Author Topic: bike starts overheating high idle? (Read 8323 times)

xsmooth69x · « **on:** August 20, 2012, 05:29:28 PM »

so i was riding on the highway with my cb550 and it was dead locked traffic i bet my bike didnt move for 45 min.

at that time my idle started going higher and higher i backed off my idle screw to the point it did absolutely nothing. it idles around 2k-3k and at that high of an idle its very hard for me to put my bike back into neutral. so i was practically stuck in first gear having a death grip on my clutch lever since i could not get it into neutral.

im thinking since the bike got so hot from not moving the oil got so hot and thin that the engine started idling high? i also have rotella T6 (5w-40) oil in the bike. im thinking now that it is way to thin and i should change it out to the 15w-40 rotella?

or i have no idea what im talking about

killersoundz · « **Reply #1 on:** August 20, 2012, 05:44:59 PM »

Quote from: xsmooth69x on August 20, 2012, 05:29:28 PM

so i was riding on the highway with my cb550 and it was dead locked traffic i bet my bike didnt move for 45 min.

at that time my idle started going higher and higher i backed off my idle screw to the point it did absolutely nothing. it idles around 2k-3k and at that high of an idle its very hard for me to put my bike back into neutral. so i was practically stuck in first gear having a death grip on my clutch lever since i could not get it into neutral.

im thinking since the bike got so hot from not moving the oil got so hot and thin that the engine started idling high? i also have rotella T6 (5w-40) oil in the bike. im thinking now that it is way to thin and i should change it out to the 15w-40 rotella?

or i have no idea what im talking about

you should be using 20w-50 in these bikes

If it's hotter than 70F out I wouldn't idle my bike for more than maybe 15 or 20 minutes max. They just can't cool down

I know what you mean about not being able to get it in neutral. My bike is impossible to get into neutral sometimes regardless of the idle. And other times it goes right in. Sometimes rocking the bike back and forth a little bit will help but there are still a few times in traffic I couldn't get it in either.

w1sa · « **Reply #2 on:** August 20, 2012, 06:37:56 PM »

The 5w,10w,20w, etc prefix to the oil grade is only to do with its viscosity/thickness/flow characteristics at extreme (below freezing) temperatures. The 30,40,50 etc suffix is the oil's hot temperature viscosity........so a 5w40 oil will be in the same viscosity range and therefore have the same/very similar thickness/flow characteristics as other ##w-40.

The main differences in same grade hot temperature (viscosity) performance are a result of whether the oil is 'light' or 'heavy' for its grade...e.g. ##w-40 can have a hot temperature (100C) viscosity between 13 and just above 16....... and, the quality of the oil. Better quality oils generally retain more of their (hot temperature) viscosity/shear performance, during use.

Bob Wessner · « **Reply #3 on:** August 20, 2012, 06:53:11 PM »

If you were really stopped that long, why not turn the engine off? I 've done it in dead stop tie-ups.

TwoTired · « **Reply #4 on:** August 20, 2012, 07:00:29 PM »

Hard to know what happened to your oil. Usually, if it breaks down, the engine slows down as the pistons start to seize.

I speculate that you carbs were getting pretty hot, effecting the mixture, as well as dimensional stability. If your idle screw stopped having effect to bring the idle down, then you have the dreaded "I skewed all the individual slide adjusters during carb sync so the slides don't reach the bottom of travel syndrome". Drill bits as sync tools are evil for your carb style, and sets the stage for other problems.

No air flow IS the bane of air cooled motors. And, when the oil is over temped above it's withstand, it is damaged (sometimes turns to tar).
Best to change it. It won't matter what viscosity it is, if it becomes over temped, it's damaged and needs replacement.

It is precisely because of unforseen situations as you've encountered, that I like to have a synthetic blend in the oil supply, as synthetic has a higher breakdown withstand to save the engine bits. Still have to change it after an overtemp occurance, but at least it's just oil to change and not pistons/and rings.
If you expect to see routine high temps, full synthetic may be your only hope to save both engine and clutch. Or, install an electric fan on the bike to push replacement air over the fins while at a standstill.

