lopey idle till ~1800 rpm

[serrow]

So I've been doing this and that for my carbs. Noticed the front left was cold, so cleaned the heck out of it with shotgun and peashooter and its running from the start now.

bike idles high (has since i got her a few months back) at 1400 rpm or so till it gets nice and warm where she wants to die at stopsigns and such. does not do it if i keep her idling at 2000 rpm or so. even a touch of the gas keeps her moving nice and consistent.

I've been told rich bikes run worse worse warm, but i've never been able to get the idle low. so it pretty much runs bad at any temp if i were to run her to factory idle speeds. The bike runs great at speed, strong enough to give me the wonderfun oil lite flash.

one known issue is that one of my pilot screws seems to lack resistance when compared to the others, and one diaphram is in need of some patching, but as much as i've read, diaphrams affect when the needle comes into play more.

so where else shall i look? could the slightly bad diaphram be causing my sync readings to be goofy? i also have horrible gas mileage. very very bad, but have not checked since i got the cylinder working at idle.


i hate bugging you guys so much with my postings, but the yahoo group is just too slow to help with any type of discussion.

 

[shawn kloker]

Sounds to me like it is still way out of sync.

 

[4gasem]

i hate bugging you guys so much with my postings, but the yahoo group is just too slow to help with any type of discussion.

I don't understand this statement... That's what we are all here for...:thumbs up:

I would for sure replace the known bad parts and go from there... If you have one bad diaphragm I would replace it (not patch it). U motors is the cheapest place to get them...:thumbs up:

Then once you have that sorted check the syn again. I set my idle at a very low 900rpm's. I like it low and it seems to run ok.:confused2:

 

[serrow]

THANKS, just ordered a diarphragm and 2 mixture screws and will see if it helps the probblems a bit.

yes, thought the sync was off. i had my home made tool on last night. would sync up, then i'd switch cylinders, then go back to it, and it would be way off. I'm pretyt much sure its that my tool blows and need to have something better to set it with.

 

[4gasem]

THANKS, just ordered a diarphragm and 2 mixture screws and will see if it helps the probblems a bit.

yes, thought the sync was off. i had my home made tool on last night. would sync up, then i'd switch cylinders, then go back to it, and it would be way off. I'm pretyt much sure its that my tool blows and need to have something better to set it with.

A four cylinder model makes life easier...:thumbs up:

 

[serrow]

UGH,

I replaced 2 slides, and a couple mixture screws. did my sync, removed the carbs, cleaned them, blessed them, and its pretty much the EXACT same problem. Add this to my grossly bad gas mileage of about 15 mpg and I am lost.

when i removed the carbs i cleaned all but the starter pluger assembly. cylinders seem to warm up well, but damn if i cant get it all worked out. so much points to the idle circuit but im lost. I will shotgun again but do any of you have any other suggestions? electrics seem to work fine cause the bike seems to run fine above 3000

 

[4gasem]

UGH,

I replaced 2 slides, and a couple mixture screws. did my sync, removed the carbs, cleaned them, blessed them, and its pretty much the EXACT same problem. Add this to my grossly bad gas mileage of about 15 mpg and I am lost.

when i removed the carbs i cleaned all but the starter pluger assembly. cylinders seem to warm up well, but damn if i cant get it all worked out. so much points to the idle circuit but im lost. I will shotgun again but do any of you have any other suggestions? electrics seem to work fine cause the bike seems to run fine above 3000

Maleko89 tends to be our resident carb expert. Try P/Ming him about it.:thumbs up:

 

[maleko89]

The first think I would do is test your ignition system and clean all three major grounds. The engine ground is by the oil filler cap, frame ground is on right side near the air box and the rectifier/regulator ground.

How do your plugs look? Plug wires? What's the resistance when measuring from the plug wire boot to ground?

What's your float level? When tearing into your carbs did you remove the pilot fuel jet from the jet block? Are the rubber caps in the right places in the jet block? Do your slides move smoothly? Use a strand from regular copper wire and make sure each float bowl orifice is clean and clear.

Are the rubber caps fastened securely to the sync nipples?

