Help with carb sync

[gearhead13]

Jets are stock. I raised the float height on 2 and 4 (from 0.88" to 0.94"). Now 4 doesn't smoke if the idle mixture screw is all the way in, 2 still smokes a little. I made a video of the bike running to see if maybe someone on here may be able to tell something from the way it sounds. Keep in mind I don't have a stock exhaust they are individual turned out pipes with mufflers on 2 and 3 and just pieces of metal that look like leaves on the inside of 1 and 4. I really like the look of the pipes but hate the sound, to loud for me. Also, you may want to close your eyes watching it, I just hung the camera off my wrist so the video is a little crazy.

http://www.youtube.com/watch?v=OP9f0hfPXk8

The main idea with 4 carbs feeding 4 cylinders is that all 4 carbs need to be set exactly the same to run right, by messing with float heights with just two you are messing them up. Set the float heights the exact same and fix what is really wrong. Sounds like your bigger problem is when you give it gas which means pilots and/or needle heights. Do your slides move freely? how clean did you get them? are all the spacers on the needles in the same positions?
EDIT: Airbox or pods?

 

[glstine]

Yowza. It sounds like it's only running on two cylinders half the time.

You may have ignition problems along with your fuel problems.

By the way, increasing the numbers on your float height actually lowers the floats. You have to remember that they are set while the carbs are upside down, so increasing the number is moving the float farther from the carb. When you turn the carbs back right side up, the floats are still farther from the carb body, meaning lower.

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My goal was to lower the fuel level in 2 and 4 due to the rich condition. I get spark on all 4 cylinders. One thing I didn't mention in this thread, but I think I did in another, when I replaced the starter I had to take the cam chain tensioner off. When I put the starter in, I hit the start button briefly to make sure the starter worked (this was the second time I had to put the starter back in and wanted to make sure it worked before putting it all back together, which I didn't do the first time). Unfortunately, I did this before putting the cam chain tensioner back on. I pulled the valve cover and checked the timing and it was as it should be. Is it possible that somehow it could still be screwed up?

 

[glstine]

The main idea with 4 carbs feeding 4 cylinders is that all 4 carbs need to be set exactly the same to run right, by messing with float heights with just two you are messing them up. Set the float heights the exact same and fix what is really wrong. Sounds like your bigger problem is when you give it gas which means pilots and/or needle heights. Do your slides move freely? how clean did you get them? are all the spacers on the needles in the same positions?
EDIT: Airbox or pods?

Airbox and OEM filter. The slides move freely, I haven't messed with the needles at all. Since there is more to the fuel delivery than just the carb settings, I suppose mainly the amount of vacuum from each cylinder, doesn't each carb need to be tweaked individually?

 

[gearhead13]

Airbox and OEM filter. The slides move freely, I haven't messed with the needles at all. Since there is more to the fuel delivery than just the carb settings, I suppose mainly the amount of vacuum from each cylinder, doesn't each carb need to be tweaked individually?

With your compression numbers differences in vacuum shouldnt be an issue. You need to take all variables out of the equation, not make your own by setting float levels differently. Maybe your po messed with them, been known to happen Did you pull it apart and check?

 

[glstine]

With your compression numbers differences in vacuum shouldnt be an issue. You need to take all variables out of the equation, not make your own by setting float levels differently. Maybe your po messed with them, been known to happen Did you pull it apart and check?

I've never taken the needles out, I guess I will do that, it's the only thing I haven't checked on the carbs. Never had a problem for 3000 miles (after the first time I cleaned the carbs) until taking the carbs apart due to the grit in them. For the first 3000 miles they only had a bench sync and I never checked the fuel level in the float bowls. That's part of what makes this so aggravating.

 

[Nessism]

Something fundamental is wrong with your carbs if 2 and 4 are rich with the pilot screws turned all the way in. I'd open them up to 2 turns and try riding the bike again to see if it runs better. I don't know if weak spark could cause the bike to run rich like that but it might be part of the problem.

 

[glstine]

Something fundamental is wrong with your carbs if 2 and 4 are rich with the pilot screws turned all the way in. I'd open them up to 2 turns and try riding the bike again to see if it runs better. I don't know if weak spark could cause the bike to run rich like that but it might be part of the problem.

This actually made an improvement, still not there though. For more information these are the plugs after making a run up and down the street with the idle mixture screws turned out (in order of 1,2,3,4). Not as apparent as I had hoped but 2 and 4 plugs are wet. I should add with the idle mixture screws turned all the way in the plugs weren't wet, just had fluffy black deposits, so I am pretty sure it is rich and not oil fouling.

