Help me fix this 2001 YZF 600R

[Bonz]

Good, thanks for the clarification. Spaying more cleaner into the carburetors and chasing it with compressed air isn't going to work better the second, third or fourth time around. You've done all of the steps that typically leave guys right where you are with a bike that's still not running like it should. The only real step left is to take them fully apart. The carbs need unracked which means separate them individually and take everything out, soak them in carb cleaner or get an $80 ultrasonic cleaner and do it right. The YZF600R is a fantastic all-around bike. You'll be so happy if you just take the time instead of spending the same time to do the same things over again. You can get the carburetors close enough to know if it's going to run by syncing the carburetors with them off the bike. Go on YouTube and look up "bench sync carbs". Do this once you have taken the carburetors apart and soaked them individually with all of the parts removed. Just do it you will be glad.

 

[jeff78]

What's the idle speed set at? Might be something as simple as it being set too low and the engine can't hold the idle. I don't know the idle speed for this bike in particular, but if I had to guess, it's probably 1100-1300 rpm. And/or the carbs are way out of sync. Turn the idle speed screw up and see what happens. You mentioned that the bike couldn't hold an idle even before the owner abandoned it, so there's a possibility the problem wasn't originally the carbs. They just became an additional problem due to neglect. Same as with riding a bike, target fixation can cause problems with troubleshooting too. Replace the plugs. Check for vacuum leaks. Test the battery and charging system. Could be a number of other things, but those are the easier/cheaper ones to try. Is the engine running on all cylinders? If the exhaust is aftermarket, you should be able to hear if it's misfiring. With an OEM exhaust you'll need a good ear. Doesn't even need to be your ear - you can take a video of the bike and post it up and see what others say. The video quality doesn't need to be good, but the audio should be. Almost forgot - bikes made during the dying days of the carburetor have throttle position sensors. If they act up (not uncommon), they can cause all sorts of running problems. And get a factory service manual for the bike. I'm sure you can find a PDF copy floating around somewhere.

 

[ZeeOSix]

Originally Posted by Bonz

The only real step left is to take them fully apart. The carbs need unracked which means separate them individually and take everything out, soak them in carb cleaner or get an $80 ultrasonic cleaner and do it right.

Yep, the simple cleaning didn't seem to get the job done. On the synchronization ... those sound like vacuum actuated slides, so you can't even do a rouge sync without removing the whole carb 4-set assembly and visually watching the butterfly plates/valves on the head side. If you can see the butterfly plates you could do a rough manual sync and put the carb set back on just to see if it's going to run better. Might be worth a try before going down the total disassembly and cleaning of all the carbs route.

 

[02SE]

I wasn't being flippant when I suggested taking it to someone who is familiar with motorcycle carbs. It's easy to cause damage forcing wire or other things through openings. Deform needles, seats, etc through injudicious use of screwdrivers, etc. Cause damage with certain chemicals, etc. Setting up carbs is as much an art, as it is mechanical ability.

 

[Bonz]

Jeff, Zee and 02, good thoughts all. He said in the first post it ran fine on starter fluid, even up to 7,000 RPM. That says there isn't proper fuel coming out of the carburetors to mix with the air. It wouldn't be a problem with spark or other issues. We know and he knows that the bike wants to run. In a later post, he said fuel was coming out the bowl gaskets so he doesn't have an issue with the fuel pump providing go juice. Those carbs do have a throttle position sensor however that is not going to cause these issues. If he simply leaves it unhooked then the ECU will default to the normal timing curve based on RPM. TPS simply was a way to smooth out the throttle response with lean carburetor settings for emissions purposes in the mid-range. If he goes to wide open throttle even right off idle the ECU goes straight to RPM based timing adjustment. And the TPS doesn't do anything to the timing curve at lower RPM so I think he's okay there. I found the simplest way to bench synchronize the carbs is adjust so the butterfly valve covers the pilot hole in the carb at the bottom edge of each butterfly equally. Keep in mind there is the one hole at the edge of the butterfly and there are probably three or four holes just behind the butterfly. The pilot screw only controls the one hole at the edge of the butterfly. The other holes are fed a constant supply from the pilot jet and the pilot screw does nothing to control them. So if the pilot jet or any orifice in that circuit is plugged it's not only messing up idle but it's messing up any type of light throttle application before the needle or main jet comes into play. Again, I'm right back where I was and I want to stand firm on it without coming across wrong. The carbs have to be taken apart completely and cleaned, preferably ultrasonically or soak them in carb dip and then spray the crud out of them with carb spray and compressed air. There are carb cleaning wire sets that can be used to insert through any size teeny tiny hole in any jet or any carburetor and they really won't do any damage unless you're extremely ham-fisted. Used in conjunction with a proper disassembly and cleaning I bet anyting his bike will run. To have such a nice bike and not do it right at this point after all the quick and easy methods have failed just seems counterintuitive.

