Stroker Questions
- Thread starter wwholden
- Start date
How is he green gasket junk? Looks heavy duty to me. Plus is what vitos ships their cranks with...
order yourself 2 OEM or Cometic gaskets and compare them to the green gaskets, you can clearly see the difference,
if i'm not mistaken, at least the OEM's(cometic?) are a coated metal gasket, not construction paper
couple that with the known number of green paper gasket failures, causing massive airleaks = frying top ends almost instantly,
2 attributed to yours truely
Ok I got some pics while I got the jug off again.
Green gasket was contacting crank case and aluminum was in contact with the jug. Green one ripped when removing the spacer. Im temporarily running an old gasket I had laying around.
And here is the swirly head I was talking about:
Green gasket was contacting crank case and aluminum was in contact with the jug. Green one ripped when removing the spacer. Im temporarily running an old gasket I had laying around.
And here is the swirly head I was talking about:
Blaner
Your Friendly South African Ambassador
Ok, I see a VESRAH conrod whioch is exactly what I run. that head is a farce, you are losing air velocity by forcing it into a spiral by making it travel a distance along a curve which is longer than it it is if it were straight, the result is that the air/fuel takes longer to effect its movement from the squish band to the combustion dome and similarly, the combustion takes longer to occur because of the angular nature which is forced upon the movement of the air.
As for the crank, that is STOCK. The reason for the spacer is to help raise the transfers and the exhaust port so that they become fully uncovered by the piston during the stroke,( which on a stock blaster they normally dont do) in essence this then allows greater port area as well as longer port duration. Also it improves/corrects the port timing! This setup is exactly what I run. PROVIDED you skim a calculated amount of material off the top of the barrel to cater for the spacer.
As for the crank, that is STOCK. The reason for the spacer is to help raise the transfers and the exhaust port so that they become fully uncovered by the piston during the stroke,( which on a stock blaster they normally dont do) in essence this then allows greater port area as well as longer port duration. Also it improves/corrects the port timing! This setup is exactly what I run. PROVIDED you skim a calculated amount of material off the top of the barrel to cater for the spacer.
Blaner
Your Friendly South African Ambassador
you do hower need a gasket on either side of that spacer. do me a favour: get hold of a vernier caliper and measure the thickness of the spacer, if im right, it should be 1mm thick and not 1.5mm thick.
My thoughts are that you have there a McDizzy style motor.
My thoughts are that you have there a McDizzy style motor.
Blaner
Your Friendly South African Ambassador
Quote from McDizzy:
Refinement
It became clear to me after running some numbers through the two-stroke software I'm evaluating for the other part of this article that I could obtain the target HP value I was shooting for by using a combination of a 1 mm thick aluminum base plate spacer and its required additional base gasket. This raises the barrel a total of 1.5 mm. Not only would it let the transfer ports become fully uncovered and increasing their time area, it would allow the piston edge to be completely below the exhaust port when it was at BDC. I never like it when a piston is always exposed to the hot exhaust gasses - never having a chance to get out of the hot exhaust stream to cool off like it should. It seems that even a small adjustment here could mean the difference between detonating and not. Designing the engine this way requires milling the deck of the barrel to compensate for the base plate spacer setup. Decking was already going to be done since I previously discovered the squish thickness was far too thick for good throttle response but now I can calculate exactly how much to remove because I know what the final port timing specs are going to be. With the cylinder raised to its final position the exhaust port now opens at 88.5° ATDC for a duration of 183°. The transfer ports now open at 116.5° ATDC for a duration of 127°.
