I have read the thread on getting more snap from your bike by utilising an "O" ring on the carby. I would very much appreciate your input if this adjustment was suitable for a week end trail warrior. By that will it make the bike a better single and tight trail machine and will it hurt fuel economy etc. Cheers
I'm an old fat guy and my best riding days were in the 70's. I prefer the O-ring because, IMO, it gives the bike a quicker snap while lightly blipping the throttle in tighter stuff. I prefer quicker response versus having to twist more. It takes a bit to get used to the different response characteristic, and there's the risk of launching yourself into a tree or rock if you can't finesse the throttle, but I like the effect and have adapted my riding style accordingly. I think the best way to describe the effect of the O-ring on throttle response is that it makes a 4t feel more like a big bore two-stroke when blipping the throttle quickly.
It is ideal for a weekend trail rider. It works in conjunction with the leak jet size to change how the squirt is delivered. You should then be able to loft the front wheel easier over obstacles on the trail. The really nice thing about it is that can be added or removed at any time. Simply take 1 screw off, remove the plastic cover, and put on the o-ring. I've put one on, off, on, off, on, dozens of times. It changes how the bike works a bit.
Thanks for the input guys, very much appreciated. Its now 7 am Sydney time so I am off to my shed to bung the O ring on. Will be riding in the high country over Xmas and will let you know how it worked for me. The other question I had was does it materially affect fuel consumption? Ciao.
Here you go... http://www.cafehusky.com/forums/showthread.php?t=6889 I do not think putting an O-ring on the AP arm as shown in that thread makes any difference in mpg. When the throttle is rapidly opened the fuel squirts more but that makes the bike go faster, as opposed to less of a squirt and the bike not going as fast. I've not noticed any change in mpg.
Eric has adjusted the duration of the fuel squirt on our bikes, but he did it by tapping in an adjustment screw in the body of the carb that prevents the AP arm from opening all the way. This is a pretty cool mod in that it allows for more adjustability and doesn't cost much at all. All you need is a drill bit and tap, 4mm screw and a tiny spring...less than $10. We did up my 610 and it really gave me a lot of snap right off the bottom. It made a huge difference The duration of the fuel squirt in stock form was about 4 seconds and we cut that down to about .5 seconds. The beauty of the screw is that you can fine tune it to your preference. We've had 5 FCR carbs (WR426, WR250F, 450 EXC, LC4 640e, SM610) and they were all over the map as far as duration. WoodsChick
Delaying the accelerator pump and going with a g2 throttle to provide a longer turn makes a pretty nice combo for tight trail work. Also gives improved fuel economy. jeff
I noticed the "O" ring change immediately. It is modest and not explosive, just a slightly quicker response in the initial throttle twist. It was great in the tight for helping to loft the front or keep momentum up. It might also save a bit a clutch usage. I was not apparent that mpg's were affected. Thanks for the tip and info everyone.
It's is a good one as it takes no time, no dollars, is immediately beneficial. It also makes you feel good imparting this tip to the unwashed masses who ride Yammies and KTM's etc.
So I decided to go out and do this today. Popped off the cover, and noticed immediately that there was no cap over AP screw. Was kinda shocked to see that. I went ahead and slipped on a couple different o-rings till I found the one that fit the best. I didn't make any adjustment to the AP screw... will I still notice a difference? I didn't have time to ride or even start it today!!
I'm not sure what the 2009 TXCs have, my guess would be no AP disable cap is necessary to qualify for the emissions. As per this chart, if nothing has changed and you are at about 2.75 mm on the adjustment, you will get about the same squirt but it will happen much faster, which is when you want it to happen if you are whacking the throttle fast to loft the front tire a bit. Instead of .35 seconds to deliver the squirt it takes about .2 seconds, which if you really think about it, is much more appropriate. Actually it depends on how strong a Oring, how many, etc. I experimented with many many things. For the record, trying to connect the AP linkage together has been around for a long time, at least that is what I read over on TT years ago from what Eddie typed.
Great info Coffee. I have a micrometer, but not a caliper... .my "non scientific" way of measuring the adjustment gave me about 2.35mm. I suppose I'll just have to play around with it some and see what it gets me. I'm also on the ebay hunt for a good caliper. Very suprisingly, I've had good luck with quality used tools there.
I safety-wire the arms together. So did the factory race teams before "the change". O-rings sack out pretty quick and can (will) break. Carry spares. Just my .02
OHH, that's very interesting. Do you happen to have a pic of that? I'm curious. I love safety wire and think that's a great idea. I use fairly thick wire and am not sure about getting it in there and it being unobtrusive.
The wire thing has been around as long or before the ring. Use normal safety wire (0.32" SS or so) and route it along the same lines as the o-ring follows.
