Which Mikuni ?

[Mark Kramer]

Well, getting close. Covered, painted and assembled. Engine time. I’m planning on two mikuni’s, and have read everything I can find. I have two questions. One, is there two types of float valves? Is this true? I am not going to use a fuel pump, so do I need to specify when buying the carbs? The other thing is, I have heard that the 2 stroke carbs are more tuneable, if so are they what should be used on our 1/2 vws ?Or use the 4 stroke versions? I’ve been told not to buy cheap versions from places like eBay, but to get the real deal from Summit racing. I live in Maine, any place closer than Texas? Also gonna do a new post about current instruments. Any input on these questions would be a great help.
Thanks Mark

[Kamcoman77]

VM26-606 4-stroke Mikuni is a good one to consider. Has 26 mm venturi which will give you high velocity airflow through carb ensuring good atomization. The 2-stroke carbs may be more "tunable" but you might find yourself chasing the perfect tune forever. Sometimes it is better to go with simpler and enjoy flying instead of constantly fiddling with extra adjustments. I'm pretty sure almost all the guys flying Mikunis are using a 4-stroke version. Some of the Eaglers with 45 HP engines may be using a 28 mm carb with success, but I've read that Leonard says a 26 mm is almost the perfect size for a 1/2 VW. 

[Mark Kramer]

Thanks Kamcoman
Makes sense to me. Not sure about the float valve thing though. Read somewhere that there are two types. Pump or gravity. I think I will call to place my order and ask about that. My engine is a Mosler cb40, and has bolt flanges. I hope those factory carb flange mounts are rugged enough. Oh, the other thing is where do I find the split throttle cable meant for those carbs?
Thanks again

[Kamcoman77]

Ebay has many vendors that sell the split cables. About $20 for the lowest price. Search for " SPI 05-139-02 Universal Dual Throttle Cable - Mikuni". I haven't seen anything that indicates a fuel pump or gravity feed needle valve & seat. The YouTube videos about Mikuni rebuilds and a couple of vendors do not mention this, or I missed it. I do know that some carbs (not necessarily Mikuni) have a small spring in the needle for a cushioning effect, and some do not. The needle jet can be a 2-stroke or 4-stroke type. One is called a primary, the other is called a bleed. The bleed type needle jet provides better atomization at partial & low throttle settings. If my VM26-606 Mikunis have primary, I will change them to bleed. Here is a Mikuni PDF.

[Mark Kramer]

Thanks again Kamcoman,
The 606 I believe is for 4 strokes and is the bleed type, I think. I ordered my carbs today so I hope they are correct. Will check eBay for a cable. Know anything about B-lite instruments?
Mark

[Mark Kramer]

Hey Kamcoman,
A couple of pics to show you where I’m at. The engine mount is a unusable one I used to put the engine close to where it goes. I then hung the plane from the ceiling with me in it with the pick Point at 28% from leading edge. Almost balanced perfect, just a little tail down. Will make the new mount a bit further forward. Gonna start a new post with instrument questions, maybe see you there.
Mark

[Kamcoman77]

Looks very nice. I'll be making my own instruments based on cheap sensors, an Arduino microcontroller, and LCD displays. Here is a Wikipedia quote about Belite: "On 6 June 2019, the Belite facility was destroyed by fire. The company has since been unable to continue to operate." The company may still be for sale.

[Dan_]

Looks very nice. I'll be making my own instruments based on cheap sensors, an Arduino microcontroller, and LCD displays. Here is a Wikipedia quote about Belite: "On 6 June 2019, the Belite facility was destroyed by fire. The company has since been unable to continue to operate." The company may still be for sale.

They are selling the 2 place Chipper design.  They are still in the aircraft instrument business...

https://www.chipper.aero/

[Mark Kramer]

Wish I was a bit more knowledgeable about computer stuff, particularly arduino. I would make my own EI system. Like that Belite three function asi vsi alt

[Kamcoman77]

Just found the link to Radiant Instruments (a re-direct from chipper)  http://www.beliteaircraftstore.com/ Thank you, Dan

[Mark Kramer]

Hey Kamcoman,
Will you be able to get egt probes and read those EGT temps with the arduino set up? If so, maybe on that same 4-line read out thing? As far as the Belite 3 in 1 gauge goes, I think Les Homan gave it a good review. Seems like a good deal, 3 gauges for the price of one.

[914pete]

Hey Kamcoman,
A couple of pics to show you where I’m at. The engine mount is a unusable one I used to put the engine close to where it goes. I then hung the plane from the ceiling with me in it with the pick Point at 28% from leading edge. Almost balanced perfect, just a little tail down. Will make the new mount a bit further forward. Gonna start a new post with instrument questions, maybe see you there.
Mark

Is that a bed mount?

[Kamcoman77]

Mark, The CHT probes are ring-type that go under the spark plug. The EGT probes will screw into nuts brazed to the exhaust tubes. The Arduino will read all four probes and display the CHT on the upper two lines and the EGT will display on the lower two. The probes come with a driver board called a MAX6675. Each probe has its own MAX6675. The probes & drivers cost around $5 each. My 4-line display was $10 and the Arduinos range from $10 to $30 depending on how much stuff you want to input/output. My complete CHT/EGT setup cost me about $45 not counting batteries. I haven't weighed the items to get a total weight, but they don't weigh much.

[Mark Kramer]

Wow! Awesome. Now, at the risk of being a pain, I wonder if you would be kind enough to tell me where to buy all these components? Accessing stuff I need has been the most difficult aspect of this project by far. I read somewhere a little bit about writing programs for arduino, doesn’t seem too awefully difficult.

[Kamcoman77]

eBay, Banggood.com, aliexpress.com are the three places where I get most of my stuff. Most of the software I find on websites mentioned in YouTube videos. For the CHT/EGT I searched YouTube for MAX6675 arduino. After I got a couple of sensors to work, it was fairly simple to add more and just copy several lines of code over for each new sensor.