nsr250 Posted December 14, 2014 Author Share Posted December 14, 2014 Pair has been removed but your instructions don't get into the charcoal canister, PCV and associated vacuum lines. I'd love for you to explain to me what to do with the rest. rip that crap off!!! the big tubes tube are gas over flow lines.. replace them with some thin clear line and rout them down under the bike. the thin tubes too to be vac lines. cap them off and the problem disappears did you down load the manual for the non cali model? follow the gas line routing. very simple Well, I ripped that crap off!! Plugged any vacuum lines. It now runs even worse. Just cruising along the bike does nothing but surge constantly loading and unloading. Medium to full acceleration is great. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted December 15, 2014 Member Contributer Share Posted December 15, 2014 you should have NO vacuum lines left!! 4 screws in the intake manifolds.. thats it. then a tube from the gastank for over flow to behind the motor.. connects to nothing... follow the non cali vent line pic in the manual. did you tighten the boots ? Link to comment Share on other sites More sharing options...
nsr250 Posted December 15, 2014 Author Share Posted December 15, 2014 you should have NO vacuum lines left!! 4 screws in the intake manifolds.. thats it. then a tube from the gastank for over flow to behind the motor.. connects to nothing... follow the non cali vent line pic in the manual. did you tighten the boots ? Had one vacuum line going to the ASV (?) behind the steering head. Blocked it off because I can't get to the end at the carbs. What non-california vent line pic are you talking about? I don't see that in the manual. Boots are tight. With the choke at halfway I can spray carb cleaner at the boot(s) and it definitely affects the idle. When not using the choke it's not very noticeable. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted December 16, 2014 Member Contributer Share Posted December 16, 2014 you can remove all the vac lines and replace the port with screws ,with out removing the carbs. its clear you leak some place.. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted December 16, 2014 Member Contributer Share Posted December 16, 2014 this is what you WANT>>>> this is what you HAVE>>>> so to repeat it it one more time... remove vac ports # 1,2,3,4 in the cali pic.. replace with a screw.. detach # 6 hose to evap control. and toss it,, ditto for all evap crap and remove the remainind PAIR stuff if you havent already.. plug the or weld up the pair tubes.. Link to comment Share on other sites More sharing options...
Magna86 Posted December 16, 2014 Share Posted December 16, 2014 If you tighten the boots too much you can cause the leak to be worse. So either cracked boots finally letting to much air pass, dirty carbs, and or a failing coil or wire since it become more problematic once heated up. My bikes had only parts of the PAIR system attached and they run great. If you swap the boots might as well clean the carbs to check for blockage and worn needle valves. Easy to do don't have to totally disassemble them. Can of carb cleaner, compressed air and some thin wire for passages. You can check the resistance of the wires and coils I believe to see if they are failing. Link to comment Share on other sites More sharing options...
nsr250 Posted December 16, 2014 Author Share Posted December 16, 2014 If you tighten the boots too much you can cause the leak to be worse. So either cracked boots finally letting to much air pass, dirty carbs, and or a failing coil or wire since it become more problematic once heated up. My bikes had only parts of the PAIR system attached and they run great. If you swap the boots might as well clean the carbs to check for blockage and worn needle valves. Easy to do don't have to totally disassemble them. Can of carb cleaner, compressed air and some thin wire for passages. You can check the resistance of the wires and coils I believe to see if they are failing. Already dealt with a failing plug cap and swapped all the coils with no change. All the wires tested good. Just going to order the carb boots and replace them. They're 24 years old. It'll give me a chance to take the carbs out and clean them. Link to comment Share on other sites More sharing options...
Guest Posted December 16, 2014 Share Posted December 16, 2014 How did you test the plug wires? Old plug wires tend to internally break down over time. Fractures in the internal wire and corrosion from moisture that has penetrated the broken down rubber over the years cause all kinds of odd problems. Simple continuity tests with a multimeter (edit: or even with a spark gap tester as in my case) don't guarantee that the internal wires can carry enough current to generate a good spark under all conditions. Add to the fact that the rubber can swell when it gets hot effectively turning a small fracture in the wire into an actual gap. From painful experience I can tell you that swapping 1 12+ yr old part for another 12+ yr old part is no guarantee that that particular part is working correctly Link to comment Share on other sites More sharing options...
nsr250 Posted December 16, 2014 Author Share Posted December 16, 2014 How did you test the plug wires? Old plug wires tend to internally break down over time. Fractures in the internal wire and corrosion from moisture that has penetrated the broken down rubber over the years cause all kinds of odd problems. Simple continuity tests with a multimeter (edit: or even with a spark gap tester as in my case) don't guarantee that the internal wires can carry enough current to generate a good spark under all conditions. Add to the fact that the rubber can swell when it gets hot effectively turning a small fracture in the wire into an actual gap. From painful experience I can tell you that swapping 1 12+ yr old part for another 12+ yr old part is no guarantee that that particular part is working correctly Very true. I've considered replacing the wires in the when this all started and it's probably a good idea to do it anyway. Any recommendations? Link to comment Share on other sites More sharing options...
