Motorcycle misfiring under load

Original Poster.

Club car engine snubber

Penelope Stoppedit. Search My Stuff What's New 3 12 24 Prev of 2 2 Next. Wolvesboy Original Poster posts 93 months. Hi All, Symptoms : misfire under load then revs out as normal after 2k. No misfire when revving normally without load. I pushed 3 lead back on and ok for 10 minutes then started again. I have tightened them since. Surely if the lead keeps jumping off it would misfire all of the time? Also my battery is a little low. Any help appreciated as now becoming v annoying!

TwinKam 1, posts 47 months. What do you mean by "battery is a little low"? Penelope Stoppedit 6, posts 61 months. Loose plug leads will burn the plug tops and the inside of the plug lead terminals, it's worth taking a look Do you have an Alternator Warning Light come on at the same time as the oil light when turning the ignition on, if the warning light circuit isn't functioning correctly the battery wont be charging until the Alternator cuts in at high Revs, the Alternator cuts in at lower Revs when the warning light circuit is functioning correctly Edited by Penelope Stoppedit on Monday 27th November Stick a meter on the battery.

My alternator semi packed up and I got a nasty misfire under load due to a weak spark. You want to be seeing Also worth checking that there is a good 12V at the coil packs while running. Can't remember which terminals are the 12V supply though. I bought two sets recently and they brought about immediate minor misfire in the cerb and rendered the Supra barely able to make 30MPH. Bad batch, forgeries, I don't know but binned and replaced with NGK and instantly fixed.

Maybe lack of charge in the battery opens up a multitude of sins Thanks for the quick replies. Will definitely assess the battery.

This is a definite delay. Then it turns for a a short while or so before starting. It is frustrating that some of the plug leads keep coming off - I spent some time a few weeks ago ensuring every spark plug and lead were connected fully. When i had the original 4. I had a problem with my first Chimaera where one or two plug leads would touch the heat shield material on the under side of the bonnet.

That caused them to short and result in a misfire. Do you have a distributor cap? It may be the centre carbon.Hi everyone, Im having problems with my Honda motorbike.

How to Fix a Misfire

I have only recently aquired it and dont know anything about its history other than its pretty old! I think its a 70's C, it has points on the end of the camshaft.

The bike will start and now idle with a few adjustments ive made to the carb idle etc. I have set the static timing and set the ponits gap. The bike will run ok, but at high rpm or under load it starts to misfire quite badly until i drop the rpms down.

I have noticed when i removed the flywheel cover that a little engine oil is present in the flywheel. Should this be there? The handlebar engine stop switch doesnt work. Any advice would be greatly appreciated!! Several things to check here; Firstly, yes, there should be a small amount of oil present when you remove the generator cover.

As for the misfire: had a similar problem many, many years ago on a SL same engine - turned out the stator windings around the generator had failed. Had to have this diagnosed by a Honda dealer. You are sure this is a misfire and not a fuelling issue?

Would also check: ignition points and condensor - replace with new parts, chances are the bits in your bike are donkey's years old and well past their best. Setting the timing static is more than good enough for these engines; I used to strobe mine, but then I have rampant OCD You say the kill switch doesn't work; is it still wired to the harness? If so, the switch itself may be faulty, causing the problem. A dodgy ignition coil could also be the problem - you takes your chances with electrical items that are second-hand, don't assume a used replacement is going to be any better than the one you have unless you have it properly tested.

Hi Rick thanks for the info.

Oppo headset diagram diagram base website headset diagram

The coil was brand new also the spark plug. The points havent been replaced but they look ok with no signs of pitting etc.

Harley Softail Misfire (Engine Runs But Misses)

The engine stop switch is still wired up but I have un plugged its wiring and the problem is still there. You mentioned about fuel. Thats interesting because sometimes when it misfires it blows black smoke from its exhaust. The needle jet is on the middle ring setting. I have played about with the carb mixer screw whilst it is misfiring but this has no effect other than lowering rpm.

motorcycle misfiring under load

Do you know how i can test the generator coil or is it just a matter of replacing it? It has me puzzled because the bike is ok at low to mid rpm. The bike is also fitted with a sponge type air filter.

The colour on the spark plug is darkish, which possibly could be over fueling do you think? As this bike is only for my son to use on my land I dont want to spend heaps on it, but he says it just loses all power when going up hills etc under full throttle.

