Honda Shadow Spirit 750 Hypercharger Install Guide

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First I want to say thanks to the site's write up which was done by Paul Cook (The site seems to be down or take over by some ad site now), and the forum users who help answer my questions regarding how to install the Hypercharger on the Shadow Spirit 750 without these I would not have known how to get started on this project. I intend to do this write up as I go from the Stock intake, and Stock Exhaust with the hole saw mod, to Stock Intake with the Hard Krome Strippers Exhaust, and then finally the Kuryakyn Hypercharger intake, with a rejet and the Hard Krome Strippers Exhaust. I hope to be able to provide some pictures and video/sound of each stage of the project so as to be able to see and hear the differences along the way.


Use this information at your own risk. I will not be held responsible for any damage done to your bike by you trying to perform these same procedures. This write up is just to document my experience and share that experience with others in the hopes it may help someone else that wants to customize their bike also.

Parts list so far:

  • Kuryakyn Hypercharger Part # 608446 $145  (included shipping and the below adapter kit from EBay)

  • Thunder Mfg. adapter kit Part # 40102A 134/138 main jets (included with above from EBay)

  • Factory Pro Jet kit Part #CRB-H39-1.0 $36 including shipping from EBay (this fell through)

  • DynoJet Stage 1 Jet kit from Honda dealer $90

  • 2 feet of 1/4 fuel line rubber hose $2.15 at Napa Auto Parts

  • 5/8 inch Brass Fuel fitting $2.15 at Auto Zone (not sure on the size, I just got the smallest one they had)

  • Brass Compression fitting for the Fuel Fitting, I had laying around in my garage luckily, but you could probably get this at the hardware store, etc...

  • Custom Chrome Billet Hypercharger Cover $36 (included shipping from EBay)

So far I have $275.30 invested in the parts which is a lot less than most would have paid for the same kit with adapter and jet kit, the Hypercharger were used on EBay, although never installed, the Hypercharger has some small scratches on it I will try and polish out, but over all its a great deal at 145 including the adapter.

Pressurizing the Carb's

My first attempt at pressurizing the float bowls was a wasted effort, I either was not getting enough air because the fitting was too narrow of an opening, or the placement of the fitting, although I suspect the former. I later just used the fitting that was included in the adapter kit, and it worked like a champ connecting it to the back/rear of the Hypercharger at the part where it narrows to a point, it already had a threaded hole there, and a couple of plastic fittings to screw right in, and I used the larger one, and it worked great.

First attempt which did not work for me...

The first challenge I faced was whether or not the Shadow Spirit 750 needed the float bowls of the carb's pressurized, and from asking around on the forum and elsewhere this was more often than not, a resounding YES! So I decided to follow the advice of others who have gone before and I purchased some parts similar to what others had done to create a new port on the front the Hypercharger body to pull some air for pressurizing the float bowls on the SS750.

I used a brass fitting that was designed to be used for fuel according to Auto Zone, it seemed large enough to allow plenty of air flow through it as it was 3/16 inch inside diameter. The threaded end I just got a compression fitting for it and drilled out a 7/16 inch hole in the Hypercharger near the front, outside the edge of where the K & N filter sits, and then used the compression fitting a nut to hold it in the unit. I then cut a pipe screen (purchased from a local smoke shop) and cut it to fit inside the compression fitting, so when it's installed the screen and the brass fitting are held into place by the nut. There was already a hole at the tapered end of the Hypercharger but as it was too small for my fitting, and I was unsure of how much air flow it would get, I went ahead and made the new hole near the front of the unit as some others had done. We will see how this works out, and if needed, I can always drill out the other hole and use it if I need to. The Kuryakyn unit actually shipped with two different plastic fittings that threaded into the hole near the back, you could probably use the fitting and hole as supplied, I felt better having the metal ones personally since others had success with the hole near the front.

I had to re-drill the hole for the Carb pressurization as the one I did was too close to the holes where the adapter plates connected. I will be updating the pics soon for all the below steps.

Next I purchased two feet of 1/4 inch inside diameter fuel hose, this seemed a lot more sturdy so as not crimp around bends and constrict airflow, and it seems to fit the brass fitting very snugly. Again, not exactly the same as what others had done, so we will see the results when I complete this project.

