carb air flow technical question

[Agemax]

ok, so i have standard VM26's with stage 3 dynojets and bellmouths on a 1085cc motor. i now have a stainless plate covering the gap in the frame where the airbox used to fit. see old photo with pods, but plate is the same.

question is bearing in mind my knees/boots will be covering up most of the side area behind the carbs, will the plate assist in flowing air into the carbs as i am moving forward or will it disrupt the air flow, or should i remove the plate?
technical advise/ criticism accepted thanks

 

[hampshirehog]

You won't be able to notice any difference. You won't get any ram air effect or anything like that. I suspect that if you got up to maybe 100+ mph then pulled the clutch in and let the bike tickover you might notice some fluctuating.

 

[Big T]

That air is so turbulent from the front of your bike that it really won't make a difference

 

[TheCafeKid]

Age mate if ya look at some photos of old race bikes you may see a similar contraption used. The ones I've seen actually radius around the carbs and for a sort of "side-less" air box. I asked Dave who used to build old race bikes in SA and he said they're used to restrict turbulence in the air being sucked into the bellmouths to assist in creating a nice smooth flow.
This all goes back to the merits of polishing your intake runners. On a race bike it's done to acheive smooth flow. On a street bike, being as they're generally not run at the ragged edge of RPMs the imperfections in the runners aid in atomizing the air fuel mixture. So a polished head on a street bike might make for a odd throttle response. Flat down low and then peaky high up maybe.
I dont think you'll find any difference in your set up, although I'd maybe watch and see what your plugs look like as you go on. That'll be a tell, if you've set your carbs up similarly, whether the inner two arent getting as much air as the outers, but I doubt it.

 

[tkent02]

I think you should cut a clear (or blue) window in the side of the Venturi so you can see the airflow.

 

[Agemax]

I think you should cut a clear (or blue) window in the side of the Venturi so you can see the airflow.

lol you design one then! and ill build it

 

[KEITH KRAUSE]

Don't be concerned with it. The pods will breath fine. I have a black/mirrored plastic piece that covers the battery and stuff too.
And on the subject of flow, be sure to remove the two floatbowl vent lines and leave the ports open to breath better. Fuel starvation, at varying levels, will result if you leave the vent lines on.
What jetting did you decide on? (Main jet, jet needle e-clip position, pilot jet, pilot fuel screw and side air screw settings?)

 

[Agemax]

Don't be concerned with it. The pods will breath fine. I have a black/mirrored plastic piece that covers the battery and stuff too.
And on the subject of flow, be sure to remove the two floatbowl vent lines and leave the ports open to breath better. Fuel starvation, at varying levels, will result if you leave the vent lines on.
What jetting did you decide on? (Main jet, jet needle e-clip position, pilot jet, pilot fuel screw and side air screw settings?)

i am running belmouths now, not pods. it has a dynojet stage 3 kit in. the vent tubes have been removed

 

[rapidray]

Yoy offer a LOT of "advice" on this site about PERFORMANCE work & have a 1085 motor with WORK done to it, with STOCK 26 VMs on it?!!! You just lost a LOT of my respect! Stick to BOLTING stuff on to your bike! WTF?!!! Is that enough criticism for you? Ray.

 

[Agemax]

Yoy offer a LOT of "advice" on this site about PERFORMANCE work & have a 1085 motor with WORK done to it, with STOCK 26 VMs on it?!!! You just lost a LOT of my respect! Stick to BOLTING stuff on to your bike! WTF?!!! Is that enough criticism for you? Ray.

thanks Ray. it actually runs fine with the 26's. i plan to get some bigger carbs when i can afford them but being unemployed makes it a bit tricky.

as for "bolting" stuff on, take another look and see what has been MADE, or modified to fit, by me. i dont just sit here and flick through a catalogue and buy stuff to bolt on, i use my imagination and ingenuity to personalise my bike the way i want it

 

[rapidray]

A set of CR 31s would be a BIG change in power!! You aren't afraid of POWER are you? LOL! Good work! Let me know when I can get clutch covers for 16 valve 1100s! Ray.

