Yeah, you read that right. I'm thoroughly confused. On the new 84, when i stop at a stoplight, the bike idles at about 1200. But after a few seconds, the idle will bump up to about 1500-1600. If I press the rear brake, the idle will settle right back down to 1200. As soon as i take my foot off the brake, it goes right back up. I see NO way for those two systems to be interconnected. Thoughts??
Thanks,
Ryan
You are correct, no interconnection between brakes and carbs. 1200 idle is too high. Adjust idle down to 1,000. Do blip test for air idle adjustments. If idle is good at start, then increases as engine warms up, it is rich. If idle is good at start then decreases as engine gets hot, it is lean. Check for vacuum leaks. Do suck test on #2 vacuum line that goes to the TCI. Should be tight.
Quote from: ryanschoebel on March 28, 2019, 01:26:13 PM
........ If I press the rear brake, the idle will settle right back down to 1200. As soon as i take my foot off the brake, it goes right back up.
Thanks,
Ryan
Does the actual idle speed change or just the tacho reading?
Did you repeat this enough times to establish a pattern or was it a one off coincidence?
Noel
Quote from: ribbert on March 28, 2019, 06:15:48 PM
Quote from: ryanschoebel on March 28, 2019, 01:26:13 PM
........ If I press the rear brake, the idle will settle right back down to 1200. As soon as i take my foot off the brake, it goes right back up.
Thanks,
Ryan
Does the actual idle speed change or just the tacho reading?
Did you repeat this enough times to establish a pattern or was it a one off coincidence?
Noel
The actual idle speed. And i did it about a dozen times, to make sure i wasnt imagining it. It happens every time.
stepping on the brake adds an electrical load which can draw down the engine speed.
Did you keep your carbs from Atlas...?
Quote from: RPM - Robert on March 28, 2019, 07:42:37 PM
stepping on the brake adds an electrical load which can draw down the engine speed.
Did you keep your carbs from Atlas...?
Unfortunately, no. I figured I would just send you guys this set within a few months. Suck test is good, no leaks. It hold pressure well. How do I do the blip test?
In the blip test you are checking to see if you have a hanging idle or idle dip.
This is the final test you do to set your air/fuel idle adjustments.
Adjust the valves.
Balance your carbs. (assuming clean heathy carbs)
Set your idle speed @1k
Hook up your aux tank, you need the tank off for access to the carbs.
Start, warm the bike up.
Blip the throttle,
1) when throttle is snapped shut, does the engine rpm hang at high rpms before slowly returning to idle rpm?
Too rich, turn idle air/fuel screws in (clockwise)
2) when throttle is snapped shut, does the rpm drop below idle speed then slowly rise to idle rpm?
Too lean, turn air/fuel screws out (counterclockwise)
Adjust in 1/4 turn increments.
Thanks Pat, I'll try that after work tomorrow. Tim says carbs were done, but that was 18 months ago. Any number of seals could have corroded. I hate to be that guy, but the idle air fuel screws are the screws that i see just to the engine sides of the carbs, right on top?
Remember to keep air moving on your engine with a fan or two. Air cooled engines can idle for only so long with no moving air to cool it, till they over heat.
It sounds like you have it..
(http://fjowners.com/gallery/2/medium_10_18_05_11_2_03_59_3.jpeg)
A - This is the idle mixture adjustment screw. Each carb has one.
Quote from: Pat Conlon on March 28, 2019, 09:54:51 PM
Set your idle speed @1k
+/- 50 RPM
I error on the plus side
Fred
Quote from: Pat Conlon on March 28, 2019, 11:39:28 PM
A - This is the idle mixture adjustment screw. Each carb has one.
Perfect, thats the one I thought. Thanks all, I'll let you know how it goes tomorrow
At the risk of a tongue lashing about how carbs can't be cleaned without taking them off, I've found that the occasional bottle of Techron in the tank does fix some minor fueling issues due to partially blocked jets... my '84 has the stock carbs and the combination of running Chevron fuel and adding a bottle of Techron every few months has kept it running well for the past few years since carbs were gone through. After not riding it for a few weeks, I add the Techron to minimize the buildup of gunk from the dried fuel... If you have a slightly lean condition (matches your symptoms), the Techron might just do the trick by removing some of the fuel system deposits.
Interestingly, I've found the flatsides on the '92 react quickly to the Techron treatment. Several times over the years it has started to run poorly, especially at low speed... Add the Techron and it's always fixed itself within that tank full.