Use a screw driver to push the slide back and then twist the throttle. Do the butterflies open smoothly? Are all four pretty close to closed when throttle is closed and parallel to the carb bores when at wide open throttle?

How is your fuel filter? How do your carb, airbox and vboost rubber boots look? Try using starter fluid and see if you have any air leaks.

Mark
#1098

 

[serrow]

Maleko,

I've tried all but checking the grounds and changing the spark plug wires (not sure they need it). I'll check the resistance as soon as i can, but if the bike only performs poorly at idle wouldnt this point me in a different direction?

also hows the starter fluid? does it like to smoke? will it burst into flames? I'm a city dweller and thats never a good idea to smoke out all the condos.

 

[maleko89]

Electrics do some strange stuff sometimes. When I bought my bike it had Dyna hot coils. It would idle fine but would cut out at various rpms. We caught it on the dyno. I'm assuming you tested your ignition coils and pickup coils?

As for the starting fluid the engine rpm will go up if there are air leaks.

Mark
#1098

 

[serrow]

Maleko, what should the resistance be if testing from the spark plug cap to the engine bolt. The manual tells only if you test each individual piece.

 

[maleko89]

You can add the resistances together. It should be anywhere from 19 KOhms to 23 KOhms.

Mark
#1098

 

[serrow]

new update. I was able to get a perfect sync on the carbs and thanks to the morgan, I was able to see that when the bike sits there at idle (like at a stoplight) I see all the stainless steel rods all fall at once. Sometimes coming back, but often dying.

all cylinders loosing vaccuum all at once? what could it be? I'm getting tired of troubleshooting, but I feel i'd be even more tired of dropping dough to have a mechanic do the same thing and tell me i just need to clean carbs.

i've cleaned carbs, changed plugs, checked for vacuum leakes. bike smells of gas but the floats seem ok, but i have horrible mileage of about 40 mp tank.

if it's electrical, I could sure use a starting point. the fuel consumption issue keeps me looking at the intake and carbs.

also had a weird issue where if i slam the enrichener on too quickly, she likes to die.

wow... now i think im lost.

 

[gleno]

new update. I was able to get a perfect sync on the carbs and thanks to the morgan, I was able to see that when the bike sits there at idle (like at a stoplight) I see all the stainless steel rods all fall at once. Sometimes coming back, but often dying.

all cylinders loosing vaccuum all at once? what could it be? I'm getting tired of troubleshooting, but I feel i'd be even more tired of dropping dough to have a mechanic do the same thing and tell me i just need to clean carbs.

i've cleaned carbs, changed plugs, checked for vacuum leakes. bike smells of gas but the floats seem ok, but i have horrible mileage of about 40 mp tank.

if it's electrical, I could sure use a starting point. the fuel consumption issue keeps me looking at the intake and carbs.

also had a weird issue where if i slam the enrichener on too quickly, she likes to die.

wow... now i think im lost.

Sorry to hear that you are still having problems with your bike.

Sometimes the simplest explanation is usually the correct one.

You mentioned that at one point, one of the cylinders remained cool to touch. This would indicate that it was not firing. The only reasons it stays cold will be either;

1)No fuel or
2)No fire

Fuel no longer seems to be a likely cause because you seem to have addressed the carb related issues i.e. replacing faulty slides, cleaning the jets etc AND you have managed to get a sync on the carbs.

To sync the carbs you had to have a relatively stable idle so for the moment lets assume that the carbs are not the problem.

If you have a weak or intermittent spark you would still be able to get a relatively stable idle and sync the carbs.

So lets concentrate on the fire. Apart from fuel and air, combustion requires an ignition source i.e. an electrical spark.

Which cylinders have no fire?

You might notice that when you first start the bike, some of the cylinders and header pipes will heat up quickly and some will not.

Identify the ones that do not heat up quickly. You can feel the headers with your hand, immediately after starting the engine while it is idling. The headers heat up quickly so if you prefer you can use the cylinder walls. After 30 seconds or so, it will be obvious which cylinders are firing and which ones are not.

