Freshly rebuilt carbs

[dueller]

Okie.....well, I fully rebuilt the carbs. Soaked overnight, new orings from Mr. Barr. reassembled and put back on the bike. Question is about the operation of the choke circuit. When I start my bike up from cold start, full choke. If reasonable warm out will idle up to about 4K rpm. Back off choke to get back down to about 2500RPM. Then warms up a little more and idle climbs again and bring it back down to 2500 again. Question is, is this the way it is supposed to work? Just wanted to check cuz only my second bike. Last one was several years ago and don't really remember how that one worked. I thought my carb boots were ok. Looked good when was disassembling and seemed pretty pliable, but now I notice that the rubber is cracking where it mates with the metal flange. So I am getting some from Ranger as he just replaced his before his bike's unfortunate demise! So, is this normal choke circuit operation and if not, could this be because of the boots possibly being bad?

I originally decided to rebuild the carbs because when I tried starting the bike for the begining of the season I couldn't get it to run. Tried a shot of ether (I know not really good for it, but wanted to see if fuel delivery was the problem) and the bike would fire and run for a few seconds. Upon removing the float bowls found rust sediment in bowls. So decided to rebuild them. Thanks for your help in advance!

 

[Nessism]

Air leak from the intake boots and/or O-rings would be my guess.

 

[dueller]

Not orings

Not orings

replaced those with the SS cap screws from Mr. Barr. Have to see what happens when I get the new boots....thought I would throw it out there and see if anyone else had the same thing. How exactly IS the choke supposed to work? Is the behavior I am describing incorrect functioning?

 

[chuck hahn]

As the engine warms up two, things happen. Cylinder and piston heat increases and cause the fuel to burn much more efficiently. Then the heat from the engine also makes the vacuum on the cylinders improve and draw cool air thru the carbs better..So in short to the question yes. As it warms up and your not moving the choke, the RPMS will climb Then you use less choke and less and less till it warms up enough to idle without choke.

 

[dueller]

That's what I thought....

That's what I thought....

But just wanted to make sure I was thinking correctly. Should it be a gradual thing or a snap thing though? Like it'll sit and idle at 2500 for maybe 45 seconds and then kinda rapidly climb to 4500-5000. This usually happens twice. I still need to do a sync on it. I was hopin to do that on a day off this weekend but no day off so prolly just do it after work one day here.

 

[old_chopper]

Sounds fine to me. Does it idle smoothly (or close) when warmed up with no choke? After it's hot it shouldn't run very well or at all with the choke on.
The choke (actually enrichener) circuit provides a fuel rich mixture to the engine to aid in cold start and running due to the conditions described above by Chuck. The engine odesn't need the mixture that rich after warming up.
I hope this helps!

 

[chuck hahn]

Wher does it normally idle at..should be around 1000 to 1100 rpms roughly..you can turn the big knob to adjust the idle..once its warmed up .

 

[dueller]

Idle is all over the place...

Idle is all over the place...

The drast temp changes haven't really helped much. Sometimes it idles really low and sometimes it idles up around 2500-3000. I haven't synced it yet. I have a basic manometer with just vacuum gages that I borrowed from a friend of a friend. Haven't played with that yet. It will idle down at little over 1200 and then idle down over about 15 seconds or more and then die from low idle. I need to get the boots on from Ranger. Those should be here this week. Thinkin I have an air leak cuz of intake boots that appeared to be in good condition when removing carbs rack but now seem to be cracking at the plate that mounts to the head. It doesn't die or run rough when I give it some choke just idles up. Like I say, Michigan has been between 50-90 degrees just in the last week! So been kinda hard to track down to a temp issue. It doesn't always get up to temp either. I'll have to try thechoke on when at temp. I think it just idles up like 5K or more. I am pretty sure it's runnin lean but not sure if that's cuz of the 4-1 pipe or boots being bad. Has stock airbox and I think I have that connected up to the carbs well. I would like to do the pods but just don't have the money for the pods and jet kit. Was hopin to get thru the summer and do that in the fall.

 

[Guest]

Once you get the boots for the motor and new O-rings, your Idle should settle down unless your air box boots are trash too. Four into One exhaust and standard air box should require some re-jetting, but it's nothing as radical as pods and pipes. Do yourself a favor and keep the Air box. In the long run it will be a lot less work and expense. I like my under seat tool box, but I would have never done it if I had known the work it would entail.

 

[BassCliff]

Hi,

In order to be redundant and to repeat what has already been re-stated again ...

Question is about the operation of the choke circuit. When I start my bike up from cold start, full choke. If reasonable warm out will idle up to about 4K rpm. Back off choke to get back down to about 2500RPM. Then warms up a little more and idle climbs again and bring it back down to 2500 again. Question is, is this the way it is supposed to work?

That's pretty much the way my bike behaves when I start it up in the morning on my way to work. I start it with about 3/4 choke. While I'm putting on my helmet and gloves, zipping my jacket, etc, I'm pushing the choke back in to keep the idle about 2500 rpm. Otherwise it will rev up to 4K as it warms up. This routine takes a minute or so until I jump on the bike, push the choke until the engine is at about 2000 rpm, and then hit the road. I turn off the choke fully before I get to the freeway about 2.5 miles away.

But if your intake boots are leaking then your idle will be unstable no matter if the bike is warm or cold. Do you have the new boots on yet?


