Scott.D.Lang
Member
that piston on a dax bottom end with the arrow big top end and that piston would be kick ass
Is there any other piston that will work with this engine?
- Thread starter mrfubs
- Start date
mew905
New Member
I'm excited to hear how the whole thing runs. The added compression would be crazy, but I am a bit worried it'll hit the head once warmed up. Also looking forward to hearing about the balance. Do you have a link to where you got the tools to do your ports? I've been looking for a way to do them more quickly, my 1/4" rotary cutter bit gets so dull after raising the exhaust port a bit its virtually useless for a full port job.
mrfubs
Member
im very confident on the added longevity of the cyl. that piston should add as far as how it will run? **** i hope like a raped ape! i hope i didnt over port the transfer and may cause "short circuiting" with out a power valve. but lets hope not!
And sure thing pal.
this is the main bit iv used on 3 cylinders and still cuts like new due to the double cutter cutting pattern on the bit.
http://www.amazon.com/Shank-Double-Cut-Carbide-Grinding-Burr/dp/B005LVRCIQ
OR you can just buy this set and will last you a good while and have a great variety!
http://www.ebay.com/itm/10-Tungsten...remel-Rotary-Tool-Drill-Bit-New-/330752153839
I cant seem to find the other set i bought they where all 1/8 bits or even smaller to get into tight corners, i bought on ebay for $12 for like 6 i believe where called high speed cutters. Any way those double cutters will remove as much materiel as you want with out dulling.
And sure thing pal.
this is the main bit iv used on 3 cylinders and still cuts like new due to the double cutter cutting pattern on the bit.
http://www.amazon.com/Shank-Double-Cut-Carbide-Grinding-Burr/dp/B005LVRCIQ
OR you can just buy this set and will last you a good while and have a great variety!
http://www.ebay.com/itm/10-Tungsten...remel-Rotary-Tool-Drill-Bit-New-/330752153839
I cant seem to find the other set i bought they where all 1/8 bits or even smaller to get into tight corners, i bought on ebay for $12 for like 6 i believe where called high speed cutters. Any way those double cutters will remove as much materiel as you want with out dulling.
mew905
New Member
thats awesome, mine are just single cutters and get dull really quickly, those would definitely speed things up, looks like they'll cut our aluminum like butter! As for short circuiting, it's a real possibility with how open those ports are. Just make sure the transfers are dead even, and I imagine you'll be fine, these motors short-circuit like crazy out of the box anyway (having the motor apart, I bet you noticed the transfers are actually partly aimed toward the exhaust!) Rather than filling with JB and restricting flow, reshaping the whole transfer will allow more flow AND let you correct it! win-win.
mrfubs
Member
ohhh yeah! the double cutters tear that chrome wall up with no problem, and as soon as they hit the raw aluminum they really start digging! Also the single cutters get clogged with access metal in short order. I have a single cutter round bit and a double cutter, talk about a night and day difference.. i use the double cutters when i need to remove a 1/8 inch or more of materiel anything less i use single cutters and the single mini-ish high speed cutters to get the sharp corners.
I have the transfers dead nuts even on both sides, from the factory one port was like 3mm lower than the other... thats some serious torque loss in the high R's.
My transfers where pointing toward the intake port stock. on my previous build i had that 3rd T port added remember? well this new cyl is not running a 3rd t port, i want to see what difference i will notice.
from cylinder to cylinder the one on my current bike has way way less T port work than my brand new one and still resemble the stock pointing towards the intake.
Anyway i think that the only thing will happen is the powerband will kick in at a higher rpm. Once that scavenge of fuel reaches the tuned part of the yz80 pipe it will kick ass!
i have some more porting advice ill have to take a pic in a few to show you what i mean.
I have the transfers dead nuts even on both sides, from the factory one port was like 3mm lower than the other... thats some serious torque loss in the high R's.
My transfers where pointing toward the intake port stock. on my previous build i had that 3rd T port added remember? well this new cyl is not running a 3rd t port, i want to see what difference i will notice.
from cylinder to cylinder the one on my current bike has way way less T port work than my brand new one and still resemble the stock pointing towards the intake.
Anyway i think that the only thing will happen is the powerband will kick in at a higher rpm. Once that scavenge of fuel reaches the tuned part of the yz80 pipe it will kick ass!
i have some more porting advice ill have to take a pic in a few to show you what i mean.
mrfubs
Member
Alright so your going to wanna sharpen the wall on the T port sides of the base of the cyl. You can see the first pic on my junk cyl that the cyl wall is jagged and not smooth or arrow dynamically sharp.
With the base of the T ports ported as well with the case ported the same will gain a lot better flow and more.
I also have a pic of a weed eater engine cylinder to show that there isn't even wall in between the T ports.
With the base of the T ports ported as well with the case ported the same will gain a lot better flow and more.