I found a Custom Chrome Billet Hypercharger Cover on EBay I will be adding this to the finished project to give a more custom look and cover some scratches on the Hypercharger I bought off EBay.


The Hard Krome Strippers are installed, pics and video updated in the Myss750 page, I am still waiting on the jet kit, hopefully Monday July 9th it will be here.

Well it's Monday July 9th, I am counting on the Jet kit coming today or tomorrow, so I am beginning the dismantling of the bike as soon as my digital camera is fully charged this morning.

Seat Removal

Using a number 6 metric hex key I removed the two bolts holding my Mustang seat in place.


Gas Tank Removal

Using a number 5 hex key I removed the two bolts holding the speedometer to the tank, I let it hang in front of the radiator for now. Next I shut off the fuel, and then loosened the 12mm bolt holding the tank in place using a 12mm socket ratchet, removed the fuel line, look out for a little gasoline escaping from the line, then I pulled the tank vent hose out of the guts of the bike and removed the tank and set it aside.

Side Covers removal

Removed the side covers in order to make easier access to the other things I need to remove, and to be able to hook up a trickle charger since I think my battery needs it from sitting too long.

Stock Air box removal

Loosen the bolts and clamp holding the stock air box in place using a 10mm ratchet and phillips screw driver.

Connecting the adapter to the stock air box boot

There are two adapter plates and some gaskets, I used the two plates and one gasket to attach the stock rubber boot to the two plates and then connect these to the Hypercharger backing plate. I also took this opportunity to "charge" the new K&N Filter with some filter oil. I purchased the filter recharge kit from the Honda dealer for $14.99 its good for about 4 or 5 cleaning and recharge cycles for the filter. I then reassembled the new Hypercharger and its ready to bolt on once I complete the Carb rejet.

Ignition Coil Removal

I had to loosen and remove the ignition coil to make more room to get to the carb's. I also used a zip tie to hold back the radiator hose to the back bone of the frame to get it out of the way.

Label your hoses

I used some small circular stickers and red sharpie markers to label hoses and connections I had removed, as I went... I also took lots of hi resolution pics so I could use them for reference later if needed.

Choke Lever removal

Loosen and remove the head bolt holding the choke lever knob, I put the head bolt back in for now and let the choke knob dangle for now.

Throttle Cable's removal

Remove the throttle cable assembly and to do this, I had to remove the bracket that held the chrome throttle cover. Remove the throttle cable ends from the carb's

Removing the Carb's

Next I loosened the clamps that hold the two large rubber tubes connecting the Carbs to the Cylinders themselves.  Loosen the TOP ring clamp.  The one that connects to the Carbs.  Do NOT loosen the bottom clamp that connects to the cylinder. I did not get any good pics of these clamps, they are similar to the ones holding the black plastic air intake housing to the top of the carbs, but there are two sets on each carb body, only loosen the one on the TOP. Leave the one on the bottom tightened to the cylinder head.

Jetting the Carb's

I installed the main jets 134 front and 138 rear that came with the Hypercharger. I replaced the stock needles with the DynoJet stage ones and the springs clips etc... everything but the mains which I installed from the Hypercharger kit. I put the clip on the third notch from the top. And I set the mix screws to 3 turns out on the front, and 3.5 turns out on the rear. I did not take pics of the needle and spring replacement, it is pretty straight forward, and the jet kit had a crude picture of it for instructions.

Drilling for the Vacuum  fitting on one of the Carb's

I drilled out the available but plugged vacuum port on the left/front carb as it was more accessible for my drill/bit and would be right behind the Hypercharger body. This will be the vacuum line connection for the butterflies. The port is near the lower right side of this pic below.

Connecting to the Float Bowl Vents to pressurize the Carb's

My second attempt for pressurizing the float bowls... This one worked great...

The float bowl vent tubes already had a t-connection with hose attached that was just hanging loose for venting purposes I guess, I reused that line and it reached fine to attach to the port on back/rear of the Hypercharger. I used the included plastic connection (it came with my Hypercharger adapter kit) and it screwed right into the threaded hole on the rear of the Hypercharger (on bike facing side near the part where it narrows down to a point, it gave the best response for more pressure in the carbs. I also used some metal strapping to help secure the Hypercharger body to the head on the front of the engine, as it was not very stable for me and kept wanting to come loose from the rubber boot. I donít have pics of these parts, so I will get those updated on the site soon.

