Low dollar to high dollar budget estimates to use a 48mm BBK

Does your Spree/Elite already run great, and you're trying to make it quicker/faster? Need a monster motor swap? Discuss your ideas here.

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eclark5483
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by eclark5483 »

You are very much correct. Running the BBK and deleting the pump is very advisable for maximum power. However, when running the BBK and keeping the stock carb, I advise to keep the pump. The reason being, is that the stock carb needs all the help it can get. Burdening it with having to supply oil as well as gas to the engine could be more detrimental then risking a pump failure.

For the most part, Honda makes an excellent pump, and the chances that it will fail are very slim. Removing the pump and running straight premix is great for peace of mind and over all HP, but what you lose by deleting it, is fuel delivery. If you go with an aftermarket carb, this is not an issue at all, and in fact is highly advisable. But when you are dealing with the stock carb, you wanna keep everything else that makes the engine run as stock as possible for maximum power.

The more gas you allow the carb to deliver on a stock carb, the better off you will be. An oil pump ensures that you are letting the maximum fuel the carb can put out on an already weak carb system, gets delivered into the piston chamber. Whichever one decides... keep the pump or ditch the pump, DO NOT try running the BBK with straight gas in the tank, you will burn up that piston real quick!!

Here is a video showing and explaining what happens when you let the carb give all it has to give while using a stock intake, which is very restricted. In this video, the BBK was ran with the stock carb and intake using the standard jet (#90) supplied with a BBK, on a Dynojet 250i. The carb was allowed to run free air with no filter so as to allow the maximum amount of air in that it could handle. As you will see in the video, analysis showed the INTAKE is what is holding the BBK back, not the carb or air coming in. Your stoich AIR/FUEL ratio, which should ideally be in the 12's, is stuck hanging in the high 13's and low 14's.

Because of a weak intake system, you get a bottleneck after the venturi where the Spree wants to breathe in more of the air/fuel mix, but can't. This is why a performance intake is very vital.

https://www.youtube.com/watch?v=GIVuMWGCNm4
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Last edited by eclark5483 on Thu Dec 29, 2016 1:55 pm, edited 2 times in total.
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by Meatball »

eclark5483 wrote:For the most part, Honda makes an excellent pump, and the chances that it will fail are very slim.
Although an oil pump failure is a very real possibility, I cant remember the last time someone posted "My oil pump failed and it destroyed my motor". These bike are hovering around 30yrs old and amazingly the pump reliability seem to be a non-issue. Too bad these bikes aren't equipped with a pump monitoring system to alert a failure but who's to say THAT system wouldn't become non-functional before the pump does?
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by benji »

Exactly. The best part about premixing is simplicity but that pump is nice to have on a street ridden bike. I'm keeping the pump on my prebug just so I can use pump gas easier. Koso sells a high output adjustable oil pump for minarelli motors but im not sure if there's one available for honda motors
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by MrJumps »

Theres no higher flow pump for a spree. If you are trying to make it "easier to fill at the pump" by keeping the oil pump you still have to premix a little at the pump anyway. If you expect to just dump a capfull of oil in every fill and just guess and try that out then your gonna blow it up over time. Don't be lazy carry a backpack to premix with or buy a 4stroke.
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by eclark5483 »

About the only way you could possibly get by with adding a bit of oil at every fill up is by placing exactly 1/2 gallon of gas in the tank and topping it off with 20ml of oil for 96:1 or 23.6ml for 80:1. If that's the way you want to go, then I'd just buy some vials and pre-messure a few to take along with you. Works great if you have a glove box, or trunk or underseat storage or whatever. Then you could just keep the vial with the bike and fill as needed. Would be very stupid to try and guess the ratio each time. That's just looking to burn up the piston. You'd have to be precise about your fill-ups all the time... too much hassle IMHO. But then, on my Spree, I keep 2-1 ounce (60ml) vials in the trunk so I can do 32:1 with a 1/2 tank fill up... Beats having to go all the way home to get the premix gas out of the garage.
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by tazland001 »

eclark what is the ID on that intake?

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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by eclark5483 »

Last edited by eclark5483 on Tue Jan 10, 2017 3:43 pm, edited 1 time in total.
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Re: Low dollar to high dollar budget estimates to use a 48mm

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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by Meatball »

Wish there was a WeBike in the US. :(
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by eclark5483 »

I know. They have some decent stuff that will swap out fine on these old Hondas (search under the HONDA TACT for Aero/Spree parts that will probably swap). It's just shipping time and cost to get the stuff kind of stinks.
Last edited by eclark5483 on Tue Jan 10, 2017 3:58 pm, edited 2 times in total.
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by eclark5483 »

But anyways, the Kitaco comes packaged like this:

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Re: Low dollar to high dollar budget estimates to use a 48mm

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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by eclark5483 »

Just a note: I had to lower the jet on my pilot on the Polini. This indicates those who are using a stock carb will be just fine with a stock pilot. Stock is like, 34 or something. Polini comes standard with a 40, you go over 34, it gets too rich on the pilot. Just one less thing to worry about by using the stock carb.

Right now I'm using a 100 main jet Polini, still undecided if this is too much and I can go lower, or not enough and I can go higher. If the jets that taz sells make you gurgle out, then it's the intake to blame, not the carb. I see no reason a 100 jet from his store wouldn't work.
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by eclark5483 »

So, I guess a slight revision is now in order now that the Kitaco intake has been discontinued. So what can you do?

From what I have seen, the Mikuni+Kitaco combo IS still available. If you want to get your hands on one of these now VERY RARE intakes, that is the path you are forced to take if you are going for "BEST OF THE BEST" to run the BBK. If ANYBODY has a link to an adapter for the Spree/Aero/Tact, 2 bolt intake, PLEASE share it!! On the other hand, the COMBO that is (for now), still available, gets you everything you need to run like an animal save for the ported reeds.

If you simply can't find a better intake solution, then the only alternative is PORTING. Port the intake, port the reeds PORT THE BBK!!!!!. Find a path to making your 48mm BBK breathe better then stock AFTER it has passed through the venturi. Adjusting the air BEFORE the venturi is a piece of cake, though NOW it is more important then ever, that you keep your oil pump, and keep your air box.

Again, when you delete the pump, you are asking the carb to do more then it was intended, the oil pump is your friend, the air box is your friend. When using a 48mm BBK, FOCUS ON THE AIR COMING IN AFTER THE VENTURI, which means the intake, and reeds for the most part. You have control over those no matter what aftermarket options are available, you should maximize their efficiency as best as possible. This MAY OR MAY NOT cost you money depending on your personal level of engine building skills, but it DOES lower the price on the minimum it would take to properly run your BBK.
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Re: Low dollar to high dollar budget estimates to use a 48mm

Post by jakubman1 »

So the directions that came with the kit is B.S.? Cause you gotta spend close to a grand just to make it work properly ? :crazy:
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