Author Topic: Exhaust temps???? (Read 2519 times)

JAG · « **on:** March 23, 2008, 08:23:50 PM »

I have a popping sound coming out of my exhaust pipe, and it's very sparatic and suddel but it's there.. I got out the pyrometer to check the exhaust temps, and the one that is popping is way high, atleast higher than the other three exhaust temps.. On average I get a temp of around 400 degrees.. But from the number four header, it goes up well past 500 degrees. Now I don't know if the temp and the popping is related, but I just started noticing it.. Any suggestions??

I have all new spark plugs.
Checked the timing- accurate - and set at .0014.
Oil has been changed
Carbs sync'ed

I have searched the threads and haven't found anything.

Thanks in advance

Jay B · « **Reply #1 on:** March 23, 2008, 08:26:19 PM »

Lean = hot exhaust temps. Maybe a partially plugged jet???

JAG · « **Reply #2 on:** March 23, 2008, 08:31:04 PM »

Also noticed a lot of

?steam

? coming out of the tube that connects to the top of the heads that runs down in front of the back tire..

Also there is moisture coming out of the exhaust, but I just assumed it was normal. Kind of like starting your car on a cold morning-there is steam or smoke that comes out of the exhaust.

JAG · « **Reply #3 on:** March 23, 2008, 08:33:31 PM »

that's what I am thinking.. I pulled the petcock off and noticed some chips of rust, that must have came off the interior walls of the gas tank, in the small filter that is contained inside of it.

I also thought if it was running to lean that it wasn't receiving the right amount of fuel, and so I adjusted the float accordingly.. But nothing seems to fix the "popping" noise..

750goes · « **Reply #4 on:** March 23, 2008, 08:46:33 PM »

check your vacuum sync on the carbs - and I think both slow and main jet, as you have not indicated if it is just at idle or higher up rpm ??..

check your float bowl for sediment, and possibly reset your float height to be the same as the others... also give the float valve a once over to make sure it is not sticky...

other than that are all the spark plugs the same style and rating ?

JAG · « **Reply #5 on:** March 23, 2008, 09:16:41 PM »

This whole problem started with a surge in power at around 3-3500 rpms.. Assuming caused from the cylinders moving up and down and not having any spark, or something of that nature. So I bought new spark plugs which are all NGK D8EA if I'm not mistaken. And they are all set roughly at .25 or .26... When I took the old ones out, I believe every single one of them were of a different rating!!!

But problems fixed, no more surge. Now I'm just trying to deal with the popping.. $:-\$

This all occurs at idle.. I cannot tell if there is any sputtering while I'm going down the road, simply because of the wind. But the sputtering/ popping sound only occurs once the engine is warmed up.

There is a slight build up of sediment in the float bowls. Brown in color= rust I'm sure, from the tank. I really hate to take those carbs back off, because they are so hard to pull off and put back on. And I don't have a carb sync tool, which means I have to load up the bike in the back of the truck and haul it 30 miles down the road to have it done.

The float valves are functional. I tried with the floats off and using my finger as an "on/off" and they worked as they should.

It's hard to tell where the bike is idling at because my tach is near irresponsive. I had the gauge completely pulled apart and I squirted WD40 in it and worked the tach needle with my finger for about 10 minutes and hooked back up the bike and it worked for a day or so, and now it's back to it's unresponsive self

750goes · « **Reply #6 on:** March 23, 2008, 10:05:35 PM »

check your connectors from carbs to head are firm on both sides....are the connectors supple or cracked and hard...

best thoughts would be the idle jet/s are slightly clogged...and clean the rust out of the bowls - 5 minute job....

754 · « **Reply #7 on:** March 23, 2008, 10:15:18 PM »

If the popping occurs after you get off the throttle..it is likely an exhaust leak..

goon 1492 · « **Reply #8 on:** March 24, 2008, 06:52:36 AM »

I 'd say your carb could be only part of the problem, you might get a compression tester and check that, you might have a bad valve seat that is not sealing totally.

JAG · « **Reply #9 on:** March 24, 2008, 11:43:30 AM »

The "connectors" connecting the heads to the carbs, are in really good shape, no cracking or anything of the sort.

The popping only occurs while it is sitting still at idle.. If it was an exhaust leak, what are the measure to fix that?

I'm going to clean out the bowls and jets and see if it makes any difference this afternoon..

daniel son · « **Reply #10 on:** March 24, 2008, 11:49:12 AM »

i had my 650 popping when i came off the throttle after i put pods on it. i have only just fixed it yesterday, it turned out it didnt have any manifold gaskets in there. it never done that before i put the pods on and it had never had the gaskets either!!!
anyway i have fixed it now
just though id mention this

i thought i still had carb problems....