If your clutch now drags and makes the gears clunk going from neutral, the oil is probably bad, I don't care how many miles are on it or how old it is. You can cook brand new oil and make it bad in less than an hour.

Cheers,

killersoundz · « **Reply #5 on:** August 20, 2012, 09:29:57 PM »

Quote from: TwoTired on August 20, 2012, 07:00:29 PM

Hard to know what happened to your oil. Usually, if it breaks down, the engine slows down as the pistons start to seize.

I speculate that you carbs were getting pretty hot, effecting the mixture, as well as dimensional stability. If your idle screw stopped having effect to bring the idle down, then you have the dreaded "I skewed all the individual slide adjusters during carb sync so the slides don't reach the bottom of travel syndrome". Drill bits as sync tools are evil for your carb style, and sets the stage for other problems.

No air flow IS the bane of air cooled motors. And, when the oil is over temped above it's withstand, it is damaged (sometimes turns to tar).
Best to change it. It won't matter what viscosity it is, if it becomes over temped, it's damaged and needs replacement.

It is precisely because of unforseen situations as you've encountered, that I like to have a synthetic blend in the oil supply, as synthetic has a higher breakdown withstand to save the engine bits. Still have to change it after an overtemp occurance, but at least it's just oil to change and not pistons/and rings.
If you expect to see routine high temps, full synthetic may be your only hope to save both engine and clutch. Or, install an electric fan on the bike to push replacement air over the fins while at a standstill.

If your clutch now drags and makes the gears clunk going from neutral, the oil is probably bad, I don't care how many miles are on it or how old it is. You can cook brand new oil and make it bad in less than an hour.

Cheers,

THIS IS VERYYY INTERESTING to me. Seems VERY relevant. I have about 200 miles on my break in with fresh oil obviously. I JUST changed the oil today, that stuff came out almost pitch black. I don't believe my engine has been running rich, at least that much to make that oil look like that in so little miles.

I did let it get very hot sitting in traffic one time. I was thinking it was running very hot but not to the absolute extreme. It was to the point where you could start smelling a funky oil smell radiating up. So what you have to say here sounds very relevant to me and also scary.

xsmooth69x · « **Reply #6 on:** August 21, 2012, 06:25:09 AM »

T6 is a synthetic blend

but I'll change out the oil and..... ya shutting off the bike would've been smart duh on my part

the technological J · « **Reply #7 on:** August 21, 2012, 07:27:21 AM »

i always shut my bike off at even red lights when i dont feel like finding neutral and want my hands free... also acts as a brake if your on a slope

bollingball · « **Reply #8 on:** August 21, 2012, 07:48:50 AM »

Pull over and TURN IT OFF. What are you thinking. This is NOT a water cooled engine.
Ken

xsmooth69x · « **Reply #9 on:** August 21, 2012, 07:57:28 AM »

well i wasnt thinking and its my first bike. i didnt know the bikes couldnt sit for more than 15min....

i would love to turn my bike off all day long but im having issues with my starter so its kick only atm

but i do have an oil cooler adapter for the bike and a radiator so maybe i should get some new fittings and tubs and hook that bad boy up

goldarrow · « **Reply #10 on:** August 21, 2012, 08:04:21 AM »

Now you know these engines are air cooled and that you didnt severely damage your engine....

xsmooth69x · « **Reply #11 on:** August 21, 2012, 08:18:38 AM »

checked it out this morning rode fine checked the oil it looked fine.

all is well and i know now.

might re sync my carbs.

when i said i backed off the idle screw and it didnt do anything was because it was so far backed out it didnt touch the carb rack anymore.

when i synced my carbs i literally only screwed it in a couple turns so the screw touched the carb rack then synched. maybe i should screw the idle screw in half ways then sync it so i have more length to unscrew

Teatimetim · « **Reply #12 on:** August 21, 2012, 08:35:40 AM »

you just have to make sure the slides will close all the way before the carb screw is all the way out. Took me a few tries at that, but when I bench sync now, I adjust the #2 to the bottom, then use the idle screw to raise it up till the drill bit just slides under, then I adjust the rest of carbs to that one. then when finished, I back out the carb screw and make sure no carb has any light coming through so I know the slides will all close with room to spare and the idle adjustment.

