New to forum, new gs650, new to 4strokes.

[robtronic]

Does that make me a newbie? I just picked up a pretty clean gs650 for pretty cheap, well under the general rule for slightly effed up bikes of a dollar a cc. I just wanted to make introductions, and let you all know where this bike stands as I have not had any experience with 4 strokes (if you don't count old volvos) or dohc engines yet and will probably be relying on the experience of others...

I will try to post a pic or two, but it's a gs650 that looks bone stock, starts fine with the starter, it appears to have had some headwork done due to the yamabond spooging out from the head, and it currently idles at about 4000, which is the first problem. pulling the choke makes it go to about 6000, which i assume is a vacuum leak of some sort, but really I just got it home at about 1030 last night and I haven't even pulled the plugs to read them. (The first thing in the 2 stroke world.)

So the unfortunate thing is that I have to use coffee shop internet, so there may be a lag in response time, but any information as to where to start would be appreciated. I found a service manual that's not great, and have access to a clymers online thru ebscohost. So I am going to start with the plug color and compression on each cylinder. Any other ideas would be greatly appreciated.

Thanks all.

[doctorgonzo]

Somebody will post the full mantra at some point, but clean carbs, like take them apart and clean them, adjust valves, and replace rubber intake boots (if it has them, they are the "manifold" between the carbs and the engine) are probably first order of business.

[reddirtrider]

Somebody will post the full mantra at some point, but clean carbs, like take them apart and clean them, adjust valves, and replace rubber intake boots (if it has them, they are the "manifold" between the carbs and the engine) are probably first order of business.

What he said. Intake boots or o-rings and clean the carbs thoroughly - completely disassemble and dip. After 30 years or so, this is mandatory.

[flyingace]

I know this is heresy, but taking those carbs apart and dipping them is a big task. Before you do that, make sure you have no intake leaks or that the throttle cable isn't getting bound up under the tank. To me, a high idle doesn't sound like gummed up carbs.

[robtronic]

I intend on getting to the carbs soon, but I just picked up some tools from my old house to take to the girls house to start on it. I figure checking the plugs will tell me a little, like if they are not starved for gas, it will mean no leak, which leads me down the road of the throttle, but starvation is either carbs or boots or some other drastic leak, hopefully not a seal (crank or clutch?) or gasket.

I did hear about a trick about spraying specific points of the engine with starter fluid to help isolate a vacuum leak, because the ether will cause a change in rpm when it gets sucked into the leak. I may try that when I get back to the bike. I want to get some idea before i tear that rack of carbs off, but I know it IS inevitable.

Thanks again.

[robtronic]

Is there a domestic parts supplier you guys use, I haven't checked yet but if the dealer can get most of the gt250, then they should have almost everything for a 81 bike.

[buddha]

Might want to double-check the idle set screw and make sure it doesn't have the carbs jacked open with the throttle closed. Could be an even easier fix that you might imagine. The knob is located between the #2 and #3 carbs, just below the air filter box, inlet side.

[robtronic]

would that lower or raise all 4 in sync? How does one get to it? Remove the airbox?

I just found the parts page for the local dealer, all available from them. Found the search function too. Hopefully i'll keep the redundant questions to a minimum.

[robtronic]

That was it!! a quarter turn and slowed down to 1300. I guess the previous owner just couldn't find it. Checking the plugs and running it in the garage for 15 or so minutes made it overly clear that I am running very rich. From the diagram of the carb rebuild that was linked from this site shows air screws located on top of each carb, and that 2 turns out from bottoming out is standard. I'm going to see what their at and try this, but I was getting puffs of black smoke at 6-7000 or 3/4 throttle so it looks like I may be getting those cv's off to check the o rings after all, when I check to see if the mains are correct. Is the air screw like on the vm, only controling air mixture at idle?

Thanks for the help.

[Larry D]

Yes, they only control the idle mixture.
If you're not going to tear the carbs apart, keep an eye out for gas leaks. You may get lucky, however keep in mind the rubber o-rings are 25+ years old and are going to give out eventually...

And check out Cliff's site. Tons of info there....

http://members.dslextreme.com/users/bikecliff/

[robtronic]

I think tearing into them is inevitable. I found cliff's site, and the carb rebuild link, unfortunately I have yet to get internet at the new house, so I can't flip thru the excelent pictoral sequence that is there. I just have an old pdf of a clymer's to go by when I'm there. (Oh, I need to unscrew that unidentifiable black and gray blob in diagram 10....) But at any rate, I think I have my project for the day, dip and carb cleaner ready, I'll post back with what I find.

[Steve]

Wherever you get your internet, you can save that file so you can page through it at your leisure.

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[robtronic]

I opened each page as it's own page so i can check them off as each is completed. Got the airbox off and the rack out of the bike, going to tear them apart tonight. But Jeez, I am going to have to get some pod filters because the thought of puting that box back in there, and pulling it out again everytime i want to check the floatlevel or anything makes me want to throw up a little bit into my mouth.

[reddirtrider]

I know this is heresy, but taking those carbs apart and dipping them is a big task. Before you do that, make sure you have no intake leaks or that the throttle cable isn't getting bound up under the tank. To me, a high idle doesn't sound like gummed up carbs.

It isn't, but they will be the next problem after the intake leak is solved. It isn't that big of a task. The biggest pain is taking them off and putting them back on and you need to do that anyway.

[Steve]

Just buck up, grit your teeth, use the stock airbox. By using the stock parts and stock jetting, you know it will be right and you will only have to do it ONCE.

The guys that brag about how easy it is to remove the carbs with pods on them are only saying that because they HAVE to take them off so many times to get the jetting right.

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