Thunderchild Posted August 9, 2012 Posted August 9, 2012 As per my other posts, I've still not managed to get my XVS 125 going and missing the summer sun : ( Having gone through various 'causes' of her problem, she is now back together and starts up fine. Whilst idling, she sounds like she is wobbling slightly instead of a steady tone. I have just taken her for a spin and I'm still struggling to get out of first gear before she cuts out completely. Things I've done so far: Changed plugs, oil and oil filter.Cleaned out air filter.Checked throttle cable.Removed tank and checked fuel lines and petcock.Sealed the silencer carb junction with gasket seal.Sealed cracks in carb manifold (very minor), with gasket seal.Removed carb, stripped, checked, cleaned out and put back together. She originally died one afternoon whilst out on her and limped her back doing 15mph. Not been able to fix her since. There is no oil leaks and fuel appears to be flowing into and out of petcock. She is not smoking from the exhaust (so I don't think it's the rings but may I be wrong?). I've not checked compression as I haven't got a gauge yet. She doesn't cut out whilst idling (just sounds slightly wobbly). Any other ideas? Any advice better than taking it to the garage. Cheers.
Paulwhite Posted August 9, 2012 Posted August 9, 2012 can you post a pic up of your spark plugs? (or what colour are they?) sounds to me like the carb either hasnt been cleaned properly or needs adjusting ......dont suppose you can give me a rundown of what you did to clean the carb?
Moderator Airhead Posted August 9, 2012 Moderator Posted August 9, 2012 have you got a manual... If it were me i'd be checking the throttle position sensor at this stage, its an easy test with a multimeter and is detailed in the manual, basically it is a variable resistor mounted on the carb so its simply to test if it is within spec...if it isnt or has gone open cct it will affect the ignition timing
Thunderchild Posted August 9, 2012 Author Posted August 9, 2012 Paul/Airhead thanks for getting back, I've just checked the new plugs again and despite only having the bike idle or taking it 200 meters down the road a couple of times to test it, they both have very heavy black carbonisation (dry), on them. Could this be a weak ignition or do I need a new air filter instead of just cleaning it? It could be the ignition timing is retarded to far I suppose. As for the carb, I followed the manual to strip and reassemble, and cleaned it with carb cleaner. To be honest, it was pretty clean anyway and none of the jets appeared to be blocked.
Moderator Airhead Posted August 9, 2012 Moderator Posted August 9, 2012 is the TPS ok then? has it passed 'The Test' ?
Thunderchild Posted August 9, 2012 Author Posted August 9, 2012 I'm waiting for my multimeter to come back this w'end before I can test it. It's looking like a possibility though atm Airhead.
Thunderchild Posted August 14, 2012 Author Posted August 14, 2012 Back to my problem. I've tested the resistance on my TPS: blue/black = 5.30 (service manual 4.0 - 6.0), so that's fine. yellow/black = 910 - 4.17 (service manual 520 - 900 to 4.0 - 6.0), for opening throttle. Although it was a gradual increase on the second test, my starting position of 910 ohms was higher than the upper recommended limit of 400 - 900! Does that mean the TPS has had it? I know you can adjust it, but I've read that it rarely works anyway and is easier to replace. What do we think? Is this the cause of my original problems for lack of acceleration?
dt502001 Posted August 14, 2012 Posted August 14, 2012 If you leave the tps unpluged and run it how does it run? The purter shold set a base value and alow it to run not great but ok The 910 ohms starting point is high but what temp were you checking it at try putting it in the freezer or ice it down and see how big a diff you get. Also sweep it slowly and look for a dead spot in you readings
Thunderchild Posted August 15, 2012 Author Posted August 15, 2012 Hey dt, She ran better with the TPS unplugged, I even took her down the road to test her. The acceleration seemed better to start with in lower gears, but she still maxed out at 20 mph in 3rd fully open. I tested the TPS below 20 deg C (values are at 20 deg C in service manual), so to be over the upper limit at the start of the test seems rather high to me. The throttle swept fine at a steady rate with no apparent dead spots during the test. You think the TPS is dead? I know it either idles or retards when plugged in and the acceleration was better unplugged, but should the bike still only max out at 20 in 3rd with it unplugged?
dt502001 Posted August 15, 2012 Posted August 15, 2012 NO . It should still run semi normal just less power when the puter dosen't get the TPS signal it sets a base value and maps the ing by that You should check you stator and pickup coil. Stator for the key alingment and pick up coil loose. And as others have said realy go over that carb with air to be totlay sure you don't have a pluged up circut.