 

[Agemax]

A set of CR 31s would be a BIG change in power!! You aren't afraid of POWER are you? LOL! Good work! Let me know when I can get clutch covers for 16 valve 1100s! Ray.

id love more power but power costs money, how much we talking for a decent set of 31's? plus new inlet rubbers, plus new filters? lots me thinks

working on a gsx1100 clutch cover now

 

[KEITH KRAUSE]

Agemax, sorry about the reference to pods. I guess the pic confused me even though you did say bellmouths.
I have to doubt the plate will interupt flow but couldn't say for sure. If it's an issue then I suppose you could cut a hole out for each bell or one oblong hole for the whole set. Still would hide the batt' and stuff and eliminate any chance there is of a flow issue.
29 smoothies fit the 1000 perfectly but as you said we're talking some money and possible jetting and parts headaches. Too easy to get an abused set these days with all kinds of incorrect parts. Maybe pick up 3 or 4 tenths in the quarter? The 26's work fine and are much easier to live with. I've ran the 26's all these 32 years and I have a V&H pipe, K&N pods and 1085 kit. I KNOW the stockers partly restrict the added flow of pods/pipe but I can enjoy what I have and don't need headaches anymore.
As for the bellmouths, they MIGHT add 1 more HP at about 8K rpm but that's it. I've seen tests done long ago by a respected source that was posted here before too. GS1000 with stock intake vs pods vs bellmouths, vs wide open carbs... Only 1 HP difference from the pods and wide open.
I'm not knocking your set up but if you keep the bike long term then bellmouths aren't a good choice. Very minimal power pick up and only at optimum rpm. Filtration is very poor even if you have screens. They look cool but quality pods are a better choice especially if you have a set up that may be compromising the bell's flow.
I figured you had a stage 3 DJ kit but was just wondering what final jetting you chose.

 

[Agemax]

Agemax, sorry about the reference to pods. I guess the pic confused me even though you did say bellmouths.
I have to doubt the plate will interupt flow but couldn't say for sure. If it's an issue then I suppose you could cut a hole out for each bell or one oblong hole for the whole set. Still would hide the batt' and stuff and eliminate any chance there is of a flow issue.
29 smoothies fit the 1000 perfectly but as you said we're talking some money and possible jetting and parts headaches. Too easy to get an abused set these days with all kinds of incorrect parts. Maybe pick up 3 or 4 tenths in the quarter? The 26's work fine and are much easier to live with. I've ran the 26's all these 32 years and I have a V&H pipe, K&N pods and 1085 kit. I KNOW the stockers partly restrict the added flow of pods/pipe but I can enjoy what I have and don't need headaches anymore.
As for the bellmouths, they MIGHT add 1 more HP at about 8K rpm but that's it. I've seen tests done long ago by a respected source that was posted here before too. GS1000 with stock intake vs pods vs bellmouths, vs wide open carbs... Only 1 HP difference from the pods and wide open.
I'm not knocking your set up but if you keep the bike long term then bellmouths aren't a good choice. Very minimal power pick up and only at optimum rpm. Filtration is very poor even if you have screens. They look cool but quality pods are a better choice especially if you have a set up that may be compromising the bell's flow.
I figured you had a stage 3 DJ kit but was just wondering what final jetting you chose.

thanks, im running the 142 dynojet mains at the moment. the bike seems to pull a lot harder with the belmouths but i think i will revert to the pods for street use, for obvious reasons(flies,bees,children, young mothers etc,etc)

 

[KEITH KRAUSE]

thanks, im running the 142 dynojet mains at the moment. the bike seems to pull a lot harder with the belmouths but i think i will revert to the pods for street use, for obvious reasons(flies,bees,children, young mothers etc,etc)

OK. Most 1000 owners run the 138 mains but that's with the pods.
My bike would accept the 142's but it did feel just a tad on the rich side but the biggest issue was a moderate bog during roll on's such as typical passing. I KNEW I had the jet needles set right and I guess the momentary overlap of the two circuits while opening to 3/4 and full throttle created a bog. No way I was going to compromise the jet needle since that's the circuit you ride with most of the time. So I went to the 138's and it runs well. Maybe a 140 if available would be perefect but I'm good with it.
Most owners end up with the jet needle e-clip in position 4 from the top, just to let you know. Each bike can vary a bit but that's by far the most common setting I've found over the years in combination with a quality pipe and K&N pods.

