xomojo Posted January 28, 2009 Share Posted January 28, 2009 This bike is driving me nuts.. I would appreciate any help.. I was told the CDI box could either cut out all together or go out intermittently giving the symptoms of many other problems.. SO, since I had an extra I put it on along with the new carb I got for it which I first cleaned.. It fired up first push of the button.. Previous to this it would idle fine but not run under load (ran great parked but try to ride it and no go, sputter pop) So off to the end of the yard and back and she pulled through the rev range (for the first time in a year).. I get her out the gate to take down the road and thats all she's got, like it's scared of the street or something it goes limp, stalling and won't start or hold idle anymore.. back to how its acted with 3 previous carburetors and the previous CDI.. With 700 original miles I checked under the ignition cover and everything under there looks brand new.. I've replaced the ignition coil once before with no results.. Got a new plug too.. It has an inline fuel filter so I doubt its the freshly cleaned carb that shot us across the yard with no problems.. What could it be.??? What in the world is causeing this bike not to go.? Why would it work great for 50 feet then go back to not going at all 10 minutes later.? And in the manual it says something like 'if the electrical system produces a spark then the entire electrical system can be considered good' has anyone ever heard some crap like that before.? is this true.? Cause I doubt it.. I don't know if my problem is electrical, carburetion or otherwise so any help troubleshooting would be fantastic.. This has been an on and off project for over a year now and yesterdays high of having it work great for 10 minutes only to break my heart 10 minutes later has really got me pulling my hair out.. thanks, Joe 04 FZ1 86 radian 81 sr250 Link to comment Share on other sites More sharing options...
shed hermit Posted January 28, 2009 Share Posted January 28, 2009 my brother-in -law has the same problem with a '93 sr250. he has changed everything and it would go for a while and stop. turns out it might be the pick up coil. got another one and im going to pick up his bike at the weekend (300 mile round trip) and fit it then. i will let you know how i get on. Link to comment Share on other sites More sharing options...
Moderator YamaHead Posted January 28, 2009 Moderator Share Posted January 28, 2009 Tend to agree with Shed Hermit here...... Bad Pick-Up coils have a notorious habit of going flat after they've been "brought up to temp". Had the same symptoms with my XT....replaced the pick-up coil & have had NO probs since. Link to comment Share on other sites More sharing options...
xomojo Posted January 28, 2009 Author Share Posted January 28, 2009 Thanks guys, I'll replace it with one of my spares and get back to you.. Crossing my fingers.. thanks, Joe Link to comment Share on other sites More sharing options...
xomojo Posted January 29, 2009 Author Share Posted January 29, 2009 Ok, so I took a pickup coil off of one of my parts motors, it looks 28 years old, and replaced the one on my motor with it which looked brand new and still doing the same thing.. But the battery needs charging and I've had enough failure for today so I'm going to let the batt charge and look up that pickup coil air gap measurement and try some more later or tomorrow.. But as far as I can tell so far the pickup coil isn't the problem because the symptoms haven't changed and it still won't run for more then 8 seconds and has no idle and no response (other then to die quicker) to gas.. Any other idea if the air gap doesn't fix it..? thanks, joe Link to comment Share on other sites More sharing options...
xomojo Posted January 29, 2009 Author Share Posted January 29, 2009 Holly fixed it batman.. Like I said I changed out the pickup coil and nothing changed.. Then for the heck of it, while it was trying to run, I sprayed some starting flud into the airbox and BRUMPTHUMPTHUMPTHUMP.. Reacted to throttle and everything until the starting fluid was gone.. So off with the carb and the mother flippin float was stuck.. SO NOW, after a test ride THE FIRST ONE EVER that didn't end in the back of a pickup truck.. I have new symptoms/problems.. Finally a 'driving down the road' problem I'm so excited.. Basically it sputters at full (or 3/4) throttle maybe even as low as half throttle.. It doesn't sputter real bad but generally feels weak and has the ocassional sputter that you feel in the chasis as it losses power for a sec... At small throttle openings it seems fine.. Even peels out in the dirt.. My 81 xr200 feels faster then this thing though.. Anyway, tomorrow I'm going to adjust the valves and re-goop my vacuume hose as it has pulled out of the intake manifold and I found it leaking today after the ride, patched it and went for another with no difference in the behavior so once the tank is off I want to make sure its patched leak free.. The bike is stock except the exhaust.. I cut off the expansion chamber (was rotting off anyway), welded a patch over it and wrapped the whole exhaust in that muffler wrap stuff.. The carb is the 4th one I've put on and in the best shape of all of them I have.. And the only one I have with the plug still over the mixture screw.. Wouldn't this problem generally be carb issue.? midrange and top end is the needle and main jet size right.? Why would it need jetting or adjustment if its basically stock.? could the exhaust mod be causing an issue.? I didn't check my plug yet either.. The reading I mean, do I have to cut off the bike DURING that sputtering symptom for it to read correctly.? Sorry this is so long a post.. Thanks for th help so far.. -Joe Link to comment Share on other sites More sharing options...
