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1988 CBR250R starting issue

Discussion in 'Technical and Troubleshooting Torque' started by 88cbr250r, Mar 6, 2016.

  1. Hi everyone. Im hoping to get some advise to diagnose a starting problem that began yesterday. My bike started just fine yesterday morning when cold, rode to work (about 15 minute trip) done the usual things when i arrived at work ie: neutral, stand down, killswitch, key and turn petcock to off. When i finished work about 7hrs later i started her up just fine as usual then rode home and again done my usaul dismount. A short time later (maybe an hour or so) i started her up just fine again and headed back in town (same trip) usual dismount again. Parked on a slight incline but nothing crazy. About half hour later tried to start her up but to my surprise the engine cranked but would not fire. I checked my starting procedure and tried again (only about 8 seconds each time). Next i thought ill add some choke and see what happens. Still no fire. Baffeled i thought it might be silly but let's adjust the position of the bike. Of course still nothing. Figured buy now its probably a bit flooded and i should wait a while so i did for about 10 minutes. Then with relief she started up and i was on my way back home. Started fine this morning again. Rode to work done the usual. This time not starting again after work. Left it for an hour and tried again but same deal. Im now waiting to try and get a trailer. Im guessing plugs or rich fuel but im hoping someone has a possible diagnosis on here. Any help is greatly appreciated thanks for reading

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  2. Hard to say. If you can reach them, give the carbies a light tap with the handle of a screwdriver when the problem presents itself. It could be the floats are sticking and letting the carbs empty but not refill. So too it could be the fuel tap isn't turning on properly, give it a tap as well. It could also be that there's crud building up in there, so opening the drain screws and dumping any junk in the float bowls out might help. You might also be due for a valve clearance adjustment. If you're not confident to do that yourself take it to a bike mechanic. The carbs will need balancing after the valves are adjusted, so include that in your time/cost estimates.
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  3. Thanks. I just tried to start her again and got a backfire with a small fire ball out of the exhaust while it was cranking and then she immediately started up. Let it idle for 10 minutes to build up the temperature. Seemed to be fine so i just rode her home. Ill have to start working on it tomorrow arvo. Thought it was strange though. Seems to be happening when the motor is hot
  4. I would be giving the kill switch a good spray of electrical spray and work the switch while spraying.
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  5. Thanks mate. Ill give that a go first before i do anything else
  6. Just an update on how its going. Before i done anything, i started cibby up yesterday arvo and she was fine. I know shes running rich and when i filled her up from the jerry can last week i realised that it was premium 98 fuel that i used. This may be nieve of me but im guessing there was a blockage that cleared with the backfire and if i replace the 98 with 91(as it should be running) i assume she will be ok. Rode to and from work today without any issues apart from it running rich. What do you guys think? Should i still go ahead with checking plugs , leads, carby bowls, ect? Or just wait and see over the next week or so? This is the oldest bike ive owned and i know how temperamental the old cbr's can be. Thanks again for the help
  7. Wouldn't hurt to do the checks anyway, but they are pretty fussy about fuel. Especially with carbies. If its been tuned or running fine on 91 leave it on 91 and see how it goes. The mixture may have not been correct for 98.
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