Cool to touch = No fire
Warm to touch = Weak fire
Hot to touch = raging fire

Eventually they will all warm up because the cylinders that are firing will heat the engine coolant and this heat will transfer to the non-firing cylinders.

If you have identified some suspect cylinders, you will need to test these cylinders for an ignition pulse to see if you have a spark. You can do this by attaching an inductive timing light if you have one or, you can test this by removing a plug lead from the spark plug (leave the plug in the motor), starting the bike and letting it idle. If you remove a plug lead from a cylinder and it makes little or no difference to the idle, you have probably identified an ignition fault. i.e. it probably wasn’t working well or at all and so makes no, or little difference when disconnected.

If you remove a plug lead and the idle becomes rough, the bike won’t start or barely runs, then you have probably disabled a good ignition signal. i.e. it probably was working well so makes a big difference when disconnected.

By now, you should have isolated the suspect cylinders and you will have to identify the cause of the fault.

Why isn’t it working?

Common ignition faults that prevent a cylinder firing can be found in;

1)Faulty spark plug
2)Faulty plug lead
3)Faulty coil

Check the simple stuff first.

You can check a spark plug by taking it out of the motor, plugging it into the plug cap and earthing it to the cylinder head by holding the threaded section against a bare metal part of the cylinder head. You don’t want the bike to start, you just want to crank it over a few times to check for a consistent, bright spark.

Remove all the plugs prior to testing. This makes the engine easy to crank over off the starter motor and prevents the engine running with a plug removed.

Clean and gap your plugs to specification.

Get someone else to hit the starter and turn the engine over while you hold the threaded section against a bare metal part of the cylinder head.

HINT: you may want to wear a thick glove when you do this to avoid an unpleasant electrical shock.

When the engine is cranked off the starter, you should see a nice regular spark jump between the centre electrode and the curved ground electrode at the end of the spark plug.

If you don’t see a spark or the spark is intermittent or the spark is present but not jumping between the electrodes, swap the plug for one of the other plugs and repeat the test. If the other plugs are fine then the first was faulty. Replace it.

If the other plugs also show no spark, a faint spark, or intermittent sparks on the same lead i.e. all spark plugs behave the same way on that lead; then you may have a faulty plug cap, lead or coil.

You repeat this test with each cylinder lead.

NOTE: There are other sources of ignition faults as well but I’m not going to go into those now. I just want to describe what you can do that might isolate obvious faults that are easily fixed by a non-mechanic, with minimal tools.



You should now have identified;

1)Which spark plugs are good and which are bad.
2)Which cylinders may have faulty ignition.

The spark plug leads and caps form the high voltage electrical conductor between the spark plug and the coil. The spark plug leads can be tested with a multimeter. The quick test is to place the positive lead of the multimeter inside the plug cap so it is seated on the metal connection that clicks on top of the spark plug connecting terminal i.e. the small threaded bit at the pointy end of the plug. The negative lead on the multimeter should be contacted to a suitable ground such as the ground lead connection to the engine case located next to the oil filler cap. The measured resistance should be somewhere within the range of 19000 - 23000 ohms (19k - 23k ohms) or very close to it (thanks Mark). Outside this range would suggest a faulty connecting lead or coil.

On the V-max the leads typically have three connecting junctions between the spark plug and the coil. Faults can occur at any of these connecting points.

1)At the top of the plug cap on its inside, is a metal cap that sits on the top of the spark plugs terminal cap thread. This connection can be the cause of a bad electrical connection if it is corroded or dirty.
2)At the top of the plug cap on its outside is a threaded spike that looks like a screw. The plug lead is screwed onto this spike and usually covered with an insulating rubber cap. This connection can be the cause of a bad electrical connection if it is corroded or dirty. This is more likely with leads that use a wire core conductor. Leads that use a carbon core can become fractured and pulverised by mechanical stress, which makes it conduct inefficiently. This may occur at the threaded fitting or anywhere along the length of the lead.
3)The far end of the plug lead connects to a metal pin or spike in the end of the coil. The spike has no thread and the lead is pushed into the spike. The connection is then secured with a rubber grommet and a threaded cap, which holds the lead in contact with the coil spike. This connection can be the cause of a bad electrical connection if it is corroded or dirty. This is more likely with leads that use a wire core conductor. Leads that use a carbon core can become fractured and pulverised by mechanical stress, which makes it conduct inefficiently. This may occur at the spike fitting or anywhere along the length of the lead.

