hey man fun question for you. say ppl keep telling me to build my own pipe but im not a build a pipe guy but get the science. would you design me a pipe to build for a 70ish cc 2 stroke? i make around 20-22hp but in the wrong areas really. and the next pipe is about 300-400 bux. absolutely stupid.
@@AutoBeta2T its a minarelli scooter motor with a racy cylinder on it. the yasuni c16 is pretty close to what i need. and i might have gotten my hands on a design to make a clone of one of those.
Hi Dave, when I was tuning back in the day I thought about making a ram Air Scoop for an RD. Dunno if the air ducting would make much difference but even if it doesn't there's a massive sheet of metal which will conduct heat. One more thing I never got round to 😆
It's definitely something to think about. CHT could be used to see how effective it is. I'd also like to try a custom billet head with a lot more mass and surface area... See if that could help too?
I've seen replacement RD heads cast that way, the gold ones with radial fins and I know from experience they work but no better than I did with head skims and squish band always thought maybe they were just an expensive answer for a cheap question. Edit The couple of Rds I had with those heads were no faster than the ones I skimmed and reprofiled and cos I didn't have a clue about combustion chambers at the time and there's were no better, , I think you'll see where that's going, design something pretty
@@AutoBeta2T My"quick fix" was to use an LC head on an RD but turned around so the coll water went round the exhaust side first. Takes a bit of.grinding in the water passages but it worked, looked absolutely ridiculous tho
I did a huge amount of this sort of flow testing on a home built rig in the 1980's on classic honda twins. One comment I would make is run the hoover for a good old while before starting to take measurements as to let the motor warm up and stabalise. Love what your doing, wish I'd had the software back then.
@@AutoBeta2T I learned a lot about reverse flow caused by turbulance at the wall boundaries and experimented with an aviation tuning technique called ratchet flow to try and counteract it. Check the vacuum drop for every 1/4 mil of port opening some flow everything in first few mil of opening, for me that meant rapid lift cams with shorter overlap. Others flowed through the whole of the valve lift meaning longer duration was better.
@mercedesvan-doors34 cool, so it helped then. I did a Google for ratchet flow tuning but it doesn't really come up with anything. Is it referred to another way? Are you able to explain a little about the technique? Cheers Dave
@@AutoBeta2T Even then it was almost unheard of, I have a book somewhere, if I can find it I'll get you the details. In essence it consisted of cutting small angled grooves in the inlet port to stop reverse flow at the boundary wall. Remember I was tuning 4 strokes. You have to forget about the charge acting like a slow moving fluid it is travelling at very high speed, friction against the inlet walls slows the charge down and this causes eddy currentls that restrict the effective diameter of the inlet, in some cases the layer next to the boundary can flow backwards. The small grooves were intended to kill off this behaviour.
Watching third video today so subscribed. If I watch more than two it's a channel I like. Professor Gordon Blair designed the quiet performance silencers for Norton 850 Commando, one of the very first totally scientific simulation designs that increased performance and was quieter than anything previously used. Pretty sure that's when I first heard about him? Computers and programs have made this so much faster and easier than working it out with paper and pencil (early 70's, we didn't even have calculators until 1975~76.)
Hi, I'm pleased you are enjoying the content and have subscribed cheers. There will be more to come :) Yes, the Blair research really helped out to get to a good point quickly. The simulators and calculators I use are mainly based on his and his colleagues research at QUB. I spent a lot of time in the virtual tuning world so now this project is a chance to get into real world tuning of two strokes. cheers
I worked in a Suzuki/Yamaha dealers in 80's. Hated those little Kawasaki 50's, they were always completely trashed after about 3 months. (nearest Kawasaki dealer was about 20 miles away in Cardiff) Everything was worn out, shock bushings, swing arm bearings, seals, even the wiring and switches. Honda MT50 was impossible to tune (British market ones couldn't be ported to 'continental' spec of 6.5bhp) Yamaha was the easiest to tune and slightly better build quality than Suzuki. (was tuning 'Fizzers' in 70's, although knew a lot less so 63mph was best I could get) Stan Stephens was the 'go to' two stroke tuner back then and 'everyone' wanted Micron's on RD and GT 250's😁 Many years ago, I fitted a Suzuki RG125 'learner special' tank onto Honda RS125 road racer for Ian Lougher to do TT Lot of work cutting out complete bottom and making it fit Honda like it was supposed to be there. He removed all the fuel filters though and seized it 2~3 miles in when a bit of rust or dirt got into carb. LOL, it's probably 40 years since I heard 'southern shandy drinker'
Yah, I think a lot of 16 year olds didn't know how to look after their bikes! My first bike was a Honda MT 50, and yes it was pretty slow... slower than my mates AR 50 anyway... which is why I got one
Cool, I assumed he was born in the UK. There is a lot of interesting stuff on his channel. Although 4 stroke I feel some of it applies to 2 strokes too.