TwoTired · « **Reply #11 on:** March 24, 2008, 11:49:41 AM »

Quote from: JAG on March 24, 2008, 11:43:30 AM

The popping only occurs while it is sitting still at idle.. If it was an exhaust leak, what are the measure to fix that?

Float level too high? Or, restricted Idle system in carbs. What have you set your Pilot screws at?

JAG · « **Reply #12 on:** March 24, 2008, 12:58:04 PM »

The pilot screws are all set at 2 full rounds out. What would be the restricted idling system in the carbs?

I do have pods on there.

I don't have a tool to set the floats, I am doing them all visually. I remove the bowls to see the level of the gas, and try and get them all about the same. On the #4 carb, I came off of it a bit more to try and reduce the level of gas in it, but it never changed the problem, and the header is still running way hotter which it sounds like it's running lean, as Jay B mentioned before..

JAG · « **Reply #13 on:** March 24, 2008, 01:48:04 PM »

Well I checked the main jet and slow jet in #3 and #4 and all is as it should be. I went ahead anyways a took a small gauge wire and poked through each individual hole just for good measure and put everything back into it's place.

Fired it up, let it idle till it got warm and the popping came back, and there is still moisture seeping out of the end of the exhaust just on that side, and it is a lot of smoke coming out of the exhaust until it warms up all the way, but it has always done that. Is that bad? Is moisture anything to worry about?

Checked the temp of all the header after it warmed up and all four are running at 475F degrees. Does anyone know the normal operating temperature that they are supposed to be running at?

TwoTired · « **Reply #14 on:** March 24, 2008, 02:09:44 PM »

Quote from: JAG on March 24, 2008, 12:58:04 PM

The pilot screws are all set at 2 full rounds out. What would be the restricted idling system in the carbs?

I do have pods on there.

I don't have a tool to set the floats, I am doing them all visually. I remove the bowls to see the level of the gas, and try and get them all about the same. On the #4 carb, I came off of it a bit more to try and reduce the level of gas in it, but it never changed the problem, and the header is still running way hotter which it sounds like it's running lean, as Jay B mentioned before..

Why 2 turns out? With pods it would run leaner due to the loss of throat vacuum. I expect your throttle response under load isn't very good. Are your pods oiled?
Turn the screws in a quarter at a time and ride to check throttle response. Keep turning them in until throttle response no longer improves from low RPM. You should be able to snap the throttle to 1/2 of travel and get good response.

The carb body has 4 holes in it for the slow system; the air jet, the slow jet, the air adjust screw, and the carb throat hole. I test for flow to from each hole to all the others by squirting carb cleaner. This shows the passageways and the jets are clear.

You may have an exhaust leak, as well. Perhaps at the pipe to head junction. Or, before the muffler. Air infiltration adds oxygen, lights off the mixture, and it pops.
Popping can be caused by unequal vacuum sync, too.

JAG · « **Reply #15 on:** March 24, 2008, 02:32:36 PM »

I originally adjusted each screw to try and get the fastest idle, going from one screw to the next, after getting what I assume to be the best idle from all four screws, I would then set idle set screw back down to try and achieve around 1200 rpms. But now that my tach is working inproperly, I just set all screws at 2 full turns out. I will try your method and see if I can test the responses a little better..

My pods are not oiled? How would I go about doing this, and what is the proper oiling method, and what kind of oil do you use?

I took the mufflers off the exhaust, and the popping still occurred. I will try and see if it needs tightening at the point of contact with the head.

I have no way of testing the vacuum on the bike, as I don't have the proper tools, is there any other way to try and sort of "bench" test it so to speak, without having the proper vacuum sync tool?

JAG · « **Reply #16 on:** March 24, 2008, 03:38:06 PM »

NOw I have adjusted all the float heights to allow less fuel in.. The smoking out of the exhaust has subsided as well as the popping/sputtering noise, but it won't hold a good idle and now the oil light is on. It seems like it is getting not enough gas, as the bike just quite after just a short while of sitting there idling.

Also the #4 exhaust header that was 100 degrees over the rest is now showing almost 200 degrees less than the rest of them. numbers 1-3 are running a temperature of roughly 375 degrees, while the #4 is at 150!!

What is the deal?!!? As I am now completely lost....

frustrated....

JAG

TwoTired · « **Reply #17 on:** March 24, 2008, 03:58:58 PM »

Quote from: JAG on March 24, 2008, 02:32:36 PM

I originally adjusted each screw to try and get the fastest idle, going from one screw to the next, after getting what I assume to be the best idle from all four screws, I would then set idle set screw back down to try and achieve around 1200 rpms.

