Shimming CV carb needles – never fails to amaze…

[salty_monk]

I think to really get the benefit of this you also need to richen the pilot circuit which most all of us do as a matter of course anyway.

I suspect a pilot circuit that has been tweaked going to a stock needle would probably highlight the transition between the two as you'll be going from say a 14 - 16 -1 fuel air ratio down to a 12-1 or something so pulling the needle up a bit smooths the transition bringing the needle up to the same 14-1 or so as the pilot (I think I got that right... that in theory the sweet spot should be about 14-1. Anyway if not you no doubt get the idea I'm putting across).

When the bike is warm I expect that also helps to bridge the transition which would be why it is noticed most when cold I guess...

Just my thoughts on it....

[KEITH KRAUSE]

Bruce, you have a good point. I thought the same.
I didn't want to continue this discussion because some people get offended over things and I figured "hey, if it seems to work then I won't question it further." I said my piece about being cautious and that's all.
The needle does kick in and have an overlap effect sooner than most people think and charts show. So I can see where throttling it some will obviously get the needle involved and help get the bike moving. But as for warm ups, the way the carbs were designed to work, the pilot and choke circuits are the only active circuits at that time. You're not supposed to touch the throttle during warm up, if you do it bypasses the choke circuit.
Perhaps if the bike were allowed enough time to warm up that would help a lot.
The CV carbs obviously react differently than other carbs, such as the VM's. If I went out and raised the needle a full position on a VM equipped bike, one that may be a little lean from the factory, that bike would run very rich and the negatives would far outweigh any positives.
I still think the readers of this thread should just be careful before they make an adjustment that may cause them problems.

[waterman]

Bruce, you have a good point. I thought the same.
I didn't want to continue this discussion because some people get offended over things and I figured "hey, if it seems to work then I won't question it further." I said my piece about being cautious and that's all.
The needle does kick in and have an overlap effect sooner than most people think and charts show. So I can see where throttling it some will obviously get the needle involved and help get the bike moving. But as for warm ups, the way the carbs were designed to work, the pilot and choke circuits are the only active circuits at that time. You're not supposed to touch the throttle during warm up, if you do it bypasses the choke circuit.
Perhaps if the bike were allowed enough time to warm up that would help a lot.
The CV carbs obviously react differently than other carbs, such as the VM's. If I went out and raised the needle a full position on a VM equipped bike, one that may be a little lean from the factory, that bike would run very rich and the negatives would far outweigh any positives.
I still think the readers of this thread should just be careful before they make an adjustment that may cause them problems.

At the risk of offending others, I suggest we do discuss the finer points of carb jetting since all of us use carbs. While I agree that name calling and grandstanding does little to benefit anyone here, some in depth Technical discussion helps the rest of us non techies better understand the finer details of our machines. It also reinforces the knowledge that we may already possess.

I would also interject into this discussion that not all of the bikes that suzuki produced were inherently lean from the factory. My experience with the 650g shows that after setting highest maximum idle, the bikes will warm up and run cleanly within seconds after start up. Only when the weather is quite chilly (under 40 F) do I need to run on choke for more than say 30 seconds.

Conversely, my 550 is cold blooded, even after adjusting pilot screw settings. This one I will adjust the needle position to see if it helps. Still working on getting it to run correctly.

Finally, Ed, your bike is beautiful, shames me to call mine a Suzuki. Likewise, you respond to anyone with questions and truly are a site superstar please keep up good work.

Keith, I have always enjoyed reading your comments, they are usually well detailed and very logical in approach. Thank you for your contributions also.

[madbikebreaker]

Can't hurt

So regardless of the GS one is dealing with it doesn't sound like it couldn't hurt to give it a try as long as you don't get carried away right? The washers are cheap, I picked them up at Orcahrd for like $.12 a piece. If you don't need to pull the carbs it sounds like you could gain a lot for minimal effort and cost. Now I want to try it, if it don't work, I'll put it back the way it is. I'll do i this weekend and document the results.

[posplayr]

So regardless of the GS one is dealing with it doesn't sound like it couldn't hurt to give it a try as long as you don't get carried away right? The washers are cheap, I picked them up at Orcahrd for like $.12 a piece. If you don't need to pull the carbs it sounds like you could gain a lot for minimal effort and cost. Now I want to try it, if it don't work, I'll put it back the way it is. I'll do i this weekend and document the results.

I think the ED's run pretty lean as well.

[salty_monk]

Keith,

Almost stock setup on my GS1000G using a Canadian needle with clip positions on it that measured otherwise identical to my stock CALI needles - The bike would run pretty well on ANY of the clip settings.... I have tried them all. Obviously it would smoke a bit on the richer ones & running it lean is not good but as far as "feel" from the saddle it was fairly similar on all settings. I was one over on the mains though.
I think on the CV carbs the slides compensate in some way for a degree of inaccuracy in needle placement that you maybe don't get with the VM's.

However I have to say I never noticed the problems that Ed is talking about on that bike but then I never ran it 100% completely stock.

Dan

[KEITH KRAUSE]

Keith,

Almost stock setup on my GS1000G using a Canadian needle with clip positions on it that measured otherwise identical to my stock CALI needles - The bike would run pretty well on ANY of the clip settings.... I have tried them all. Obviously it would smoke a bit on the richer ones & running it lean is not good but as far as "feel" from the saddle it was fairly similar on all settings. I was one over on the mains though.
I think on the CV carbs the slides compensate in some way for a degree of inaccuracy in needle placement that you maybe don't get with the VM's.

However I have to say I never noticed the problems that Ed is talking about on that bike but then I never ran it 100% completely stock.

Dan

Well, if you're saying your bike would run pretty well/similar with the jet needle set anywhere from the first to fifth position, then I simply can't understand it. What good are the needle settings that jet kits suggest if there wouldn't be any significant change? If the positions did nothing/almost nothing, there would be no reason for a choice and the needle would be fixed.
Please don't take any of my typed words the wrong way (don't know why I should ever have to even say that here...) but your experience above contradicts a million posts at this site regarding jetting, testing, and how various needle positions gave obvious results ranging anywhere from "running like crap" to "running perfect", all because of a jet needle position change.
I don't know what could be going on in your case. It makes no sense to me.

[salty_monk]

It did make a difference but certainly not the huge one I was expecting, I suspect I could have given the bike to most people with the needle set in any of the 3 central positions & they would have been hard pushed to tell any difference without riding the other settings back to back.

I guess what that proves more than anything is that all bikes are slightly different but I do think that it can't really hurt & most likely will help to raise the needles slightly on most CV equipped Suzuki's with the exception of perhaps if you're at altitude.

It makes sense to me that if most richen the pilot circuit you would also want the needle circuit slightly richer to smooth the transition between the two.

At one point I got needle swaps down to 20 mins from putting it on the stand to riding away again. For that sort of time investment it's no big deal to try it out. You can always go back.

I don't agree that any vehicle should need to be left idling to warm up for any length of time before it can be safely ridden away with the choke part way on. That just leads to increased engine wear caused by an elongated warm up.

Dan

[posplayr]

It did make a difference but certainly not the huge one I was expecting, I suspect I could have given the bike to most people with the needle set in any of the 3 central positions & they would have been hard pushed to tell any difference without riding the other settings back to back.

Dan

Dan,
I think you need to know what to look for. Bill helped me on the ED and the main diff was a slight (but noticeable) bobble in part 1/8 throttle that the needle adjustment would correct. Certainly it would be hard to figure the needle position when you are WOT .
Jim