Reinstalling the Carb's

Reverse the process and reinstall the carb's, they are tight fit, but I got them back together, and reconnected everything in reverse of the above process.

Connecting the Hypercharger Intake

I had to find a different bolt to attach the Hypercharger adapter plate to the engine, I used a 7/16 hex bolt and the supplied 7/16 lock nut and washer.

Reconnecting the Throttle Cables

Reconnect the throttle cables.

Reconnecting the Choke Lever

Reconnect the choke knob/lever.

Reinstalling the Tank and Seat

Reinstall the tank being careful not to turn the fuel knob to the on position before you get the fuel line reconnected, don't ask me how I know :) Reinstall the seat.

Starting up to hear the new sound

It took a few tries, but it fired up, and man is it a lot louder... I took it for a spin and it bogs a little when I get up to speed, I am not going to mess with it today, I spent almost 8 hours on it through out the day, so I will try some tweaking tomorrow. Currently the air mixture screws are out 1 1/2 turns on the front, and 2 turns the rear, I was getting some popping on deceleration so I will adjust those out some to compensate. Hopefully this will help on the bogging as well. I may need to try different main jets, or a bigger vacuum port so I will try some things one at a time and test to see what gives.


First I am going to turn out the air mix screws some to see if I can get better operation from that. At least to reduce the popping on deceleration. Well I ended up adjusting the mix screws to 3.0 turns out on the front/right carb and 3.5 turns out on the left/rear carb, and this greatly reduced the popping on deceleration to almost none. It still bogs slightly when I give it the throttle, and at speeds above 50 it bogs and surges the faster I go.

Next I will try the larger plastic pressure fitting and port on the rear of the Hypercharger to see if this gives better response and gets rid of the bogging and surging at higher speeds. If not, it may be time to change the needle clip settings to three or four, instead of two from the top.

Well that helped a lot, I used the supplied plastic fitting that screwed into the rear of the Hypercharger, sorry no pics, but I think they all have these now, and it ran a lot better still not as crisp a throttle response as I would like even from the low end, but it did not bog down when I gave it the gas or when I was cruising above 50.

It's been raining here, so I need it to dry out today so I can ride it some more to test, but it seems a lot better with more air pressure flowing to the carbs. This makes me think it was running too lean, so I will be ordering some larger slow jets (42) and trying the needle clip on the third notch when I rejet next. Not going to be doing that anytime soon, as I need to get the tank empty to let it air out so I can get it painted. I may go ahead and do the rejet while the parts are being painted I just wont be able to test until I get the parts back, mainly the tank :) Look for updates on the site in a couple of weeks. Thanks for looking.

After it dried out, I drove it to work and back Tuesday July 10th 2007, and it ran fine, not a crisp response as I would like as I said before, however, no bogging down at high speeds. I will be adjusting the needle clips to give it the fuel I think it needs to be more responsive  and see how it goes.

Update on July 15th 2007: After some discussion on the forum, I decided against the larger slow jets and will just move the needle clip on my next rejet. This should give me the increased fuel flow I need to get the bike running right. I have not decided on the 3rd or 4th notch yet. I have seen others that have it on the third some on the fourth, so I will research this a little more before deciding, and will be doing some other things to the bike in the garage while its torn down for the painting.

Update on July 18th 2007: I rejetted today double checking the main jets, and making sure the 134 was on the front carb, and the 138 was on the rear carb, and I changed the needle clip settings to the third notch from the top. The second time rejetting was much easier, I could do it again, in less than an hour now I think. I am still waiting on the tank and fenders to get back from painting, so I cannot test drive it yet after the latest rejet. Will update as soon as I get it back together after painting.

Update on August 5th 2007: All done modifying for now, the rejet seems to have made it run better with the needle clips on the third notch from the top, I may need to go to larger slow jets, as there is still some popping on deceleration, very little, but its there, I will try adjusting the pilot screws out a little farther, but it runs really strong now off the line and through all the gears.

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