But the New piston is probaly longer than the old piston But if the crankcase cr Will Better With the old. What you can test is make a bigger headgasget en make an Nice squish clearance
Timo yes he could but for the back to back comparison of the Piston Port to Reed it's be best to just do that to begin with rather than doing more changes than one. And it only need some holes drilled in the old piston and Alex is adept at using the die grinder if need be to do the job, and it would take the least amount of work to do that way.
My thoughts on the new piston and raising the cylinder that far although it wont change port timing it will increase crankcase volume which might be a decrease in horsepower. as for the reeds it would be cool if you can add in a rear boost port but I doubt you can because there probably isnt enough meat on the cylinder above the intake port to build a port. Maybe you can do channels from the intake port down to the transfers? they call them boyesen ports and almost always help.
Hey buddy I always look forward to videos like this from you but it seems like once we get in there and it goes nowhere I dam. These are the kind of videos I really look forward to seeing from you brother you are one of the best and this just sucks that it went for the next video it’s not what I was expecting
There will be a little less power at the top end but you will lot of power low end and more power throughout the midrange if you do not cut the inlet (intake) port so that this port stop being a piston ported inlet system but you will more torque all over the power band even below the point the power band starts to kick in, in fact, you will find that you will have more than either way at the below power band either way.
That wasn’t my comment the other day I was hacked. I think your channel & videos are great. The bicycle in the beginning of this video was awesome. I also am making it to stroke power bicycle from an old Tecumseh motor. You can see the video on my channel I just uploaded it.
The problem is wrist pin location. Those engines have have a high and a low wrist pin piston. You need to keep with the high wrist pen piston, you originally had
get the type B piston instead of type A. Or cut a window in your original piston. Without some work on the transfers and maybe cutting a third, you wont see much increase in power. The real trick here is to mount the reed valve to the case below the cylinder and block off intake port. This is the ultimate modification.
Steven Legere i was reading (dragonfly76) for non reed case the reed has to pretty much touch the cylinder or stuff the crank case or youll lose power.
They make pistons for high hole and low hole. It goes by the number on your crank then you look that number up and it will be high or low hole. A af80 crank is a long crank
4.56 HP - you will loose bottom end power and max power will come later in the power band. As mentioned - these engines comes with low wrist pin and high wrist pin. As your engine is 38 mm stroke you now have a piston for a 40 mm stroke which i guess can screw up your port timing - you would have an easier time if you just windowed the std piston 😊
changing the position of the wrist pin doesnt change the stroke or the displacement of the engine because the piston deck is say 3mm higher at top dead center but its also 3mm higher at bottom dead center. it won't change the port timing either as long as you raise the cylinder in relation to the deck height.
raising the cylinder will change the port timing , its a sinus calculation since the stroke doesnt move equaly to the degrees. Exemple at top dead center you need to turn more to do more stroke displacement rather than at the middle of the cylinder
if the deck height of the piston is moved up 2mm like in the video and he in turn moves the cylinder up 2mm port timing WILL NOT change. IDK where you people don't understand.
The new carb itself will increase power so my guess 4,5 HP and probably better midrange. Really inspiring videos, keep up the good work! Looking forward to the porting part, have an extra cylinder in the garage for my engine but would like to wait for your results.
I'd try running the OEM piston reeded as is, then "windowed" a bit, then try running a spacer on the jug. Your kit is for a short rod motor (there are 3 variants, lol). The Reed kit is a chineseum alloy "hop up" kit (DIO clone reeds). The carb is the chineseum "oko" clone they hawk as a " matching part" with the kit, but also as an improved carb for a worked stock piston ported setup. My predictions: 4 1/4 ponies Reed stock piston unwindowed, 4 3/8 stock windowed a bit, and just under 4 1/2 shimmed jug Reed piston, each peakier than the last, with the Reed piston ALL top end. It would be interesting to see the "bike engine Reed intake" set up too, it has much smaller reeds and Reed case. That kit actually costs about as much as the motor kit, btw, while the small Reed set up is around 25 bucks US if bought from China, a bit more from a retailer
4.26hp Hey, did I tell you about dragonfly75? If not, you NEED to read his stuff. He has some amazing information about the motorized bicycle kits, lots of tuning etc! I read all articles on his website and they provide great knowledge and tips.
