Vacuum Lines Not Attached is very common. Tight the outer two clamps initially in stages before starting on 2 and 3. Use a bit of oil in the inside diameter of the manifold to help them slip in easier. When inserting a bank of 4 carbs into a 4 cylinder it can be very difficult to get them to seat right. Make sure the carbs are seated in the manifolds properly. Poor assembly accounts for another large portion of air leak created issues.
Suzuki 250 bad spark plug symptoms cracked#
Over time they become hard, brittle and cracked and suffer from dry rot due to excessive heat at an accelerated rate.Ĭracking can create air leaks which create lean conditions. The carburetors fit into these manifolds and are clamped. Rubber Intake Manifolds - Most modern motorcycles (Mid 1970's on) have rubber manifolds attached to the cylinder head. There a few common issues that pop up with motorcycles that have carbs.ġ. You can get a light colored rag and place it over the exhaust lightly and rev it to see if you get carbon/black residue on the rag. Runs worse at altitude - If the bike starts to run worse at higher altitude with reduced oxygen, it's likely a rich condition.īlack Smoke - If you have black exhaust when you rev it, it's rich. Runs better with more air - If you remove your air filter and the engine begins to run a bit better with more oxygen in the mix it is likely you have a rich condition. This could be due to a grounded out sparkplug from too much carbon buildup preventing the combustion process in a cylinder or so much fuel that combustion is not occurring.
Odor of unburned fuel - In cases of a very, very rich mixture you may smell some unburned fuel coming out of your exhaust. A properly jetted carburetor will leave a nice grey scale color in the end of the exhaust pipe. You can clean the sparkplug with carburetor cleaner and re-use.Įxhaust Exit is Black and Sooty - Excessive carbon buildup in the exhaust is thick and overly grimy. When this condition occurs there will be no spark. Carbon is a conductor of electricity and getting considerable carbon buildup from a rich condition with ground the inner electrode down the positive insulator. Spark Plugs Black - Carbon buildup on insulator and electrodes of plug. Unlike a miss-fire on a spark plug this idle seems fine if the idle is turned up just a bit. Rough Idle - Combustion takes a just a bit longer with more fuel and at lower RPM's the engine can idle rough. Reduced Fuel Mileage - Your using more fuel per cycle so your mileage becomes worse. Reduced Power - It has less power but seems to be OK and runs. Although NOx is present in all exhaust it can be more pronounced in higher combustion temperatures associated with lean conditions with more oxygen. It's created by high temperatures in the combustion process between nitrogen and oxygen.
Sharp Odor - The exhaust smell may be sharp and burn your nose. Typically a lean condition caused by an air leak between the butterfly and the head or a vacuum line that is not attached. Hanging idle - The engine idles high and then drops and stalls. Idles poorly - Fluctuations in idle RPM, stallingĮngine runs hot - Due to more oxygen than fuel combustion temperatures are hotter reflecting on a temp gauge. Runs on choke - The vehicle may run on choke when it's warm but stalls if the choke is turned off. Runs better at higher altitudes - AFR becomes normalized due to reduced atmospheric pressure allowing fuel into the venturi easier.īackfires - Popping on deceleration for a lean idle circuit or backfires in general. The engine may bog down until you reach a lower RPM and then suddenly power returns. Reduced Power - Sluggish at certain RPM's. Here are some basic symptoms, some duplicate Fuel is metered through the main by the jet needle at different throttle positions.Ĭhoke circuit - Initiated by a valve or butterfly that increases the vacuum and opens the circuit up. Needle jet/jet needle - Mid range circuit
Suzuki 250 bad spark plug symptoms full#
Higher effect at lower RPM's with decreasing effect to full throttle Motorcycle carbs have a few circuits that effect different throttle positions. I will try and clarify between the two conditions and attempt to give you guidelines in troubleshooting between the two. In your post you indicate that some of the symptoms you have read are contradictory. Lean and Rich Symptoms in Motorcycle Carburetors
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