 

[ccs368]

In my experience with all the carb'd bikes I have owned or worked on, synchronizing the carb with mercury sticks (Motion Pro) was the only way to visualize and confirm if the multi bank carbs has any chance with respect to vacuum to be eliminated out of the equation. And to answer this question, YES I have numerous times where my '95 900RR will not idle because the synch was way off. Even when completely removing the carbs and working on them, I found that even tightening them back on, the rubber boots were not perfectly sealed as before and you end up chasing your tail every time the carb has to be removed. I believe the fruits of your labor is going to be confirming and dialing in the vacuum to within acceptable limits for your carbs. When you get the hoses installed into your intakes and everything is ready, you're going to instantly hear the behavior of your bike when adjusting the synch screws AND seeing the actual measuring on what that is with the type of gauge you use. I do agree you have to initially adjust the idle knob on the bike just to get it to rev continuously higher when you're synching but not so much that you could accidently suck mercury into the engine. The RPM will also not stay there and will go up or down accordingly when you start your tuning. What Motion Pro does not teach you is if you can get to this point, adjust carb 1 to 2 (left screw). Don't care what carb 3 and 4 is reading. They will be way off from one another but don't fret. Then synch carb 3 to 4 (right screw) until the delta between those two are within 0.25" of Hg of each other. Now bare in mind 1 and 2 are synch'd ( <0.25" Hg) and now 3 and 4 are synch'd (<0.25" of Hg) BUT 1 and 2 could be reading 10" of Hg and 3 and 4 could be 15" of Hg. Now for the money shot, synch all banks together (middle screw) to get all carbs to within 0.25" of Hg. Basically remember outside-in. Don't adjust the middle until the left and right are good. If you synch middle first and then left or right screw...from my experience you end up again chasing your tail and takes longer to synch. Remember, when doing this, you may need to tweek the idle knob just to synch at a RPM that you want to tune the bike at. Also lightly blip the throttle several times when you think you have the adjustment where you want it, to see the behavior. All good points from above and my suggestion is while separating each individual bank and complete cleaning has its merit, try synching with a tool first before doing this because I don't think you're wasting your time or money investing in a carb synch because I think you needed this anyways. I wish I was in your position, because like you said, the wealth of info you obtain when you determine root cause whether it was mechanical (valve adjustment...yes I did this with shims under bucket style), fuel (filter, pump, jets), air (boots, dirt), or electrical (battery, coils) you can pass this down to all of us.

 

[Bonz]

First thing to remember: This bike doesn't run! I agree that carbs need to be synced with the tool, however he doesn't have one and the best way he can make it so it will run is to visually bench sync. Until the bike runs there's nothing to work with.

 

[ccs368]

Yes and I had a bike that didn't run either and couldn't idle too but at some point you have to mount the carb and tune it dynamically and that could mean dialing up the idle knob temporarily until you see what baseline you're working with on the vacuum measurements. Maybe in this case a bench synch to get in a general vicinity would help because the synch screws were adjusted haphazard so perhaps in this state this would be ok. However, I am only recommending based on OP's skillset so that is why there are things that I would not do and others that I would highly go through that would result or at least point to better direction. I had a 15+ year old bike and every time I dismounted, the synch had to be readjusted to match the cylinders. That's just a fact with something that is less than prestine. So what I've read and the # of times the carbs were soaked and cleaned, you need to mount and minimize anecdotal tuning and get measurable data. The bike did run on its own and rev'd better and even if I have to hold the throttle open and get the measurements and adjust so it can behave on its own, I think this is a reasonable path.