Refinement
It became clear to me after running some numbers through the two-stroke software I'm evaluating for the other part of this article that I could obtain the target HP value I was shooting for by using a combination of a 1 mm thick aluminum base plate spacer and its required additional base gasket. This raises the barrel a total of 1.5 mm. Not only would it let the transfer ports become fully uncovered and increasing their time area, it would allow the piston edge to be completely below the exhaust port when it was at BDC. I never like it when a piston is always exposed to the hot exhaust gasses - never having a chance to get out of the hot exhaust stream to cool off like it should. It seems that even a small adjustment here could mean the difference between detonating and not. Designing the engine this way requires milling the deck of the barrel to compensate for the base plate spacer setup. Decking was already going to be done since I previously discovered the squish thickness was far too thick for good throttle response but now I can calculate exactly how much to remove because I know what the final port timing specs are going to be. With the cylinder raised to its final position the exhaust port now opens at 88.5° ATDC for a duration of 183°. The transfer ports now open at 116.5° ATDC for a duration of 127°.
Blaner
Your Friendly South African Ambassador
The following is a compilation of my reading and is loosely based on McDizzy's theory, some stuff is quaoted others are my thoughts.
PORT DURATION ISSUES.
It became clear to me after running some numbers through the two-stroke software I'm evaluating for the other part of this article that I could obtain the target HP value I was shooting for by using a combination of a 1 mm thick aluminum base plate spacer and its required additional base gasket. This raises the barrel a total of 1.5 mm. Not only would it let the transfer ports become fully uncovered and increasing their time area, it would allow the piston edge to be completely below the exhaust port when it was at BDC. I never like it when a piston is always exposed to the hot exhaust gasses - never having a chance to get out of the hot exhaust stream to cool off like it should. It seems that even a small adjustment here could mean the difference between detonating and not. Designing the engine this way requires milling the deck of the barrel to compensate for the base plate spacer setup. Decking was already going to be done since I previously discovered the squish thickness was far too thick for good throttle response but now I can calculate exactly how much to remove because I know what the final port timing specs are going to be.
THIS ENGINES PORT TIMING HAS BEEN DETERMINED AS BEING:
STOCK BLASTER:
Exhaust: Opens: 91.5 degrees (33mm below deck height) ATDC
Duration: 177 degree
Transfers: Opens: 119.5 degree ATDC
Duration: 121 degree
Boost Port: Opens: 125 degree ATDC
Duration: 110 degree
Blowdown: 28 degrees (from exhause port opening until first transfer opens)
WITH 1mm SPACER
Exhaust: Opens: 88.5 degrees (33mm below deck height) ATDC
Duration: 1183 degree
Transfers: Opens: 116.5 degree ATDC
Duration: 127 degree
Boost Port: Opens: 128 degree ATDC
Duration: 116 degree
Blowdown: 28 degrees (from exhause port opening until first transfer opens)
Graham Bells Performance Tuning Specifications,
EXHAUST DURATION:
NOTE: a 200cc motor is not included on his list but if you look, a raised barrel will put the duration specs (183degrees) well within range of a good setting, ie between a 175 and a 250 as opposed to 177degrees which according to the list is what a 1x400cc 2stroke needs....The same problem is found with all the ports, they are set to what would be a good setting for a 400cc 2stroke, well out of range of a high performance 200cc!
CC STYLE RPM EX Port Duration
175 enduro 9000 184-186
175 enduro 9500 186-188
250 enduro 8000 180-182
400 enduro 7000 175-177
PICS from MCDIZZY:
STOCK: note piston partially covering Exhaust and transfer ports...
The piston is installed on the rod in order to discover and record the port timing. I found it of particular interest that when the piston is located at BCD, it is still covering a little over a millimeter of the transfer port windows. Additionally the exhaust port was covered by the piston about 1/2 of that amount. I think it would be wise to raise this barrel if I was going to raise all of the ports for increased power. It seems as if it was designed that way in order to later be taken advantage of... Hmmm
1MM BASE PLATE ADDED
Inside the cylinder I noticed a much better port match as well as improved time area numbers. This area increase is necessary for improved output at higher rev levels
I like the way the piston aligns with the port floor at BDC after the changes. The bumpy area on the crown is actually grease left over after I sealed and CCed the head.
PORT DURATION ISSUES.