If you hold the throttle on full when its at a stand still the engine seems to choke itself and misfire and even brings the rpm down to nearly stalling until you release the throttle! Don't know of any way of diagnosing the stator other than taking it to a dealer I'm afraid - I'm guessing it'll need to be tested under load to see how it performs.

Let's assume the coil and condenser are ok; have you checked the valve clearances at all? Best to start with basics and work from there. Before that, worth checking the valve timing is right. Next up: has the bike got its original airbox, airfilter etc? If not, that could be contributing to issues.

Does it have the original intake rubber between carb and airbox?After a short ride, we stopped for her to get gas. On the way home, her Harley started to misfire and run poorly. I lost sight of her so I pulled over. After about 15 mins she showed up and said her bike would not stay running. At each stop, it would stall but would always start after the fact. It died in the driveway. We tried to troubleshoot the problem but have been unsuccessful so far. Checked the fuel pump, getting gas, changed the plugs and checked the wires for leaks, no leaks.

We then changed the coil with no success. The bike would start at high idle and then slow to a stall. We fixed the wire at the coil, and tried to start the bike again with the same result. I then did another code check and at P I got a blank screen and then a no rSP- no response?

As you can see, I need help. My wife is a ride-aholoic and I have to live with her and 1 running motorcycle. It gets embarrassing riding on the back of your own motorcycle to keep peace in the house.

Note from the guys:. If you were chasing a fuel problem you would want to see what you have for, running fuel pressure. However, this problem sounds much more like a failing sensor.

If you can not pick up any relevant codes on your own, you may need to submit to having a dealer plug in their scanalizer. If it takes them an hour labor time to come up with a definitive diagnosis, it may save you a lot of aggravation.

Click here to cancel reply. Problem was a dirty air filter.Hello, We just inherited family deal a Windstar V6 handicap van or should I say handicapped. It has K miles and supposedly about 5k on a new engine, what ever that may be.

It looks very nice but runs pretty rough. However as soon as you start an up hill grade or try to accelerate from a stop or significantly increase speed the engine misses pretty severely.

Doing so is smoother than punching the gas to down shift and nicely does the trick to keep the engine running smoothly while climbing the hill. Either will keep the engine from missing. You must have a check engine light. Many auto parts stores will pull the codes for free. This means there is an ignition coil sitting just above every spark plug. The plugs might be old and worn out, and you might have one, two, or more bad coils.

Missing under load is a symptom of bad plugs and bad coils. Many people assume a worn out salvage yard motor is a new engine. Plugs and wires are a low cost task I could handle if I can figure out how to access the other 3 on the back side. Does this have to be done from below or is there access? There is a sound like an exhaust leak around the front of the van. Bad news related to compression suggestion? The issues with accessing those back 3 plugs on cars like this are legendary.

One common way is - yes to get at them from down below. Not sure if this will be seen after the time lag since the last post but… Finally got the codes read. Mis-fire on cyl 1 was the report. Does that seem a bit steep? I may have to see if I can access those back plugs and do it myself. Other issues to be checked…An EGR valve not closing on acceleration demand. A partially plugged fuel filter…. My first inclination was toward a fuel pump or filter, but with a consistent misfire on 1it could be the plug, wire, injector or low compression.

It was just a simple, free, code read. Paper work that came with it indicated someone diagnosed a bad PCV connection that I doubt has been fixed. To the question about the CEL, it was off when I picked it up and came on during the mile trip home during one of the instances climbing a hill. I noticed it would flash sometimes during the mis-firing while pulling a hill never saw one do that beforebut not every time. There can be no air leaks at all between the MAF sensor and the throttle plate inside the throttle body so I would definitely investigate that.

It should not be a serious matter to fix. I actually went through this a year or so back with one of my cars. It had developed a miss at times sometimes a bad one but everything checked out fine and no fault codes.

motorcycle misfiring under load

The bucking would only occur about half the time and only around 50 MPH when accelerating out of a curve.Hi everyone, Im having problems with my Honda motorbike. I have only recently aquired it and dont know anything about its history other than its pretty old! I think its a 70's C, it has points on the end of the camshaft. The bike will start and now idle with a few adjustments ive made to the carb idle etc.

Misfire under load (again &again & again)

I have set the static timing and set the ponits gap. The bike will run ok, but at high rpm or under load it starts to misfire quite badly until i drop the rpms down. I have noticed when i removed the flywheel cover that a little engine oil is present in the flywheel. Should this be there?