Hi, I'm not sure tbh. Disk valves, in theory, are better for max power as they offer no resistance when open but have fixed timing. Reed valves allow variable timing that's dictated by the engine itself.
Sweet, that's pretty cool AI is recommending me :) I'm pleased you enjoyed it. I've done a few more pipe videos. In this one, I play with the length of the dwell and header a bit. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-yZXhKxrykCc.htmlsi=QIQv7JIDjYsvVvF_ I should really do another and focus on the changes to the curve from length changes. It certainly does make a difference.
@@AutoBeta2T No problem most of the time, a couple got stuck tho, forgot to cut the earth electrode off the spark plug and pack it with plasticine 😆 I found it best to pour it in stages for large combustion chambers, sometimes filling the whole thing it shrinks. No use for transfers tho, that silicon stuff you're using is prolly the only thing you'll get out of those. Edit Obviously the wax is harder to cut in half as well.
Hello, I'm from Brazil. 2-stroke engine enthusiast and I've been following your videos. Another very informative video/class. In my engines, I try to adjust the flow according to the design shown on the top of the piston... I know it's not ideal either, but I realize that the closer to the center the burning is located, the engines have a better response, even in the heads. I noticed that there is a more localized burn in the exhaust region, as if the flow was actually going backwards, pushing the gases towards the exhaust.
Hi, I'm pleased you are enjoying the videos. In your adjustments is it usually to the rear of the cylinder you adjust the flow? I want to do some tests with different transfer angles.
@@AutoBeta2T I make small changes to the transfers, directing the transfer flow backwards until I find symmetry in the flow at the piston crown. Most of the engines I work with are Av10 72.5cc, they only have 2 side transfers and one rear.
I wonder if there is any difference between a flat topped piston and a domed piston that approximates the slope at the top of the exhaust port. Excellent video!
Ive just come across your channel possibly by watching 2 stroke stuffing, but as a 16 yr old i had the autisa 93cc on my AR, i machined my head to lower the compression as i could never get the head to seal, I only got it to run right for short periods and never understood 2 strokes properly, but in 1998 YT didnt exist and i never had the funds for a tuner and so long as it got me to the training school i was happy ish, great content and many thanks as I yern for another try.
I loved my AR93 when I was 16, too. Like you say, there wasn't a lot of information around then. No Internet or anything. How did we manage? It sounds like the algorithm has figured cover the same subject as Alex and is pointing people this way. Thanks for the comment, and I'm pleased you are enjoying 😀
Could you broaden the area under the curve with a valved stinger in theory? Start with a stinger larger than you would run, test some restrictions in it,build a map like you do for ignition timing, install a valve controlled by rpm. I was thinking the heat in the pipe is controlled by stinger size, and sonic wave speed varies with heat,etc. Maybe having to get rid of the exhaust gasses or it just not working in this manner makes this idea impractical. Or just dumb😂.
Yes, you could. I did some tests on my race bike some years ago with the stinger and smaller did give more power. However, I got greedy and melted the motor. The ignitech would be able to control what you suggest. I was thinking water injection but a variable stinger restriction should work similar.
I estimate the initial entrance angle of the transfer flow Is about 45° from vertical. but on a engine revving over let's say 7,000 RPM, the time that it crosses that zone is very small.
Yeah, it's such a short time. I'm not sure of the rpm that I did the tests at but 1000 to 1500 max... so, really low but I guess a clue to what may be going on?
Interesting re the stall of air on the piston at half way, my thinking of flow from Gordon Murray on the t50 rear diffuser, anything more than "I think 17 deg" and it would stall.
Yes, it was. I'd like to do some more research into this at some point and certainly into flow inside the two-stroke engine. It's such a simple design, but so complex too. Yes, an angle of attack greater than about that, and the airofoil will start to stall. Maybe filling the lower exhaust duct is helping to keep the flow attached to the front face of the piston better?
I suggest putting on the chain guard or wearing a protective cover on your left 🦵 leg . That chain can break and wrap around your leg 🦵 and rip it apart. Pr the engine could toss that rod into either 🦵 leg .please think and be safe. It only takes 1 accident to hurt yourself use some wisdom!.
Необходимо достичь рабочих RPM, установить головку цилиндра, а также каким то образом создать волны резонанса и только после этого наблюдать за движением газов) Удачи и успехов!
