Hard starting GS 340

Gorkon

Gorkon

New member
Joined
Aug 15, 2007
Messages
442
Location
Edmonton, Alberta
I just got a great deal on 77 GS 340 for the kids, It's in great shape, but would not start unless you dumped a bunch of raw fuel down the throat. Took the old pumper carb off and dissasembled it expecting to find diaphram crumbs. Instead everything looks good, a little dirty here there, cleaned it all up, put it back on, pulled the rope and it fired right up, them promptly died starving for fuel.

Checked the fuel filter and have a new one on order, took it off for the moment and tried again, not sucking any fuel till I started playing with the fuel level adjustment screw on the bottom, then she fired up and ran to beat the ban. However, I could not get the fuel level to come up to where its supposed to be and turned the adjustment screw up all the way till it died. Taking it back a little allowed it to suck fuel again and run, but its nearly all the way up and the fuel level is still not all the way up in the tube? Anyway, it seemed to run fine so I shut it off and left it overnight. Today I had to pull and pull and it would not suck any fuel till I put my finger over the little hole in the choke plate to completely seal it, then it started and ran okay? What am I missing? All the other hoses appear to be good, though I am planning on replacing them with genuine Yamaha line asap. This things in awesome condition and the kids are chomping at the bit for snow, but I don't want to the only able to start the thing! Any suggestions? G.
 
i am by no means an expert with these sleds, but a few things did come to mind. the first is what you already plan to do, change the fuel and pulse hoses. next would be check the carb boot on the engine side for a poor seal. just a few guesses. good luck :)
 
clean fuel tank
does that machine have a prefilter with ball valve inside the tank? check to see that it is not plugged and the ball valve is functioning.
sometimes those carb diaphrams get weak and dont meter fuel properly even though they look good. check for small cracks.
do a compression check.
 
I got a pretty good look at the diapram as it was quite dirty on top and I cleaned it and it seemed to be fine. There is a fuel filter in the tank which is being replaced, didn't see any ball valve. For now the hose is just in a gerry can, till I get this sorted out and the new filter gets here. Waiting for the primary to go back together before I putz with it anymore. G.
 
we had a 1974gs338 (same sled basically) that would do this a bit. what the problem was was the rings where not seated properly on the cylinder walls. we had burnt a hole in the piston and put a used one in with the origional rings. it took a year of driving the snot out of it for the rings to seat back in. broke the recoil 2wice getting it running. ran great once it was started.


what i would suggest to do is pour a capful of seafoam in each spark plug hole with the piston at top dead centre (do one piston at a time) and let it sit for 24hrs. this will free up the rings if they are stuck in the piston with varnish or carbon. then put the rest in the fuel tank once you are shure it is clean. that should clean the old bugger right out and make it run like the champ it is. make shure you change the vaccume pulse line from the bottom end to the fuel pump. had one of those mess with me on a different 340 for 3 weeks untill i found it.
 
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Thanks, but "seafoam"???? Pardon my ignorance, but what is it and where does one obtain it? Is it a product designed for this sort of thing?

Hey, was just at a wrecker and was drooling over the 410 in one of two Enticer II's formerly used by a ski hill, They don't look that good on the outside, but underneath the hood they look almost new! In my minds eye, I could almost see that 410 under the hood of the old GS! I don't think the axial fan shrouding would fit, but the brain was working on it already!!! Best. G.
 
seafoam is only availible at uap/napa stores in canada. it cleans up stuck rings and deposits in carbureators. also is a fuel stablizer and water remover. works great. i use it in everything we have that runs gas. helped with a lot of my carburator issues on a lawnmower and have seen it straighten out a poorly running sled as well.


that sled wrecker have a website??? if those et410 had reverse i am very interested. bro has a ss440 longtrack in the works that reverse would be a bounus and uncle has a vk540 that it would bolt in as well.
 
Maim said:
seafoam is only availible at uap/napa stores in canada. it cleans up stuck rings and deposits in carbureators. also is a fuel stablizer and water remover. works great. i use it in everything we have that runs gas. helped with a lot of my carburator issues on a lawnmower and have seen it straighten out a poorly running sled as well.


that sled wrecker have a website??? if those et410 had reverse i am very interested. bro has a ss440 longtrack in the works that reverse would be a bounus and uncle has a vk540 that it would bolt in as well.
Click to expand...

Yeah, "Sled Parlor" near Carstairs Alberta, good guy, Landon. He's also got 5!!! Yes 5, VK 540's in not too bad shape, mostly sun damage. Used by survey crews and then left to rot. Not sure what year, they're blue. Under the hoods look like new! The Enticers are presently complete, don't know if they have reverse. Good luck. G.
 
Well I got everything done to the old girl and she started not too bad the first time and then right up each time while we adjusted track tension and alignment. But then we left it sit in the heated garage for twenty minutes before we took it out and she wouldn't start again!!!!! Finally got it running after nearly twenty pulls with some choke. So that problem is still around! I've also noticed a new one if anyone has any suggestions, the lights are really dull, completely insufficient. One of my guesses is that due to sitting outside for a time, the magnets are possibly covered with a layer of corrosion. I've seen this with small engines before, but don't know if that could be affecting things here or not. I think that primarliy it needs to be used, get the kids to take it run the bag off it for a day before doing anything else. Any ideas or suggestions? G.
 
i think she just needs to be run hard for a season to fix the starting problem.


might have a bad ground for the lighting problem. that should only have an incandesant headlight bulb. they suck for illumination. they do make a halogen bulb to go into that housing whitch should improve the front. the rear light never was the brightest on all the older sleds we have had over the years. as long as it lights up it should be fone unless you want to polish the lens becaise it could be dull.
 
I checked the ground and its good, so am unsure what could be the problem? The light is a dim yellow and not anywhere close to what it should be, even for stock. I'm not too worried about the rear, though it is dull too proportionate to the front, but I'd sure like the kids to able to see where they're going. Going to putter with it some more tommorrow night and hopefully sort some of this out, then maybe take some pics to post. She's looking pretty good, now if it would just run the same! I tend to agree that it needs to be ran hard for a bit, that may even improve the lighting, now if we'd just get some snow!

Did you get ahold Sled Parlor and find what you were looking for? G.
 
haven't had time yet. was hauling moose out of the bush yesterday. pics and story are in the atv site under same user name in picture section.
 
I grew up doing that, yummy, but a lot of work! We didn't have quads to do it either back then because there was no such thing. We'd have to dress it and quarter it on site and then pack out the quarters on your shoulder, let me tell you it was hard work! Best. G.
 
I'll check for ya, turns out I have to call him as well. Picked up a 95 800 that a tree fell on, need parts and as I recall he has them! Get back here when I have it.

Took the mag apart and cleaned it on the GS, was filthy. Yamaha had the oil breather hose dumping right in front of the fan???? Thirty years of oil being sucked in there. Cleaned it all with Varsol and brush, wiped it all down and then sprayed it with brake cleaner, Points are in good shape, sanded some corrosion off the magnets, put her back together, started right up and the headlight is as bright as new! Looks like its gonna be an awesome little sled for the kids. G.
 
Oh geez! I just checked the number and feel like a complete fool. His number is correct except I typed the wrong area code. So terribly sorry! The correct area code and number is (403) 337-4093. Try that, it should work fine.

Sheesh! See what running around with open pipes on your sled all of the time does to you? I guess I just thought the ringing stopped! I do apoligize for the error. G.
 
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