steelmesh

They could probably talk out of legal issues by saying they had engine problems 

Hopefully the belt slipped instead of shearing the key!

Very cool Andy!  For the rear axles, is that a flexible material to act like a suspension?  Or do those balloons do a good job soaking up the earth?

Agree with toploader, fuel leaking from a float carb is related to the needle valve (valve, seat, float arm, float, shaft, etc).

11 hours ago, mackaypara said:

Hi Everyone,

I am new to paramotoring and have basic mechanically knowledge. Bought myself a black devil M25Y and having difficulties starting the motor due to the high compression of the motr. I have cleaned the decompression valve and drilled additional holes to lower the compression level but I still need to use both hands to start with the paramotor tied down on a cradle. Would be virtually impossible to start on my back. Appreciate any feedback.

Thanks Tim

 

I have a low hours Top 80, it has mad compression.  With the prop off, the first time I pulled on the starter to start it, I lifted the whole motor up.  I have to put my foot on the frame and hold the hoop with the other hand.

On my back starting it, if I pull outwards too much it will nearly flip the motor over my back (pulling it over my head).  I must use both hands to start it on my back.  However, I don't have a decompression valve.

I have a dudek and the manual says use a soft sponge and water, do not use chemicals or alcohol as they can damage the fabric.  I used warm water and paper towel, unfortunately it was taking too much effort so I didn't keep going.  I think that stain was there when I got the wing last summer (used), so it may bode well to clean it asap.

Yup polycarbonate is very tough stuff, it's what bullet resistant glass is made of and also acceptable for use on racecars to replace glass.  

The paramotor dry weight is 48 lbs (21.8 kg).  

4mm thick polycarbonate (lexan) back support:

Custom pull starter pulley bracket:

Custom fuel bulkhead I made sealed with fuel resistant sealer permaseal.  The tank vent is filtered with a 1-way valve (dirt bike tank breather):

Primer bulb and lightweight airbox mounting system lol:

21 minutes ago, toploader said:

Im sick of being told what i can or cant do  to be honest.  Im off to the dunes as soon as its flyable!

They said the sky is falling though, won't you be in the sky while it's falling?  Seems dangerous.

A hang check is in my future indeed!  I picked up some wood and dreaming up a design.  I've got an AC TIG in my garage; and with that comes filler rod which comes in handy for various things...like a choke actuator on a walbro 

Finally assembled this pile of parts.  I have no prior experience with paramotors, however I am an engineer/mechanic/technician/machinist/fabricator.  I don't want to pretend to know it all, sadly I don't, so part of the reason I'm posting is to see if I did it wrong (I'm embarrassed to label myself an engineer with that, because engineers know it all).  At first I was concerned with taking on this project, but after seeing many non-mechanic amateurs wrenching on their paramotors not dying, I moved forward with this diy build.  I decided to purchase a frame because I do not have a good understanding of paramotor geometry.  Technically I didn't build this, more like assembled it.

Engine: Top 80 w/ vittorazi throttle

Frame: Skycruiser Simple Aluminum

Harness: APCO SLT high hang

Southwest Top 80 throttle linkage mod (L-bracket).  I could not believe Top 80 / Miniplane will run the cable through that metal hole at 90 degree angle, I could not sleep at night:

Choke Linkage, 3/32" steel filler rod:

Choke OFF:

Choke ON:

CHT sensor display:

Throttle with RPM gage:

Kuntzleman SC103 strobe (meets FAR 103 requirement), custom mount (aluminium split collar I tig welded to):

The seat bottom has 3 inches / 75mm worth of impact foam:

Waiting on the pull starter pulley (looks lost in the mail).  I will follow up with fuel system pictures and an overall mass.

See page 21 for comments on the foam I used: https://web.wpi.edu/Pubs/E-project/Available/E-project-042710-200525/unrestricted/Final_MQP_FSAE_Racecar_Crash_Protection.pdf

On 03/02/2020 at 13:27, SamiK said:

Just kiting, not launching. Basically a reverse with out being clipped in and holding the riser in my hands. I do this every time to check the lines and setup the wing. 

Ever since I started ground handling to this very day I get the flip from time to time and every time I ask myself "Why, what am I doing wrong?"

I get my mistake if it just falls to the side, stalls, overshoots etc, but never figured out the "flip". 

Could it be just a case of sudden wind direction change / gust? I've had this happen so many times I don't think it's likely.  As I said, I always have streamers with me so I shouldn't be off more than 10-15 degrees at most to the prevailing wind.

 Check all the lines are free, as in something could be pulling to that side causing the wing to always turn.  Otherwise it may be changing wind conditions, are you in an area without many obstructions?  When I started I went to parks and the local school football field and it was so difficult then once I started practicing at an air field and another large field things got way easier and more consistent.

15 minutes ago, Blackburn Mark said:

That would be a bit pricy!
You can pick up a new, complete 150cc GY6 for £170... parts are cheap up to 180cc.
A CRF250F, not so much and its not air-cooled so I have my doubts about getting it down to 14kg
 

With enough time and money anything is possible!  Note: I'm approaching this 4T dream engine as a Moster killer.   

I'm having a tough time getting an idea of what HP we're talking about with the GY6, also what is the mass?  I see the performance part dealers selling upgrades, but haven't seen an expected HP rating.  I found here-say source that claims 14hp at 12,000 rpms. 