xomojo Posted January 29, 2009 Author Share Posted January 29, 2009 Thought you might want to see what your helping with.. thanks again Link to comment Share on other sites More sharing options...
Moderator mervin Posted January 29, 2009 Moderator Share Posted January 29, 2009 Do ya live in that topbox??? i thought the one on 650 was big. but that lil 250 must get blown backwards in head winds with that Link to comment Share on other sites More sharing options...
gabby Posted January 29, 2009 Share Posted January 29, 2009 check the float hieght if theres not enough fuel in the float chamber it could be struggling when you open the throttle but will run fine at tickover/ low revs.. worth a try since you seem to have everything else checked. and that top box is waaaay too big Link to comment Share on other sites More sharing options...
xomojo Posted January 29, 2009 Author Share Posted January 29, 2009 LOL.. Yes, me and the wifey and the 2 kids live in there.. Believe that is the stock top box.? crazy huh.. I forgot to show off the wrapped exhaust, I think it looks cool.. I'll check the float height and report back.. The top box could not be here for this photo he's still very upset about the ridicule ;-) Link to comment Share on other sites More sharing options...
xomojo Posted January 30, 2009 Author Share Posted January 30, 2009 Ok, adjusted the valves, sealed vacuume tube and checked AND raised float height.. Now if it would only stop raining I could see if it helped anything.. Talk to ya when it dries up.. -Joe Link to comment Share on other sites More sharing options...
xomojo Posted January 30, 2009 Author Share Posted January 30, 2009 STILL DOES IT.. sort of.. It feels now like the top end may be fixed but the mid range still stumbles.. and the bike feels generally more powerfull then before the float height adjustment, so it did some good but didn't fix it altogether.. I suspect my cutting off the exhaust expansion chamber has changed something that I need to compensate for.. OH, and what does a tiny pop (backfire) when I turn the bike off mean.? So what in the carb effects the midrange again.. Main jet.? needle height.? Anyone familiar with the mikuni bs34, same carb thats on xs's.. I'm not sure what to do to it, or where to get jets/parts for it.. Help please, its almost there.. thanks, joe Link to comment Share on other sites More sharing options...
Moderator drewpy Posted January 30, 2009 Moderator Share Posted January 30, 2009 check the Carb diaphram for splits and tears which will weaken the mid to top end Link to comment Share on other sites More sharing options...
xomojo Posted January 30, 2009 Author Share Posted January 30, 2009 Nope, I checked that when I cleaned and installed this carb, he diaphram looks great.. I was thinking of trying a larger main to see what happens, maybe raising the needle a little too.. We'll see what happens after that.. thanks, Joe Link to comment Share on other sites More sharing options...
Khunangkaro Posted March 14, 2009 Share Posted March 14, 2009 xomojo said: Nope, I checked that when I cleaned and installed this carb, he diaphram looks great.. I was thinking of trying a larger main to see what happens, maybe raising the needle a little too.. We'll see what happens after that.. thanks, Joe Had spark but dirty black plug, finally it did not want to run at all. If you have a petrol inline valve using the vacuum. Disconnect the vacuum hose and close it of with a screw to prevent air flowing into your inlet. If you not use that hose anyway make sure that false air never can enter at where it is on your inlet. Put your petrol gauge at "PRImer". Then it has free flow. The other ways it should be closed. Start and go. If this was the problem, then diafragms in the petrol valve are leaking and sucks more or less illigal petrol through the hose that makes running terribel, or not at all. Link to comment Share on other sites More sharing options...
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