Any choke at all causes rpm nearing 5 k!???

[jonathanhly]

I just bought a 2001. She idled rough and any choke whatsoever would cause a huge, delayed, and inconsistant jump of rpms that nearing (possibly passing- I never wait to see what happens) 5k. These things I noticed before I bought it. 

I just finished a valve adjustment, a basic carb jet clean, and replaced all the fuel lines and inline filters, all of which seemed to go smoothly. Two valves needed adjusted, and one of the pilot jets was clogged.

After buttoning it up, she starts up with no choke, idles around 1100, and still has the erratic choke response. This is cold engine, with an outside temperature around 52.



I'm worried that she now runs worse than before, although I have never actually started her up cold.

Where should idle RPM be on a cold engine as compared to a hot?
Where should RPM be on full choke? and should it stay at that rpm for the most part?

I plan on doing a carb synch, but I think I should get her to a steady idle before I attempt it.

Any suggestions?

[jonathanhly]

Also I had little to no throttle response for the first 3 minutes or so she ran.

[BockinBboy]

Something is definitely awry here. Possibly several things at once.
However, you need to check and eliminate some variables to get down to it.

Check your carb float height via the U-tube drain method to ensure proper fuel delivery to both carbs.
Check your plugs to see if the bike is running lean(whitish)or rich(dark) and if both sides are running similar mixture (they should look the same)
Erratic idle can be a symptom of out sync carbs, or even a vacuum leak.  If both carbs are getting correct amount of fuel, then spray carb cleaner around the intake boots of the carbs and other areas of the carbs to listen for an rpm change indicating a vacuum leak.

You mention inline fuel filter(s) as well... There is little reason to have one unless there is rust in the tank, and you should only need one if that's the case. Also, the filter you are using, is it designed for gravity fed motorcycle fuel lines? Regular ones will restrict flow and you could have fuel starvation problems such as your delayed throttle response, or worse (stalling).

- Bboy

[adidasguy]

It is good to check that the choke cable is properly installed on the carbs.
I have seen it NOT correctly installed and has the symptoms you describe - basically all or nothing.

Idle should be around 1200 (per the manual). We go 3k to 4k at initial start up when really cold and bring it down in a minute or less to maybe 2k then down to 1200 when she seems stable. My warm up times are less than a minute before my bikes are ready to go. Usually I take off after 30 seconds or less and take the choke down in another 20 seconds or so.

Carb sync can cause problems. Do it now. You can roughly do it if you search for "hillbilly carb sync". A way to do it with no tools and get you close. Better than nothing.

[jonathanhly]

I have inline fuel filters for a few reasons. They are simple gravity fed filters. I have one in both the reserve line and the main supply line, before the petcock. The bike had them before, I simply replaced them. I kept them because the tank does have some rust ( I think). The entire inside is a light brown color (with an occasional silver area), however it appears to be smooth, so I think it is just minor surface rust. I also removed the tank petcock and found the filter to be disintegrated/absent. For these reasons, I think an inline filter is necessary (however fuel coming out of the tank appears to be free of any sediment).

The choke cable is installed properly. It opens and closes fully, and I made sure to install the spring correctly.

This is my first bike, and I am new to all this.

If this helps, the bike is a 2001 and it has only 4600 miles. So it sat in a garage, for a long LONG time.

Here are the problems prior to any work I had done:

Very erratic choke. High (5k) rpm with any choke.
"un-happy" idle. Some sputtering and changes in rpm, even while warm. No issues other than at idle.
Occasional valve clicking noise.

I performed a valve adjustment.
This seemed to go well. I check all clearances afterwards as well.

I opened the bottom of the carbs. Cleaned the bowls, removed and cleaned the jets. I made the mistake of messing with the idle while the carbs were off the bike. So I need to reset this.

I replaced all fuel lines.

Here are my issues now, after work:
Erratic choke
even more of an "un happy" idle.
Some sort of engine noise. Sounds like a very faint pop occasionally.
Little to no throttle response for extended period of time.

Granted this was in my cold garage.
First things first, I will start it up tomorrow during the day (warmer temps), and try to set the idle around 1200, and see how she runs.

[adidasguy]

Photos help. Is the tank off so you can take a picture of the choke connection to the carbs?
I only ask that so we can eliminate that as a problem.  as mentioned, I have seen choke problems when the choke cable and the spring are not installed exactly right.

Coke going fully on or fully off (no in-between) can make throttle act weird when cold and even when hot as it will make it run rich (choke fully on) or lean (choke off). That can make it hard to set everything else.

The choke things can be cleaned and dirt blown out. In the manuals you will find it listed as the "Starter circuit" or "Starting Circuit". They don't use the word "choke".

[Zethioth]

I have asked this very same thing about 3 times. I always got the same answer "That is how the chokes on these bikes work."

But now everyone is saying that something is wrong in your case. My choke does the same thing 4.5-5k on choke either full, when I move it down an inch, the choke is completely off and the bike will die if it isn't warm.

Someone, please explain how the choke should properly work on these bikes? RPM adjustable depending on choke position? Or all or nothing?

