Diaphragm Carburetors - Ibea vs Tillotson?

Areomyst

Scootin' America!
I've been looking at a few different diaphragm style carbs, and I was wondering if anyone has used Tillotson style carbs on scooter setups before. They look a good bit different.

km114.jpg

This is the Tillotson. Tillotson's website states that it is good for kart use. I assume it could be made to work with a scoot as well, provided the proper inlet modifications/flange were taken care of.

ibeal2.jpg

Here's a photo of the Ibea carb. They have both 2 and 3 jet models available. I assume the 3 jet model will be a little bit more "fine tunable". Many weed whacker and chainsaw carburetors work off of the same principals that these do, and I have some experience with the smaller ones, but not with these particular sizes, and not on scooter or karting setups.

Experience is the best teacher. :p The Tillotson is a good bit cheaper, but it does not look like a real performance carburetor. What do you all think? This will be used with an EVO setup eventually. For now, I am simply exploring possibilities, and I am not making a purchase yet.

As important as carburation is in 2 strokes, I don't really want to take any large risks (especially with a high end cylinder) , but I'd like to know if anyone else has explored this possibility. I know people here have used the Ibea carb. The Tillotson looks more like a lawn and garden type, and not as suited for performance tuning but I'd like to know if anyone's tried.

When push comes to shove, I want something different. Seems like more and more people over here are going with EVO, so I may turn a different direction when it comes time to purchase the parts...

~Josh
 
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I have tried.

The Ibea is the better one, far better quality.
The picture of your ibea is the three jet model. The extra is the one in the intake. U won`t be using that. So use the 2 jet or the three with the extra screwed 'off'.

People have had high scores with those kartcarburators. (with IBEA, Baroni)
But now a days here, no one uses them anymore....why? i think that with other better parts the advantages of a kartcarburator are less interesting. However i believe that the short intake and gasreaction will always rule over normal carburators.

But the weathersensitivity will keep u tuning it. And that best tuning will mean that u will be running with a gas/air mixture on the edge of being to low. A testbench (?) with mixturesensor is preferable.
 
Here's a link to a seemingly higher end Tillotson carburetor.
http://www.tillotson.ie/till3.html

I think I'm going to give it a shot. I have not seen any of these setups in the States yet, though I'm sure there are a few. IBEA seems to be the more popular of them with scooter tuning. Is there a particular reason? Easier to tune, or better performance? Pricing is better compared to other models? :)

~Josh
 
Here's a link to a seemingly higher end Tillotson carburetor.
http://www.tillotson.ie/till3.html

I think I'm going to give it a shot. I have not seen any of these setups in the States yet, though I'm sure there are a few. IBEA seems to be the more popular of them with scooter tuning. Is there a particular reason? Easier to tune, or better performance? Pricing is better compared to other models? :)

~Josh


I've used both of them!

The Tillotson is good compromise between the usability and the performance. Sure it's not a real performace carburettor, and also it's quality isn't the best, but it's cheap.
Usually the Tillotsons are not as sensitive as the real race carburettors they tolerate the different weather conditions quite well. You can also adjust a quite stable and low idle rpm, if it's important for you.There are general type carburettors for chainsaw etc, and there are carburettors for karting.

The Ibea is the total opposite of the Tillotson. It's the ultimate best kart carburettor. It's quality amazing the finishing is perfect.

But because they are optimised for racing kart application, they are very sensitive, and they need more attention. I mean you should adjust the pressure well, if you not do this you cannot adjust the carburettor well, or they will be unreliable.
You can't adjust the idle, and because they are for 100-125 cc engines, you will have high idle rpm on scooter. I've used the 29,5 mm guillotine type version, and I adjusted the idle rpm with a custom made blade with recalibreted hole!

You can reach much more better perforamce with the Ibea (if we compare it with the bowl style carburettors).
Ibea has less resistance, nice profile venturi and better fuel metering. You can fine adjust very well (if you have experiences). The accelration, the gas reaction is amazing with the Ibea.
I reached ~1,5 horsepower more compared to a Keihin carburettor.

The two jet type is enough for you, however the 3 jet type recommended. The third jet is not 100% equivalent to the power jet. You can adjust the "rpm" where you need more fuel for better internal cooling. It's a safety method for the critical conditions. But if you konow karts you know what I mean. Sure you can close it. You can mount the carburettor directly to the engine, so you have a totally straight intake channel. You can easily adjust the intake length with different spacer. The intake length is same as the expansion cmber, so you have to adjust it well. Not the shortes is the best for every engine. The Ibea needs "constant" vacum, so bypass the reed cage with a tube.

I can't say I share Tinnes view..

First of all the third jet is good to have on scooters too.

Secondly..