 

[Bonz]

Originally Posted by Kurtatron

Update Still isn't fixed. I tightened the pilot jets until snug. Drilled out the pilot fuel screw and put in new ones. tightened till snug and backed out 2.5 turns. Everything seemed great. I even tried blowing on the needle screws, no leaks. Installed the carburator, fired right up, with the choke. It wouldn't rev. After fiddling around with the air adjustment screw, I was able to get it to rev. It revved much better than before. No starter fluid needed. But it still will not idle without the choke. I got frustrated and started messing with the synchronizer screws. I know, totally dumb, without a tool. Eventually it wouldn't start at all. What do you guys think, how much of this poor running can be related to a bad synchronize? It revved great, idled OK before I messed with the screws, but still no idle without choke. Help me out guys, I'm still not giving up on this bike. This is all a learning experience for me.

Look at the most recent update, the bike doesn't run. He needs to do a bench sync and it will run at least as well as it did when he had to use the choke for it to idle. Then he could hook up the sync gauges and take a look while it's idling with the choke. For the love of all things good, don't rev it with the gauges attached, it will suck the gauge fluid into the engine.

 

[ZeeOSix]

Originally Posted by Bonz

Jeff, Zee and 02, good thoughts all. He said in the first post it ran fine on starter fluid, even up to 7,000 RPM. That says there isn't proper fuel coming out of the carburetors to mix with the air. It wouldn't be a problem with spark or other issues. We know and he knows that the bike wants to run. In a later post, he said fuel was coming out the bowl gaskets so he doesn't have an issue with the fuel pump providing go juice. Those carbs do have a throttle position sensor however that is not going to cause these issues. If he simply leaves it unhooked then the ECU will default to the normal timing curve based on RPM. TPS simply was a way to smooth out the throttle response with lean carburetor settings for emissions purposes in the mid-range. If he goes to wide open throttle even right off idle the ECU goes straight to RPM based timing adjustment. And the TPS doesn't do anything to the timing curve at lower RPM so I think he's okay there. I found the simplest way to bench synchronize the carbs is adjust so the butterfly valve covers the pilot hole in the carb at the bottom edge of each butterfly equally. Keep in mind there is the one hole at the edge of the butterfly and there are probably three or four holes just behind the butterfly. The pilot screw only controls the one hole at the edge of the butterfly. The other holes are fed a constant supply from the pilot jet and the pilot screw does nothing to control them. So if the pilot jet or any orifice in that circuit is plugged it's not only messing up idle but it's messing up any type of light throttle application before the needle or main jet comes into play. Again, I'm right back where I was and I want to stand firm on it without coming across wrong. The carbs have to be taken apart completely and cleaned, preferably ultrasonically or soak them in carb dip and then spray the crud out of them with carb spray and compressed air. There are carb cleaning wire sets that can be used to insert through any size teeny tiny hole in any jet or any carburetor and they really won't do any damage unless you're extremely ham-fisted. Used in conjunction with a proper disassembly and cleaning I bet anyting his bike will run. To have such a nice bike and not do it right at this point after all the quick and easy methods have failed just seems counterintuitive.

All spot on ... good post.

 

[Kurtatron]

UPDATE I think I know WHAT'S WRONG. I am opened it up again, and inspected the pilot JETs and have concluded they are clogged! It's not bad gas, but green tarnish/corrosion. I stuck a flashlight on the other side of a pilot jet and NO LIGHT came through. On a less corroded jet. light CAME THROUGH. I notice that carb cleaner does not clean green corrosion. I am going to clean them with something else until light comes through all of them. This would explain the poor idling! hard to see, but light is coming through the center of that one, but others, no visible light comes through!

 

[Kurtatron]

3 out of 4 had no light penetration. I am feeling optimistic.

 

[Bonz]

Yeah! Good work! I think you are well on your way now.

