Proof that you don't need fancy videos with crazy editing.... I've learned more from these simple animations and your words than any other videos. Much appreciated for you sharing your knowledge!
Thank you for a superb series of videos on diaphragm carbs which I've just seen .Perfect for filling the gaps (large 🤔) and very educational and clear. ,in my knowledge I've had trouble with my Strimmer so today, after getting the spares, I found that instead of being flat, the fuel pump diaphragm had a dimple in it the size of my finger end .so it didn't have full travel. Symptoms were four stroking and lack of power and inability to idle. It's a Ruixing 142 A -23 carb and seems very well made , loctite on the threads etc but spares are very difficult to obtain..All running my Husqvarna 129 ld. Hope this helps someone, Thanks again Sir 😊👍
That's exactly what my saw is doin. Idles great. Will rev high for a few seconds. An then bogs and dies. Chaulky white sparkplug. Lean. I thought it might have a vacuum leak. Crank seals maybe. But there is not many hours on the saw. I got gas that had water an dirt in it. From the Gomart. An my saw has been messed up since. I knew something was wrong in about 5 minutes after filling the saw with gas. Let my saw warm up. An first cut. It died in full throttle. Thanks for this video. I believe you just helped me. Fingers crossed
first I have to thank you for all your great info and the effort you put there to inform carb engine users ! but you mentioned a fully oscillating motion for the metering diaphragm which is technically true as all the motions and behavior of an engine is oscillatory due to its nature of cycling motion yet looking at a single work point of an engine for example a mildly open throttle the engine has a base line fuel flow which has pretty minor oscillations due to small variations on the baseline vacuum in the carb venturi which will end up in the metering diaphragm to be pulled down by some amount and the needle valve to be half open (and all of them have minor vibrations at their positions) allowing the baseline fuel flow needed for that specific operating point. you have correctly mentioned that a stiff metering diaphragm can not act at all when fuel is consumed underneath it or it might not act fast when an engine is suddenly pushed to the full throttle and cause "bug down" yet it could also cause the exact opposite also which is when an engine is throttled down back to idle a pulled down back to idle and the pulled diaphragm can not bounce back up fast or not go up at all causing a flood of fuel and supper rich rough idle and engine stall and die on throttling back to idle !
One issue missed is the opposite of the hardened diaphragm issue. When the diaphragm is too loose. Like a wet noodle. It needs to be just the right elasticity. I've had diaphragms that were so loose (thin) that they were collapsing on the perimeter too much and preventing the piston from pushing the lever.
This is probably the single most important diagram you show. All carburetors have a base setting that can change the balance between air/ fuel entering the carburetor. Adjusting the L screw not only changes the low speed setting or idle speed, it affects the high speed setting. Manufacturers usually have a base setting between the two screws and fine tuning can be achieved by slightly turning the screws. An air leak at the base of a two stroke engine can greatly affect the performance of the engine. Any bad seals allowing air to enter the base or intake on a two stroke can cause an engine to run too lean, make it hard starting or even cause the engine to overheat and melt the piston or cause extreme internal damage due to heat damage in the cylinder, drying out the piston rings causes the rings to wear extremely fast, cause the rings to break and score the cylinder or cause the piston to break due to Spark knock a condition where the extreme heat causes the fuel to detonate prematurely ,destroying the piston.
Daniel Rodriguez, hi, thank you very much for taking the time to write this comment, it's posts like this that really motivate me to keep making these videos. Thanks again, Craig
Pls tell what should be the length of diaphragm ln mm. And length of spring. This cn be measure or not? Original measurements of diaphragm pin and spring. This is very knowledgeable and nicely explains by you. Thank u so much. I will be highly thankful to you if answer my question.
What a nice tutorial!!! We have a bit weird designed Kawasaki carb with an additional outside manual lever connected to the metering diaphragm plunger with a spring. So, we can press this lever bending this diaphragm up and down as a pump. Can you tell me what is this for, please? Thank you
MATT MOSS, hi Matt, first of all, thank you for your motivating comment, it really does keep me producing these videos reading posts like yours. Secondly, is it the Main Nozzle on a four stroke, or two stroke engine you would like to know about? Thanks, Craig
Hi craig, sorry for the delayed reply. I repair two stroke engines, mainly chainsaws and such like and i have accumilated a drawer full of bad carbs. I have looked into rebuilding a few and learnt a lot, i have found a main issue with some being the check valves going bad/stuck. Some can be pressed out and replaced if you can get the replacement. Your videos explin a lot. Thanks for posting.
I have found with really dirty carbs that have been contaminated with allsorts that completley stripping them and boiling them in water, then rebuilding with a new kit can revive a lot of them. But some have been damaged deyond repair with heavy adjustment of the jet screws. Its just a hobby really but i thought i would look further into why the carbs were bad rather than chucking them.
All Episodes -for 2-Stroke Carburetors Here. Thanks. Craig:
th-cam.com/play/PLrlXp3PlwgRI5OLvm3P91LJr1CYnO5TRD.html
Proof that you don't need fancy videos with crazy editing.... I've learned more from these simple animations and your words than any other videos. Much appreciated for you sharing your knowledge!
Thank you for a superb series of videos on diaphragm carbs which I've just seen .Perfect for filling the gaps (large 🤔) and very educational and clear. ,in my knowledge
I've had trouble with my Strimmer so today, after getting the spares, I found that instead of being flat, the fuel pump diaphragm had a dimple in it the size of my finger end .so it didn't have full travel.
Symptoms were four stroking and lack of power and inability to idle.
