CV40 Master Kit:
1. How long does it take to install?
2. After installing the power tube, how do I set my jetting?
3. Is the Yost Power Tube and Yost Racers Kit the same thing?
4. I have the CV40 Master Kit type L, what revisions were made for the CV40 REV 1?
5. Can the Thunderjet and the Yost Power Tube be used together?
6. Can the Dyno Jet Thunder Slide and the Yost Power Tube be used together?
7. Will this modification effect my extended warranty?
8. The body of the spark plug is pretty black and sooty, but the tip is a nice tan color...
9. In the instructions for this kit it says Remove the stock slow speed jet (or low speed jet)...
10. If I got your kit and my carb (CV40) is already due a rebuild, would your kit take care of...
11. Is there a reliable way to tell if maybe your kit has already been installed prior to me buying the bike?

1. How long does it take to install?
With the CV40 or CV44 master kit, installation time is about 30 mins. Check out our instruction sheet at Yost Power Tube Instructions.

2. After installing the power tube, how do I set my jetting?
I will give you the standard setup for 0-2000 feet above sea level. 46-48 slow speed jet, red needle (3rd slot), 195 main jet, drill the vacuum port hole in the slide to 1/8". That should work, this is a good performance setup. Economy is different. For economy use the blue needle, and drill out the vacuum port hole in the slide no larger the 7/64". Feel free to call me personally if you have any questions. If you are making other modifications at the same time, you can call our tech line 320 983-5410 M-F 9-5 CST.

3. Is the Yost Power Tube and Yost Racers Kit the same thing?
Our racers kit is still a performance kit, but it is limited in adjustment and more for stock bikes which the owners desire fuel economy. Our CV40 Master Kit can be set up for economy, but was designed more for performance. Personally if I had a choice between the two, being an old speed freak, I would choose the CV40 Master Kit REV 1

4. I have the CV40 Master Kit type L, what revisions were made for the CV40 REV 1?
We redid the tube for more power and even better throttle response. After replacing the spring and the tube, take it for a drive. You'll see 80 mph before you know it. It's immediate. The rest of the parts are the same. We know you do not need all the extra jets and needles.

5. Can the Thunderjet and the Yost Power Tube be used together?
Yes, you can use the Yost Power Tube and the Thunderjet together successfully.

6. Can the Dyno Jet Thunder Slide and the Yost Power Tube be used together?
In all honesty, the Yost Power Tube and the Dyno jet Thunderslide have different fuel curves and really cannot be used together. If you have the Dyno jet Thunderslide, you can install our CV40 Master Kit REV 1 if you also purchase a new slide.

7. Will this modification effect my extended warranty?
Technically speaking, any modification whatsoever that alters almost anything on your bike including most honest to god Harley Davidson dealer installed items could void your warranty. If I were you, I would read the fine print on your extended warranty policy.

8. The body of the spark plug is pretty black and sooty, but the tip is a nice tan color. My pipes have a grayish black color inside at the ends. Could you please point me in the right direction?
When it comes to reading spark plugs, look at the center ceramic electrode only, you will find some color where the ground electrode meets the center ceramic electrode. The metallic threaded part of the spark plug on harleys will always be black

9. In the instructions for this kit it says Remove the stock slow speed jet (or low speed jet) and replace with a #45.
There is not a #45 included in the kit or else Iām overlooking it. Could you please let me know what this is referring to and if Iām missing a part in the kit I ordered?
Due to the wide variety of models and modifications, the part is not included in the kit. Some bikes do not need the part and other bikes already have the part as stock. If you need the #45 slow speed jet, you can purchase it at your local harley dealer.

10. If I got your kit and my carb (CV40) is already due a rebuild, would your kit take care of the rebuild?? Or would I have to get a carb rebuild kit from Harley?
Although the Yost Power Tube increases horsepower and creates better throttle response making your carburetor run much more efficiently, it will not replace a rebuild. I would suggest rebuilding the carb first. Making sure that your carb is in the best condition with improve results all around.

11. Is there a reliable way to tell if maybe your kit has already been installed prior to me buying the bike?
If the needle is painted either red or blue, then it is probably our needle. Also, if the needle is stepped about half way down the needle then it is probably our needle. If you remove the main jet and take a look inside where the main jet is screwed in and you see a tube that has been pressed in front of the main jet, then yes you do have our kit.

If your question is not listed here, customerservice@yostperformance.com

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1. How long does it take to install?
With the CV40 or CV44 master kit, installation time is about 30 mins. Check out our instruction sheet at Yost Power Tube Instructions.

2. Which jet and needle combination I should install in my CV44?
You should have a minimum of a #48 on the slow speed jet, the CV44 red needle with one washer underneath the e-clip and the e-clip set in the 3rd slot, and a #225 main jet. Vacuum port hole in the slide should be drilled with the 7/64" drill bit.

3. Can the Thunderjet and the Yost Power Tube be used together?
Yes, you can use the Yost Power Tube and the Thunderjet together successfully.

4. Can the Dyno Jet Thunder Slide and the Yost Power Tue be used together?
In all honesty, the Yost Power Tube and the Dyno jet Thunderslide have different fuel curves and really cannot be used together. If you have the Dyno jet Thunderslide, you can install our CV40 Master Kit REV 1 if you also purchase a new slide.