 

[ZeeOSix]

You're on the right track. A full carb disassembly and chemical soaking and compressed air blowing out would have cleaned all that green gunk out of everywhere.

 

[Kurtatron]

IT RUNS! Hey Team, It is works stupendously! I can't believe it! It fired RIGHT UP without the choke! No choke was even necessary. Hot day of course, but It idled so smoothly, and it revs like new. I guess clogged pilot jets really was the problem! It was running a little rich, but adjusting the fuel pilot SCREWS fixed that. I did resort to bench synching (small bbs while slowly opening the butterfly valves), but it runs well enough. It doesn't even leak anymore. We intend to ride it sunday. I'll post a picture. The gorgeous Thundercat has risen from the grave! Thanks everyone for your help.

 

[ZeeOSix]

^^^

 

[Bonz]

Awesome!

 

[Merek]

Happens a lot with small engines that are ran with that e crap they are selling these days. I try to run only pure gas in mine and it's fuel injected too. I have a Ninja 650 and the only problems which has happened twice now is when running the gas with 10% ethanol, according to the owner's manual that states you can use it I've had problems with water separation which sinks to the bottom of the tank as it's heavier so it gets sucked up first. If I have to use that gas I will try to add Seafoam as soon as I can because it helps remove any moisture that's in there.

I suggest filling it with pure gas along with some Seafoam but glad you could get it resolved!

 

[Bonz]

Ethanol will do things to degrade incompatible fuel system parts and it will also gather water, per se, as stated above. Carburetors have been gunking up from every gas manufactured since a carburetor was first on a bike or in a car. E10 in and of itself does not gunk up carburetors. Any gas will accomplish the same thing when left to sit years.

If ethanol gas is gathering that much water in the tank, that in itself should be looked into as to why the gas is sitting in the tank and not being used. That sounds like issues with storage of the bike vs regular use.

 

[Merek]

Most likely I had received bad fuel from the stations where I purchased it. I don't remember which time but I had issues with it only a week after I filled up, everyone I've talked too says that it should take a lot longer for that much separation to happen and not for that short of time. I removed the tank to drain it and put fresh fuel in but the water was still in the system so I ended up just taking it to the dealer and they didn't charge very much either. The second time I ended up taking it to another dealer to get a different opinion and it was the same thing water in the fuel, that time they said the fuel was red and looked like diesel fuel but I know some fuel has dye to color it and MMO is red but I've never used it in the bike, also I was riding with my dad and we filled up at 7-11, he filled his Burgman 650 first and then I filled mine from the same nozzle, his ran fine and had no issues with it even after sitting for awhile but the next time I went to ride it wouldn't even start and both bikes are stored in the same spot together. I try to run treatment at least every tank or every other tank and I haven't had anymore issues with water, also I try not to use the ethanol gas whenever I can but it's not always feasible to do as stations that carry it are few and far in between sometimes and I try to plan my trips where there's a station along the way that has pure gas. All the typical stations around here carry e10 and most who I have talked to says that shouldn't be a problem but evidently mine has issues with it. One of the last things you want to do while out riding is to get stranded somewhere.

Ethanol in the gas is a double edged sword really, it does absorb water droplets in the air and it gets mixed in with the fuel, overtime the water separates out and ends at the bottom of the tank typically after it's been sitting for a long time. Usually when water is mixed with the ethanol as long as it's not too much it will burn but at reduced performance but the key is that it will still run. Both times I had issues was after I filled up with E10 gas.

When using regular gas since there is no ethanol in the fuel then it shouldn't absorb moisture from the air into the tank so that's one problem solved, the other is that gasoline doesn't like to mix with water which overtime separates out and ends at the bottom of the tank so most likely when using this type of gas you shouldn't have issues with moisture unless you picked up bad gas from somewhere.

The picture he posted clearly shows the ethanol damage with the green goo that gets in there and clogs everything up, but yes even regular gas can clog up carburetors but the ethanol makes it way more of a problem. You can always tell if ethanol has been used because of the green stuff, pure gas doesn't turn it green or tarnish it.