TwoTired · « **Reply #13 on:** August 21, 2012, 09:24:28 AM »

Quote from: xsmooth69x on August 21, 2012, 06:25:09 AM

T6 is a synthetic blend but I'll change out the oil and.....

That may have just saved your engine.

You might want to read up on synthetic oil, as just the synthetic label doesn't always get you a higher temperature withstand. Used to be that Synthetic oil was man made from stocks that naturally had a a higher temp withstand. The oil companies, looking for cheaper processes, got API to approve the synthetic label after a Hydrocracking process change to their regular crude oil base stocks.

Further, Semi synthetics are up to 30% "synthetic" blends. Leaving most of the volume of oil at a lower temperature withstand.

An oil cooler is mostly a placebo for a stationary air cooled engine. If it makes YOU feel good having it, go ahead. The oil cooler radiator need airflow through it to perform it's job and still, it cools the oil. It is so tiny compared to the mass of fins and external area of the engine, that it is a band aid over an amputation comparison. The oil is still heated by the engine, a circulation is for oiling purposes, not cooling purposes.

Quote from: xsmooth69x on August 21, 2012, 08:18:38 AM

when i said i backed off the idle screw and it didnt do anything was because it was so far backed out it didnt touch the carb rack anymore.

when i synced my carbs i literally only screwed it in a couple turns so the screw touched the carb rack then synched. maybe i should screw the idle screw in half ways then sync it so i have more length to unscrew

No. You should back the big screw out, pick one carb and adjust it so it will rest on the floor. Lock it down and assign it as master. Paint it red if you have too. Then adjust the other three to match the position and vacuum of the master carb.

If a job is worth doing, it's worth doing twice!

Cheers,

the technological J · « **Reply #14 on:** August 21, 2012, 10:31:59 AM »

do you have any play in your throttle cable? you might have an airleak somewhere also

bjatwood · « **Reply #15 on:** August 21, 2012, 10:35:51 AM »

My bike does the same with the higher rpms when it gets hot, and the clutch gets quite grabby too. I usually shut it down and give it 10 minutes to recoupe and drop temp.

xsmooth69x · « **Reply #16 on:** August 21, 2012, 01:02:45 PM »

ya i did the whole drill bit thing but i think i moved the individual carb screws around that it might have moved?

so when u do the drill bit thing the carb u drill bit you do not adjust at all when doing to carb sync??

also i was reading around that if one of my carb boots are ripped or cracked or leaking this causes high idles too? idk if that makes sense cuz the bike only does it after it gets hot.

xsmooth69x · « **Reply #17 on:** August 21, 2012, 01:03:12 PM »

Quote from: the technological J on August 21, 2012, 10:31:59 AM

do you have any play in your throttle cable? you might have an airleak somewhere also

no play in the throttle cables

TwoTired · « **Reply #18 on:** August 21, 2012, 01:19:51 PM »

Quote from: xsmooth69x on August 21, 2012, 01:02:45 PM

ya i did the whole drill bit thing but i think i moved the individual carb screws around that it might have moved?

so when u do the drill bit thing the carb u drill bit you do not adjust at all when doing to carb sync??

You SET the master carb with the drill bit. You insure that it can rest on the floor as end point of travel. I use light cut off on the bench, and never use drill bits. And, the light cut off can then be used on each carb in turn. However, if you have drill bits laying around begging to be used, then after you have locked down the master, use the idle knob to adjust the master slide position to just fit your selected drill bit, and then proceed to adjust the other three's individual adjusted to the drill bit you selected, and don't mess with the idle knob during.

Quote from: xsmooth69x on August 21, 2012, 01:02:45 PM

also i was reading around that if one of my carb boots are ripped or cracked or leaking this causes high idles too? idk if that makes sense cuz the bike only does it after it gets hot.

Leaking boots CAN cause high idles. Not usually temperature sensitive. I would expect hot, soft boots would seal better than cold hard ones, though. And rubber contracts with heat.

