Just another AF16 Spree Swap

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eclark5483
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Re: Just another AF16 Spree Swap

Post by eclark5483 » Wed Aug 29, 2018 3:54 am

Now that I think of it, what is the circumference of your carb? I think I have an UP4112-AST in my garage. Actually, I'm almost positive that I do. It's the one I used on my Spree carb during dyno testing so it's had very very little use (used for like maybe 20 minutes on the bike). If you want it, you can have it for free. Just shoot me your address in PM and I'll send it out to ya. Pretty sure the air intake mouth's are the same. I have no use for it as I use the Polini CP carbs on my bikes. I'm sure Meatball would know if they are the same part # I'm thinking of. He's the one who recommended it to me initially. It's been so long I don't remember, but I do know it's the angled UNI filter. If I remember correctly, Meatball has a post on here somewhere showing a picture of how he blocked it off with the water bottle. Very ingenuous hack to lock in on a good backpressure.
Indian Motorcycle tech @ Polaris Industries, B.A. Information Technology, A.A. Engineering
3 Sprees
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World's Greatest Spree: https://www.youtube.com/watch?v=lU49lL_Xx4s
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Re: Just another AF16 Spree Swap

Post by ntonar » Thu Aug 30, 2018 7:13 pm

Filter is on order, I run it tonight without the airbox and it never bogged. I lost to touch on the top end but figured it would be bogging from to much air. Is this normal with a #84 jet?

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Re: Just another AF16 Spree Swap

Post by Meatball » Fri Aug 31, 2018 1:09 am

Your throttle response when you blip the throttle from idle is likely garbage. It needs a certain amount of restriction from the air filter to revv clean quickly. Not too much or too little...the “restriction-to-air flow” balance has to be just right or response will be mad lean/rich and bog or gurgle.

Also finding the right main jet, needle clip notch and mixture screw position is also a fun adventure. It can be done with persistence.
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Re: Just another AF16 Spree Swap

Post by eclark5483 » Fri Aug 31, 2018 2:16 am

I've always used a vacuum cleaner analogy to explain how the back pressure gives you more power (especially at launch). My explanation is think of different vacuum cleaner attachments and how much suction they have, the wide attachment has less suction then the corner attachment. Another way to observe this, is make a big "O" with your lips, get a piece of tissue and suck in, try to hold the tissue up with just suction. Now do it again with a tighter "O". Notice how a smaller "O" will produce more suction. If you try holding the tissue with a huge "O", you run out of lung power real quick, and it takes more effort, but a smaller "O", you can hold the sheet of tissue for quite some time.

You can think of the air filter tweaking the same way. You look for the right amount of backpressure (resistance), which will in turn create a better suction. Remember, a carb does not push gas/air into the piston, suction/vacuum does. And when you twist back the throttle, you are not giving it more gas, you are in fact, giving it more air. When you can find a tighter vacuum without restricting flow too much, you'll be able to pull in more fuel from the bowl which will mix with the air in the venturi. Getting this just right will actually improve fuel efficiency as well. If the engine doesn't have to work as hard to pull fuel from the bowl, you won't need a huge main jet to compensate. I think this is probably the main mistake people make when trying to jet. They'll read the plug and think.. well, I'm running lean, better feed it a bigger jet, when really what they need to focus on, is how well the fuel is being delivered, not so much how much. Hope this helps.

EDIT: This phenomena that I just explained is the reason why I will tell people time and time again to NOT use a pod filter on their Spree, but rather, use the air box instead. You have to give Honda engineers credit here. They knew what they were doing when designing the Spree, although it is a very weak engine. The airbox is tuned to the weak intake system. It simply will not and can not run a bigger piston because of the intake restriction that prevents a better vacuum from happening. This is why I have stated in my tutorial (in my signature) on making a stock Spree go fast, that one MUST start with porting/changing the intake. This same principal applies to your AF16 as well even though it is a far superior engine.
Indian Motorcycle tech @ Polaris Industries, B.A. Information Technology, A.A. Engineering
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World's Greatest Spree: https://www.youtube.com/watch?v=lU49lL_Xx4s
Want to make a Spree engine go fast? CLICK HERE: LINK

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Re: Just another AF16 Spree Swap

Post by Meatball » Fri Aug 31, 2018 7:17 am

Just use the inlet holes in the stock airbox as a guide to gauge the amount of holes to use. This will get you in the ballpark.