"But now a days here, no one uses them anymore....why? i think that with other better parts the advantages of a kartcarburator are less interesting. "

I think not this is the reason. Most of the people can't adjust the carburettor well, they screw the jets pell-mell. Or they can adjust, but don't like to adjust the carburettor every time they start the engine! They are to lazy and adjusting the carburettor is torture for them:p
Checking the pressure, and see the diapragm condition is also a pain for lot of people!

The other reason they are not very popular, is the price, you can buy min 3 Koso carburettors for the Ibea's price!

A bowl style carburettor seems to be much more simple and more comfortable for them. Bowl style carburettors also tolerate the incorrect adjustments or the different weather condition better.

But if performance is more important than the comfort just choose the Ibea!
 
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I can't say I share Tinnes view..

I think people choose to have a 'stable' carburator, so they have more 'time' for other things. And with all the new cilinders and such i think that is more interesting. And having a not to worry carb is probebly giving a better sleep at night ;)

But i must say that even the top scootertuners here have tried Ibea`s and such...and they don`t anymore. Even a top kartingteam/shop uses 'normal' carbs like Keihin`s for their karts. That does mean something.

Using kartcarbs. can be more unstable, takes more time, maybe more knowledge? and dynojet time etc...

But can give more horsepower, better looks imo ;) is original and will surely give a better gasreaction...i know that from experience....

For what purpose is the engine/scooter then?








Not for beginners then?
 
At what kind of RPM do you find your idle when using the Ibea? I don't have a problem with a high RPM, but I'm curious as to what speed the engine will be at when idling. Did you have to toy with the clutch at all to keep it from engaging, or did you already have strong enough springs, etc? :) Eventually, the scoot that I'm tuning will be for drag use anyway, so it's not that important that idle is great.

Excellent information friends, thank you.
 
I also used the Ibea. You can buy them for a fair price at local kartshops (second hand). Mine was just 50 eur (looked like new!)!

I used a spacer for letting it run idle, so when throttle was closed, the valve would still be open slightly. It would run like 4000 rpm idle.

I changed carb because I found the carb I have now (TM28SS) more precize. I never gained any more power from a Kart carb. It was running fine (I have movies of it) and was giving not any less power as a conventional carb, but I never got the advantages.

Maybe it was the carb, that I bought it second hand for 50 eur and something was wrong with it. I sold it eventually.

I have 100cc kart at home with a Baroni or Ibea on it. Can test that some day.

Ohyea, another thing I had was that it's fuel consumption was out of this world. Even you American people wouldn't like that!

Btw, go for the real deal and buy an Ibea! You can find them on ebay for reasonable prices.
 
At what kind of RPM do you find your idle when using the Ibea? I don't have a problem with a high RPM, but I'm curious as to what speed the engine will be at when idling. Did you have to toy with the clutch at all to keep it from engaging, or did you already have strong enough springs, etc? :) Eventually, the scoot that I'm tuning will be for drag use anyway, so it's not that important that idle is great.

Excellent information friends, thank you.


My 29,6 mm Ibea Slide carburettor is a different story, with a 24 mm butterfly type Ibea you can adjust it's position quite well, you may adjust have a reasonably good idle. With my Ibea the idle rpm was 8000 1/min with the original slide, and 4500-5000 1/min with my custom made slide!
 
If you want to know any and all about these carb's call E C Distributing at 615-446-6807 www.eccarburetors.com The guy to talk to is named Carol. He set me up with the HL-334B. These are the go to guy's, for kart carbs in the U.S. I sent him a port map for the 70 cc evo2. They really don't get the scooter thing, but when Carol saw the evo map, he said "he saw the potential". I also sent him a map for the 2fast4race. He told me that this set up would call for a different carb. than the Evo. Have them send you their catalog. They have alot of different carbs including Ibea There is a pic. of a dual Barrel set-up that is used in Kart raceing in the U.S.( Really crazy looking)
If you have the money they will build you anything you can dream up in this style of carb. They have 3 levels of carbs. They also do blue printing and flow bench if you are into the fuel to oxyegen ratio stuff. (This is way beyond my ability) I will let you know how it works out for me when my project is complete. The reason I'm going with this style of carb is because you can rig it up to remotely adjust the settings like the kart people do. I live an area where the humidity goes up and down all of the time. I also have a Micron egt. to watch for detonation. The down side is you have to rebuild the things and I don't think I'm going to like that. A lot of parts. This is where the problems are with these carbs. They have what is called a pop off. This must be set to your engine. It has to do with how the low and high circuit work in the carb. I have only begone to learn about this. The 2 stroke part of http://karting.4cycle.com/forumdisplay.php?f=26 will answer questions about this. Also check out the forum at E.C. Carb Hope this helps. Cheers, Tim
 
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