Guest Posted December 16, 2014 Share Posted December 16, 2014 I don't have a 91 so i cant really help on selection of affordable parts. I can, however, suggest that a cheap in-line spark light would be a good next purchase if the carb boots don't sort out your problem. That's how I finally diagnosed my issue with 1 bad plug wire and another bad coil (only when hot). The in-line spark light lets you run the bike while checking (roughly) that you still have good spark. If the light gets dimmer or goes out as the bike warms up, then you know you have an issue with your electricals. Link to comment Share on other sites More sharing options...
nsr250 Posted January 4, 2015 Author Share Posted January 4, 2015 Well, finally had time to replace the carb boots. Wasn't bad at all. Went for a ride today in 60° degree weather. After 15 minutes I declared victory. Unfortunately 5 minutes later it started again. Since I've already swapped all the coils (for used ones) and there was no change at all, I'm going to swap in some used plug wires to see if there is any change. If there's any change at all I'll buy new wires. Supposed to start getting cold again so it may be a while before I can test the plug wire theory. Link to comment Share on other sites More sharing options...
Member Contributer taglicious Posted February 24, 2015 Member Contributer Share Posted February 24, 2015 Lol i tried finding this post for a couple of days. Please, try this. . . THIS PROCESS TAKES TIME. HAVE PATIENCE Remove fuel tank. IF you have a shop manual, check out chapter 6-4. FUEL SYSTEM SECTION. there is a diagram, of the carbs removed ABOVE the bike. Over piston #3, at thd back right hand side of the carb, there is a sub air filter hose line. *you should be able to remove this hose FROM THAT sub air cleaner case* . . twist, and pull gently it should come right off. (The hose is shaped with a bend) While using a compressor, place and of compressor nozzle into that hose. Look down each of the 'air funnels' < weird name, as you apply air pressure into the hose, ALL of the slides should go up into the diaphram area. If not, check for stiction on EACH slide. If one sticks, pull the carbs, pop the tops, remove the slides. You may not need to check needle and seat, but do so anyway. CLEAN SLIDES, DIAPHRAMS, SLIDE AREAS, AND MAKE ABSOLUTELY CERTAIN THERE ARE NO TEARS in the diaphrams, use rubber gloves and your favorite 2-stroke oil to rub clean any residue.(on the slides AND slide areas... Do not use sandpaper, or steel wool (these are your carbs man). Do this until you are satisfied with cleanliness, wipe clean with clean cloth. Re-apply 2 stroke oil upon re-assembly (i do this with ALL CARB RELATED SESSIONS) MAKE SURE YOU GINGERLY tighten the top cap for diaphrams, like you would replacing and torquing a car wheel. Align the top caps correctly theres a bump for the air hole in the diaphram ***if youve made it this far youll know what im talking about*** Replace carbs to the boots, have fuel line from a gas can to your tank fuel line fire the bike up. You should notice a difference. If satisfied, button her up and go :-) This is a cost effective, albeit time consuming process. IF YOU NEED HELP SYNCING CARBS OR ANY OTHER QUESTIONS, PM ME prior to placing carbs. *** carb plate removal might be necessary *** Tool for that is :: http://www.harborfreight.com/impact-screwdriver-set-with-case-37530.html Link to comment Share on other sites More sharing options...
SoCal97VFR Posted February 24, 2015 Share Posted February 24, 2015 I browsed from the beginning of this thread and there is a lot to follow but I will add some more. Surging or hunting at part throttle is a common sign of a lean condition. Spraying around the boots and hearing a change in the engine rpm supports the lean condition theory due to a vacuum leak of some sort. Maybe boots, maybe something in the near proximity. Since you replaced the boots, run this test again, and ensure the idle no longer changes while spraying. Regardless if this is the cause of your main issue, this is an issue that needs to be dealt with. Sometimes a sticking float can over fill the bowl and you get similar symptoms, however it has been my experience that the carb will leak out the vent tube when this happens so you would have no question that is occurring so I dont think this is your issue. Coils and plug wires can be tricky, but more often seem to fail when the temp/humidity swings. It sounds like you are running the tests on this now so I'm interested in your results. Again, a good maintenance item anyhow so no matter what you are ahead. What stands out to me the most, is that it only does it when warmed up. If you were tuning a jet kit I might have some other things I would consider but since nothing had changed, this sounds like metal expansion. My first though is you have a valve that is very tight, and when it warms up it fails to close entirely. Exhaust would not be hugely evident although they tend to wear faster but an intake would act as you describe as combustion pulses begin to disturb your vacuum signal. If you have the means and patience, it might be worth checking the vacuum at each port and looking for excessive pulsing after heat up. If so then check that valve clearance. I have over 130,000 miles on mine and the valves never budged, but I still check them every 30,000 as part of routine maintenance. Link to comment Share on other sites More sharing options...
