Keihin Help!!

[John21]

I have been a member of this sight for a long time. But, I had to completely re-register. Oh well..................

My problem is that I have a 1998 Exec Sprint with Keihin carbs. I need to adjust the fuel air ratio at idle. Where can I get the ratio meter that screws into the exhaust port? Also, where can I get a flex screw driver that will fit the idle adjust screw on the bottom of my Keihins?

You can reply directly to me at jlbonnie2000@yahoo.com

thanks.....John

[trypcil]

Make you own, http://www.jetlink.net/~okayfine/su/airfuel.html and Triumph does a right angled screw driver , don't know the part #

[John21]

I went to a Triumph websight and found that the right angle screw driver from Triumph is about $160. I think I can devise a much cheaper way just to turn a screw.

In the case of my Exec, I believe I am fighting a design issue with these Keihins. When I bought the bike out west in higher altitudes, it ran perfect. Here in the midwest, it runs like crap and has from the very first day I moved back.

Like I said, if I turn the choke on just a little bit, the bike runs perfect. My plan is to get the required fuel air ratio meter and see what my ratio is with the choke partially on. Then, all I should have to do is to adjust the carbs to match this ratio.

Building a fuel air meter sounds pretty easy to do. Since I am trying to adjust the idle circuit, all I should need to do is to set the guage in the garage and observe it.

The screw hole in the exhaust pipe of the Sprint is very small. Most oxygen sensors are pretty big close to 1/2 inch thread. I wonder what they make that will screw into the exisitng Triumph port?

This gives me something to think about. For now, I can ride my bike in perfect comfort by leaving the choke partially applied.

John

[seumas]

Sounds to me like maybe it was jetted for the altitude and now you're running lean since you're at lower altitude.
I live a 4500 ft. and mine ran rich with stock jetting, before I started making mods.

[trypcil]

Can you see the fuel screws under the carbs? Maybe they've never been en-richened? The old guide line was they came lean for epa purposes but the quick fix was to open them up to 2 1/2 turns but no more than 3 turns from a gentle close. Just take the airbox off and then flip the carbs and adjust them individually.

[John21]

I am going to approach this carb issue in two steps. But, before that, I do believe my Exec came set up exceptionally lean.

The first step is to find some kind of tool that will let me adjust those carbs. I looked at AutoZone and they sell a flex screw driver. It's only $15, but it does not look like it will make a tight enough bend.

My neighbor was telling me about a ratchet he saw once where you could twist the end to make a socket turn. Now, this might have possibilities.

I need something that can be reliable to adjust the carbs. I want to turn them maybe a 1/4 turn at a time. I am thinking going out with the adjustment will make it richer. I am not sure which way is which. One person said turning the screw out made the mixture richer. Another person said turning it in made the mixture richer. Which way is which??

I don't want to have to remove the carbs to make each adjutsment. That takes a couple of hours to do.

The next issue is finding an oxygen sensor that will fit the stock port already in the pipe. Triumph put them there for a reason.

Like I said, my bike runs 100% perfect if I turn the choke on just a little. The idle comes up from 1100 to 1300, which is easy to live with. I made a mark on the bar so I can set the choke at the same spot each time. If I can get a fuel/air reading with a guage and choke applies, then setting the carbs to this reading with the choke off should be relative easy.

Does anyone know of a fuel/air meter that will definitely fit a Triumph??

thanks....John

[John21]

Ok, my problem is 99% fixed. This is what I did..................

Here in Arkansas, we have a business called Hobby Lobby. I was looking for a small round wheel made of wood with a small hole in the center. My idea for an adjusting screw driver is to take a small bit about an inch long and press it into the hole in the wheel. This way, I have a very short screw driver with enough "width" to be able to run it.

This worked abo****ely perfect on the outside two carbs. The center carb was a bear to adjust. But, I managed to do it with a lot of skin scrathced off my hands.

I decided that turing the adjustment screw out made it richer. I came to this conclusion as most carbs have a "set" air amount in the idle intake. The gas is what you adjust. Back the needle out and more gas (richer).

I ended up right. My idle screws were all set for 1.5 turns initially. This is OK at 3000+ feet in altitude, but just horrible at sea level. I turned each one an accurate "guess-ta-ment" of an additional 1.25 turns for an entire amount of 2 .75 turns. Or half way between 2.5 and 3.0 turns.

The first thing I noticed was the bike started cold instantly. It has never done that before. Usually, it would back-fire once and require 15 seconds of cranking before it would start..

After a 1/2 mile, I decided to turn the choke off. I gritted my teeth in anticipation of the miss-firing and lurching at low speeds. Wierd?? There was none.

Now the take off test. I leave a stop sign by not giving the engine much gas. I just let it take off at an idle as I let the clutch out, then give it some gas. There was a tiny miss-fire, but not the horrible lurching of before. I did find if I give it a tiny bit of gas talking off, there is no miss-firing at all.

Next was the idle. Before, even with the choke on, the tach needle would wander around. Not this time. Dead solid.

Finally, I applied a little choke to see if I could improve the quality of the bike. When I did, the engine died. This is good!! This now tells me that enrichening the engine even just a tad is too much.

I do feel if I had an exhaust fuel/air guage, I could nail this carb adjustment 100%. I think 14.7 is a perfect idle amount. I am probably just a tad lean at say 15.0............................John

[seumas]

Sounds like you're on the right track John.

[John21]

I think I finally got it!! My carb idle adjustment was set to 1.5 turns from the factory. Taking them to 2.5 turns really helped. 3.0 turns eliminated all the miss-firing......John