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09' Carb Tweak

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Recently picked up an 09' and immediately installed the GSXR can. Never even rode it w/stock exhuast. No carb or air box mods. It ran awful. Off idle bog and heavy surging up and into midrange. Found idle air screw out maybe 1/2 inch.

Made various adjustments/tests and found that it wants to be at 2 3/4 turns out. Seems like a lot but it runs about like my 08', set up exactly the same way. The 08' lives at 2 1/8 turns out. Everything same same, no airbox mods only the GSXR can. Seems like a lot of idle air but that's were they both want to run good at.

I've not had the time to go into the carbs as advised by others here, just yet. The brass plug covering the air screw is hard to "punch" or pick out because of where it is...use a dremel, etc. to make a small hole in the plug, then turn a small screw into that hole. Pull down on the screw and the soft plug will come right out. Small flat blade screwdriver for the adjustment...I made a very short one out of an 8 penny nail, easier to manuever under the carb.

If you have a doggy running new bike, as posted here by others, by all means adjust the idle air screw as instructed here on the forum!

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Recently picked up an 09' and immediately installed the GSXR can. Never even rode it w/stock exhuast. No carb or air box mods. It ran awful. Off idle bog and heavy surging up and into midrange. Found idle air screw out maybe 1/2 inch.

Made various adjustments/tests and found that it wants to be at 2 3/4 turns out. Seems like a lot but it runs about like my 08', set up exactly the same way. The 08' lives at 2 1/8 turns out. Everything same same, no airbox mods only the GSXR can. Seems like a lot of idle air but that's were they both want to run good at.

I've not had the time to go into the carbs as advised by others here, just yet. The brass plug covering the air screw is hard to "punch" or pick out because of where it is...use a dremel, etc. to make a small hole in the plug, then turn a small screw into that hole. Pull down on the screw and the soft plug will come right out. Small flat blade screwdriver for the adjustment...I made a very short one out of an 8 penny nail, easier to manuever under the carb.

If you have a doggy running new bike, as posted here by others, by all means adjust the idle air screw as instructed here on the forum!

You are thinking two-stroke with "idle air". :cheers: Pilot screws on carbs that have the pilot screw between the head and the slide control fuel. So opening the screw is richening the mixture. Pilot screws behind the slide control air flow so opening the screw leans the mixture. 2-3/4 turns out on the pilot is pretty rich.... you are over richening the pilot circuit trying to make up for the lean needle setting. You'd be much better off shimming that needle up .030-.040" and then getting that pilot screw back down to about 1-1/4 to 1-1/2 turns out. The main is rich enough to allow removal of the snorkel so you can have a nice over-all performance gain by doing the above mods. :moon:

Edited by mx_rob

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Copy that. The 09' is my Lower 48 bike, it's about to rain for a week out west (again) so...maybe pull the carb and do it up right. I looked at one spark plug tonight and it is a bit too black for my taste (I see what you're saying about running rich). Tempted to spring for a TM40 pre-jetted, etc. from ProCycle right now and be done with it...hopefully.

Likely gonna try to massage this one for now and save the $.

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Copy that. The 09' is my Lower 48 bike, it's about to rain for a week out west (again) so...maybe pull the carb and do it up right. I looked at one spark plug tonight and it is a bit too black for my taste (I see what you're saying about running rich). Tempted to spring for a TM40 pre-jetted, etc. from ProCycle right now and be done with it...hopefully.

Likely gonna try to massage this one for now and save the $.