I suggest a series of small holes as opposed to one large one. Its easier to add additional small holes (if needed) while tuning rather than trying to incrementally enlarging a big one. Again, I used a soldering iron with the pointy tip to make perfect small holes and the motor is picky enough that even ONE hole too many gave a muddy response. Start with a few and add as needed.
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Re: Just another AF16 Spree Swap

Post by ntonar » Tue Sep 04, 2018 9:52 pm

Intake came in today and found an old water bottle that was a perfect fit on the filter. I am looking to start drilling holes on the left non rear wheel side to keep road dust/mud away from it.

Any suggestions on drill hole sizes or locations Meatball?

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Re: Just another AF16 Spree Swap

Post by Meatball » Tue Sep 04, 2018 10:33 pm

That looks perfect! If you angle it down and inward slightly you’ll find the sweet spot that clears the body plastics and everything internal. Take in account that when you sit on the scoot and hit road bumps, the shock compresses and the filter needs to be able travel up n down unobstructed. I think mine had a slight rub because of the robust water bottle I used. No issues from it tho.

Id start with a few small holes and see if she’ll run. Can always add if needed. I ended up with 5-6 holes the size of a coffee straw (or soldering iron tip) in the end and also two larger holes in the side about the diameter of a standard drinking straw. This gave me good throttle response when I blip the wrist from idle to full open. Every other series of holes would make it gurgle and bog OR would result in muddy acceleration. Its really frustration after the 15th try but maybe you’ll get lucky and find success sooner.

Tip: I upjetted the main to compensate for the pod filter. I cant remember exactly the jet used but it wasnt much. Maybe #10 larger than stock. Also, dont abandon your hole configuration without FIRST adjusting your mixture screw to confirm the holes are incorrect. I suggest always having your screw at 1.5 turns out as a base line when testing holes. If it runs like garbage, twist screw in and out to confirm that holes need adjustment. My screw ended up at only 1 turn out once I found the right holes.
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Re: Just another AF16 Spree Swap

Post by eclark5483 » Wed Sep 05, 2018 4:43 am

That looks, soo good!! Man, what a nice fit. I like the color of the bottle and form. Back gives you a nice circle to work with. Happy tuning !!
Indian Motorcycle tech @ Polaris Industries, B.A. Information Technology, A.A. Engineering
3 Sprees
1 ATM50-A1
1 Indian AMI-50
World's Greatest Spree: https://www.youtube.com/watch?v=lU49lL_Xx4s
Want to make a Spree engine go fast? CLICK HERE: LINK

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Re: Just another AF16 Spree Swap

Post by ntonar » Wed Sep 05, 2018 6:51 pm

So far I have 13 holes on the end and 7 on the side. She still wants more air, I am thinking of swapping to an #80 or #82 jet. It is still a bit more restricted then the OEM box with the tab knocked out. I pulled the bottle cover to have a 1/4in gap around the filter (to let more air in) and it ran great with the current setup.

Thoughts?