In short, you might try a bottle of Techron and a tank of high quality fuel before you start into carb adjustments.
On a related note... do your carbs have flat bottomed slides? If so, you have a unique beast and I might have the jet sizes/adjustments you need. Randy told me I'm the only person he knows of that actually tuned the flat bottoms instead of swapping to the curved bottom slides. Stormy (my '84) runs beautifully...
Frank
Quote from: Flynt on March 29, 2019, 09:52:11 AM
At the risk of a tongue lashing about how carbs can't be cleaned without taking them off, I've found that the occasional bottle of Techron in the tank does fix some minor fueling issues due to partially blocked jets... my '84 has the stock carbs and the combination of running Chevron fuel and adding a bottle of Techron every few months has kept it running well for the past few years since carbs were gone through. After not riding it for a few weeks, I add the Techron to minimize the buildup of gunk from the dried fuel... If you have a slightly lean condition (matches your symptoms), the Techron might just do the trick by removing some of the fuel system deposits.
Frank
Bring out the pitchforks! :diablo:
But yes some sort of fuel additive definitely helps with the fuel problems from sitting. Check out fuel phase separation http://www.lcbamarketing.com/phase_separation_in_ethanol_blen.htm (http://www.lcbamarketing.com/phase_separation_in_ethanol_blen.htm)
Quote from: Flynt on March 29, 2019, 09:52:11 AM
At the risk of a tongue lashing about how carbs can't be cleaned without taking them off, I've found that the occasional bottle of Techron in the tank does fix some minor fueling issues due to partially blocked jets... my '84 has the stock carbs and the combination of running Chevron fuel and adding a bottle of Techron every few months has kept it running well for the past few years since carbs were gone through. After not riding it for a few weeks, I add the Techron to minimize the buildup of gunk from the dried fuel... If you have a slightly lean condition (matches your symptoms), the Techron might just do the trick by removing some of the fuel system deposits.
Interestingly, I've found the flatsides on the '92 react quickly to the Techron treatment. Several times over the years it has started to run poorly, especially at low speed... Add the Techron and it's always fixed itself within that tank full.
In short, you might try a bottle of Techron and a tank of high quality fuel before you start into carb adjustments.
On a related note... do your carbs have flat bottomed slides? If so, you have a unique beast and I might have the jet sizes/adjustments you need. Randy told me I'm the only person he knows of that actually tuned the flat bottoms instead of swapping to the curved bottom slides. Stormy (my '84) runs beautifully...
Frank
Where would I buy said techron? I usually just run Seafoam through my carbs. As for gas, I only run premium, but it is still ethanol fuel.
That said, I was thinking about it last night and today, and i have questions about using an aux tank for the testing. If i hang a tank, and just run hose to the carbs, wouldn't that flood it? Don't i need some sort of impedance, IE, the petcock in line to make sure it isnt flooding from constant fuel? What sort of aux tanks have people used?
Techron is the additive that Chevron makes, u can get it at chevrons, or any parts store. Sea foam, K100, or star tron are also additives like techron along with probably about 50 others.. The K100 is the one we have been using most recently and have had the best results with. Bikes sat since the RPM fall rally and they started right up with no problems this week.
Quote from: ryanschoebel on March 29, 2019, 10:11:14 AMWhere would I buy said techron? I usually just run Seafoam through my carbs. As for gas, I only run premium, but it is still ethanol fuel.
That said, I was thinking about it last night and today, and i have questions about using an aux tank for the testing. If i hang a tank, and just run hose to the carbs, wouldn't that flood it? Don't i need some sort of impedance, IE, the petcock in line to make sure it isnt flooding from constant fuel? What sort of aux tanks have people used?
Ryan,
Man, don't get too wrapped around the axle on this! Yes, there IS a connection between the rear brake and the engine ignition, and it is the electrical system. Before you tear into mechanical stuff that may not be sick, try this process. Run the bike until warm. Idle the engine, ignore the brake pedal, and pull on the switch that turns on the brake light. If the revs drop, then the taillight circuit is pulling too much power. Simple as that. You may have installed an LED in the taillight (pulling too much power now), or you may have a corroded bulb socket, or you may have chafed wiring somewhere in the circuit. Brakes do not affect carbs, or fuel mixtures. Brake lights can affect the ignition voltage, but only if the electrical system has other problems like too many gadgets, a failing voltage regulator, corrosion at connections, or bad wiring insulation..