No need to pull the carb! Just loosen the air boot and manifold clamps, remove the screw from the rear brake fluid reservoir to allow the float bowl to swing right, remove the choke assembly from the carb to keep the cheap-o plastic cable guide from breaking into many useless pieces. Remove the cable ties around the frame to allow the throttle cables to swing away from the frame, while still mounted on the carb, without tweaking them. You can have the cap off the carb and the slide out in minutes (give or take an hour or two based on your mechanical prowess). :smirk:

Caution! Use a very sharp (not worn out) #2 phillips head screwdriver to remove the vacuum cap screws. Hold the bottom of the float bowl with one hand as you press very firmly into the screwdriver handle with the other. Your downard force must exceed your twisting force or the POS screw heads will strip out faster than you can say W*T*F? :cheers:

Pick up a couple of 3mm stainless steel flat washers from you local hardware store. They generally are about 1/2mm (.020") thick. Make sure to put the shims between the white plastic spacer and needle clip... not under the spacer. The spacers are kinda tight on the needle. Put the needle tip on some rubber or soft wood to prevent damaging the tip and press the spacer off. Install the two shims and flip the needle over and press the spacer back on. Make sure the shims are held tightly against the clip. Reassemble and snatch that snorkel out just before installing the seat. :moon::smirk:

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I'm making that my project for next week, If at all possible. I did roll my carb w/in the boot to access the pesky brass plug earlier...will do same as you say, for the needle mod, and report back w/results.

I feel the need to "pay" somehow for all the free consultation here. PM sent.

Thanks

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Done deal. I had just enough time before dark to access/shim the needle as instructed above and wow! Whole different bike. Only had time for a short 3 mile test ride but the surge, bog, abrubtness of throttle, all seem gone. Started right up as well. Snorkle removed = just enough more throaty thump too, Bonus! Awesome mod, thanks MX ROB!

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Done deal. I had just enough time before dark to access/shim the needle as instructed above and wow! Whole different bike. Only had time for a short 3 mile test ride but the surge, bog, abrubtness of throttle, all seem gone. Started right up as well. Snorkle removed = just enough more throaty thump too, Bonus! Awesome mod, thanks MX ROB!

:moon::smirk::cheers::smirk:

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How do remove the choke assembly from the carb? I know it must be simple but this is the first carb mod i have done on my new DR. '09 with 106 miles on her.

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If you look where the choke cable enters the carb, there is a black plastic peice that looks like a nut, attached to the carb right where the cable enters. Unscrew it with your fingers, if it does not budge, a small open end wrench can be fit in around it, just enough to losen it. Everything slides right out after that. It helps to remove the plate/two screws that support the throttle cables to the side of the carb. Don't over tighten that plastic retainer nut when reinstalling the choke cable, i think finger tight is ok.

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Thanks Iceman, once i really looked it was pretty obvious. Just trying not to trash my new DR, before she is broke in.

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And further, the sooner you can shim that fuel needle and obtain a GSXR muffler...the better off you and the bike will be! Can't say enough good about it. Have fun with your new DR!

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No need to pull the carb! Just loosen the air boot and manifold clamps, remove the screw from the rear brake fluid reservoir to allow the float bowl to swing right, remove the choke assembly from the carb to keep the cheap-o plastic cable guide from breaking into many useless pieces. Remove the cable ties around the frame to allow the throttle cables to swing away from the frame, while still mounted on the carb, without tweaking them. You can have the cap off the carb and the slide out in minutes (give or take an hour or two based on your mechanical prowess).🤣

Caution! Use a very sharp (not worn out) #2 phillips head screwdriver to remove the vacuum cap screws. Hold the bottom of the float bowl with one hand as you press very firmly into the screwdriver handle with the other. Your downard force must exceed your twisting force or the POS screw heads will strip out faster than you can say W*T*F? :smirk:

Pick up a couple of 3mm stainless steel flat washers from you local hardware store. They generally are about 1/2mm (.020") thick. Make sure to put the shims between the white plastic spacer and needle clip... not under the spacer. The spacers are kinda tight on the needle. Put the needle tip on some rubber or soft wood to prevent damaging the tip and press the spacer off. Install the two shims and flip the needle over and press the spacer back on. Make sure the shims are held tightly against the clip. Reassemble and snatch that snorkel out just before installing the seat. :smirk::ride:

With these instructions, and pics from the FAQ, I went ahead and did the shims and drilling the slide. While i had the top off, I squirted some carb cleaner down the hole at the bottom since i saw a little gum accumulated on the needle.

