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Post by Brian VT on Mar 3, 2011 20:34:55 GMT -5
I'm stumped by this water pump. It's a chainsaw engine (XL ?) but there's no throttle control. The carb. is a Walbro HDC-68 that has a HS, but no LS needle. There is a "governor" jet(?) screwed into the hole where the idle screw would be. It doesn't seem to be adjustable. With the choke on, it starts and soon dies, like you'd expect. I put it on 1/2 choke, or no choke, and start it. It revs. really high, so I shut it down. I cleaned the carb. (it was very clean anyway) and installed a carb. kit and checked the lever height. It runs the same. I backed the HS from 1 out to 2 out. It runs the same. I pulled the carb. connector base and looked at the reed. It wasn't sitting flat, so I flipped it over. It runs the same. There's no impulse line to replace. The fuel line and filter seem fine. What now ? How can I slow the rpms on this thing ? Has anyone run one before ? I can't believe they're supposed to run this fast. Maybe I should just put a chainsaw carb. on it and rig a throttle ?
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Post by hawtsawz on Mar 3, 2011 20:51:21 GMT -5
Does it rev high when pumping water? Maybe its set up to be run under load?
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Post by Brian VT on Mar 3, 2011 21:05:04 GMT -5
Thanks for the reply. I did have the pump full of water, per the instructions, and hooked up the hoses with the intake in a bucket of water. It revs so high, right from the start, that I was scared to let it run long enough to see what happens when it does start pumping.
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Post by MCS on Mar 3, 2011 22:55:42 GMT -5
The carburetor does have a throttle plate doesn't it? Something must be connected to the shaft that would somehow control the operation of the butterfly. Is there any type of vane by the flywheel that would get some airflow from it?
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Post by tribulation138 on Mar 4, 2011 6:13:59 GMT -5
take some pics
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Post by Brian VT on Mar 4, 2011 7:27:24 GMT -5
The carburetor does have a throttle plate doesn't it? Something must be connected to the shaft that would somehow control the operation of the butterfly. Is there any type of vane by the flywheel that would get some airflow from it? No throttle plate. Just a choke plate.
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Post by MCS on Mar 4, 2011 9:30:19 GMT -5
I found the picture you posted on the net and from the starter side it looks like it could be a Super 2 engine. If the carburetor doesn't have a throttle plate then it is designed to run wide open with the only thing limiting the speed would be to richen the fuel mixture and make it miss.
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Post by MCS on Mar 4, 2011 9:43:36 GMT -5
This is from the Walbro Service Manual Uploaded with ImageShack.us
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Post by Brian VT on Mar 4, 2011 10:15:15 GMT -5
Thanks MCS ! I had Googled "Walbro carb governor". etc., yesterday and didn't come up with anything. Really ! Ya da man.
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Post by Brian VT on Mar 4, 2011 18:42:09 GMT -5
Armed with the new knowledge that this thing wasn't headed for self-destruction, I ran it again tonight. I primed it with water and stuck the suction hose in a 5 gal. bucket of water and fired it up. I was "feathering" the choke lever because I just couldn't bring myself to let it scream, even if it is 4-stroking due to the governor. Well, the prime took pretty quickly and it started pumping and the engine leaned out into the sweet 2-stroking sound we know and love. Just as I started to smile, the engine started revving up like it was headed to the moon again. It turned out that the bucket was empty. This little bugger throws some water ! Thanks again for the ideas and advice. You guys are great. I hope I will soon have enough maple sap that I can run this thing for more than 30 seconds. ;D
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Post by MCS on Mar 5, 2011 12:11:11 GMT -5
Here is what's in the 1985 Product Listing Uploaded with ImageShack.us
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Post by Brian VT on Mar 5, 2011 13:40:09 GMT -5
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Post by Brian VT on Mar 5, 2011 18:54:32 GMT -5
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Post by wildman1024 on Mar 5, 2011 19:03:54 GMT -5
Damn she really moves alot of water quick. I guess she is also designed to scream while doing it to.
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Post by Brian VT on Mar 5, 2011 19:54:56 GMT -5
I guess she is also designed to scream while doing it to. Yup. If I knew that before I started messing with it I would have know that it was normal and I wouldn't have been chasing an air leak or put in a carb. kit that it didn't need. LOL Dumb of me to not think to recirculate the water when testing. Mine sucked a 5 gal. pail dry in a few seconds and I decided that I didn't want to get a bigger pail to try running it longer. DOH ! I'm still thinking that I may want to put a normal carb. on it and rig up a throttle control. I won't often need full speed and I certainly don't want the noise if I don't need full power.
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