Depends much on the exhaust pipes area of power, making a spacer on the bottom end of the cylinder will rise the port and exhaust timings so high that it will lose power, im guessing 3,2hp
Suggestion : If you make a spacer be sur the diagrams wont be higher in order to have a real view Of the gain ! In the mean Time the volume below the piston must be différent, the compression in the bottom engine will be lower, same for the Shape Of the piston (« squish » band, chamber volume) To me, and i am far to be good mechanics, the best way to see the bénéfices Of the reed valves is to make the same hole in the previous piston. Then We can compare piston and find the best one! Anyway my guess are With old holed piston +1.2hp With new piston and spacer +1.5hp Cheers
Maybe you received a #B piston when you need a #A, measure your intake studs, center to center, if it's 32mm and your conrod has a Z casting mark you need the taller piston, from crown to wristpin center
From what I understand reeds usually increase low to mid range torque and cause loss on top end, however the material used and the quality of such material can have dramatic effect on how severe this is. For an engine that peaks at an RPM as low as this one, we still might not see a any kind of negative effect with reeds. There are too many extraneous/confounding variables I personally believe for this to be a clear cut comparison for reed/piston port though. E.g. You would also be changing crank case volume adding whatever room the reed block utilises which would likely lower performance. I estimate around 4.38hp peak with more torque down low.
A spacer is not the answer. There are several configurations of these engines and you simply have the wrong piston. I would just cut a window in the original piston. Also, you should cut a boost port in the cylinder as well.
So what I would do is window the stock piston but still raise the cylinder some with a spacer and mill the head or deck the top of the cylinder the same as you raise it or maybe even a bit more for a tighter squish. I would try a 1mm spacer to raise all the ports and help with the low port timing. unless you can get into those transfers with your porting tools then I would raise the transfers and widen/raise exhaust by porting and lower/widen the intake some if you haven't already.
I think about 3.9 hp, it will give more spreaded power. that's how it worked out on my Puch, valve inlet at the crankcase instead of piston ported gave me more power overall. btw, 13hp:)
a fuller powerband more from Idle but a little less max horsepower at the top end when using the reed valve instead of piston port as it was before the change out. maybe 3,6 hp or around 3,55 hp if it makes 3,9 hp as a piston port style of engine.
I would guess power will be about the same after a little tuning. maybe a little less. so 3.6-3.8 hp but it will have better low end response and better midrange. There is a reason yamaha called their RD series "Torque induction" when they went from piston port to reeds.
SecretShop Bali it is lol, i said that bc diesel pistons' crowns often get to the point where that piston went. they have a longer stroke than gasoline engines, hence why they have low rpm limitations and lots of torque. sorry if my english is shitty. not my first language
Of course when you install a reed kit on a standard piston port engine you'll get a power increase. But that comparison is not completely fair. The only fair test is to first optimize the intake duration on the piston port engine and then use a leaner needle for it then test it. Then hole the piston skirt and make a boost port in the cylinder and then put in richer jets and richer needle in the carb which is what reed valved engines like. Then do the same test. Then you see they are the same. I've done just that which is why I know.
I hate to say that you are wrong about the piston and stroke, however if you have a longer rod then you need the type b window piston. The motor can come with the short shaft which uses the low hole piston or a longer 40mm shaft which requires the high hole piston to work without a spacer.
Reed kit will add .75 hp but I doubt it will be due to the intake but more likely the larger carb. Also the kit engines have 38mm stroke and some have 40mm. The sellers very rarely specify which one you're getting.
I built a Bike Berry 2 stroke mtb, and it was stolen, so, I built a second bike, using a Predator 212cc 4 stroke ohv, a Commet 30 series torque convertor, "mag" rear wheel (6 spoke), straight pipe, 30mm suspension front forks, wide sprung seat, Harley LED deadlight & tail-light, and magneto .I'm getting at least 10 hp, and 60mph at 5,000 rpm. I understand your fascination with squeezing out as much power as humanly possible, but, you must admit, those castings made out of scrap can barely hold a thread, the worst castings I've ever seen. If going fast, reliably, on a mtb that rides just like a motorcycle with an automatic tranny, I HIGHLY recommend the Predator "Death row " bike kit. You will need a full size frame, and will have to remake the front down-tube, with an 8" rad. at the bottom, and watch for clearance issues with the forks, when turned to 90 degrees. I welded a lug under the top bar, and made motor mounts attached to the gas tank ears. This extra mount was not necessary, but it made me feel good. The Predator non-hemi is a very nice engine, the hemi version has no QC so hit, and miss. If you want to build up one of these to 20 or 30 hp, I suggest starting with a Tillotson 223, heavily re-enforced block. All the after-market performance parts are available up to 10,000 rpm, Best of all, no mixing gas and oil. Just pull up to pumps and fill. I replaced the 2 1/2 liter gas tank with a 1 imp gal tank and I use 10" riser bars with motorcycle mirrors. The ONLY part that is not YET available is a billet aluminum 3 magnet flywheel. They only make cast iron "starter fltwheels", so, I limit my rpm to 5,000 so that the ignition magnet stays put. As soon as someone figures out how to EDM burn the magnet pockets into billet flywheels, I'll have to keep it under 60mph. I'm almost 69, blind, deaf, with no balance, and I intend to ride my bike into the ground. PS, you may want to extend the hardtail 6" to 10" to help keep the front wheel on the ground when starting from a stop. If you love the freedom, this set-up is very reliable, and great fun. I never did catch the thief.
