CBR600 won't start - out of ideas!

[Nipedley]

Hi guys,

The bike is a CBR600F 1988 model (1987-1990 were the same, F1)

The problem:
Bike won't start, turns over nice and strong, good strong spark

What I've done:
1. Checked the pulser coils, one read slightly over the resistance specified in Haynes (something like 600 ohms where it should be 500 ohms) but I couldn't see that causing a massive issue?

2. Fitted new ignition coils and HT leads (one ignition coil read slightly bad when I did a general electrical check many months ago, so I did this out of precaution anyway). New leads are sparking strong.

3. Rewired CDI (previous owner cut all the connectors off so it was loose uninsulated terminals, I've put new connectors on.. no difference. Looks a hell of a lot better mind you)

4. Cleaned out the carbs (due to various issues they've been cleaned 5 or 6 times in the last 4 months)


The solution?
I had the spark plugs out today and they were all a bit black and oily, so I am thinking get a new set of plugs and a compression tester just for the lolz. The backstory is the bike was working fine, had a couple electrical glitches but still ran before I went on holiday. I got back from holiday, got halfway down the road and it felt like I lost a cylinder, park up, clean the carbs out, bike fires up normally and runs for about 20 seconds then dies and has never started since.

Any suggestions significantly appreciated, my next steps are replace the spark plugs and check the compression on each cylinder but after that I'm buggered

[Copycat73]

will it run disconnected from the alternator ?
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[yen_powell]

Dicky fuel pump, it'll be one of those dodgy Mitsubishi ones with the self welding points? Try filling the tank right up and bypassing it to see if it starts.
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[Vincent]

Do the plugs smell of fuel after trying to start?
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[Nipedley]

Thanks for the replies guys, it doesn't run disconnected from the alternator either no.

It's not the fuel pump, that already failed on me last year and I replaced it with a solid state jobbie that's been fantastic, pumps fuel like nobody's business Unfortunately there's definitely fuel reaching the carbs, and those have all been thoroughly cleaned (bowls & jets) and drained several times so I know there's fuel in there.

I'm going to replace all the plugs, turn her over a few times and (if it still doesn't start) pull them and check to see if there's fuel on them or any other signs, as the ones I pulled earlier were quite mucky though I did my best to clean them. It's worth noting those plugs are only 700 miles old as I replaced them during a service.

[temeluchus]

[Bikeless]

First thing is check for wet plugs,make sure the tank petcock filter is clean and floatbowls are clean,use fresh fuel,check carb pilot jets,main jets,emulsion tubes are clean.

[ssray]

Will it run with a quick blast of easystart? can you warm the plugs over a gas flame first, then stick them in quick and try to start then.
completly disconnect the regulator, like disconnecting the alt as it may have an internal short

[Nipedley]

Hi guys,

Just to let you know it fired up today. I sprayed some carb cleaner in the intakes (apparently an alternative to start ya bastard) and it fired up running on the carb cleaner, which told me it wasn't a compression or ignition issue - so I gave it another very thorough carb clean (maybe the 5th of which this bike has had in the past 4 or 5 months, so I'm not convinced it was that that really sorted it) and gave it some fresh fuel from a mate's bike and it fired up right away.

The fuel in the tank is only maybe 2 months old, and this problem cropped up when the fuel in the tank was about 3 weeks - 1 month old, but I'm not going to complain, it's started and I'm going to get it some fresh fuel.

Thanks for the suggestions guys