If you are unable to stop the bike by closing off the carb's air supply via the slides, where can you imagine the engine gets enough air to speed up?
And, what would be common to all four cylinders?

xsmooth69x · « **Reply #19 on:** August 21, 2012, 01:25:49 PM »

i have to take off my carbs to bench sync them again dont i.....

TwoTired · « **Reply #20 on:** August 21, 2012, 01:36:43 PM »

Depends on the air filter arrangement you have. You need to see at least one side as it bottoms to travel limits with the big idle knob backed out.

There are other ways, to infer slide position. But, you have to be smart about what you are seeing is actually the slide reaching the carb bore "floor".

You might consider complaining to the prior mechanic.

Maybe he'll back up his work?

Cheers,

xsmooth69x · « **Reply #21 on:** August 21, 2012, 05:07:28 PM »

Quote from: TwoTired on August 21, 2012, 01:36:43 PM

Depends on the air filter arrangement you have. You need to see at least one side as it bottoms to travel limits with the big idle knob backed out.

There are other ways, to infer slide position. But, you have to be smart about what you are seeing is actually the slide reaching the carb bore "floor".

You might consider complaining to the prior mechanic. Maybe he'll back up his work?

Cheers,

that would be this guy right here lol

dave500 · « **Reply #22 on:** August 21, 2012, 05:11:17 PM »

i thought you had a vacuum set xsmooth?if you do just resync them on the bike,back the idle screw out,then wind the sync screws untill the idle drops and drops,then do your sync,bringing up the idle screw as you need.

TwoTired · « **Reply #23 on:** August 21, 2012, 05:41:53 PM »

If you have a vacuum set, here's another method.
Pick a carb to be the master.
Hook up the vacuum gauges.
On the master carb adjust the individual carb to the highest vacuum it can achieve. Since you'll be shutting off a cylinder, you'll have to keep adjusting the big knob to keep it running on three. But, the highest vacuum should occur just when the slide is fully closed and full closure travel obtained.

When you can't get the master vacuum level any higher, lock its adjuster down. Then start adjusting the others, in turn, to whatever the master has. It will change, but you don't care. Just get the rest equal to the master's vacuum level. You'll have to keep twiddling the big idle knob to keep 1050 RPM on the dial. When you get all the others to equal vacuum, you're done. And you should be able to kill the motor, just be backing the idle knob outwards. The engine can't run without air.

Cheers,

the technological J · « **Reply #24 on:** August 21, 2012, 10:14:19 PM »

you want a little play in the cable... to test for airleaks just spray wd 40 or starting fluid between your carbs and engine while its running if theres any change in the idle you have a leak

xsmooth69x · « **Reply #25 on:** August 22, 2012, 12:36:07 PM »

ok... lol im getting confused

when we say backing out that means turning the idle screw counter clockwise the loosen it

and clock wise would be bringing it in right?

ya i have a sync set with the 4 gauges

right now the idle screw is all the way backed out (counter clock wise) and brought in (clockwise) maybe a full 3-4 rotations. this is the reason i have no to really lower lower the idle because if i back it out any more (counter clockwise) the idle screw dosnt even touch the rack anymore.

also this highest vacuum thing.... i thought u where supposed to get the lowest possible? in the picture is gauge 1 or gauge 2 higher?

xsmooth69x · « **Reply #26 on:** August 22, 2012, 12:44:52 PM »

ok

turn on bike.

put on gauges

move idle screw (clock wise) in maybe the middle position of the screw. this would make the engine run at a high idle.

move the individual slide screws so the engine comes down in idle just so that bike isnt idling high.

now the fine tuning stuff.......................

pick one carb, lets say the one all the way to the left if your sitting on the bike. ill make that the master. now start making that master carb have a very high vacuum ( which after someone tells me which way the needle should move to show high vacuum) (i think that would be picture 1). once i cant get the master vacuum any higher i lock the nut in place.

then i sync the other 3 carbs while moving the idle screw as needed to keep the bike alive and once it matches up with the master carb that is locked in. i lock the rest of the 3 carbs in place and im done?

now i will have more travel and control up or down the idle range

xsmooth69x · « **Reply #27 on:** August 22, 2012, 12:47:23 PM »

Quote from: the technological J on August 21, 2012, 10:14:19 PM

you want a little play in the cable... to test for airleaks just spray wd 40 or starting fluid between your carbs and engine while its running if theres any change in the idle you have a leak

there is a little play in the lines. also i have the over rev and under rev screws set so moving the grip backwards and forwards fast wont do anything crazy or stall out the bike coming from a quick stop

the carb boots are good if i still have problems i will shoot some wd40 on it. the boots are practically mint so i doubt its that. i was just referring to a vacuum leak because thats what i read and searched before i posted this thread.