Thank you for your indulgence,

BassCliff

 

[dueller]

Okay....

Okay....

Hi,

In order to be redundant and to repeat what has already been re-stated again ...

Never hurts to get a 2nd consensus

That's pretty much the way my bike behaves when I start it up in the morning on my way to work. I start it with about 3/4 choke. While I'm putting on my helmet and gloves, zipping my jacket, etc, I'm pushing the choke back in to keep the idle about 2500 rpm. Otherwise it will rev up to 4K as it warms up. This routine takes a minute or so until I jump on the bike, push the choke until the engine is at about 2000 rpm, and then hit the road. I turn off the choke fully before I get to the freeway about 2.5 miles away.

But if your intake boots are leaking then your idle will be unstable no matter if the bike is warm or cold. Do you have the new boots on yet?


Thank you for your indulgence,

BassCliff

Okay, I was more concerned with how QUICKLY it shoots up in idle. Shoulda made that more clear. It will not gradually idle up....it will idle at about 2500 then shoots up to bout 5K then I bring it back down to 2500 then shoots up again and then I do much the same. I hop on and let just putter it out till it gets warmer, just takin it easy till it gets a little more heat in the engine, so thanks for the confirmation. That was going to be another post as to how most of you guys start out with a cold start at the beginning of the day.

 

[dueller]

Once you get the boots for the motor and new O-rings, your Idle should settle down unless your air box boots are trash too. Four into One exhaust and standard air box should require some re-jetting, but it's nothing as radical as pods and pipes. Do yourself a favor and keep the Air box. In the long run it will be a lot less work and expense. I like my under seat tool box, but I would have never done it if I had known the work it would entail.

Yeah, I want to do the pod conversion to get a little more performance ( not that this bike really needs it, but would be fun, already VERY impressed by the power it has!) and maintainance is such a PIA getting the carbs in and out of that stupid space between the head and the airbox. I just can't handle the cost at the moment of the Dynojet kit and pods. Figure that would be almost $300 and I need to put that into tires and new forks! So best to leave well enuf alone for now. May try and do that as a winter conversion and dink with it next spring. I will take the box out in one piece though in case I want to go back. I can follow Jwhelan65 and another member did when they rebuilt their 700's.

 

[Steve]

Yeah, I want to do the pod conversion to get a little more performance ( not that this bike really needs it, but would be fun, already VERY impressed by the power it has!) and maintainance is such a PIA getting the carbs in and out of that stupid space between the head and the airbox.

Not sure exactly how much performance you will gain, but I'll bet you will only be able to measure it at a drag strip.

You might get a few ponies out of the swap, but consider what you will have to do to get them.

After removing the airbox and installing the pods, you will have to re-jet the carbs. No question about it. The chance that you will nail the jetting on the first try is rather small, so you will be taking the carbs out more than once. Yes, it's easier without the airbox, but remember, it's because of the (missing) airbox that you are having to do this.

"Maintenance is such a PIA getting the carbs in and out"? What maintenance are you doing that requres removing the carbs?
After getting the carbs done on my wife's bike (several years ago), there was only ONE TIME that I had to pull the carbs for any "maintenance" duty. I had to replace the cam chain tensioner gasket. If I had replaced it when I did the carbs, it would not have been necessary to do it when I did. SIX YEARS went by, doing all the normal "maintenance", only pulled the carbs ONE TIME. If that is what you are calling "PIA", you don't need to be riding a 30-year-old bike.

.

 

[dueller]

Guess I shouldn't have said maintenance....

Guess I shouldn't have said maintenance....

Meant more working on anything around the carbs. Oil cooler lines, chain tensioner, heck even starter work would probably require the carbs to be pulled it seems. I see your point though. I guess I thought that the pod swap gave a little more than a little more performance that you would actually notice like quicker response or somethin. I wasn't really too worried about jetting cuz I have two fine examples in Jwhelan65's rebuild and tejasmud. True though if I do all that stuff at once probably wont have to mess with it for another 20 years. I don't mind owning a 20 year old bike Been wrenchin on stuff all my life. Heck, I was 8 years old helpin my dad put a timing chain on our old dodge van

 

[dueller]

Sooo....

Sooo....

was rollin down the road at about 55MPH and bout 1/4 throttle I'm guessin with the bike mostly up to temp and put on bout 3/4 choke and pulled in clutch.....and it shot up to bout 7500 RPM's sounds like an air leak eh? Ranger should be getting the boots to me next few days. Have to see what that does. I already did the O-rings and SS bolts from cycle o-rings. When I took off the boots to do the O-rings didn't seem bad. Didn't notice any cracks. Guess cracks developed when putting carbs back on

 

[dueller]

Okay...

Okay...

So long time comin, but I installed the intake boots finally. Now the choke appears to work the way it's supposed to (well, best I can figure as the cable broke last week!! ) If I put more choke (right now I just reach over and pull on the choke rod with my left hand) to it when it is warm, it starts to die out when warm, but now I have a midrange stumble. The only thing different than stock is a Uni air filter (oil type) cuz the old 25 year old one disintegrated when I tried to clean it and a 4-1 pipe with a Supertrapp muffler. But if I WOT it, seems to pull just fine. I haven't done the vacuum sync yet. Do you think this would cause this behavior? I am hoping to get to that this week. I also probably need to change my plug boots. I have to research what I need.