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750 SS starting problems

Discussion in 'Supersport (1974-2007)' started by Happy Chapie, Nov 10, 2013.

  1. Hi Chaps,
    I have a 1994 750 SS I’ve owned for the past 15 years although it wasn’t used for a few years. It has only 10,600 miles on the clock. I have however been using it daily since May 2013. One day last week when the weather was more suitable for fish, I left it out in the rain for a few hours. Next day it started first time as usual and run for about 20 seconds then stopped and has been almost impossible to start since. Everything has been given a good dose of WD40 and there appears to be a good spark on both cylinders. Plenty of backfiring and plugs appear to be quite wet when removed. Plugs are NGK DPR8EA-9 although the Haynes Manual states Champion RA 6 HC. Everything else is standard. Any thoughts would be welcome??? Steve in Crewe
    #1 Happy Chapie, Nov 10, 2013
    Last edited: Nov 10, 2013
  2. Just had a very similar problem with mine since the weather has turned damp with the same type of plug. It turned out one had gone bad, put one of the old plugs back in and all was well again. It was only one cylinder but alot of back firing and rough running. It too looked to have a good spark, as good as the one that replaced it.
  3. Could be many things of course but considering what you have said it sounds like water in the carb float bowls and also possibly in the fuel tank. Does fuel pump motor sound the same as usual? There is a facility to drain both float bowls albeit a little tricky (and be careful not to overtighten screws when finished). If you can catch the contents in a receptacle (particularly if you are lucky enough to have drain tubes still connected) you can prove/disprove the water content theory.
    #3 Chris, Nov 10, 2013
    Last edited: Nov 10, 2013
  4. Thanks Chris, You could be correct as it ran for a few seconds. Fuel pump sounds the same. I've drained one float bowl, The other one looks impossible to drain without removal. I can't work out why the drain screws are both on the same side ? I 've believe the water is heavier than fuel and I read somewhere you can put meths in and it will mix with the water and burn off eventualy ?
  5. float bowls are a common casting - the drain screws have cheaply stamped shallow heads which make it easy to slip with a spanner - best to use full hex 1/4 drive socket if possible. I've never tried the meths trick but I suppose it's one option. If you persevere you will get on the other one - it's much harder on an Elefant :)
  6. What Chris says about the float bowl drains......I'm no doubt wrong, but I'm inclined to think it is water in the HT side of the electrics........

    Change the plugs anyway and keep to NGKs, I found the Champion ones these days are sh*te.

    Wipe down the leads thoroughly and inside the plug caps (remove the caps from the leads so you can clean that connection too) plus check up at the coils end.....

  7. Well its running now :upyeah:, Looks like you were right Chris. I drained the carbs and tank and refilled with fresh fuel, and it fired up straight away. Running a bit rough though !!!!
  8. Good news but almost certainly means there will be water in the tank also so probably best to use remote fuel can for now if possible.
  9. Bloody water, gets everywhere!!

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