How much voltage do you read at the battery? Are all of the battery connections shiny-clean and tight?
You could install a coil relay, to feed full battery power to the coils, which should fix the problem permanently. These electrical systems are getting old, and corrosion takes its' toll in passing power along. Most riders report a noticeable power boost from installing a coil relay.
I use a small gas tank from my lawnmower when I balance my carbs.I just put a cupful of gas at a time in it.your float valves will keep your carbs from flooding, when your engine is running there is always unrestricted fuel flow from the gas tank.the flooding occurs over extended time if your petcock doesn't shut off the flow when the engine is not running.
Okay, so I measured voltage with the rear brake pressed, and not. No voltage change at all. maybe .1 to .2 volts less. I think I'm going to hold off on the blip test for now, and I'll probably just end up sending the carbs to the guys at RPM. The reason being, I filled up the bike 2 days ago, and and reset the trip. When I looked again today, I have 23 miles on the trip and half a tank of gas. No leaking around the bike, and I haven't checked oil yet. Its always smelled DUMB rich, but I wrote it off. But seeing how much its eating fuel, I'm figuring that this must just be some sort of carb issue. Thoughts?
Yea, you've got some carb issues for sure....You know the drill.
Get Frank's jetting info he used on Stormy.
IIRC his choice for main jets was larger than customary.
Quote from: ryanschoebel on March 29, 2019, 08:13:03 PM
Thoughts?
I think you got a Lemon!! :unknown:
Look, I'm a nice guy and I'll take it off your hands for you Ryan... :i_am_so_happy:
Cheers
Alan
Quote from: Sparky84 on March 29, 2019, 09:03:55 PM
Quote from: ryanschoebel on March 29, 2019, 08:13:03 PM
Thoughts?
I think you got a Lemon!! :unknown:
Look, I'm a nice guy and I'll take it off your hands for you Ryan... :i_am_so_happy:
Cheers
Alan
:rofl: I don't even want to see the shipping and customs to ship a whole ass bike down under haha. Pat, I sure do. Ill send Frank a PM
Quote from: ryanschoebel on March 29, 2019, 08:13:03 PM
Its always smelled DUMB rich, but I wrote it off. But seeing how much its eating fuel, I'm figuring that this must just be some sort of carb issue. Thoughts?
Hold a flame to the exhaust to see if you can throw flames out... :shok:
Quote from: FJmonkey on March 29, 2019, 10:08:14 PM
Quote from: ryanschoebel on March 29, 2019, 08:13:03 PM
Its always smelled DUMB rich, but I wrote it off. But seeing how much its eating fuel, I'm figuring that this must just be some sort of carb issue. Thoughts?
Hold a flame to the exhaust to see if you can throw flames out... :shok:
And that would be the last we would ever see Ryan.
Joe
Quote from: FJmonkey on March 29, 2019, 10:08:14 PM
Hold a flame to the exhaust to see if you can throw flames out... :shok:
Just dumb enough to qualify for a Darwin Award, just fun enough to try... Not :sarcastic: :bomb:
Quote from: ryanschoebel on March 29, 2019, 11:19:26 PM
Quote from: FJmonkey on March 29, 2019, 10:08:14 PM
Hold a flame to the exhaust to see if you can throw flames out... :shok:
Just dumb enough to qualify for a Darwin Award, just fun enough to try... Not :sarcastic: :bomb:
Eyebrows will be the first to go...they are overrated anyway!
Quote from: ryanschoebel on March 29, 2019, 08:13:03 PM
Okay, so I measured voltage with the rear brake pressed, and not. No voltage change at all. maybe .1 to .2 volts less.
Correct. That means your voltage regulator is working properly. The VR is dumb; it doesn't know anything except the voltage in the system. And it adjusts the alternator to keep that voltage at one set level. So when you press the brake pedal, and therefore turn on the brake light, there is a slight voltage drop in the system. The VR sees this and tells the alternator to convert more mechanical (rotational) energy into electrical energy. Which drags the engine revs down...
The strange part is that your brake light bulbs are drawing enough current to drag the engine revs down. What do ya got back there... couple of headlight bulbs? :biggrin:
Bill
Ryan, my 86 used to pulse at idle when the indicator was on. For me the cure all was the direct relay coil mod, see the files for a great write up by some FJ genius. I did this ages ago getting all the parts from radio shack, but you can probably find it all on Amazon. It was an easy enough job, cheap and saved a bunch of troubleshooting time.