ESE's works engine tuner

[F5 Dave]

Yeah it could the only way to be sure is to suck and see. Admittedly i posted the pic wasn't great example of what i was meaning (i was in a hurry.)
I do believe it will be a bit more rigid then you think though.remember (vacuum cleaners) They have amazing strength in regards to crush from their shape and material concentration.
Hence its uses on some automotive intakes. From memory some FWD cars and even karts also have sturdy steel convoluted tubes as well on exhausts.

intakes are open at one end. All I know is I did suck it & see, but by all means, go ahead & retry what I already know.

[TZ350]

Page 460 already ....

[husaberg]

intakes are open at one end. All I know is I did suck it & see, but by all means, go ahead & retry what I already know.

Not sure really how to take that Dave, but wouldn't it be a little more constructive to suggest what you did try and didn't work.
That is the idea of the thread after-all. I did a search on boost bottles on the thread and came up empty in regards to what you had tried, just this.

Pah! What a load of bollocks (no offense I mean the bolt on goodies merchants website). I love these descriptions of what is supposed to be happening & how it will cure the common cold etc.

Yamaha made these famous in the 80s on their MX bikes. But there is a reason you don't see them on modern high performance bikes. (well infact the RG150 has one, but in the form of a long rubber tube). They are really only useful as a plaster for a badly designed (or rather mismatched) pipe. TSR software will tell you how to design one for the area you are trying to affect.

I made an adjustable one for the H100 (now Sketchys bike). The reason was the pipe I designed had too steep of a baffle cone & it caused a dip before peak power. As it was just a for fun bike & I couldn't weld back then (or worth a damn now), I left the pipe as it was. It curved around so modifying it was a big job.

So on with the bottle of the ~right size & I trimmed the tube to suit. I then made an adjustable bottle & plugged it into the manifold. Worked quite nicely to flatten out the dip, at least a bit.

Yeah with regards to materials Yamaha's IT175 one was from memory plastic and not that thick. Come to think of it so were the NSR ones.
Here is another plastic bottle combo Dave. Maybe suck rather than spit?

[TZ350]

Remember that Vtec thing we made from an old SU carb in the hope of improving the bottom end. And it worked OK cleaning up the low end carburation nicely but made the carb stick out to far and limited the top end over rev.



well, now that the plenum is going to get another outing it looks like the Vtec thing will fit inside OK and could do something usefull too.

Instead of the long tuned length spacer going under the bell mouth, the Vtec thing could go there. The hose on the spacer is an oil feed line.

And here it is simulated in EngMod2T.



A graph of the Plenum and Vtec thing.

Red line is with the Vetec valve open and Blue line with it closed and the Orange line is with it opening at 10,000.

Some of these old projects are starting to look usefull again.

[TZ350]

EngMod2T

I have been trying to simulate my plenum and a boost bottle and found EngMod was not a 100% setup for that configuration so I talked to Wobbly about it and he must have talked with Neels because today I receved an update that covered several plenum layout options.

Now, how is that for service....... dam good I recon.



This is the layout I am trying to model.



These are the other configurations.

[Frits Overmars]

A boost bottle evens out the flow fluctuations in the inlet system so that the flow through the carb is more constant. But a plenum does the same job more effectively. So if you use a plenum, you don't need a boost bottle.
If you insist on using a boost bottle, pick a bottle volume of about twice the cylinder capacity, use a hose diameter of about 0.7 * the carb diameter, start with a hose of about 200 mm length and tune it step by step with a pair of scissors. None of the components are critical; you just need to search the right combination. And that will only cost you a length of hose.

There are two things to remember:
First: because a boost bottle produces a more even flow velocity through the carb, the suction signal will be weaker, so you may need to fit bigger main and needle jets. That is also valid for a plenum.
Second: mount the boost bottle so that petrol cannot form a puddle inside the bottle, or it will play havoc with your carburation.

[husaberg]

A boost bottle evens out the flow fluctuations in the inlet system so that the flow through the carb is more constant. But a plenum does the same job more effectively. So if you use a plenum, you don't need a boost bottle.
If you insist on using a boost bottle, pick a bottle volume of about twice the cylinder capacity, use a hose diameter of about 0.7 * the carb diameter, start with a hose of about 200 mm length and tune it step by step with a pair of scissors. None of the components are critical; you just need to search the right combination. And that will only cost you a length of hose.

Thanks Fits but how do you stop the plenum upsetting the carburation?is there a way to do it without this happening?
i seem to remember tz having to pump out the wet fuel previously.

[TZ350]

Thanks Fits but how do you stop the plenum upsetting the carburation?is there a way to do it without this happening?
i seem to remember tz having to pump out the wet fuel previously.

I have a scaveng pump drawing from the bottom of the plenum, but any ideas would be very helpfull.

[Frits Overmars]

Thanks Fits but how do you stop the plenum upsetting the carburation?is there a way to do it without this happening?

I have a scaveng pump drawing from the bottom of the plenum, but any ideas would be very helpfull.

How about having the exit from the plenum to the engine at the lowest point of the plenum? Goes for boost bottles too. Just a thought....

[TZ350]

A boost bottle evens out the flow fluctuations in the inlet system so that the flow through the carb is .........

Thanks for the info on Boost Bottles. If BB's are your thing its worth checking out Frits post.

How about having the exit from the plenum to the engine at the lowest point of the plenum? Just a thought....

I intend recycling my old plenum for a few tests and if the results and EngMod simulations are really encouraging I will see what can be done.

I remember you suggested this before and it would be ideal, unfortunately its a bit hard to arrange, but is what we will do if the plenum idea looks like it has merit. And with a plenum of 2-3L I have to make provision for releasing any combustion pressure (BIG BANGS) that might occur in the plenum itself.

[TZ350]

This is the arrangement that I tried ages ago to get around the restriction of a 24mm carb. At the time every one sortof thought a 125 couldnt get past 20 RWHP because of the carb restriction. Well that turned out not to be true, but now at 35 crank hp I think we are getting to the limit of the 24, so its time to re visit the plenum idea.

Basicaly the plenum gives the 24 carb more time to pass the required air so we can push the hp up a bit further.



One of EngMod2T's optional layouts is like my arrangement with the carb on the outside and the cylinder drawing air/fuel mixture directly from the plenum.

The idea was that the motor sucked from the plenum through a big unrestricted inlet and the 24mm carb had plenty of time to refill the plenum between suction events.

[F5 Dave]

Not sure really how to take that Dave, but wouldn't it be a little more constructive to suggest what you did try and didn't work.

Well I'll tell you a lightweight plastic bottle will get sucked flat.

[wobbly]

Havnt had a chance to look at the sim TeeZee.I was at Hampton watching Andy battle in the Superbikes, and Discombe battle the pre 89, 600 diesels
on his C model pre 82 TZ350.Great racing.

[jasonu]

I will get that sim update sorted.



This would have been usefull at Te Puke.



An ATAC valve is very much on my to do list.

Here ya go a brandy new one
http://www.ebay.co.uk/itm/HONDA-RS12...item2a1b30bd45

[bucketracer]

Here ya go a brandy new one
http://www.ebay.co.uk/itm/HONDA-RS12...item2a1b30bd45

Interesting that the blade opens inline with the gas flow and not accross it like we thought it should.