Comer K80 with Tillotson carb won't start, floods
- Thread starter Laszlo70
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maxpower49
Member
25:1 is wayyyyy rich, especially with the synthetic oil, with modern synthetic oil you can safely lower the amount of oil and be able to safely run at 40:1 I know several people with two stroke atv's (myself Included) that recommend running at 32:1 that safely run at 50:1 (I stick with 40:1 out of paranoia) with amsoil dominator and the like. I would recommend draining all the fuel again, buy fresh gas of the highest octane you can and mixing up some 40:1 fuel. If you compression is too high and you are using low octane fuel it could be detonating before the piston gets to tdc and gets lit by the spark plug, causing it to rip out of your hand and if it is pinging when it is running it could be blowing back into the carb because the port is not closed when the engine fires and causing pressure in the carb. Plus when an engine is detonating it typically runs like crud.
Also the vent I was referring to is the hole in the gas cap that prevents pressure build up when the tank heats up or keeps it from sucking in when the temp gets cold. If the flywheel key is only slightly messed up it could be off just enough to cause issues when starting, I had a Tecumseh 5hp engine that would rip the cord out of my hands every now and then and leave a nice blood blister, it would run great once fired but it kicked back almost every time, replaced the key and all was right with it.
Also the vent I was referring to is the hole in the gas cap that prevents pressure build up when the tank heats up or keeps it from sucking in when the temp gets cold. If the flywheel key is only slightly messed up it could be off just enough to cause issues when starting, I had a Tecumseh 5hp engine that would rip the cord out of my hands every now and then and leave a nice blood blister, it would run great once fired but it kicked back almost every time, replaced the key and all was right with it.
well, see this is like asking a type and weight of the oil to be used on an engine. I spoke to a guy who rebuilds and tunes Comer K80 engines for kart racers. he said what I did was too lean. he said I need to add 8oz to 1 Gallon to make it ok. I used 5oz to 1 Gallon.
Anyway neither will cause the engine to not start at all. It is flooded all the way. Today I changed the spark plug - Again , the 2nd time - and purchased a new diaphragm. No difference. Somebody said an off the shelf carb could have came with an old diaphragm and that will flood the engine. Well it did not fix my issue.
In searching for hours on the net, I found a guy who said the needles were all wrong for his brand new Tillotson carb and He had to re-use an old longer ones. So I will go out to the garage and try screwing them all the way in to see if that makes a difference.
Time and patience are both running out for me. If I can not start by x-mas the engine will go to ebay. I will not spend more of my time on this darn machine.
I want reliable easy to start engine, not this. 9 months I have been fighting with this no-start flooding the engine problem, if I have to count it at least 200 different settings were tried, I removed the spark plug about 200 times too. It is not normal.
In a m meantime we rebuilt a Corvette Z06 engine and built an another kart and all working fine but this engine and its brand new carb is not working. This has to be the biggest dilemma I have ever came across. I have spark and I have fuel and still no ignition. I know the reason, I have way too much fuel in a carb. Adjusting it all the way down still did not make a difference though. It is just the same every time I try it.
Anyway neither will cause the engine to not start at all. It is flooded all the way. Today I changed the spark plug - Again , the 2nd time - and purchased a new diaphragm. No difference. Somebody said an off the shelf carb could have came with an old diaphragm and that will flood the engine. Well it did not fix my issue.
In searching for hours on the net, I found a guy who said the needles were all wrong for his brand new Tillotson carb and He had to re-use an old longer ones. So I will go out to the garage and try screwing them all the way in to see if that makes a difference.
Time and patience are both running out for me. If I can not start by x-mas the engine will go to ebay. I will not spend more of my time on this darn machine.
I want reliable easy to start engine, not this. 9 months I have been fighting with this no-start flooding the engine problem, if I have to count it at least 200 different settings were tried, I removed the spark plug about 200 times too. It is not normal.
In a m meantime we rebuilt a Corvette Z06 engine and built an another kart and all working fine but this engine and its brand new carb is not working. This has to be the biggest dilemma I have ever came across. I have spark and I have fuel and still no ignition. I know the reason, I have way too much fuel in a carb. Adjusting it all the way down still did not make a difference though. It is just the same every time I try it.
maxpower49
Member
I beg to differ, what is easier to light on fire gas or oil? Too much oil and not enough gas will cause it not to light off or cause it to not burn properly because there is not enough fuel to burn and produce enough heat to burn the oil that is mixed in. Needing to change the plugs multiple times because they are fouled in my opinion is too much oil. And I have ran into weed wackers with the diaphragm carbs that would flood out because of too much oil preventing the needle from seating because the gas was too thick.
Also too much oil in the cylinder can bump up the compression, when doing a compression test on an engine and if it tests low you can dump some oil in the cylinders and if the rings are failing it will bump the compression up.
