From: 1/24/00 02:10 Subject: Keihin Carb Mods - Continuing Saga...To: Triumph Newslist , "triumphtiger@onelist.com" Blake, Here is the message I just posted to the Triumph list--I hope I haven't done anything dumb. -Nah. Even if it was dumb they need some little matter to get steamed up on every once in a while! You would think that their asses have stuck to the seat during this cold weather, by some of the posts. But this is pertinent to all Triumphs. And it seems to be the rare message that is actually on topic now during the depths of winter! So I'm porting my reply to the lists as well. Dear All, Some of you wanted to know how I made out with getting rid of my Thunderbird's acceleration problem (going along at 3,000-4000, hit the gas, and experience a moment of nothing, followed by OK acceleration, followed by very good acceleration). I decided to try one thing at a time, and so I started with shimming the needles, and it has done wonders. It still isn't perfect, but the hesitation is barely noticeable (and might just mean that I've reached the limits of physics). First, the setup: '99 T'bird, Keihin carbs, competition pipes, mixture screws set by the dealer at 2 1/4--2 2/3. Anyway, I came up with a "clever" way to shim the needles, and I would like everyone to take a close look at this and make sure I'm not being too "clever" for my own safety. I went down to the hardware store and bought some steel washers, approx. 1/32" thick (just a hair thinner, actually), with an ID of 3 mm and and OD of 8mm. I put the needles through the washers and dropped them down into the slides. Then I put the plastic sleeves over them, and put the springs and tops back on. The "clever" part of this is that the OD of 8 mm means that the washers fit perfectly inside the plastic sleeves, resting on the raised ring inside sleeves that would normally touch the top of the little cylinder inside the slide, thereby preserving the "wiggle room" above the needle head. I really hope this is not a bad idea, because it works (and Blake, I hope I haven't missed your point about the wiggle room). -Nope it needs to be in there. Been thinking on the washer's shape, size, and purpose here.....and if the cage can not fall down and the needle still has freeplay then you are all set I think! -This is a good idea (well, if it works over time.....) and is a bit simpler than doing the washer resection and trim, and the required reassembly. Sounds good. Now the bike accelerates powerfully and immediately (well, almost) from any reasonable rpm (3000 and up). The only down side is that when I stopped the engine and started it right back up, it took about three revolutions to catch (seems like it used to fire immediately, but then the bike is very new and I can't remember exactly how it was before). I hope it isn't running too rich now and fouling the plugs. I kind of doubt it, but I'll post a note later when I've ridden with this setup for a while. -Never noticed a change on mine with the startup with all the mods I made. As long as it starts easily on a cold morning is all you should worry about. The next thing is doing a bit of work to the main jet. Really easy and nice benefits as well. Floats are a bit more labor intensive but an extra 1mm will help. I also put duct tape around the seam in the airbox (not the filter box) because I noticed it wasn't fitted together very well and was letting in air through the sides. Maybe that made a difference, too. -Might be. These things can be influenced by some seemingly trivial things! Now I have a new beef. I rode the bike at night for the first time today, and the headlight is putting out this idiotic "V" shaped pattern on the road, so that everything immediately in front of me is well lit, but nothing more than twenty-five feet ahead is visible in the dark. It has occurred to me that the lamp might be installed upside down, but I didn't feel like fooling with it tonight. Anybody else notice a similar problem? -Yes! Low beams are designed to be truly useless pieces of crap. That's why I run my high-beams at night also! If it is really dark out I will dip them while you are coming at me, but not for long. You cant see shit with the normal lights. I thought that it was a Tiger problem, but it is endemic to all I am afraid. -If you are blinded then you have noticed me, this is a positive thing. -Loud pipes don't save lives, blinding lights do! Thanks to all who have given me advice, and I look forward to any and all replies to this posting-- John -----Original Message----- From: Blake Mantel To: John McMahon ; triumphtiger@onelist.com Date: Saturday, January 22, 2000 1:23 AM Subject: Re: Keihin carb mods Hi John. This topic we are discussing is great for the Tiger news list so I'm going to cc my reply to them as well. If you had a question, chances are someone else will too. Blake ------------------------------------------------------ John McMahon wrote: Blake, Sounds like a winner to me! How has the bike run since you first modified it? Any further news to report? -Nope, runs great! 36-39MPG depending on throttle abuse. Even started up yesterday at 12'F though had to jump start the bike, battery was just not making enough to crank it over at all. - My problem is exactly the same as yours, a noticeable bog when the throttle is snapped open. Once the bog is over, the bike takes off like a rocket, but , of course, I have to have perfection. A few questions: 1) I'm not sure I understand the part about how to raise the needle. Are you saying that you need to remove the needle from the washer that is already around the top, then grind the top of the needle down, then fix the new washer around the top with Loctite? -In the Keihin's that the Triumphs use, the needle (more like a tapered, small aluminum rod) is held captive at the top by a thick aluminum washer. This assembly is staked together and is designed to not be adjustable in any way. -So if we want to move the needle up some you have to move the washer up also (since it's attached) and a simple shim under the washer will eliminate the small amount of freeplay in the system that keeps it from binding up. (IMPORTANT!) -So the only other answer is to remove the needle from the washer. Reduce the thickness of the washer by the amount of the shim. Stake and loctite them back together. And replace with the added shim now under the washer. The washer that had part of it's head ground off reducing the thickness. -So you reduce the aluminum washer (that holds the needle) by say .025 and add .025 shim washer underneath it upon replacing the newly staked assembly back into the carb. This moves the needle up the desired .025 without causing binding in the little plastic cage. -Trust me, it is more obvious when the pieces are out and sitting next to you! 2) Do you think any benefit could be gained simply by changing the needle without changing the main jet or the float? -Yes, it would help some. But not very much. You should do the whole course because each step enriches the mixture slightly, but not horribly much. My gas mileage was unchanged from stock as far as my records show.. -Justin (earthlink@the-spa.com) had his jets opened .001 greater than mine were. -I believe that he also did not have much of a change in MPG. Justin please correct me if I'm wrong here. -His jets were taken out to .040 (.038 is stock) and this gives a calculated increase of almost 10% for fuel flow. (I did the numbers a long time ago but I remember that .040 almost doubled the flow increase from .039. The calculated increase at .039 was a tad more than 5%) -So I would recommend going up to .040" form .038". 3) In any case, what size jet (in Keihin terms) would I need to replace the old one (#98)? -Not a friggin clue! Though it is possible to purchase the one with the correct aperture. -But you don't have to replace them, just purchase a set of carb jet drills (or a single .040 drill) and enlarge them slightly to the proper size. Or if you choose to have your local wrench do it he should own a set. (If he doesn't would run away VERY quickly!) -The amount of removed brass is a mere shaving, not much at all. 4) What did you end up doing about the idle mixture? Mine were set by the dealer when the competition pipes were added. The outside screws are 2 1/4 turns out, and the middle is 2 2/3 out. It starts right up and is off choke in under a minute even at freezing temps, so I think I might leave mine as is. -I agree with you here, and I would not have changed mine with what I know today. my bike has never shown cold-bloodedness problems, and now at 3 turns I think it idles a bit on the rich side. But not enough to really worry about. Thanks in advance for any assistance you can offer-- John -No problem, enjoy! -Blake -- CUM CATAPULTAE PROSCRIPTAE ERUNT TUM SOLI PROSCRIPTI CATAPULTAS HABEBUNT. (When catapults are outlawed, only outlaws will have catapults....) Triumph Tiger Motorcycle page at: http://www.tiac.net/users/blakem/