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Help! Bike won't Start!?

11599 Views 29 Replies 8 Participants Last post by  jaraxle1zx
I have a 1994 CBR900RR which after rebuilding ran great and rode nice. One day while starting it up after a 2 day rest, it started roughly and and while applying a little choke it stalled, never to start again! Spin, Spin, Spin no bang! Checked Spark, it's good. Checked fuel, it's getting it.

After many attempts to start it, it finally started backfiring as the only sign of life. After another 6 days of checking, testing, verifying electrical, etc. it started making the weirdest gurgling sounds in the exhaust (like it was under water and sloooowww...), neat, but not the sounds I or anyone would really want to hear from a Blade... it started backfiring along with the gurgling and at one point it started and ran! Rev'd somewhat decently, but still with loud backfiring intermitently. Turn it off, won't start.

Checking the plugs throughout the trials and tribulations, it seemed they were consistently wet with gas each time. This leads me to believe 2 things, the bike is flooding for one of 50 different reasons, or the cam timing has skipped a tooth and valve timing is off. Checking the carbs and float needle operation turned up no visible signs of malfunction.

Is it possible that the pressure switch has gone on the fuel pump? Does it have one on this model? Can the fuel pump provide too much pressure and force fuel past the needle valves? This is extremely frustrating given that the bike was running fine 2 days earlier! Several bike mechanically/electrically inclined friends with loads of experience are scratching their heads as their particular area of expertise seems to check out.

Your help and wisdom is greatly appreciated by a new member without his ride... Thank you.
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I have checked all components of the fuel systems as far as I can without being a professional... intake boots, diaphragms, passages, etc. As far as the rebuild, it was structural rather than engine rebuild, forgot to clarify. it has been put back together in stock form. Have had no luck with tracking it down to an electrical problem, as a senior automotive electrical engineer I know has even looked into it and performed all sorts of tests and bypasses, checked with a crazy scope, etc... all is well with the electrical.

Fresh fuel used every time we changed something and tried again, and like I said it did run for a minute or so, just popping alot and really loud!

I'm not sure how to check if the timing may have skipped, other than to follow my haynes and align the timing marks under the case cover. I do have a timing light come to think of it...

All your help is greatly appreciated, I'm lost as to what I should do next other than check the timing. But why would that go out if it was running just fine before? Not crashed, just one tip over long before bike was ever disassembled in the first place.

All suggestions welcome, and thanks again..

-CBRless guy
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@Bladeracer: backfiring... I used the wrong word. popping is something my ol' school GS750 does on decel. with the after market megaphone pipes (sounds Niiiiceee lol)
30K on engine, never disassembled other than removal from frame, never really abused. Tensioner never touched. Haven't smelled crankcase for fuel, and the plugs are new. It sat for 1 month between initial problem and initial repair attempts as I was moving from Ontario to BC. Bike has sat no more than 3 days in a row between wrench sessions.

@ Eepromking: Will check the exhaust system for fuel, although I'm certain it's there... it backfires readily and smells a bit like gas at the can when cranking for a bit.

I'm going crazy here..:confused: I've had 5 bikes, most of which have had various perplexing problems, but have managed to figure out the cause and solutions with only a fairly small amount of difficulty. This one takes the cake and is honestly starting to shake my faith in Honda a little, with many others I know having horrid times with their various models... but boy they sure are top dogs when running right! Which is why I want this fixed so badly that I'm now starting to be tempted to turn it over to the clutches of commercial thievery. At least if it doesn't run, I don't pay (much).

Thanks again and all suggestions are welcome. I really don't like the shops around here (small area, big costs), so would like to avoid them if I can, other than for parts.
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