It's a Ruixing 142 A -23 carb and seems very well made , loctite on the threads etc but spares are very difficult to obtain..All running my Husqvarna 129 ld.
Hope this helps someone, Thanks again Sir 😊👍
I must agree with Mr Welser, superb video. very grateful. Thanks.
Ben Roberts, thank you so much for your kind feedback.
That's exactly what my saw is doin. Idles great. Will rev high for a few seconds. An then bogs and dies. Chaulky white sparkplug. Lean. I thought it might have a vacuum leak. Crank seals maybe. But there is not many hours on the saw. I got gas that had water an dirt in it. From the Gomart. An my saw has been messed up since. I knew something was wrong in about 5 minutes after filling the saw with gas. Let my saw warm up. An first cut. It died in full throttle. Thanks for this video. I believe you just helped me. Fingers crossed
Another superb video,you are a master teacher,,keep that good job going on.
André Welser Hi, I really appreciate your comment. It really helps motivate me to keep making these videos. Thanks again, Craig
first I have to thank you for all your great info and the effort you put there to inform carb engine users ! but you mentioned a fully oscillating motion for the metering diaphragm which is technically true as all the motions and behavior of an engine is oscillatory due to its nature of cycling motion yet looking at a single work point of an engine for example a mildly open throttle the engine has a base line fuel flow which has pretty minor oscillations due to small variations on the baseline vacuum in the carb venturi which will end up in the metering diaphragm to be pulled down by some amount and the needle valve to be half open (and all of them have minor vibrations at their positions) allowing the baseline fuel flow needed for that specific operating point.
you have correctly mentioned that a stiff metering diaphragm can not act at all when fuel is consumed underneath it or it might not act fast when an engine is suddenly pushed to the full throttle and cause "bug down" yet it could also cause the exact opposite also which is when an engine is throttled down back to idle a pulled down back to idle and the pulled diaphragm can not bounce back up fast or not go up at all causing a flood of fuel and supper rich rough idle and engine stall and die on throttling back to idle !
Thank you
One issue missed is the opposite of the hardened diaphragm issue. When the diaphragm is too loose. Like a wet noodle. It needs to be just the right elasticity. I've had diaphragms that were so loose (thin) that they were collapsing on the perimeter too much and preventing the piston from pushing the lever.
This is probably the single most important diagram you show. All carburetors have a base setting that can change the balance between air/ fuel entering the carburetor. Adjusting the L screw not only changes the low speed setting or idle speed, it affects the high speed setting. Manufacturers usually have a base setting between the two screws and fine tuning can be achieved by slightly turning the screws. An air leak at the base of a two stroke engine can greatly affect the performance of the engine. Any bad seals allowing air to enter the base or intake on a two stroke can cause an engine to run too lean, make it hard starting or even cause the engine to overheat and melt the piston or cause extreme internal damage due to heat damage in the cylinder, drying out the piston rings causes the rings to wear extremely fast, cause the rings to break and score the cylinder or cause the piston to break due to Spark knock a condition where the extreme heat causes the fuel to detonate prematurely ,destroying the piston.
I love your videos, keep them coming.
Daniel Rodriguez, hi, thank you very much for taking the time to write this comment, it's posts like this that really motivate me to keep making these videos. Thanks again, Craig
Outstanding. Thank you so much for this.
Pls tell what should be the length of diaphragm ln mm. And length of spring. This cn be measure or not? Original measurements of diaphragm pin and spring. This is very knowledgeable and nicely explains by you. Thank u so much. I will be highly thankful to you if answer my question.
Thank you for your nice feedback. The length of the items you ask for are all different depending on the make and model of different machinery.
What a nice tutorial!!! We have a bit weird designed Kawasaki carb with an additional outside manual lever connected to the metering diaphragm plunger with a spring. So, we can press this lever bending this diaphragm up and down as a pump. Can you tell me what is this for, please? Thank you
Have you any videos that explain the check valves in the maun nozzle assembly? Good explanation in vids ive watched so far! Thanks
MATT MOSS, hi Matt, first of all, thank you for your motivating comment, it really does keep me producing these videos reading posts like yours. Secondly, is it the Main Nozzle on a four stroke, or two stroke engine you would like to know about? Thanks, Craig
Hi craig, sorry for the delayed reply.
I repair two stroke engines, mainly chainsaws and such like and i have accumilated a drawer full of bad carbs.
I have looked into rebuilding a few and learnt a lot, i have found a main issue with some being the check valves going bad/stuck. Some can be pressed out and replaced if you can get the replacement. Your videos explin a lot. Thanks for posting.
I have found with really dirty carbs that have been contaminated with allsorts that completley stripping them and boiling them in water, then rebuilding with a new kit can revive a lot of them.
But some have been damaged deyond repair with heavy adjustment of the jet screws.
Its just a hobby really but i thought i would look further into why the carbs were bad rather than chucking them.
Looks like walbro metering tool has the same method for 13 different models. IS THAT RIGHT?
I am a little confuced. When we have vacum at the diaphragm area the piston goes up. Right?
Yes the upward motion of the piston causes a vacuum suction pressure that moves the diaphragm via the pulse line.
@@TheRepairSpecialist sorry but I am not talking about the pulse line. I talk about the diaphragm which pusses the lever and raise the needle.
@@ΗΛΙΑΣΑΓΓΕΛΟΥ-ε3σ yes the diaphragm pushes the lever and needle down because of the vacuum pressure from the pulse line caused by the piston going up
@@TheRepairSpecialist ok. Thanks.