How to Fix a Misfire

The handlebar engine stop switch doesnt work. Any advice would be greatly appreciated!! Several things to check here; Firstly, yes, there should be a small amount of oil present when you remove the generator cover. As for the misfire: had a similar problem many, many years ago on a SL same engine - turned out the stator windings around the generator had failed.

Had to have this diagnosed by a Honda dealer. You are sure this is a misfire and not a fuelling issue? Would also check: ignition points and condensor - replace with new parts, chances are the bits in your bike are donkey's years old and well past their best.

Setting the timing static is more than good enough for these engines; I used to strobe mine, but then I have rampant OCD You say the kill switch doesn't work; is it still wired to the harness? If so, the switch itself may be faulty, causing the problem.

A dodgy ignition coil could also be the problem - you takes your chances with electrical items that are second-hand, don't assume a used replacement is going to be any better than the one you have unless you have it properly tested. Hi Rick thanks for the info. The coil was brand new also the spark plug. The points havent been replaced but they look ok with no signs of pitting etc. The engine stop switch is still wired up but I have un plugged its wiring and the problem is still there.

You mentioned about fuel. Thats interesting because sometimes when it misfires it blows black smoke from its exhaust. The needle jet is on the middle ring setting. I have played about with the carb mixer screw whilst it is misfiring but this has no effect other than lowering rpm.

Do you know how i can test the generator coil or is it just a matter of replacing it? It has me puzzled because the bike is ok at low to mid rpm. The bike is also fitted with a sponge type air filter. The colour on the spark plug is darkish, which possibly could be over fueling do you think?

As this bike is only for my son to use on my land I dont want to spend heaps on it, but he says it just loses all power when going up hills etc under full throttle.

If you hold the throttle on full when its at a stand still the engine seems to choke itself and misfire and even brings the rpm down to nearly stalling until you release the throttle!Home Articles Misfire How to Fix a Misfire Easy step by step guide on how to troubleshoot and repair an automotive engine cylinder misfire P, P, P, P, P, P, P, P and P, though appearances may vary, the process is similar for most vehicles.

Begin with the vehicle on level ground engine "OFF" and the parking brake set, wear protective gloves and clothing for safety.

Step 1 - There are several combinations of misfire conditions, steady or random, at idle or under power, which may or may not be detected by the computer and trigger a check engine or service engine soon light, read trouble codes to help pinpoint the cylinder s in question and follow the repair guide below. Check Engine Light Step 2 - If no service light is triggered with a steady misfire, use an infrared thermo gun to test the exhaust temperature of each cylinder.

Infrared Temperature Meter Step 3 - Start the engine cold, quickly take a reading at the front of each cylinder's exhaust port on the manifold while maintaining similar placement of the beam over each individual port, a misfiring cylinder will be considerably colder than the remaining cylinders. Example: Three of the exhaust ports test at degrees while one is at 81 degrees, the cylinder at 81 degrees is misfiring. Exhaust Temperature Step 4 - If no results are yet gleaned, start the engine and allow to idle, remove the fuel injector electrical connector on each cylinder one at a time while observing the engine performance, if no change is observed at a particular cylinder, the misfiring cylinder has been located.

Remove Ignition Coil Connector Step 6 - Once the misfiring cylinder has been located, remove the spark plug for inspection, before removing the spark plugs, mark the plug wires if equipped to identify their positions in the firing order, this will help for proper reassembly.

Remove Spark Plug Step 7 - When a cylinder s runs rich it will carbon foul the spark plug causing it to short circuit. Malfunctions for this condition include partially plugged fuel injector or catalytic converterlow compressionfailed fuel pressure regulator and excessive fuel mixture.

Carbon Fouled Spark Plug Step 8 - A wet spark plug with gas or oil can mean a fuel injector is stuck open, fuel regulator has failed, no cylinder compression, broken piston oil control ring, blown head gasket or excessive leakage from the valve stem seals.

Spark Plug Fouled with Gas or Oil Step 9 - A spark plug must be properly gapped with a specific measurement from the electrode, a misadjusted air gap can result in a misfire.

motorcycle misfiring under load

Misadjusted Air Gap Step 10 - Using a proper spark plug with a correct air gap will help ensure operation of the ignition system. Correct Spark Plug Step 11 - If the spark plug is wet with fuel or carbon fouled upon removal, a compression check is needed, perform a cylinder compression test to locate a mechanical failure. If compression is low, it could mean worn out or broken piston rings, flat camshaft, broken valve spring, burnt or leaking intake or exhaust valves, dropped valve seat or blown head gasket.