The process you used would be correct for a carb with an accelerator pump. If you still have stock carbs, you don't have an accelerator pump. And, setting them for max lean at idle is not the way to set up these carbs.
The book value for your idle screws is 1 turn out. Turning it out further makes the slow circuit leaner. With your pods, I would expect you to turn them in farther than the stock setting. These bike run rich at idle so that the throttle response is acceptable.

Quote from: JAG on March 24, 2008, 02:32:36 PM

My pods are not oiled? How would I go about doing this, and what is the proper oiling method, and what kind of oil do you use?

I don't know what pods you have. Foam pods need oil. Paper element pods, probably don't. Both Uni and K&N, market oil for use with pods.

Quote from: JAG on March 24, 2008, 02:32:36 PM

I took the mufflers off the exhaust, and the popping still occurred. I will try and see if it needs tightening at the point of contact with the head.

If the head pipe to head coupling gasket is compromised, simply tightening it probably won't help. It will have to be renewed. If you tighten too much, something breaks. I warn you that I'm not completely familiar with the early 750 pipe to head union. It may be different than the 550 arrangement, I'm more knowledgeable about. Something about Spigots and 750's ... $:-\$

Quote from: JAG on March 24, 2008, 02:32:36 PM

I have no way of testing the vacuum on the bike, as I don't have the proper tools, is there any other way to try and sort of "bench" test it so to speak, without having the proper vacuum sync tool?

Bench sync (adjusting slide to same height) gets you close enough to do a vacuum sync. But, unless each cylinder has exactly the same breathing characteristics (as when brand new), some cylinders will fire with more strength than others. The lazy cylinder may then pop, as the cylinder doesn't do an efficient burn.
You'll need manometers to do a proper vacuum sync. One of the joys of 4 carbs.

TwoTired · « **Reply #18 on:** March 24, 2008, 04:02:26 PM »

Quote from: JAG on March 24, 2008, 03:38:06 PM

NOw I have adjusted all the float heights to allow less fuel in.. The smoking out of the exhaust has subsided as well as the popping/sputtering noise, but it won't hold a good idle and now the oil light is on. It seems like it is getting not enough gas, as the bike just quite after just a short while of sitting there idling.

Also the #4 exhaust header that was 100 degrees over the rest is now showing almost 200 degrees less than the rest of them. numbers 1-3 are running a temperature of roughly 375 degrees, while the #4 is at 150!!

What is the deal?!!? As I am now completely lost....

You were already running too lean and when you lowered the fuel level, made it even leaner.
Your idle mixture is wrong.
Your carbs aren't properly synchronized.
IMO

754 · « **Reply #19 on:** March 24, 2008, 04:11:55 PM »

Get rid of the heat sensor, just use it to find out the pproblem cylinder.. then work on that.

Maybe you should try a compression check, could have a bad hole..

JAG · « **Reply #20 on:** March 24, 2008, 05:33:49 PM »

Okay went back adjusted float heights. all seems to be back running again and having a better idle. Popping is back but it's better. And the oil light stays on until I start moving and increase rpms, and accelerate from idle.

I have paper filiment pods. I know it's not the best but that's all I have.

Next thing I know to do is take apart the whole shebang clean every orphous every hole, bench sync it. Take it in and have some one do a compression test and carb sync.

The carbs were sync'ed up, but there must be some trash or something built back up into it causing these problems.

Something else I am noticing about the heat sensor is on #1 it fluctuates in temperature.. The needle will literally jump around ranging the temp 20 to 40 degrees.. What trouble can that spell?? If anything?

TwoTired · « **Reply #21 on:** March 24, 2008, 06:31:40 PM »

Did you readjust the idle air screws?

JAG · « **Reply #22 on:** March 24, 2008, 06:42:59 PM »

Yes I did.. I turned them all out just a quarter-half a turn.

I have taken the whole thing apart, and I'm cleaning the carbuerators with yamaha's carb cleaner. I'm going to let it all soak over night and try it again tomorrow..

JAG · « **Reply #23 on:** March 24, 2008, 08:49:06 PM »

I got it all cleaned up and the carbs put back together.

Interestingly enough I tried and replaced the main jets from 115 to 135, just for sh*ts and giggles, and it seems to be running quite nice, atleast in idle. There is no oil light on, and there is absolutely no sputtering. The only thing I seem to not be able to get away from is the dang smokiness. It happened, and it may only be a coincidence, when I adjusted the idle screw higher, when I backed off of it, it seemed to not do it as much...

I'm still going to follow up with the carb sync and vacuum test, just wish I had such tools readily available.. $:-\$

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Author Topic: Exhaust temps???? (Read 2519 times)

daniel son