The predator/honda clone scene looks a lot more supported, a lot more HP numbers to reference and even vendors are providing HP potential with their Stage kits, like nrracing.com claiming 20+hp with their Stage 4 kit.  Also, I can't see a full race engine build designed for the street able to handle sustained high RPM like a boating or aviation application.  Rebuild hours should exceed that of a 2T, this should be one of the benefits of a 4T engine over a 2T.

6 hours ago, Ben Butler said:

They thing about the GY6 engine is there is a massive aftermarket of tuning parts for these engines  you can ramp them up to silly power!

Also another angle looking at a factory "race" dirtbike, a 19' CR250F makes 42 hp out of 250cc, but the engine unit weighs maybe 60 lbs (28kg) probably because that includes the gearbox.  Imagine if they light-weighted this engine and de-tuned it 20%, they could get it under 30lbs (14kg) with over 30 hp.  We just need to get Honda leadership into paramotors, but I reckon Yamaha would be more open to the idea though 

This is an unintuitive characteristic.  Is it because the Tachometer signal wire is in parallel with the kill-switch wire, as in the Tiny Tach is mounted at the hand-throttle?

3 hours ago, Vauxscott said:

I've just fitted a priming bulb to mine. No more caveman blow tube.  To prime i just hold down the carb lever and give the bulb a wee squeeze until the air in the line clears.

It doesn't have anything to do with pop off as you are manually opening the diaphragm by pressing the lever. The reason that lever is there is to stop you pressing too much and damaging the spring behind the diaphragm.  

One or two pulls and it starts.

I used a Polini priming bulb. (probably the only decent thing Polini make.)

As for your 8mm dia fuel line, is that internal diameter? Id say thats far too big. The diaphragm pump in the carburettor wont be able to pull the fuel up that, get some smaller tygon line on there, 4mm.

Thank you for clarifying the priming procedure with this carb!

I'll save the 8mm (5/16") ID tygon for a bigger motor upgrade then. 

I have 3.175mm (1/8") ID tygon in stock...but, is the WG8 Top 80 fuel inlet supposed to work with 4mm ID fuel line?  When I measured the nipple on the carb I assumed it was for 1/8" or 3mm, I'll have to re-measure.  Looks like 4mm would be equivilent to 5/32" so at least I got that going for me if 4mm is the best practice with this engine.

My brother made fun of the paramotor strobe kits, said they were toys and not bright enough (he has been a private pilot since he was a teen).  What's your opinion, can you see other pilots pretty well with toy strobes?

With that, I picked up a FAR103 compliant (3 mile) real strobe light, 12V 500mA draw and pretty compact.  SC103 self-contained strobe light. 

For the rest of the fuel system, I am running an 8mm pickup hose with a clunk filter, that will then be stepped down to 3mm for the carburetor inlet.  My concern is if the 8mm is too large of a diameter, as far as priming the fuel hoses or if it picks up air bubbles will it require a manual air purge.  

For the fuel tank vent, I'm looking at a 6mm dirt bike vent with a one-way check valve (air in, nothing out).

I am building a paramotor using the Top 80 with the WG8.  I have a universal frame that came with a gas tank ready for drilling.  After some deeper research into specifying what I need I have learned the black springs steel on the carb is for priming, "priming level".  Based on my knowledge of similar carbs the priming lever will manually open the needle valve.

Just clarifying my understanding here, by pressurizing the fuel tank and then hitting the priming level, that would squirt fuel into the carb throat.  Is this a correct statement?

If that is the case, I think I understand how the priming bulb will work with this carb...because before I was concerned that the primer bulb inline with the main fuel feed to the carb would need to exceed pop-off pressure to force fuel through the carb.  So it appears that you build a little pressure with the inline primer bulb and then hit the manual primer lever.  I was looking at putting in an independent primer system (it's own fuel pick up and a nozzle inside the carb or airbox); until I started finding Top 80 youtube videos trying to trace their fuel lines haha, that's when I saw the primer bulb inline.

Maybe the solution is to but the prop in front of you, this way you can keep an eye on it better.

 Was getting worried there thanks for the feedback, I feel much better now! 

Speaking of, Alex just emailed me that training is still on [in the face of the plague going around]...and to send the final payment ahaha, gladly!

I'm taking the Spain APPI Pilot Course through SkySchool in a couple months, is there a problem with SkySchool in Spain?!

https://www.skyschooluk.com/learn-paramotoring/appi-ppg

For people diagnosing this: In the Walbro Manual, Page 12 has a few things to look at regarding "Poor High Speed"

Maybe your high speed circuit is too lean for the weather, because there are certain circuits in the carb that come on at different air flow demands (throttle position) where yours is unhappy with lots of throttle.   See attached chart to get the idea (from the mikuni sbn manual).  Since you're flying in cold weather, it's probably a lean condition.  

Also, check for air leaks (crankcase may be leaking 2t fuel) and check the reeds.

I've worked on similar diaphram pump carbs in watercraft where the common issue is hard starting and the common practice to solve it with these old 2T engines is to install a stand alone priming system (not just a bulb on the fuel feed). The priming system has it's own fuel pickup (using a T on the fuel feed/return hose) and squirts liquid fuel into the carb throat directly.   

Here is a $35 USD primer kit for a single carb: https://rivaracing.com/i-17284794-riva-primer-kit-single-carburetor.html