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Re: Just another AF16 Spree Swap

Post by eclark5483 » Thu Sep 06, 2018 1:05 am

If you are good at math, that 1/4" pullback that made it run good will tell you how much more volume you need. Be something like .25"x pi radius squared? Find volume, then compensate with slightly larger holes rather then add new ones. I'm betting you hit your magic spot before the weekend gets here. I'm not well versed in AF16 tuning, but the filter setup looks very very promising for you. But, stay with Meatball's tuning guide of how the bike does off the line with a quick twist to full throttle. Find your best take off. Any additional air is for top end, too much will kill the bottom. Ideally, you wanna have a pain free quick launch, and possible 4 stroking/rich main/gurgling from the start then figure out the main. Better to be rich then lean. Have you looked at your plugs?
Indian Motorcycle tech @ Polaris Industries, B.A. Information Technology, A.A. Engineering
3 Sprees
1 ATM50-A1
1 Indian AMI-50
World's Greatest Spree: https://www.youtube.com/watch?v=lU49lL_Xx4s
Want to make a Spree engine go fast? CLICK HERE: LINK

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Re: Just another AF16 Spree Swap

Post by Meatball » Thu Sep 06, 2018 6:40 am

Thats more holes than I had but every motor is different. Relative humidity, elevation, air density, etc..can make tuning completely different from one climate to another. If you have an #80-#82 jet on-hand, try them and see. Theres really no way of giving specific details that would be helpful to you. Keep trying different combos of holes, jets, screw settings. Small change makes big differences. Dont give up, youre only on day 2. Dont forget to have fun.
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Re: Just another AF16 Spree Swap

Post by eclark5483 » Fri Sep 07, 2018 12:56 am

This image here, reminds me of an old idea I had a while back. Ya know how the top of your cooking grill has that round chimney that you can adjust? You could design a filter using that same concept, start with HUGE holes, then adjust the round chimney slider till you find the back pressure that works best. Allows you to tune for the seasons as well as the initial tune. Get what I'm saying? You could put a butterfly nut on the end so adjusting it requires no tools. Beats risking drilling 1 hole too many, lets you start big and work backwards with the intake vacuum instead of starting small and hoping bigger is better. Also allows for a BBK upgrade.

EDIT: NERD ALERT. If I were going to do this to an intake filter, I'd totally hook up a little robot with a raspberry pi that could adjust it with a button press, you'd be able to make it pull open more on the top end (simple tiny servo motor attachment hack). I know, that's super geeky, but yeah man. Experiment a bit. Wanna see how this beauty turns out. LOVE, LOVE,LOVE the bike so far. Remember, you can always cut the filter in half to gain clearance, length is not the issue in your makeshift weed whacker 2 stroke, AF16 ENGINE, least (that's what she said). :smile:

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Indian Motorcycle tech @ Polaris Industries, B.A. Information Technology, A.A. Engineering
3 Sprees
1 ATM50-A1
1 Indian AMI-50
World's Greatest Spree: https://www.youtube.com/watch?v=lU49lL_Xx4s
Want to make a Spree engine go fast? CLICK HERE: LINK

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Re: Just another AF16 Spree Swap

Post by ntonar » Fri Sep 07, 2018 11:08 pm

No need to press a button, it could be easily tuned to an RPM level if you mapped it out.

I have been very busy lately. I finally got to install a #80 jet and will tune tomorrow.

The carb and filter are still way to close to the body panel under normal use. I am about to cut a small section or relocate the carb.

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Re: Just another AF16 Spree Swap

Post by eclark5483 » Sat Sep 08, 2018 2:16 am

Have you considered a CNC riser on the shock mount?

https://www.scooterswapshop.com/product ... -riser-kit

Made a huge difference for me when it came to clearance. Carb is so easy to get at now, and room to adjust filter position.
Indian Motorcycle tech @ Polaris Industries, B.A. Information Technology, A.A. Engineering
3 Sprees
1 ATM50-A1
1 Indian AMI-50
World's Greatest Spree: https://www.youtube.com/watch?v=lU49lL_Xx4s
Want to make a Spree engine go fast? CLICK HERE: LINK

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Re: Just another AF16 Spree Swap

Post by ntonar » Mon Sep 10, 2018 11:02 am

She is finished, ended up going with a #80 jet that really woke up the bike.

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