momentarily ? When you say it won't shift gears in forwards, do you mean it moves but only in one gear, or that it won't go into any forwards gears ? Just to clarify before I start looking in the books. And in reverse, it moves ? but the engine runs badly or just has no power ? If the motor is running ok, but has no power in reverse it might be a gearbox/control problem, or it might be an engine problem..

Oh yeah we always need to remove the jets to clean them, especially that emulsion tube, which is the brass tube the main jet screws into and that runs up to where the slide needle drops down into it. That emulsion tube has small holes in the sides of it that need cleaning out, and the cavity it fits into in the carb body needs cleaning out too. The float needle's seat needs taking out and checking for dirt and that it doesn't have a bad sealing O ring or washer. If it still plays up after a real careful clean then you should check the fuel pump is working correctly, and that the charging system is working and regulating.. While you have the carby off you need to check the rubber manifold it pushes into for splits too.

I did some more reading and the 1st orifice control valve, which I thought was a solenoid, was actually a shuttle valve in the valve body, and so that's unlikely to give low pressure, it will either move or not, and I think it must be moving for there to be some pressure to the clutch.. I think we can ignore that one. That leaves the pipe or the clutch pack.. or the centrifugal clutch. If that solenoid doesn't do the trick(and I'm dubious), then I think the first thing to check is the centrifugal clutch, then the shift clutch and then the pipe.. I'll keep an eye out for the progress. Good luck.

Ok.. Perseverance always wins. Giving up never does. I finally found the right book. And, looking through the diagnostic section I see there are five things that can cause low pressure to the number two clutch. Shift valve. 1st orifice control valve. 2nd shift clutch. Feed pipe A. Oil guide pin. Of those five though, only three can cause a problem with the oil pressure to number two clutch, but not number one clutch. Since number one clutch pressure is right we can conclude that it has to be one of those three.. or the centrifugal clutch is worn which would be the first thing to check as you are pulling it apart. The three possible faults that only effect number two clutch pressure are.. 1st orifice control valve. 2nd shift clutch. Feed pipe A I think I'd check the control valve first if that's easy to get at, then start pulling the front cover off.. I'm not sure where the feed pipe is but I presume it's in there. I'd check the pipe and the centrifugal clutch and the number two clutch for wear, or defective seal rings that feed the hydraulic pressure to the no 2 clutch.

Morning.. Well I haven't been able to find a manual for that model. The manuals in this site keep getting within a few seconds of completing and then fail.. repeatedly. I've been having a read in other manuals though and looking at the parts lists. If one of the clutches is worn out I'd expect it to slip in more than one gear.. if you could get it to load up enough without changing itself down that is. In cars a way to detect slip in a clutch is to pull it down manually at high revs/speed and see if it's slow/slippy feeling or doesn't brake the vehicle sharply. From my reading, if it's changing gears ok, and the only symptom is the over revving at start, then I'd be suspecting a worn clutch. If it was electrical or valve body problems then I think it would have other problems, not just a slow take off. As you are suspecting though, it seems logical the throttle position sensor, or the rev detection calculation could cause it.. But I'd suspect then some of the other changes would be at the wrong speeds. I think if it was me I'd be pulling the clutches out and inspecting them.. It's not something I'd like to do without a definite diagnosis normally, but in this case I think it's the pragmatic thing to do. I see there's also a centrifugal clutch, which will be for taking off.. It would be best to check that first though..

Not much sticks to plastic too well.. I think I'd have done a bit of a plastic weld with some scrounged up plastic strips and a small soldering iron..

That's strange about the filter being dry Gw.. Have you checked it since in case there's a blockage. That filter should be under pressure and so the oil should get through, but some bikes have a pressure bypass that lets oil bypass the filter if it gets too dirty, That bypass valve could be stuck open, or the filter might be causing an air lock.. It shouldn't, but... On some manuals they say to undo a bolt in the center of the filter cover and bleed the air and check the oils getting to there after an oil change.

I'd try the filter without the lid on the box. If that cures the problem and the bike runs ok then it means there is a blockage somewhere in the intakes piping, somewhere before the air gets to the filter housing. If it runs rough when you put the filter back in without the lid it probably means the filter is dirty or over oiled. In that case I'd wash and oil the filter if it's a foam element, or replace it if it's a paper element. If you oil the filter use engine oil and give it plenty, then work the oil all through the element by squeezing it and working it in, and then squeeze it to get all the oil you can back out of it. If you wrap the oiled filter in a rag and squeeze it it works best. If you just use your bare hands to wring the oil out it keeps getting sucked back up off your hands, but if you use a rag the rag absorbs all the excess. If a clean or new filter still makes it run rough I'd check the breather hoses on the carby are not blocked and that they are on the right places. If all that checks out ok, then I think the carby needs some adjusting.. possibly just the float level. You could check that theory by turning the fuel tap off and running it and see if it starts to run right for a while before it runs out of fuel, which should take about two minutes if you are just sitting revving it. If it runs right for a bit, turn the fuel back on and try it.. it might have cleared the spark plug and excess fuel and it might be ok.. If not, you will need to pull the carby and clean it inside.