Carb jet question

[ValkScout]

Hello all! This forum is a fantastic source of information and I've been reading everything I can find for the past few weeks. But, now I have a question for you experts.

I have a 97 Valk tour that I just got two weeks ago. It had 14k original miles, and for the most part was all original. After reading everything I could about changing out the exhaust (Yes, I decided to go with the Cobra 6 into 6), I knew that I had to re-jet the carbs. So I ordered the DynaJet carb kit. What I evidently missed was that this kit came with the needle jets, springs and mixture adjustment tool, not the main and slow jets. Everything that I've found on this forum only talks about the Main and slow jets, not needle jets. So, my question, has anyone else used these before? Now, I used the mixture adjustment tool to turn mixture screws out to 2 1/2 turns, which greatly reduced the decel popping. I have yet to actually install the needle jets and springs.

Any input would be greatly appreciated. Thanks in advance!

[sandy]

I  had DJ needles in my 98 Tourer. It was a Calif bike with Thunder Valley Headers. DJ says to set the circlip on the 3rd notch down from the top. After some fuel economy runs, I moved them to the 2nd notch down (leaner setting). That got me better gas mileage. The answer you need is that DJ needles can be used to adjust mixture ratios. The lighter Interstate springs give faster throttle response.

[Leathel]

The main jets might not need changing if all you have done is the exhaust, but here is a guide I use to tuning.... but it is a little hard to get right with no Dyno and limited access to jets but it has some good info anyway

http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

[ValkScout]

Awesome! Thank you for the input, I greatly appreciate it!

[ValkScout]

Ok, got the needle jets and springs installed. What a difference in throttle response! Much better! I'm still getting some decel popping going on that's driving me crazy. Talked to a friend of mine who said that decel popping is from too rich a mixture and that I need to increase air or decrease fuel, using the mixture screws. While I understand that, it caused some confusion and I took to the forum for some more reading.

From everything i've found so far, most posts on the subject talk about opening (turning out/counter clockwise) of the mixture screws will increase fuel or make the mixture richer. My friend stated that opening the mixture screws will make it more lean, by allowing more air to be mixed in with the fuel.

So, which is it? I'm confused as crap now and have read so much, I dont know which way is up. Please excuse my ignorance, just looking for clarification.

Thanks in advance!

[Pete]

The slow jets on a Valkyrie control fuel, more open more gas.
The main jet is also a fuel jet, raise needle more gas.

[Harryc]

The slow jets on a Valkyrie control fuel, more open more gas.
The min just is also a fuel jet, raise needle more gas.

^^^^^+1, that and your friend was misinformed about decel popping. It is usually caused by a lean condition (or an exhaust leak) and not a rich condition.

[98valk]

they lied! it never was a jet kit, always just needles.

[Hook#3287]

Vacuum hoses??  Original?

[ValkScout]

Yes, original vacuum hoses. Which are in excellent, flexible condition.

With the original exhaust, there was no decel popping that I could notice. Once Cobras were installed, with no adjustments to carbs made, there was the normal obvious decel popping. After adjusting the mixture screws out 2 1/2 turns, it reduced the decel by 80%, until at normal operating temps, then the popping was more significant.

After doing some other reading, and from what is mentioned here, it could be an air leak from the new crush washers on the exhaust that have not been re-tightened since installed with the pipes.

So, if I'm understanding the mixture screws correctly; when turning the mixture screws, they are actually turning the slow jets? And by turning them out from lightly seated, counter clockwise, it is allowing more fuel (making it more rich) to be mixed with the air. Correct? Feel free to smack me upside the head if I got this all screwed up!

Thanks

[Lyonardo]

I installed that kit myself, a couple months ago.
I definitely noticed a boost to acceleration, since the stock needle tapers off to "wide open", but the Cobra needle opens up as soon as you hit the throttle.

I made a video:
https://youtu.be/jzzLE76rWiI

[ValkScout]

I installed that kit myself, a couple months ago.
I definitely noticed a boost to acceleration, since the stock needle tapers off to "wide open", but the Cobra needle opens up as soon as you hit the throttle.

I made a video:
https://youtu.be/jzzLE76rWiI

Yea I saw that video a couple of weeks ago. Great video man, very informative!

[Dale_K]

I took a set of Cobras off the 98 Standard that I recently purchased.  It also had popping on deceleration.  When I removed the Cobras it was obvious that the end of the pipe was not making a good seal against the copper exhaust manifold washers.  The stock Honda pipes were better quality in this regard and I'm pretty sure they made a good seal.  No popping afterward.

I'd focus on the exhaust pipe connection before getting into a big carb job.

[Pete]

So, if I'm understanding the mixture screws correctly; when turning the mixture screws, they are actually turning the slow jets? And by turning them out from lightly seated, counter clockwise, it is allowing more fuel (making it more rich) to be mixed with the air. Correct? Feel free to smack me upside the head if I got this all screwed up!

Thanks

Yes you are correct.