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Discussion Starter · #1 ·
Proud to be apart of this community.

I have read many posts relating to the following issues but have yet to find a solution.

I have a '97 Honda CBR 900RR that has probably sat for 15 years till I got my hands on it (in an attempt to bring it back to life). It has about 5k miles on it and needs a fair share of TLC.

I have done the following: Rebuilt the carbs (they were terrible), new gas tank, new fuel line, new plugs and wires, new K&N air filter, new fuel in her.

In an attempt to start her up, she starts for a brief second then dies on me. The max I had her running was 10 sec(s) with half to almost full throttle while the choke was on.

It seems like each time I let her sit for a night then reattempt ignition in the morning, she starts briefly then refuses to again till the next day or several hours later (assuming b/c it's flooded but I never see any fuel leaking out).

With all this said, I am out of ideas why she refuses to come to life. To the best of my ability I believe she has spark, fuel, compression, and air.

Does she need a new battery? I attempt to start for her about 5 minutes then the battery is about dead and needs to be recharged overnight.

Or did I mess up rebuilding the carbs?

Any thoughts are appreciated, I would hate to give up on such a (soon to be) beautiful bike.

EDIT - I would like to add that when she's running, it sounds like she's trying to clear 15 years of dust out of her
 

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First test from here is a compression test. Do that before anything else. Should see over 140 psi in each cylinder and all should be within 10% of each other. If that’s good, you’ll have to do the carbs again. If you didn’t ultrasonic them for hours and replaced jets, you probably didn’t do a good enough job. Not a dig, I’ve had to clean sets multiple times after I thought they were “good”. Also, make sure your coils and plug wires are in the proper sided and proper plugs. Once that’s done, report back with numbers.
 

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Hello Nate, whilst I'm no expert at this I had a lot of problems getting mine going after it had been sat for a few years so I feel your pain, as Ian has said above I ended up stripping and cleaning the carbs at least 4-5 times before they would function close to correctly! Just to try and understand where the problem could be I have a couple of questions below:

In an attempt to start her up, she starts for a brief second then dies on me. The max I had her running was 10 sec(s) with half to almost full throttle while the choke was on.

After it had fired up, when it died, were the plugs wet or dry? If dry it indicates lack of fuel getting through (especially as you needed full choke and 1/2 to full throttle to get it to run) suggests pilot jets/passageways are blocked, or not enough air getting in? I'm assuming the mixture screws are set to factory settings?
If plugs are wet you could have a leak from the float valve or seat which is drowning the spark out (or theirs no spark from plug)

(assuming b/c it's flooded but I never see any fuel leaking out).

I went through same, the Blade doesn't have an overflow from the carbs as a lot of other carb'd bikes do, I assume they believed it was not required as the float heights are fixed (from what I found when I had issues) meaning they would be unlikely to overflow, so if their is an excess of fuel getting through it will go straight down the inlets through the bores into the oil, if you take the dipstick out does the oil smell of fuel?

Does she need a new battery? I attempt to start for her about 5 minutes then the battery is about dead and needs to be recharged overnight

If you leave the battery 'fully charged' does it hold the charge or if you leave it for 24-48 hours does it start to discharge and lose power? Whilst I don't think the early ish blades are that temperamental with voltage if your battery isn't holding charge on its own it could affect operation (I'm even less of an electrical expert than I am mechanical!)
 

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Discussion Starter · #4 ·
Thank you everyone for your responses; I made the mistake of taking out a plug to check it and forgetting to reattach the vacum line to the petcock which caused a lack of fuel. I fixed this issue and found the bike starting, but back firing heavily.

So it looks like I will be taking another look at the carbs.

Thanks agian!
 

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Discussion Starter · #5 · (Edited)
UPDATE

I had the carbs rebuilt 110% - and it fixed the issue (imagine that). After many years of sitting, she was purring back to life.

After approximately 1 or 2 minutes though, I saw white cloudy smoke pouring out from under the gas tank (looked as if it was from the carb/header area).

My assumption is a head gasket issue - I am going to check the oil and coolant tomorrow.

Any ideas? I would find it odd for it to be a gasket issue with only 5k miles, but perhaps sitting for so long caused it?

Thanks again!
 

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When you say cloudy white smoke from under tank (I know its hard to be specific in that situation) do you mean from inlet/carb or exhaust side of engine? A video will help but if we try and narrow it down, where are the exit points where smoke could escape? Inlet side - blow back through carbs? I think you'd have noticed other noises/issues if intake was pressurized excessively to blow back (or crankcases pressurized)? To take out crankcase pressure causing it try undoing the oil filler cap a turn or 2 and try starting it to see if it stops the white smoke (crankcase venting)? Exhaust side - would expect to see smoke out of the silencer not under the tank, exhaust exit at manifold - could give impression of under tank escape, poorly refitted headers in past or no gaskets used meaning gases are escaping past headers? The white smoke could just be the remnants of fuel that's got into the bores or oil burning off while you were trying to find the original issue in carbs.
 

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Discussion Starter · #8 ·
Here are two videos; one shows where the initally smoke is obsered coming from,I dont think its steam because it smells like a substance is burning and it hangs in the area for awhile.

The secound video shows constant white smoke pouring out of the exhaust (this occurs when the bikes under high revs').

1997 CBR 900RR - Smoke from headers

1997 CBR 900RR - Smoke from exhaust

I'm also having issues with the bike running without the choke on.

Thanks again for all your help.
 

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The smoke at the header looks like years of junk burning off (dirt, grime, oil, spilled fuel, etc). I think the same for the exhaust. Inside, burning off and flowing out. It would probably take some really good, prolonged heat to get rid of it all.

As far as not running off choke, still have a blockage in the slow or enrichment circuit. They can be very difficult to clear.
 
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