I also have a pic of a weed eater engine cylinder to show that there isn't even wall in between the T ports.
mew905
New Member
Wow, out of the box your transfers are better than mine. Mine point about 10-15 degrees toward the exhaust on the exhaust side (intake side is good though). Your corrected transfers are much larger and at a better angle now, I bet that thing screams compared to stock, especially with that giant exhaust port. I was actually considering removing the transfer walls in order to gain more flow but apparently the disturbance from the piston would just screw up the flow, not to mention the transfers arent completely uncovered anyway so it wouldnt do anything for me. What sort of intake are you using? You said you run a YZ80 pipe, but if you're using a stock carb/intake you could probably gain a ton with a larger carb, and even more top end with some arrow reeds and a boost port
mrfubs
Member
Well I'm really hoping it really it performs as well as it looks! And as far as carburetor I'm using the CNS that is 16mm and jetted almost to the max. Went from a 70 main jet all the way to a 92! So to answer you question it is not the stock carb, and I've done mods to the carb to make it perform the way it should. The CNS is a great carb, everyone doesn't like it because they expect to do no jetting or adjustments.?
mrfubs
Member
Unfortunately this is what happened when i first started it, about a minute of running it... cyl was well lubed so there was no dry start. I may have revved it too high too soon. My mistake so now i gotta get yet another cylinder and do it all over again! yay!
Is there no such thing as nikasil plating in china?
mew905
New Member
Ouch man, the rings are good though?? That looks like something snagged and got dragged along the cylinder. Maybe note the ring gap positions and see where they line up with the ports, perhaps they're different than ours (ours are designed so they dont run by any ports, maybe your exhaust port is too big?)
Then again it's hard to tell, my cylinder has markings similar to that, but they're mostly aesthetic. The motor doesnt run anymore?
mrfubs
Member
The engine ran just fine! i shut it off and just pulled the head off for the **** of it and seen that! and nope all my ports where chamferd really well. Thats not the only spot it did that there are other spots 1/8 to a 1/4" wide. My other motor has a 95% better looking cyl than this one with 1 min and it only has 7 Hrs on it.
The piston ring gaps are located in the same spots on the piston as ours.
This shouldnt have happend even if i revved it a little more than i should have...
Just comes to show they are really thinly plated and you have to keep the R's 3g and under untill the wall has formed a glaze on it. It was not entirely my fault most had to with thin wall plating and i was anxious to hear it run!
Im going to try and get a replacement cyl from warranty with any luck but well see how that goes lol...
The piston ring gaps are located in the same spots on the piston as ours.
This shouldnt have happend even if i revved it a little more than i should have...
Just comes to show they are really thinly plated and you have to keep the R's 3g and under untill the wall has formed a glaze on it. It was not entirely my fault most had to with thin wall plating and i was anxious to hear it run!
Im going to try and get a replacement cyl from warranty with any luck but well see how that goes lol...
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48ccbiker
New Member
I found some non-plated rings (Motobecane 47mm Airsal Piston Ring) from 1977mopeds.com that should fir the Hoca Minarelli piston and told them about the chrome-on-chrome problem and this is what they said:
"That ring (Motobecane) is not chrome plated.
Normally chrome plated rings are to be used in aluminum lined cylinders. These bicycle engine cylinders are normally lined with nikasil (a very hard very thin coating).
Uncoated rings like the Motobecane are normally used with cast iron cylinders (uncoated). That is not to say that it will not work and is probably worth a shot. However it might not be the piston rings that are the issue in this situation but it might be a cheap coating on the cylinders that is the cause of the issues.
"That ring (Motobecane) is not chrome plated.
Normally chrome plated rings are to be used in aluminum lined cylinders. These bicycle engine cylinders are normally lined with nikasil (a very hard very thin coating).
Uncoated rings like the Motobecane are normally used with cast iron cylinders (uncoated). That is not to say that it will not work and is probably worth a shot. However it might not be the piston rings that are the issue in this situation but it might be a cheap coating on the cylinders that is the cause of the issues.
mew905
New Member
I wonder if you used a different cylinder if you could put that piston to use. Here's one that Foureasy used to get 5hp.
https://www.treatland.tv/puch-gilardoni-74cc-cylinder-reed-kit-p/puch-gilardoni-74cc-with-head.htm
Apparently they randomly send you a 24mm or 19mm intake version (I imagine that's reed manifold I.D.), but you can pick up a 19mm Dellorto PHBG for $45 to complete the deal. Being a real, high performance cylinder with the proper bore size, you should be able to use the Hoca piston, and have no issues with the plating (The provided piston uses a 12mm wrist pin, and unless you can ream and bush your crank rod, it'd just be easier to use the Hoca). All you'd need to do in terms of manual labor to make it work is perhaps spacing out the mounting holes a bit more, and using a dremel to open up the transfer ramps in the case to match. Could be worth it
https://www.treatland.tv/puch-gilardoni-74cc-cylinder-reed-kit-p/puch-gilardoni-74cc-with-head.htm
Apparently they randomly send you a 24mm or 19mm intake version (I imagine that's reed manifold I.D.), but you can pick up a 19mm Dellorto PHBG for $45 to complete the deal. Being a real, high performance cylinder with the proper bore size, you should be able to use the Hoca piston, and have no issues with the plating (The provided piston uses a 12mm wrist pin, and unless you can ream and bush your crank rod, it'd just be easier to use the Hoca). All you'd need to do in terms of manual labor to make it work is perhaps spacing out the mounting holes a bit more, and using a dremel to open up the transfer ramps in the case to match. Could be worth it