[BockinBboy]

Not saying mine is without problems, but here's how mine works:
I put choke all the way on, and start the bike.  Bike fires up and quickly climbs to 3.5k, then to 4k within 10 seconds alltogether.  I try to adjust down the choke to get it to 3-3.5k as it warms up - Now finding this spot is only a mm wide for me, and sometimes I just can't get it trying with any speed and it takes two hands to find it.  If I lower it below that, I get what acts like no choke even though there is half the range left on it, and the bike will stall before its warmed up.  So for the most part, it is all or nothing except for that mm I can get 3-3.5k with it.

I have lubed the hand control a couple times, and it is easy to do after I lubed that area.  However, I think I still need to clean and lube the choke cable itself and the area it connects with the carbs to get better use of it all.

- Bboy

[Zethioth]

Thanks BBoy,

That sounds exactly like mine however, when my bike first fires it won't jump into high RPMs right away unless I give it throttle for a few seconds.

[BockinBboy]

I would try to refrain from using throttle on start-up, and instead try starting with 'PRIME'.  That will ensure there is enough fuel in the carb bowls to get her to run, and then just switch back to 'ON' after she takes.  There are mixed emotions/opinions/facts about using throttle upon start-up, and what it does to the fuel system and such.  For example, some circumstances can make a cold starting issue worsen if you use throtte on start-up.  So I just as soon get her to run without doing it all.

- Bboy

[bombsquad83]

Using the throttle on start up should not be necessary on a good running machine.  It actually makes things harder on the starter motor because you are allowing a full "breath" into the cylinders which leads to greater compression on the stroke.

[Zethioth]

How about after start up? I haven't used the throttle while starting the bike hardly ever, only in bad circumstances.

Let me rephrase what I said before. After my bike has started with full choke on it idles normally (with choke on full), once I hit the throttle it will spike up to higher revs and stay there until I turn the choke off.

I hope my issue is relating to OP, I hate hijacking his thread, but I believe our problems are similar.

[bombsquad83]

Using the throttle after startup is no problem.  I often do what you are talking about to help it warm up a little faster or check if it's ready.  I was talking about strain on the starter system which is disengaged once you let go of the button.

[jonathanhly]

I did some work today and have some new information.

The float bowls seemed to both be within about 1/4" from the "gasket-level" using the U-bend method. Is this close enough or is that too much fuel?

I looked at both the old plugs that were in it when I got it from the PO and the new ones I had just put in and run on for maybe 5 minutes total. I got a picture of the old plugs (below) before the camera died. These plugs I believe are in normal operating condition.

However the new plugs, that have ran for about 5 minutes since all the work stated above, seemed fouled. The left plug was in normal/ possibly light fowl (rich) condition, and the right plug was totally fouled, even wet on the lip of the threaded section.

Finally I removed the fuel tank and airbox, hooked up a funnel to the carb and ran her for a minute or so. For some reason, the idle seemed much more happy than last night (granted it is now 70 degrees). However this didn't last long as there was some sort of backfire in the left carb. An audible pop, followed by the engine stalling, and a little bit of grey smoke exiting from the back (slider) of the left carb. This scared me. Any thoughts?

Here are the old plugs


Here is a picture of my choke cable in closed position. I think it is correct.


Here is my line routing. The upper T connection runs over the airbox down in front of the battery. The vacuum line on the right side of the right carb runs down and back to the left side of the bike to the petcock. Correct?


And here are my inline fuel filters, just below the tank petcock.

[mustangGT90210]

OP, have you messed with the mixture screws at all on the carbs? And, have you tried swapping the coils from one cylinder to the other? If you make that change alone and the symptoms follow the coil, I would say you have weak spark. I'm in the process of trouble shooting mine right now.

It is good to check that the choke cable is properly installed on the carbs.
I have seen it NOT correctly installed and has the symptoms you describe - basically all or nothing.

Idle should be around 1200 (per the manual). We go 3k to 4k at initial start up when really cold and bring it down in a minute or less to maybe 2k then down to 1200 when she seems stable. My warm up times are less than a minute before my bikes are ready to go. Usually I take off after 30 seconds or less and take the choke down in another 20 seconds or so.

Carb sync can cause problems. Do it now. You can roughly do it if you search for "hillbilly carb sync". A way to do it with no tools and get you close. Better than nothing.

Thank you Adidas!  I had no idea that it could be done that way, but I'm gonna have to try it now

[adidasguy]

Choke mounting looks perfect.
Looking at it, insure there is smooth operation as you move the choke lever. It should side back & forth smoothly. Sometimes they get sticky and you can slowly pull the choke on, but when you go to take off the choke it sticks then at the last instant snaps back.
Plugs don't look bad.
Fuel filters look a bit small fro what I've seen used on bikes. Fuel is gravity fed. Larger filters are used - when filters are used. Normally we don't have an in-line filter. The in-tank screen filter does a pretty good  job.

[jonathanhly]

I will lube up the choke components because they do feel slightly sticky.

If the old plugs look good, and the new plugs are fowling, then would could I have done wrong? I assume it would be a carb problem.

When using the U-bend method to check float height, how close to "gasket" level of float bowl should the fuel be? I was about 1/4" off.

[BockinBboy]

 If it is 1/4" high, that may be your fouling issue. From what I have experienced, this should pretty much be spot on with the gasket surface if not a hair below. Below by that much and you'll have starvation issues.

- Bboy