Don't choke me!

Trout · Posted: January 22, 2007, 12:09 pm Post subject: Don't choke me!

On Saturday, I finished assembly of my '79 project and gave it a test run. I set the petcocks to "prime" and let the float bowls fill. I was curious to see what it would be like as a kick-only bike, so I didn't bother with the start button.

Anyway, I set the choke on and kicked away. It acted like it wanted to start but didn't. I set the choke off and it fired right up. Put the choke back on and it died. Choke off and it idled fine. I warmed it up for a minute and took it for a spin. The bike never skipped a beat.

I guess that I was having a hard time accepting the fact that the bike ran without the choke just because my Sportster requires the choke for the first minute or so on a cold engine.

Do any of you have bikes that start and run without using the choke? I'm just wondering if it's common or if something is out of whack.

ttmaniac · Full Member Joined: Dec 22, 2006 Posts: 468

Are you running stock carbs or roundslides? If it ran without choking it and it runs good then what is the problem? I run 36mm roundslides and rarely need to choke my bike.

Trout · Posted: January 22, 2007, 1:03 pm Post subject: Re: Don't choke me!

ttmaniac wrote:

Are you running stock carbs or roundslides? If it ran without choking it and it runs good then what is the problem? I run 36mm roundslides and rarely need to choke my bike.

Stock 38mm Mikuni's.

There is really not a problem... unless maybe the carbs are overly rich.

The jets are all stock sizes.

I'm just curious if this is common and expected, or if I need to do some adjustments or modifications.

ttmaniac · Full Member Joined: Dec 22, 2006 Posts: 468

If it runs good then I would just leave it alone. If it pulls hard through the rpm's then don't fiddle. Mine is a 79 and I went through hell and high water before I chucked the stock carbs and went with 36mm's. I wouldn't worry about being overly rich unless it's extreme and causing problems. I am assuming that you are running stock air cleaners cause the emgo ones plug up the carbs and cause performance problems above 4000 rpm's.

Trout · Posted: January 22, 2007, 1:54 pm Post subject: Re: Don't choke me!

ttmaniac wrote:

I am assuming that you are running stock air cleaners cause the emgo ones plug up the carbs and cause performance problems above 4000 rpm's.

Yeah, stock intake and exhaust. I just want to run it for a while. I'm not motivated to mess around with fuel/air ratio right now if I don't have to.

kingwj · Posted: January 22, 2007, 2:40 pm Post subject: Re: Don't choke me!

My 79 is the opposite. I need to choke it for quite a while, perhaps 5 minutes of riding. It is especially noticeable on acceleration from a dead stop, it just falls on it's face, or I need to get it up to about 4000 rpm and slip the clutch to get away. With the choke on it idles very poorly but will accelerate without slipping the clutch.

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

deleted

Trout · Posted: January 22, 2007, 3:48 pm Post subject: Re: Don't choke me!

kingwj wrote:

My 79 is the opposite. I need to choke it for quite a while, perhaps 5 minutes of riding. It is especially noticeable on acceleration from a dead stop, it just falls on it's face, or I need to get it up to about 4000 rpm and slip the clutch to get away. With the choke on it idles very poorly but will accelerate without slipping the clutch.

It sounds like this is a little extreme the other way from what I am experiencing. I appreciate the feedback.

y friends Wide-Glide was the same way. He got to the point where he ran the bike all the time with the choke out slightly. It was WAY lean. I fixed it by moving the needle up one slot and increasing the pilot jet one size. He's since traded the Keihin CV for a Mikuni slide.

I sometimes wish my Yamaha had a single carb like my Harley... much easier to tune.

Trout · Posted: January 22, 2007, 3:56 pm Post subject: Re: Don't choke me!

5twins wrote:

My '78 (same carbs as the '79) needs the choke for a stone cold start but not for very long, maybe 30 seconds or so. After that, it starts running rough and 8 stroking, and I can switch the choke off. I also need it sometimes when the bike is half warm/half cold. If it doesn't fire right up, I'll switch the choke on. Then it lights right up and I can pretty much immediately switch it off. It needs that initial rich mix to fire quickly.

Every machine is slightly different and has some of it's own personal traits. There may be nothing wrong with yours and this is just one of it's quirks. I would, however, take another look at your air filters. If they're dirty or plugged up, that could be causing rich running. I would remove them and see if you need the choke then. There's also a chance your float levels are set too rich (high).

Thanks for the reply.

I just cleaned the filters, but I may take your advice and start the bike with no filters. This should tell me if I'm rich because of filters.

I set the float levels exactly by the book. I'm pretty sure they are set OK.

It sounds like my bike acts pretty close to how yours acts. I guess I wouldn't even consider it a quirk (as you say). It's just different than what I'm used to on my other bike.

RainLand · Posted: January 23, 2007, 10:00 am Post subject: Re: Don't choke me!

Well, it looks damn nice parked, however it runs.

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