5. Will this modification effect my extended warranty?
Technically speaking, any modification whatsoever that alters almost anything on your bike including most honest to god Harley Davidson dealer installed items could void your warranty. If I were you, I would read the fine print on your extended warranty policy.

6. The body of the spark plug is pretty black and sooty, but the tip is a nice tan color. My pipes have a grayish black color inside at the ends. Could you please point me in the right direction?
When it comes to reading spark plugs, look at the center ceramic electrode only, you will find some color where the ground electrode meets the center ceramic electrode. The metallic threaded part of the spark plug on harleys will always be black.

7. In the instructions for this kit it says Remove the stock slow speed jet (or low speed jet) and replace with a #45. There is not a #45 included in the kit or else Iām overlooking it. Could you please let me know what this is referring to and if Iām missing a part in the kit I ordered?
Due to the wide variety of models and modifications, the part is not included in the kit. Some bikes do not need the part and other bikes already have the part as stock. If you need the #45 slow speed jet, you can purchase it at your local harley dealer.

8. Is there a reliable way to tell if maybe your kit has already been installed prior to me buying the bike?
If the needle is painted either red or blue, then it is probably our needle. Also, if the needle is stepped about half way down the needle then it is probably our needle. If you remove the main jet and take a look inside where the main jet is screwed in and you see a tube that has been pressed in front of the main jet, then yes you do have our kit.

If your question is not listed here, customerservice@yostperformance.com

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1. How long does it take to install?
This kit can be installed in about 30 mins.

2. How does the Yost Racers kit and the Dynojet rejetting kits compare?
Our racers kit and the Dynojet kits are about the same performance wise. Although we still get better fuel mileage because of basic design perimeters. Our master kit is light years ahead of the competition.

3. Is a special tool required for the install?
No special tools are required.

4. Will this modification effect my extended warranty?
Technically speaking, any modification whatsoever that alters almost anything on your bike including most honest to god Harley Davidson dealer installed items could void your warranty. If I were you, I would read the fine print on your extended warranty policy.

5. The body of the spark plug is pretty black and sooty, but the tip is a nice tan color. My pipes have a grayish black color inside at the ends. Could you please point me in the right direction?
When it comes to reading spark plugs, look at the center ceramic electrode only, you will find some color where the ground electrode meets the center ceramic electrode. The metallic threaded part of the spark plug on harleys will always be black.

6. If I got your kit and my carb (CV40) is already due a rebuild, would your kit take care of the rebuild?? Or would I have to get a carb rebuild kit from Harley?
Although the Yost Power Tube increases horsepower and creates better throttle response making your carburetor run much more efficiently, it will not replace a rebuild. I would suggest rebuilding the carb first. Making sure that your carb is in the best condition with improve results all around.

If your question is not listed here, customerservice@yostperformance.com

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1. How long does it take to install?
The average person could install this kit in 5 - 10 minutes. Check out our complete instruction sheet at Yost Power Tube Instructions.

2. Will I need to go down a size on the main jet after this installation?
As a rule, you probably will not need to change your jetting, but with all of the different parts that are available for Harleys today we simply had to tell the customer that they may and I stress may need to rejet.

3. Will the Yost Power Tube and Thunderjet Kit work together?
You can use the Yost Power Tube and Thunderjet Kit together. If you plan to, I would strongly suggest simply giving me a call personally so that we can dial in your jetting more easily. Esentially, use the same jetting that you would normally use and a #120 jet for an air bleed. This way the thunderjet is used for wide open throttle only.

4. What is the purpose of the washer?
Some of the S&S carburetors require the spacer for even performance. Most do not need the spacer. Start without the spacer and warm up the engine. Take it for a spin if it sounds lean, put the spacer in. Again, most of the S&S carburetors do not need the spacer.

5. Do I need to drill anything for the application?
Installation of the S&S power tube is very simple. Nothing needs to be drilled and rarely do you ever need to adjust jetting. Check out our complete instruction sheet at Yost Power Tube Instructions.

If your question is not listed here, customerservice@yostperformance.com

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Mikuni Pro Power Tube:
1. How long does it take to install?
2. If I am purchasing a kit for a Mikuni carburetor should not the jets fit my application?
3. If I am purchasing a kit for a Mikuni carburetor should not the jets fit my application?
4. What main jet with my set up would be a good starting point?

1. How long does it take to install?
This kit can easily be installed in about 5-10 mins. Check out our complete instruction sheet at Yost Power Tube Instructions.

2. If I am purchasing a kit for a Mikuni carburetor should not the jets fit my application? Sorry I find this issue puzzling. Also is this a project which the average weekend automotive/motorcycle mechanic perform comfortably?
The Yost Power Tube Mikuni HSR kit includes stock Keihin carburetor jets. It has been designed to accept standard Keihin stock carb jets which are available in the kit and at any Harley Davidson dealer. The jets in the kit will NOT fit into your Mikuni carburetor without the power tube installed. On the other hand, Mikuni jets will NOT fit the end of the power tube.

3. If I am purchasing a kit for a Mikuni carburetor should not the jets fit my application?
Technically speaking, you should not have to rejet your carburetor. On the Mikuni HSR 42, it should only take you 5 minutes to install the power tube and float bowl drain nut.

4. What main jet with my set up would be a good starting point?
Ideally, evolutions 165 main jet, TC88 175 main jet, 95" big bores 185 main jet as a rule of thumb. If you are unsure, please feel free to call or email or tech support 320 983-5410 or customerservice@yostperformance.com.

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