I also shot a little video of the spark I get, this would be typical of all cylinders.

http://www.youtube.com/watch?v=ry97IRX6Tg4

 

[almarconi]

What's your voltage at the coils?

 

[glstine]

What's your voltage at the coils?

I get a 0.1V loss from battery to coil, battery has been keeping a charge even with all the starting and stopping I have been doing.

 

[almarconi]

Is it firing on all cylinders?

I would take a spray bottle of water and spray some on the exhaust header pipe, if it is running properly the water will sizzle and evaporate. A pipe that is not firing will cause the water to basically roll off. If your not firing on all cylinders I would try cleaning the carbs again.

You mentioned that you turned the engine without the cam tensioner. Did you verify that the timing marks are aligned and that the cams are aligned. It could have skipped a tooth when you turned it.

It's hard to tell from the pictures but I would expect to see a discoloration (blue/brown) in the first couple of threads on the spark plug if the bike is running properly. I seem to remember chef1366 commenting on this discoloration before. The insulator should be tan and you should see discoloration on the first couple of threads if the mixture is correct.

 

[glstine]

Is it firing on all cylinders?

I would take a spray bottle of water and spray some on the exhaust header pipe, if it is running properly the water will sizzle and evaporate. A pipe that is not firing will cause the water to basically roll off. If your not firing on all cylinders I would try cleaning the carbs again.

You mentioned that you turned the engine without the cam tensioner. Did you verify that the timing marks are aligned and that the cams are aligned. It could have skipped a tooth when you turned it.

It's hard to tell from the pictures but I would expect to see a discoloration (blue/brown) in the first couple of threads on the spark plug if the bike is running properly. I seem to remember chef1366 commenting on this discoloration before. The insulator should be tan and you should see discoloration on the first couple of threads if the mixture is correct.

I did check the timing marks afterward and they were per spec. The plugs are new so I don't think they would have been used enough to discolor up the threads. I did check for firing on all cylinders by pulling the plug caps off one at a time and checking for change in rpm's.

 

[Guest]

If you have the carbs all clean and set than it's ignition.

 

[glstine]

If you have the carbs all clean and set than it's ignition.

So what do I check and how do I check it? Timing marks line up and I have spark on all 4 cylinders. I don't know what else to check.

 

[almarconi]

You say the timing marks line up, did you take the valve cover off to see if the timing marks and the cams line up correctly. Did you count the correct number of links on the cam chain. It is very easy to be off a tooth and not even realize it.

 

[glstine]

You say the timing marks line up, did you take the valve cover off to see if the timing marks and the cams line up correctly. Did you count the correct number of links on the cam chain. It is very easy to be off a tooth and not even realize it.

Yes, counted them multiple times to make sure.

 

[almarconi]

How about plug caps and wires? Did you measure the resistance of the caps and wires to rule these out? If the caps are OK try cutting a 1/4" off the wires and reinstalling the caps.

Air filter clean and airbox sealed?

Did you inspect your slide diaphragms to make sure there were no pin holes? Did all the jets and other brass parts match. There should be numbers etched on all the parts. I rebuilt a set of carbs one time and one of the cylinders would not fire, turns out one of the jets I used from a rebuild kit was not the correct one.

It's sometimes difficult to diagnose problems without actually seeing the bike. Another option would be to try another set of know good carbs to see if you are having the same problem. Its common for fuel problems to look like ignition problems and vice versa so its takes awhile to get everything sorted out.

 

[glstine]

I measured the coil resistance, but I want to make sure I did it right. For the primary resistance I measured across the two incoming wires. For this I set the meter to 200 Ohms and just got a 1 on the left of the display. I switched to 20 kOhms and got 1.04 on both coils, so I guess that is 1040 Ohms compared to the 3.5-4.5 Ohms the service manual says, I'm guessing I'm either doing something wrong or the coils are toast.

For the secondary measurement I measured across the spark plug caps and got 26 and 27 kOhms, service manual calls for 35-38 kOhms. So if I measured correctly, I guess I need to get new coils.

I have dielectric grease in the connectors, I am assuming this should have little to no effect on the readings.

 

[almarconi]

The meter I have is auto ranging. When set to resistance you get a reading in the 3-5 ohm range for the coils.

You should measure the primary resistance between one of the terminals and ground. Use one of the bars on the coil for ground or a suitable chassis ground. The secondary resistance should be measured with one probe on the spark plug wire and the other to ground. Some coils may test OK cold but fail when warm. I would also remove the cap and measure the cap for its resistance.

Try remeasuring and report back.

 

[Guest]

If they do test bad I have a good pair.

 

[almarconi]

If they do test bad I have a good pair.

Chef is there a part you DON'T have