TwoTired · « **Reply #28 on:** August 22, 2012, 01:32:02 PM »

A vacuum gauge reads zero with no vacuum. (It is actually atmospheric pressure and what you use when breathing.)

More vacuum is LESS pressure , or a higher reading on the vacuum gauge.

Standard barometric pressure is 29.92 inches of mercury. Automotive vacuum gauges use this to calibrate the needle to point to zero.

To remove the idle knob you back it out. In this case that would be counter clockwise.

xsmooth69x · « **Reply #29 on:** August 22, 2012, 04:50:38 PM »

weird my picture didnt upload

TwoTired · « **Reply #30 on:** August 22, 2012, 05:59:40 PM »

Lordy, are you really trying to do this without ANY thinking or understanding of what is happening, and how you are effecting it?

Can you read the dial and see where it is labeled pressure and, on the opposite side, vacuum?

While connected to the intake, have you EVER seen the needle point to the pressure side?

Do you understand a 4 stroke cycle?

When the intake valve is open and the piston falls, do you understand that negative pressure is created, (with respect to outside atmospheric)?
The only thing in the path from air inlet to the piston that impedes pressure equalization is the slide.
Therefore, more open slide settings produce a lower vacuum reading in the intake runner than those of a closed slide.
The goal is to obtain the most closed slide setting, which should be the highest vacuum reading for the "master" carb, so as to indicate it is completely shut off for air entry. This would be the end travel limit you are seeking, that is never tested or obtained by using drill bits under the slides. Once that end point is found by inference of vacuum readings, the idle knob can be used dominate or set idle speed, and all other slides can be individually adjusted to match any vacuum level the master carb achieves on a running engine. When all slides equal the master, which has been proven to reach full bottom travel, then ALL the slide will have achieved the same capability. Then it won't matter how hot the engine gets, you can set idle speed with the idle knob, as it has full authority slide travel end point, all the way to off or engine stopped.

If this doesn't make sense to you or you can't understand what is happening using this procedure, perhaps you are better off yanking the carbs off the bike and doing a proper bench sync with full slide travel falling under your direct visual gaze.

Good luck!

Syscrush · « **Reply #31 on:** August 24, 2012, 07:02:41 AM »

1. Glad it sounds like you didn't kill your bike. Even with synthetic oil, you easily could have destroyed that motor with what you did to that poor bike.

2. It probably got faster as it got hotter because of increased fuel atomization and/or carb parts expanding from the heat and letting more air and/or fuel in than it should. Changes in the oil viscosity would generally not result in a significant change in idle speed.

3. In stop & go traffic, definitely turn the engine off. Kicking it might be a pain, but it's a lot easier than having to push it home.

4. Even if you're not gonna leave it off for a long time, killing the engine makes it a lot easier to find neutral. Cut the engine, let out the clutch, and rock the bike back and forth a bit until it clicks into N. It is critical to let out the clutch to find N when the engine is off.

5. It's also easier to find N while the bike is rolling. If I'm stuck in bad stop & go, I'll pop it into N almost as soon as I'm moving.

6. Fix your starter! Also, put a voltmeter on your bike.

7. Don't pull the carbs to do another bench sync. Do a good vacuum sync (preferably with someone who's done it before there with you). Take your time, find some vids on YouTube that explain the theory and the practice. It's not hard, but you have to do it right. Remember that you don't want to run the bike for too long when doing the sync, but take the time you need to get it right - that might mean running for 10 mins and then shutting down for 30 to let it cool.

8. Resist the temptation to have a beer during the 30 minute cool down periods.

News:

Author Topic: bike starts overheating high idle? (Read 8323 times)

bollingball