Thanks guys!! the only real gripe I had was the bucking at low speed ( I even went with 14/46 sprockets in hopes of solving that ) This is great! Not only did it almost totally resolve the low speed bucking, the improvement otherwise in all around performance is great. She gets right up to 70ish and then some in a hurry.

I just cracked open a cold one to celebrate :cheers:

You guys ROCK!

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Thanks allot guys now i gotta go try this lol. Does the snorkel removal give you more power? It runs good stock but hey I can use power lol.

So when do you need to rejet? Only when you open the airbox?

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Thanks allot guys now i gotta go try this lol. Does the snorkel removal give you more power? It runs good stock but hey I can use power lol.

So when do you need to rejet? Only when you open the airbox?

I think you could do a dynojet kit now, with or without the airbox mod, but thats $50-60, the washers for the shim mod were 18 cents.

I kicked the dynojet idea around, or use the cash toward a TM40 carb to go with the gsxr muffler i already have.. but free time is scarce ($ too) and didn't want to get tied up with redoing it trying to get the jetting right.

I look at that muffler on the shelf every time i go into the garage.. one of these days...

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I ventured out to the garage after reading this post and less than an hour later had the snorkel out , needle shimmed and screw out lol man these things are really nice to work on. Took it out and it sounds and pulls great. I'm still chasing a hesitation ( see my hesitation thread) but otherwise it feels great. Thanks for the info and idea guys.

Gfletch this is my daily commuter and I kinda wanna retain good miliage so I'll leave the jets stock for now. It goes good with snorkel out and the 14 front sprocket

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Wow...if you've got a GSXR can laying in wait, liquidate something you don't want or need, get your mid pipe and bracket ($250 max) and get rockin'. I was in the same boat on my first Gixxer can mod...it sat around here for months. After, I kept wondering why I waited so long. The simple mods found here are so worth it.

If you go TM40, be prepared to do a little experimenting with pump adjustment, otherwise the jetting is addressed at the time you order from one of the two vendors that frequent here. Tell them what you plan to have/want and they will jet it before shipping.

In hindsight I'd say only go the pumper if you have the money, and want the refined character it offers. Otherwise, the needle shim and or jet kit option will be worth the effort.

Cannot encourage you enough to go for it asap...you will be glad you did.

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do you suppose adding the can would require a rejet or will the shims put me in the "close enough" range?

I think i waited so that they've raised the price for the midpipe kit at least once already :smirk:

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No need to re-jet. Add new muffler, shim-tune as indicated by mxrob above and pull the snorkle if you like. Done. Hacking up the airbox by cutting off the top or making big holes in it = need to re-jet.

Get to it! The mid pipe and bracket ain't gonna get any cheaper either, most llikely!

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the only real gripe I had was the bucking at low speed ( I even went with 14/46 sprockets in hopes of solving that )

The only way to get rid of the bucking at lower engine speeds is to get ride of the vacuum operated slide carb. The vacuum signal pulses so drastically at lower RPM on a big thumper that the slide is jumping up and down in response. This is the reason I never drilled my slide when I was running the BST. The single hole acts as a damper to volume... drilling another hole makes the problem worse. Same with a cut slide spring which I also tried. It does improve throttle response just like drilling the extra hole... but it causes as many problems as it makes improvements IMO. I ended up in the end with a stock slide and spring with a washer on the spring's guide post in the cap to actually provide more preload. This eliminated the normal surging caused by the BST and greatly improved low speed operation. My giant Needle Comparison thread has details. Start from the back to find it faster... :smirk: If you don't care if your thumper can't thump then it's a non-issue.

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Thanks allot guys now i gotta go try this lol. Does the snorkel removal give you more power? It runs good stock but hey I can use power lol.

So when do you need to rejet? Only when you open the airbox?

#1 Yes. You should shim the stock needle a bit leaving all the other jets stock.

#2 Yes. You need the DJ kit or a better carb if you are going to do the box mod.

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