Hi everybody!
I've bought a 1990 CBR600 a week ago and it's actually my first motorcycle experience. Unfortunately I cannot get it run, maybe somebody could make suggestions why is this may happen.

Well, when I bought it, previous owner said he ride it a year ago and it was ok, just needed carbs synchronization. Then he bought a new bike, so this one was kept in the garage for all this time. And it doesn't starting at this point.
I've brought in to home and it started just once with very low rpms, then it stalled and I cannot start it again. Tried to clean carbs with SeaFoam, but it doesn't helped. Plus changed spark plugs with brand new NGKs.

I've removed the carb and was very surprised how it started even once.



Cleaned all that crap, put everything back. And again in started with low rpms and never started again.
Here is the video how we started it: CBR600 - YouTube

Also I have a question about hoses which coming to round things on the carb:

If fitted properly I have one flange without the hose and gas coming out from it when cranking. On that picture I put the hose from second thing to that (side) flange. Sorry for such "explanation" =)

What I am thinking now is dead ignition coil, because when I removed spark plugs again, 2 of them looks like new.

However it doesn't explains why "new spark plugs" are 3 and 4 while ignition coils has another circuits. Probably the wires were misplaced there or 2 of them are dead too. I will check this out tomorrow.

Everything looks pretty simple (gas + spark) in compare with modern cars with a lot of electronics, but doesn't work and this makes me depressed...

So if someone have any ideas, please help me =)

 

First off - welcome to the forum. These old bikes are still great machines, even by modern standards, provided yours hasn't been TOO neglected.

From your video I'd say its not running on all cylinders. Could be as simple as the carbs being gummed (which they surely are!). Seafoam is a great additive to help with minor cleaning, and deposits in your engine, but it is by no means going to fix that. Did you clean the jets? They will all need pulled and get a thorough clean. I boil mine for about 10-15 minutes in 50% water/lemon juice and it works great. Spray some carb cleaner through all the passages and blow them out with compressed air. Youtube "motorcycle carb cleaning", there are some great tips.

As for that tube thing, not sure from that close up, maybe something from a Cali spec bike? If you have fuel dumping out of your overflows when cranking its a float issue. Again, the complete carb cleaning should take care of that.

I'd say if the PO was telling the truth and it ran before he stored it, it is not the coils. The new looking spark plugs would be because theres no fuel getting to the cylinders. If the spark plugs are clean and don't smell of gas, then its a carb issue. You can test each high voltage lead by grounding a plug to the case and turning the bike over.

 

Thank you
I think the same, it's a great bike especially for the beginning!

I've removed all jets and everything what can be removed, cleaned them in gas and seafoam. Also I cleaned all holes in jets with needle. But maybe there is still something left inside carb's body, that will explain why fuel is not getting into 3 and 4 cylinders.

I found a picture on ebay with better angle of view on these round things. And I've circled the flange for which I don't see any suitable hose and fuel coming out from it when cranking.

 

I see all these hoses..... mine didn't have any of those when I got my bike, or the newer set of carbs.

 

Looks like this is California stuff.
I've already ordered another carb on ebay, it should be without them. And I hope I will make one working carb from these 2

 

Yeah, I don't have that either. My best guess is it is some emissions thing. Where are you located? Cali spec bikes had more plumbing included to support the evap systems and EGR.

EDIT: I guess my computer cached this page because your response didn't show up until I submitted... Anyways. Ordering another rack is usually a last resort reserved for damaged carbs. There is no amount of 'gunk' that can render them unrepairable.

 

I'm in MA and previous owner bought it from NH. Maybe somebody brought it to the east coast long time ago.

That second carb was only $50 so I thought it might be helpful just in case.

 

Not bad. The diaphragms alone are worth that

 

where abouts in MASS? myself being another masshole with a 90 cbr 600.

 

Watertown (Boston area), how about you? Does your bike runs?

Well, mine biggest problem was pretty easy fix. Wires on the 3 and 4 spark plugs were misplaced. After I put it how they supposed to be, bike immediately started =)
However old carb seems to be not good anyway (4th diaphragm doesn't works), so idle is not stable and sometimes it needs some cranking to start. And there is also no power at low rpms (under 5k). At least I hope the problem is in the carb and not in the valves or something else. I almost finished cleaning the carb I bought on ebay and going to try it tomorrow.

Here are couple videos of how is it running now (featuring my friend):
CBR 600 First start
CBR 600 Test drive