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Post by mikem on Oct 21, 2009 8:50:04 GMT -5
I have an XL(later plastic model) apart. This saw has a primer bulb, choke and trigger lock. If the choke is intended to "richen" the mix temporarily for easier cold starting(like it has for 100 years), why complicate the process with a primer bulb ? I have several other small 2 cycle engines with a primer bulb that I do not use when starting and they start quickly and easily, but are the source of maintenance problems when the bulbs deteriorate over time. Can this bulb be eliminated by blanking off the two lines running from the carb to the primer bulb  I hate plastic saws......  |
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Post by lesorubcheek on Oct 21, 2009 9:51:36 GMT -5
"Primer bulbs" can work a couple of different ways. On our B&S mower for instance, there is no choke, and the bulb is actually squirting gas through the carb into the inlet are to richen the mixture. Works great and usually cranks first pull. The carb sits below the tank, and if gas is present, the carb has gas in it.
Bulb on Ryobi and Homelite string trimmers we have works a bit differently. Here, the sole purpose of the bulb is to get gas from the tank into the carb. I'd suspect on such a small engine, its difficult for the pulse to work the pump in the carb to get fuel to it without cranking a good bit. So on these, the bulb isn't replacing the choke, just getting the gas into the carb quicker if it needs it. Still need the choke to perform the job of actually richening the AF ratio for starting.
Dan
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Post by 925fetish on Oct 21, 2009 10:56:55 GMT -5
You can get rid of the primer bulb I do on all my two cycle stuff.You end up pulling 3 or 4 times instead of 1 or 2 to get a cold start but there isnt the headache of a rotton primer bulb every few seasons
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Post by mikem on Oct 21, 2009 11:23:41 GMT -5
"Primer bulbs" can work a couple of different ways. On our B&S mower for instance, there is no choke, and the bulb is actually squirting gas through the carb into the inlet are to richen the mixture. Works great and usually cranks first pull. The carb sits below the tank, and if gas is present, the carb has gas in it. Bulb on Ryobi and Homelite string trimmers we have works a bit differently. Here, the sole purpose of the bulb is to get gas from the tank into the carb. I'd suspect on such a small engine, its difficult for the pulse to work the pump in the carb to get fuel to it without cranking a good bit. So on these, the bulb isn't replacing the choke, just getting the gas into the carb quicker if it needs it. Still need the choke to perform the job of actually richening the AF ratio for starting. Dan Good points Dan....assuming the XL(having a seperate choke) is just priming the carb, not spraying gas directly into the carb throat, that the bulb can be eliminated at the expense of more pulls required to prime the carb as 925fetish has mentioned. 925fetish.....how do you eliminate the bulb ? Unplug the hoses from the bulb, bend and tie them off with a tie wrap or plug them at the carb ? And how ? |
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Post by 925fetish on Oct 21, 2009 13:50:25 GMT -5
Just put the supply hose with the filter on it on the inlet side fitting on the carb and put the return hose on the other side that just plugs the hole in the tank unless theres something wrong with the carb it dont return any fuel while its running.Then you pull the primer bulb out and throw it over your left shoulder.
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Post by polardoo on Oct 21, 2009 19:59:59 GMT -5
I worked on a super 2 with the primer. It really worked nicely. You can pump all day and not flood it, it just primes the carb bowl. I wish more of my saws had it, I am a wimp and I admit it.
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Post by MCS on Oct 21, 2009 20:35:09 GMT -5
I have 10 IPLs for various styles of the little XL/XL2/VIXL2 but only one shows a primer. The pictures are not very clear but from what I see the line with the fuel filter goes to the primer, another line from the primer goes to the carburetor, and then a line from the carburetor goes back to the fuel tank. The IPL doesn't say what brand of carburetor is used on this configuration of the XL. I'll go along with polardoo, the primer just takes the place of the fuel pump when the crankcase isn't creating pulses and fills the metering chamber with gas. It is still up to the choke to create the rich fuel mixture for the engine. 925's idea makes sense but if your left handed, throw it over your right shoulder ;D
As pointed out by Dan, some primers actually squirt gas into the carburetor throat creating a rich mixture, that isn't the case in this arrangement.
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Post by 925fetish on Oct 21, 2009 21:25:46 GMT -5
Throwing it over your right shoulder will make your babies be born naked
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