Yes, it's quite low rpm and no resonance effect from the exhaust and the intake... I wonder if a clear head could be made? I could do with better slow motion, too and better contrast between the smoke and the engine. And a more powerful drill to get the rpm higher. Cheers, and hopefully, we can come up with something better to visualise the chaos inside the two stroke 😊
Thanks for the link. I had seen this before - it really needs a super slow-motion camera the it would be really cool. This clear head looks good. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-45J5WnXtntQ.htmlsi=MYEDJiDtS09-Y87k
Tower of piza seems to be there in a couple of the still shots and the transfer flow from the A port looks consistent with piston wash I've seen in loads of other 2 Strokes
Hi Roy, Yes, it certainly does, which is good. I actually started to observe the emulsion of the 2t oil and the moisture from the smoke I was using, forming on the crown of the piston similar to what I've seen where the cooling wash of the transfers has stopped charing of the oil on the hot piston surface. I'm assuming this it what you have observed, too?
@@AutoBeta2T Hi again Dave, just had an idea, if you have used piston with the flow pattern compare it with the smoke stain you saw on the test one. Edit See if the angle looks the same or just similar
@@AutoBeta2T what I was thinking about with comparing the flow marks on the pistons, when the engine is running the air will be coming thru the port windows much faster and prolly won't diffuse as much as maybe the smoke test so if you're planning to re direct them you'll need to know what discrepancy you'll get between test results and a running engine. Could hardly think straight last night, had a crap day and my head was still spinning round in the "hamster wheel" 😆
Would be interesting to do the same with a clear top to seal the cylinder so you have the normal flow direction through the exhaust only. But you probably can only see the first stroke before it fogs up, but for a slowmotion sequence it may be enough.
Hi Henrik, I was thinking the same. Even without the head, I saw some footage of the smoke going out of the exhaust, but like you say, a clear head should steer it better. I wish I could have got some super slow motion, but it records such a small amount I kept missing the money shot. Yeah. It gets quite foggy quickly, and with no suction from the exhaust, it soon builds up.
I would say yes on the question. Some of the flow will be attached to the piston crown due to coanda effect =) I got another hot tip coming up soon how to read flow directions using visual of coanda effect =)
Hi Patrick, Thanks again for the inspiration. I tried with my fingers, and I could feel the direction of the flow, as you said. To note, I was getting a buildup on the piston crown of the 2 t oil and water (from the smoke) emulsion whre you tend to get the cool spots from the transfer flow in a actual engine.
Hi Cliff, welcome to the channel 😀 Yep, as you say, what I am doing here is not representative of the unsteady gas flow in two strokes, but hopefully, it gives a few pointers to what could help performance? I don't think even high-end CFD can fully model the chaotic events inside the engine. All good fun, though :) Cheers for watching Dave :)
Got to say this is one of the few channels I have come across where I can't find anything to pick at LOL. Serious question though, what kind of gain would be achievable with say just a bit of moderate port work and then winding the compression up as far as possible along with some octane booster in the the fuel? (volumetric efficiency vs thermal efficiency) Thanks.
Hi, cheers, and I'm pleased you are enjoying the videos. The ports are already fairly maxed out from standard but still have some more to go, I think - that will come. Next up is compression, but I plan to go lower first as more energy in the pipe in theory should help... but if that doesn't work, then I'll look to increase it higher. I want to do the 100mph on pump fuel, which is 97 - 99 octane as per the original chalenge but until I can do some real world runs I won't know if I can get away with it.
@@AutoBeta2T Understood with the challenge. I have only picked this up somewhere in the middle so wasn't aware. Back in the day I started out with a GP100, disk valve and all lol. Shall watch with interest 👍
I have only just had time to watch this video through. I wish I had seen a video like this when I was teaching myself (because no one else would) to build 2t pipes , it was a long lonely road with plenty of dead ends and screw ups. Still, I have picked plenty of good tips from this video. What a privilege to spend a day with an experienced guy like Mick Abbey, most tuners won't let you see how they do things. For anyone looking to learn how to make pipes, this is gold.
Me too John, it was mostly the same for me with learning how to make pipes. I did get some help from a mate in Oz but learing to weld and how to make pipes at the same time took plenty of goes. My first few pipes had so many holes in them as I struggled to get the cone faces flat and then played the game of trying to fill them before burning an even bigger hole into it. Yes, it was great spending the day watching Mick. He has so many tips and tricks to make pipes easier and it was great of him to share them with all of us. A top bloke 😄
@@AutoBeta2T I have just picked up a full oxy acetylene welding kit from the merchants today. Have not used one since I was in school metal work lol. Let see if I can make a pipe lol.
@john63397 should be interesting to see how you get on. From what I could see gas welding seemed to be more forgiving and quicker than tig. Saying that Mick has many years of practice.
@@AutoBeta2T OK, I'm back for another look at the gas welding lol. I am having reasonable results. Main issues are popping/blowing holes and deformation. I am using 1.2mm mig wire as filler , this may be causing problems. Also Mick is using a much more aggressive flame and moving quicker. But yeah, gas welding could be the way to go for faster pipe building and testing. Its got potential.