Also too much oil in the cylinder can bump up the compression, when doing a compression test on an engine and if it tests low you can dump some oil in the cylinders and if the rings are failing it will bump the compression up.
GregMartin
I like fast cars
I guess you have probably given up now but I was just reading your tail of misery and I have a couple of ideas.
My son has been racing gokarts for the last couple of years an we have used both tillotson and walbro carbys over that time they both work the same way so here is what I know:
1) gokart racing engines like caster oil with synthetic esters mixed at 20:1. If the header pipe has oil in it you can go less but most people don't.
2) the muffler is really an expansion chamber and what it does is setup a wave which in effect closes the outlet port during the cycle. So for a race engine a tuned length is important. Changing the length of the "flex" changers where the power is made.
3) now for the carby. The hole on the carby which corresponds to the hole in the engine is what pumps the diaphragm. ie this is the fuel pump bit of the puzzle.
4) I have seen lots of these carbys poring fuel out the front over the years and a rebuild will fix it but it has to be done carefully and there are a couple of important points.
5). Care must be taken to ensure that the gasket and the diaphragm is installed in the correct order i.e. which one on top.
6) gokart engine builders set the lever height and spring tension of the fulcrum leaver so I normally keep the spring and don't bend the fulcrum arm. I do of course replace the needle and check the the seat is in good order.
7) the jets should be unscrewed and inspected. When the are screwed all the way in they must not be turned to tight or you will damage the surfaces. If you can remove and clean the metering screws it might be worth while but I normally don't need to.
So there are many good instructional videos on the Internet to help with the rebuild, choose one by a gokart guy not a mower shop guy. I really think there is something wrong how the cards is being put together. I would check to see the needle is working properly is with a pop off gauge. The needle should open at about 8-10psi if it's too much less that will cause the flooding. Where you have the low and high speed jets adjust sounds about right. On our iame race engine we have the low speed at 1 3/4 turns and the high speed at 1 1/4 but that is a more powerful engine than a Comer. The drivers adjust them during a race to regulate engine temp and prevent four stroking etc.
With regard to engine timing some engine have adjustment ( by moving the magneto coil ) and some don't. You can normally check timing with a dial indicator. To do this take out the spark plug and position the dial inductor in the hole so that it touches the top of the piston when the engine is a TDC. Now wind the engine backwards until the magnet on the fly wheel is in line the the magneto coil. The dial indicator should read about 4mm or 165 thou. So this means the spark advance is 4mm which I think would be about right for a comer. So with gokart engines advance is specified is mm or thou and not in degrees.
Anyway I hope all this helps and I hope it's not too late.
My son has been racing gokarts for the last couple of years an we have used both tillotson and walbro carbys over that time they both work the same way so here is what I know:
1) gokart racing engines like caster oil with synthetic esters mixed at 20:1. If the header pipe has oil in it you can go less but most people don't.
2) the muffler is really an expansion chamber and what it does is setup a wave which in effect closes the outlet port during the cycle. So for a race engine a tuned length is important. Changing the length of the "flex" changers where the power is made.
3) now for the carby. The hole on the carby which corresponds to the hole in the engine is what pumps the diaphragm. ie this is the fuel pump bit of the puzzle.
4) I have seen lots of these carbys poring fuel out the front over the years and a rebuild will fix it but it has to be done carefully and there are a couple of important points.
5). Care must be taken to ensure that the gasket and the diaphragm is installed in the correct order i.e. which one on top.
6) gokart engine builders set the lever height and spring tension of the fulcrum leaver so I normally keep the spring and don't bend the fulcrum arm. I do of course replace the needle and check the the seat is in good order.
7) the jets should be unscrewed and inspected. When the are screwed all the way in they must not be turned to tight or you will damage the surfaces. If you can remove and clean the metering screws it might be worth while but I normally don't need to.
So there are many good instructional videos on the Internet to help with the rebuild, choose one by a gokart guy not a mower shop guy. I really think there is something wrong how the cards is being put together. I would check to see the needle is working properly is with a pop off gauge. The needle should open at about 8-10psi if it's too much less that will cause the flooding. Where you have the low and high speed jets adjust sounds about right. On our iame race engine we have the low speed at 1 3/4 turns and the high speed at 1 1/4 but that is a more powerful engine than a Comer. The drivers adjust them during a race to regulate engine temp and prevent four stroking etc.
With regard to engine timing some engine have adjustment ( by moving the magneto coil ) and some don't. You can normally check timing with a dial indicator. To do this take out the spark plug and position the dial inductor in the hole so that it touches the top of the piston when the engine is a TDC. Now wind the engine backwards until the magnet on the fly wheel is in line the the magneto coil. The dial indicator should read about 4mm or 165 thou. So this means the spark advance is 4mm which I think would be about right for a comer. So with gokart engines advance is specified is mm or thou and not in degrees.
Anyway I hope all this helps and I hope it's not too late.
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