Member Contributer paladinreed Posted February 24, 2015 Member Contributer Share Posted February 24, 2015 I had a really bad cutout issue on my 5th gen that ended up being the kickstand kill switch. Just jump the harness side connector and see if that helps. Link to comment Share on other sites More sharing options...
750 Posted February 24, 2015 Share Posted February 24, 2015 Good reading, this. Lots of good info that people can refer to. Hope you get it sorted soon, bit above my knowledge to help out Link to comment Share on other sites More sharing options...
Member Contributer taglicious Posted February 25, 2015 Member Contributer Share Posted February 25, 2015 I had a really bad cutout issue on my 5th gen that ended up being the kickstand kill switch. Just jump the harness side connector and see if that helps. ^^Hasn't everyone done this ;-) Link to comment Share on other sites More sharing options...
Member Contributer paladinreed Posted February 25, 2015 Member Contributer Share Posted February 25, 2015 Hell idk haha. I never saw that on the site or heard about it when I was researching my issue. It just hit me as the possible culprit while thinking about it in the shop one day after I got my bike on the road after sitting for a few months during its build. Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted February 25, 2015 Member Contributer Share Posted February 25, 2015 It has been mentioned above, but not really focused on, but my vote would go to the OEM fuel pump contacts pitting and sticking. Ciao, Link to comment Share on other sites More sharing options...
Member Contributer taglicious Posted February 28, 2015 Member Contributer Share Posted February 28, 2015 As long a ive had my viffer, ive had All suggested items to look at, happen at one point or another. Just like the bike does, keep 'hunting' :-) Link to comment Share on other sites More sharing options...
nsr250 Posted April 27, 2015 Author Share Posted April 27, 2015 Well, I've finally gotten motivated to get at the problem again. Took the carbs off and gave them a thorough cleaning. Remounted them and checked for leaks and this time there seems to be none. Took it out for a ride and still getting the same sputtering as before after it got hot. When I got home I got to thinking about it and realized I had an infrared temp gun. Got it out and the front left was at about 200 degrees and the other 3 were well over 400. Changed out that plug wire and started it back up. That cylinder didn't change but the rear right cylinder suddenly dropped to about 200 and the bike started running terribly. I could rev it up and the right rear temps would slowly come up but the front left would max out at about 250. The front right and left rear at idle hovered around 500 and would rise as the bike was revved up. At this point I'm wondering if the ECM is having issues. Anyone with anymore guesses? Link to comment Share on other sites More sharing options...
nsr250 Posted May 24, 2015 Author Share Posted May 24, 2015 Got back to working on it today. Took the carbs back out to check float height. They were a little low but nothing terrible. Put it back together and the front left cylinder is still dead. Only about 125 degrees compared to over 600 for the other 3. Took out the spark plug and it was black. Swapped it with one of the rears which was a light grey and the same thing, front left still dead. Swapped out the coil, plug wire and cap and still no change. I even have a second ecu and pulse generators that I swapped out and no change. Any ideas? I'm pretty convinced that one cylinder is not firing or not firing well but I can't figure out why. Link to comment Share on other sites More sharing options...
nsr250 Posted May 24, 2015 Author Share Posted May 24, 2015 Just checked continuity between the ecm and the coil and that's fine too. I'm stumped. Link to comment Share on other sites More sharing options...
Member Contributer wagzhp Posted May 24, 2015 Member Contributer Share Posted May 24, 2015 I haven't re-read the whole thread... Have you tried pulling the plug wire from the bad cylinder, attach it to a spare plug, ground that plug to the frame or engine, and hit the starter and check for spark? Link to comment Share on other sites More sharing options...
nsr250 Posted May 26, 2015 Author Share Posted May 26, 2015 I haven't re-read the whole thread... Have you tried pulling the plug wire from the bad cylinder, attach it to a spare plug, ground that plug to the frame or engine, and hit the starter and check for spark Yes, I had. Thought it looked weak so I decided to look again tonight. Looks fine. So, I'm back to thinking............carbs? Just don't know what else to check. Link to comment Share on other sites More sharing options...
nsr250 Posted June 23, 2015 Author Share Posted June 23, 2015 Finally!! (fingers crossed). I've now ridden for over 100 miles without any issues. I think the last final colonoscopy I did on the carbs must have cleaned something out. Link to comment Share on other sites More sharing options...
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