Compression Test Step 12 - If the compression test is okay along with a wet spark plug, the ignition coil needs to be tested. Test Ignition Coil Output Step 13 - Spark plug wires are designed to transfer an electrical charge from the coil to the spark plug, when these cables wear, they can short circuit causing a misfire.

Shorted Spark Plug Wires Step 14 - A fuel injector regulates the amount of fuel which is consumed by the engine, if the injector operation has failed the cylinder will misfire. Test Fuel Injector Operation Step 15 - A random misfire is can be associated with broken or dilapidated vacuum hoses or tubes on and around the engine causing a vacuum leakthese hoses are typically connected to the engine intake manifold and supply engine vacuum to various accessories such as the brake system.

If an intake gasket fails or a vacuum line that is close to an intake port it will cause a steady misfire. Repair Vacuum Leak Step 16 - Fuel pressure must maintain a constant pressure, if this flow is impeded by a clogged fuel filter or weak fuel pump the engine can produce a random misfire. Fuel Pump Pressure Check Step 17 - A mass air flow sensor sends feedback information to the computer, as this sensor wears it can produce false data causing a misfire.

Mass Air Flow Sensor Step 18 - Each intake and exhaust valve utilizes a spring which will return the valve to its original position closed. If a valve spring has broken or a cam lobe has worn down, it will cause the engine to misfire and run rough due to the loss of compression. These conditions don't always show up in a compression testbecause a compression test is performed at engine cranking speed.

If a camshaft lobe is halfway worn down, it will show up only when the engine is running and under load. Flat Camshaft Lobe Step 19 - In some conditions a broken valve spring can effect different aspects of engine performance for example: If just a small part of a coil breaks off, the spring can still close the valve but only at low RPM's, causing a high RPM misfire.

If the spring breaks somewhere in the middle it will affect both idle and power conditions. To test for this condition, remove ignition coil connector or ignition system or fuel pump fuse to disable the engine from starting.Please Log in or Create an account to join the conversation.

Topper wrote: You think that might slow the fuel supply down?

Command and conquer generals zero hour challenge maps

That'll be easy enough to look into. Any other ideas? Topper wrote: I'm getting a lot of sputtering and misfires under hard acceleration in the k rpm range. If I creep up on those high rpms it's fine. But if I'm accelerating hard it sputters when the rpms get high. What I've tried already: Set float levels with clear tube method Cleaned petcock screen Replaced fuel lines and filters Carbs have been cleaned and synced within the past year I'm thinking I need to play with either the main jet size or tweak the needle position.

Any suggestions? Which should I try and would you suggest going leaner or richer? Index of Forums Recent Topics Search.

motorcycle misfiring under load

Welcome, Guest. Username: Password: Remember me. Forgot your password? Forgot your username? Create an account.

War oil hoodoo

Sputtering Under Hard Acceleration. Sputtering Under Hard Acceleration 05 Jun I'm getting a lot of sputtering and misfires under hard acceleration in the k rpm range. Permanent and perpetual noob. Has this been an ongoing, long term problem or is it something new? I'm not sure Ed. I'm riding a little harder than I used to. Just a guess, but make sure your fuel tank vent is working properly. Sputtering Under Hard Acceleration 06 Jun You think that might slow the fuel supply down?

It's possible. One other thing might be to make sure the timing advancer is lubed and working smoothly; if it is binding that could be a problem. Sounds like you're steering me away from carburetion as the cause. You don't think this could be related to main jet size or needle position? If you haven't changed the exhaust or gone to air pods I wouldn't mess with the jets or needlesI think Ed is on to something with cleaning and lubing the timing advance.

Do you have a timing light? Last edit: by bluej It is possible that it is a carb jetting issue, but if the carbs have the stock jetting and you are using the stock airbox it seems unlikely the carb jetting is the source of the problem, so before getting into rejetting the carbs I would check out all other things that might cause the stumble.

Since the problem wasn't noticed until recently it is possible that something has changed to create the problem.


One thought on “Motorcycle misfiring under load

Leave a Reply

Your email address will not be published. Required fields are marked *