i think it will be a more even power curve, with more effect all the way from the start, but on the contrary maybe it will be messing with the tune of the exhaust pipe, i'm gonna guess there will be an ambiguous reading from the tester, more power from the beginning but flatting out on top and not succeeding previous measurements. but i bet you'll get it right at the end, you're a very skilled engineer/mechanic. how about those comments saying you could just make a hole in the old piston? i'd say that sounds like a good plan. Cheers
How would it be to build a twostroke engine but instead of reedvalves you have opening valves like I 4 stroke to the crank chase, I know the rpm would be a struggle to get the valves to keep up and close, but like this you could technically install a turbo 2 stroke engine, no hate just a thought
That's it? I got all excited for this video and failure. There are 2 different hole location on the piston for 38mm and 40mm strokes. You could of done at least a dyno run of reed and stock piston or mod stock piston. So guess we gotta wait another 2 months for another gasbike video
In the name of science, why not try the old piston unwindowed vs windowed? I'm betting unwindowed + reeds still gives an improvement somewhere in the rev range.
Wow looks Hella restrictive and that long intake runner length sucks . I say you will loose hp until you match port and then still you might loose a bunch down low and on top Hmmm I say 3.1 that piston looks like it was a stock modified so yeah 3.1 you wont even get deep into that pipe what that set up probably.. I have been wrong be for so let it rip ! What are you using for a camera the videos look awesome ? Hey how did you do that pan left with a rope ? lol Looked nice lol
Thanks! It's just an old Nikon 5100 with hacked firmware for manual control in vid mode. 50mm f1.8 lens - did the pans by hand, no rope this time, but I've used ropes before, even a drill and a skateboard.
It will make. 3.53 hp and will be a flatter diagonal line because it will only have one sweet spot at upper rpm. No science just remember what my reed valve lawn mower engine was like. I would really like to see exactly the same compression ratio used too.
sent ya a email with links to those parts the carbon fiber reeds only thing diffrent With spacing the jug up 2mm going to say 5.3hp with a big jump down low in torque.
Too many variables...Around 5.5 HP. slight gains to be had with port matching. Without knowing lower and upper limits of piston travel and where the ports are it's a shot in the dark at best. Lower blow down pressure will hurt it significantly. As it sits with the parts you have right now, i doubt that it will make even 4 HP - 3.8 HP is my forced answer.....Why? Gut feeling....
The new piston was too tall and his solution is to make a spacer to fit between the cylinder and cylinder head? Wouldn't a taller piston also be cutting off the intake and exhaust ports a bit also? I've got to be missing something. I'll watch the video again.
Hey ! :) So i seized the engine the other day by tightening the rods holding the engine head. It pushed aluminium into crankcase and pushed against the crank, making it seized :) Why do I tell it to you ? When making the engine run again, i could clearly feel how unbalanced the crank is :) :) I knew it was off because of the vibrations while running, but being able to see how bad it is was laughable. :) Anyway, could you show how to center the motorized bike crank ? You did it with other cranks, but this one is different. It is all round and instead of the flat places at bottom they just drilled holes in it. :) Thanks! :)
+2STROKE STUFFING thanks. 😊 Any tips for how to hit it with a hammer, when it's all round? I really have to make it run true. I'm not gonna do it now, but it defentely has to be done at some point. 😊
if you use the same piston holed, id say the increase in hp is not very big, my money is on the low end band, but it depends on the thickness of those reeds. 0.3 HP more maybe. I have a question for you: are you willing to do a video testing the compressed air duster to cool off main bearings and a crank rod main pin before instalation and some hard runs on the dyno to see if this shrinkage will affect those parts? i havent seen you assembling a crank rod, have you done it? thkx
I've done cranks when I worked in a shop a few years back, but never since(mostly due to the lack of a powerful press). I don't think cooling can have any noticeable permanent effect on the steel in bearings or crank pins.
More power low to mid.. I dont think it will rev fast enough to over power the reeds anyways but you never no.. you made 4.4hp in pretty sure so I'll go 6.2hp what's unreal.. can wait to hear the sound difference
With no changes other than the addition of reeds I expect better power when "off the pipe", that is to say better power down low and through the lower midrange and maybe beyond that depending on the characteristics of that engine when it doesn't have reeds. At some point the non-reed motor will probably make more power as rpms increase. Reeds help to reduce blowback at lower rpms thus increasing power there but they tend to restrict flow st higher rpms thus reducing peak power somewhat. Other changes are being made to this engine so a direct comparison does not seem to be possible here.