 

[Agemax]

ok i still have the 138's. may give them a go, when i refit the pods. midrange power is good with no flat spots so im leaving the needles as they are, middle position.
plugs do look slightly dark on a plug chop but i wouldnt risk running it to lean. i will do a plug chop with the 138's and see what it looks like

 

[KEITH KRAUSE]

ok i still have the 138's. may give them a go, when i refit the pods. midrange power is good with no flat spots so im leaving the needles as they are, middle position.
plugs do look slightly dark on a plug chop but i wouldnt risk running it to lean. i will do a plug chop with the 138's and see what it looks like

OK Just thought I'd pass that on about the mains. The 142 was pretty close but that bog was obvious overlap caused by the 142 since I was positive the jet needles were good. My bike wasn't the only one to show that effect.
As for the jet needles, with 6 positions there is no "middle" position. I've jetted quite a few 1000's with similar mod's, some myself and many others over the web. Every bike ran best with the e-clip in the 4th position from the top. ONE owner at this site said position "3 1/2" (e-clip in 4th position with jetting spacer directly on top the clip) seemed to work best for him but I can only go on what he claims. So if your dark plug reads are related to position 3 or 4 I'm surprised. If those dark reads are related to the main then I'm not surprised.
I've found literally no variation that you typically read about when jetting when it comes to the jet needle position. By the way, DJ has some good kits but their recommendations (baseline settings) are ridiculous when it comes to the jet needle adjustment. If the bike is in good tune and no compression/wear issues then the final jetting is very consistant.
So if you do happen to be using the 3rd position from the top then I believe the bike is very lean while in the 1/5 to 3/4 throttle range. Since you spend the most time riding on the jet needle circuit with a small overlap from the pilot circuit, it's really important to get that spot on. With todays fuels it's a little harder to get a good color read on the plugs when chopping off at 1/3 to 1/2 throttle but ride it at that position a good couple of miles should help, even if you have to do it in shorter runs to get that accumulation. I've sometimes had to run it about 1/2 mile a few times back to back to back to get what I believe is a good read. Just run it, pull in the clutch and quickly as possible turn around and go again. Takes a safe area though to do the testing. No downhill roads. Just level or even uphill is good. Personally, I've always been able to "feel" a lean condition maybe a little easier than some. Hold that throttle still and I could feel the surging on the jet needle with the needle in position 3. Fairly white plugs too. Position 4 typically gives a more consistant graying with a small amount of tanning, sometimes just grayish. I found richening to the 5th position gives way too rich readings everytime and position 4 1/2 still on the rich side.
Be sure the carbs are synched well first and the advance timing spot on. Too easy to get un-uniform colors if not closely synched. Which plug do you believe?
Take a piece of hosing with you when you test so you can more easily remove hot plugs. Helps thread them out the last few turns without dropping them and to start them too. Just be careful of cross-threading when re-installing if you use a hose. Might take a few times to get the "feel" of it. Sorry if you don't need any tips. Just my habit.

 

[KEITH KRAUSE]

By the way, my jet needle recommendations above assume all the factory nylon jet needle spacers are there and assembled in correct order. Larger "ring" on top the e-clip, thinner spacer under the clip. Any jet kit jetting spacer goes between the e-clip and ring. You'd be surprised how many owners find out their carbs are missing parts or parts are reversed. The ring and spacer in this case will greatly effect the jetting if not correct.
Anytime I think a chosen jetting could be a little off the norm I mention this.