dt502001 Posted August 15, 2012 Posted August 15, 2012 Now I think about it again any chance you can put your puter on anoter bike? I had a rd350 that the Cdi went funky run not run ,run like crap run good. realy sent me around the bend till I bought another rd and swaped the cdi
Thunderchild Posted August 15, 2012 Author Posted August 15, 2012 Why would it be the Stator, that just creates an AC current that goes to the rectifier to covert to DC. I can't see how that would affect the poor acceleration, unless I'm wrong. Unfortunately, I only have the one bike too atm. I'll have another look at the carb and double check there's no holes in the diaphragm or blockages. Cheers.
dt502001 Posted August 16, 2012 Posted August 16, 2012 If the stator has jumped on the key it will affect your timing same with the pickup coil beeing loose . I don't know how long you have owned the bike but if someone (after changing a charge coil)didn't torque the stator nut it could be loose
Moderator Airhead Posted August 16, 2012 Moderator Posted August 16, 2012 If the stator has jumped on the key it will affect your timing same with the pickup coil beeing loose . I don't know how long you have owned the bike but if someone (after changing a charge coil)didn't torque the stator nut it could be loose You mean Rotor
Thunderchild Posted August 16, 2012 Author Posted August 16, 2012 I've only had the bike for 16 months (it was garaged for about 6 months prior apparently), and haven't had any problems with it really. What I don't understand is that this was an intermittent problem, with an occasional loss of power since owning the bike (like when your main tank is running low or a dip in power), until it suddenly wouldn't go over 20mph. If I can't find the problem myself, I'm going to have to (reluctantly), take it to the garage at some point I think. I'll have a look and see if anything looks untoward. How about the CDI unit? If I'm losing throttle from about quarter throttle onwards, could it be that? Maybe only firing on one cylinder? Cheers.
Moderator Airhead Posted August 16, 2012 Moderator Posted August 16, 2012 have you done any check of the fuel pump? Thats in the manual too...just dont see how this can be all that serious, I'm not familiar with this bike ...is the fuel tank outlet higher than the carb fuel feed spigot...any chance you could temporarily run a tube direct ? Did you examine the carb diaphragm for cracks / Tears when you had the carb apart?
dt502001 Posted August 17, 2012 Posted August 17, 2012 Yep Air I did mean rotor oops.I keep forgeting these bikes have a fuel pump thunder, as air suggested ,you might want to give that a go mount a tempoary fuel system and directly feed the carbs. I don't recall you mentioning that this was a on going problem so I would say it pretty safe to cancel out the rotor. If it were only firing one 1 cylinder it would still rev but pull out the plugs if 1 is way diff in color.Then your onto somthing. You can also check the temp of the exhaust pipes I would be looking at the fuel system before the CDI but if you can find someone who has the same bike beg them to put your cdi on Or a local shop might have a bike to try it on. Cdi's rarely give up but as I mentioned they can sometimes go wacky ,it's a expensive guess to find out it's not the problem. Takeing it to shop is a option but they are only going to do what your doing checking everything untill they find the problem.Keep pluging away and you will find it. I know it sucks taking the carbs off again but realy give them a close inspection make sure every passage is not pluged by blowing air through or carb cleaner To check the diaphram for pin hole leaks put a bit of gas on one side if a wet spot shows up it's nfg
Thunderchild Posted August 20, 2012 Author Posted August 20, 2012 Ok, so I've now checked the fuel system. All pipes are fine, petcock is fine and running. I've also checked the fuel pump and tested it which is pumping out fine. I rechecked the TPS which is now testing within limits (as per service manual), so I'm ruling that out too. I'm now back to the carb, which I've just removed to go over again as per the service manual and suggestions on here. I'll let you know in a while once I put her back together again. Fingers crossed I find something this time.
Thunderchild Posted August 20, 2012 Author Posted August 20, 2012 OK then so a quick recap. I have just taken her for a spin and I'm still struggling to get above 15-20 mph or even out of 2nd gear! Things I've done so far:Changed plugs, oil and oil filter.Cleaned out air filter.Checked throttle cable.Removed tank and checked fuel lines and petcock.Sealed the silencer carb junction with gasket seal.Sealed cracks in carb manifold (very minor), with gasket seal.Removed carb, stripped, checked, cleaned out and put back together.Tested the TPS which is within limits according to the service manual.Checked fuel lines again.Removed petcock, cleaned and tested.Checked and tested fuel pump.Stripped carb again. Cleaned and assembled as per service manual. No blockages and diaphragm is fine. Pilot screw reset properly. She doesn't cut out whilst idling, but will cut out within 200 yards once you stop the throttle. My plugs both have heavy carbonisation again (due to running lean?). I'm now stumped! The only thing left to do (fuel wise), is to change the fuel out completely in case it's purely a bad batch of fuel.
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