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82 GS450TX will not idle

  • Thread starter Thread starter mpencegs
  • Start date Start date
M

mpencegs

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So long story short I a restoring a barn bike that has sat since 1986.. After correcting the timing and a long story about the valve cover I have the bike running. I have to give it a bit of throttle to start no matter the choke setting and I must keep the throttle open or she will die off. Basically the bike is running like a champ but any attempt to have the bike idle with the throttle fully disengaged and the bike will die off. If I keep the slightest bit of throttle then the bike will sit at what I would judge to be idle speed.

We have cleaned the carbs earlier in the project and I am just wondering if this sounds like I need to clean the idle jets again or something else. The bike is also a little slow on the throttle response. Rev it up and it seems to take half a second to come up to RPMS. Let the throttle go and takes a milisecond for the RPMS to drop. Another note is my tach seems to be working more like a compression gauge, goes up but doesn't drop so I have to replace that which means I don't have RPM readings I am just going be ear..
 
Wow.. I love this forum.. Just from what I have read around here so far.. 1)Get an air filter or make one.. Seems to make a difference for most people. 2) Check for intake system leaks.. Any other ideas out there? Just seems strange that I can get the bike to idle at low RPMS with the throttle open but not with throttle closed. I figure bike would die at same RPM either way..
 
When you cleaned the carbs, did you dip them properly for 24 hours each in Berryman's or did you just take a can and spray out the bowl? If the latter, you will want to tear down and redo them. Replace all the orings to include the ones behind the intake boots, adjust the valves, bench synch the carbs, and then break out the manometer.

Basscliff will be along later to give you the official welcome.
 
Well.. I made one of the newbie mistakes and had someone else clean my carbs at a shop.. He told me that he soaked them but I have no proof.. We opened them up and they are nice and clean inside and pilot and main jets look clear.. did not replace any orings.. Valves are adjusted.. Will educate myself on bench seating the carbs so that I can work this myself this time..
 
My guess would be that one or more of the low speed jets is clogged or partially clogged. The bore of these jets is really tiny, and it does not take much for them to clog, especially if you have any rust or dirt in the tank. In my experience, soaking the carbs will not clean out a clogged pilot jet.

Unfortunately, the jets are kind of expensive ( ~ $12 to $14 each).

You can drill them with a pin drill, size will be something like #78 to #80 (no relation to jet sizes).
http://www.amazon.com/Mini-Micro-Dr...4EV4/ref=sr_1_1?ie=UTF8&qid=1315846323&sr=8-1
I usually start with the smallest size and work up, checking the bore with the shaft of the drill before inserting the fluted end of the drill so as not to drill it out oversize.

When you do get it running right, recommend adding an in-line fuel filter.
 
any recommendations on the inline filter. I would like to get one sooner then later.. Then I should just be able to clean or install new jets and be good to go then.. Would hate to buy new and not having a filter cause the same issue again..
 
Also any recommendations on a replacement tach.. Any after markets out there? or try to find original?
 
mpencegs said:
So this would be the oring kit I need correct? I have the DOHC 2 cylinder.. I assume this is the *twin* they are referring to..
http://cycleorings.com/450.html
Click to expand...
Hmmm, interesting. This looks like a pretty fair price for those parts compared to buying them from the dealer. If you get them, I'd buy the kit that includes the rings for the intake boots.

Your engine has the intake boots that are flanged and uses two bolts to attach a boot to the cylinder head? I hadn't thought before that you could have an air leak where the intake boots bolt to the head. The o-rings would fix that. If you have an air leak here, your mixture will lean out and it would be very hard to get it to idle. To test, start the bike and spray carb cleaner where the boot meets the head. If the idle jumps way up when you do it, you may have found your problem.
 
Ajay said:
My guess would be that one or more of the low speed jets is clogged or partially clogged. The bore of these jets is really tiny, and it does not take much for them to clog, especially if you have any rust or dirt in the tank. In my experience, soaking the carbs will not clean out a clogged pilot jet.

Unfortunately, the jets are kind of expensive ( ~ $12 to $14 each).

You can drill them with a pin drill, size will be something like #78 to #80 (no relation to jet sizes).
http://www.amazon.com/Mini-Micro-Dr...4EV4/ref=sr_1_1?ie=UTF8&qid=1315846323&sr=8-1
I usually start with the smallest size and work up, checking the bore with the shaft of the drill before inserting the fluted end of the drill so as not to drill it out oversize.

When you do get it running right, recommend adding an in-line fuel filter.
Click to expand...
Yes, but it's alot safer to use a strand of copper wire to poke thru any jets as hard drill bits can score smooth brass surfaces. If you look thru old style telephone wiring, you can often find solid strands in the .5mm range.
Before adding an in-line filter, I'd remove petcock and see how the filter looks.
 
tom203 said:
Yes, but it's alot safer to use a strand of copper wire to poke thru any jets as hard drill bits can score smooth brass surfaces. If you look thru old style telephone wiring, you can often find solid strands in the .5mm range.
Before adding an in-line filter, I'd remove petcock and see how the filter looks.
Click to expand...
I agree with this advice. It depends on how clogged the pilot jets are.

Somewhere on an old computer, I made an excel spreadsheet listing Mikuni jet sizes (diameter) and corresponding number drill sizes. If you know the jet size, you can pick the correct drill. I'll see if I can find it. But usually I just try the drill in backwards and if the shaft will fit, then it's safe to drill.

Also, pilot jets from the factory are typically undersized for pollution reasons, leading to off-idle stumble. Drilling out to the next size up is a common cure.
 
I got it to idle by adjusting the Idle arm connected to the Carbs.. Not the screws but the Idle Arm adjustment.. I am still redoing the carbs since I have all the parts now but wanted to share.
 
Hi,

Your "mega-welcome" contains most of the maintenance steps needed to get a long-dormant GS motorcycle up and running. There's a lot of information there so read everything carefully so as to learn how to properly clean the carbs, adjust the valves, service the charging system, repair leaks in the air intake system, etc. Don't forget the brakes, tires, chain, and sprockets too. I've read too many stories of what happens when these bike are ridden without properly servicing the brakes.

Thank you for your indulgence,

BassCliff
 
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