Checking the suspect lead.

If you don’t have a multimeter, you can test a lead you think might be faulty by swapping it to the coil of another cylinder that tested well when you did the spark plug test. If the fault moves with the lead, then that lead is faulty.

If all leads test faulty on the same coil, chances are the coil is faulty. I am not going to go into testing the coil in this post.

NOTE: Some leads with suspect connections can produce an intermittent fault (loss of spark) or a weak spark. These can sometimes work fine at idle but break down under higher loads (higher rpm) or cause a miss at idle and smooth out as rpm increases. This can give the impression of a fuelling problem i.e. carby problems. However, the only fuel problem is the fact that fuel is not being burnt efficiently due to an ignition fault.

If you have identified a suspect lead, make sure all its connections are clean, corrosion free and that there are no obvious broken leads. Make sure the lead is securely screwed onto the threaded spike on the cap. Make sure the lead is pressed firmly onto the spike connection in the coil and the lead cap is securely screwed on.

I have had cases where brand new leads tested faulty because the leads had not been properly screwed onto the cap threads or pressed home on the coil spikes. It can be that simple.

If you can do this and let us know what you find, we can take it from there.

 

[serrow]

Thanks, this was a very healthy write-up. I've long since lost the cold cylinder but I think starting all over again cannot be a bad idea.

what struck me as interestnig was that as the sync tool was on, the idle gets lopey the longer it sits at idle w/o throttle. this always lead me to believe it was a idle circuit issue. takes about 10 seconds, but i figured the 3 carb holes were clogged. Its gotten a cleaning but I guess i will try again.

the fact that these lopey parts dropped all the vacuum on the gauge kinda was weird. is the bike dying for those minor moments?

 

[gleno]

It's hard for me to comment about what causes the 'lopey' idle or what you actually mean by 'lopey'.

If you are talking about a rise and fall in the idle speed that is rhythmic and cyclic, which some people refer to as a rolling idle then this could again be fuel or spark.

If your engine is dropping idle RPM as it cycles to the slow lope you will lose vacuum on all cylinders because its approaching a stall. As the idle cycles up to the fast lope your vacuum while rise to a peak.

The only way to find the cause is to systematically eliminate the possible causes (hopefully without spending a fortune).

Never assume that there is just one fault causing a problem.

I worked on a friends V-max trike two days ago and it was doing very similar things to yours but he had several faults contributing to the cause.

I'll write that up in a separate thread.

Oh, it runs great now.

 

[jfeagins]

When you're at wits end with this and the problem still persists, try this: Warm it up to the point where it will usually begin dying at idle, but do it where/when you can get the bike into a completely dark garage, or just in the driveway after dark. Start the bike in pitch black and get on your hands and knees and observe both sides of the bike while idling. You are looking for errant spark(s).

I have been plagued with the very symptom you describe here. Usually it's the two rear cyclinders with spark jumping to the valve cover on my bike. I thought it was because of the number of times I had the seat off and battery out for replacement that I may have loosened the connections to the coils or something. I've replaced plugs, plug wires, plug caps and still have the problem - only when the bike is very warmed up. I've also confirmed a super tight fit where the wires insert into the coils. I have good connections. The hotter the day, the quicker the problem arises.

I think I'll replace a couple coils next believing perhaps I have a hairline crack or two - though I sure can't find one even using a magnifying glass.

Fortunately, I have other bikes to ride anymore and no longer rely on the v-max for daily use. It is still my MaxAttack getaway bike. Great stress reliever. Just go down to the highway, point and twist. Headache goes away. Smile comes back after a long day at the office.

Dying at a light in traffic used to suck when the starter didn't want to crank correctly, until that is, I did a small fix found here on this forum for the old starter problem. At least it will restart quickly after dying now.

Just my thoughts. Maybe this is what's been killing your bike too?