It became clear to me after running some numbers through the two-stroke software I'm evaluating for the other part of this article that I could obtain the target HP value I was shooting for by using a combination of a 1 mm thick aluminum base plate spacer and its required additional base gasket. This raises the barrel a total of 1.5 mm. Not only would it let the transfer ports become fully uncovered and increasing their time area, it would allow the piston edge to be completely below the exhaust port when it was at BDC. I never like it when a piston is always exposed to the hot exhaust gasses - never having a chance to get out of the hot exhaust stream to cool off like it should. It seems that even a small adjustment here could mean the difference between detonating and not. Designing the engine this way requires milling the deck of the barrel to compensate for the base plate spacer setup. Decking was already going to be done since I previously discovered the squish thickness was far too thick for good throttle response but now I can calculate exactly how much to remove because I know what the final port timing specs are going to be.
THIS ENGINES PORT TIMING HAS BEEN DETERMINED AS BEING:
STOCK BLASTER:
Exhaust: Opens: 91.5 degrees (33mm below deck height) ATDC
Duration: 177 degree
Transfers: Opens: 119.5 degree ATDC
Duration: 121 degree
Boost Port: Opens: 125 degree ATDC
Duration: 110 degree
Blowdown: 28 degrees (from exhause port opening until first transfer opens)
WITH 1mm SPACER
Exhaust: Opens: 88.5 degrees (33mm below deck height) ATDC
Duration: 1183 degree
Transfers: Opens: 116.5 degree ATDC
Duration: 127 degree
Boost Port: Opens: 128 degree ATDC
Duration: 116 degree
Blowdown: 28 degrees (from exhause port opening until first transfer opens)
Graham Bells Performance Tuning Specifications,
EXHAUST DURATION:
NOTE: a 200cc motor is not included on his list but if you look, a raised barrel will put the duration specs (183degrees) well within range of a good setting, ie between a 175 and a 250 as opposed to 177degrees which according to the list is what a 1x400cc 2stroke needs....The same problem is found with all the ports, they are set to what would be a good setting for a 400cc 2stroke, well out of range of a high performance 200cc!
CC STYLE RPM EX Port Duration
175 enduro 9000 184-186
175 enduro 9500 186-188
250 enduro 8000 180-182
400 enduro 7000 175-177
PICS from MCDIZZY:
STOCK: note piston partially covering Exhaust and transfer ports...
The piston is installed on the rod in order to discover and record the port timing. I found it of particular interest that when the piston is located at BCD, it is still covering a little over a millimeter of the transfer port windows. Additionally the exhaust port was covered by the piston about 1/2 of that amount. I think it would be wise to raise this barrel if I was going to raise all of the ports for increased power. It seems as if it was designed that way in order to later be taken advantage of... Hmmm
1MM BASE PLATE ADDED
Inside the cylinder I noticed a much better port match as well as improved time area numbers. This area increase is necessary for improved output at higher rev levels
I like the way the piston aligns with the port floor at BDC after the changes. The bumpy area on the crown is actually grease left over after I sealed and CCed the head.
Thanks so much Blaner for posting your knowlege on this engine setup! I will measure the spacer when I get home 10pm EST. Check back if you can. Ill have some questions.
Its just how the light is being reflected off the piston. No major scoring at all.
I cant see how everyone can be hating so much on these paper based gaskets. Ive been using them for years. Yeah Im sure their not the best but any gasket that makes a air/oil tight seal serves the same purpose.
Besides why would Vitos Performance be shipping that type of gasket with a brand new $200 stroker crank kit. Dont think they would want to upset their customers by providing them with junk!
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I measured the spacer. Its less than a mm. I got my caliper to read .8mm. Maybe by the time I add a gasket on both sides of the spacer I will get a total of 1mm?
Theres only one pic of the piston bro? Trust me its the lighting an the glazing of two stroke gas on it. The piston is fine. If anythings bad its the tolerance between the rings and the cylinder walls.
I've tried doing some research on the great info you gave me. However Im having difficulties understanding all this.
Does the concept of the McDizzy only include raising the port 1mm to get more port area? Or does it include the concept of the head and rod.
How can I tell if the deck has been skimmed to compensate for the spacer?
From what I read the Vesrah is just a aftermarket stock rod. Nothing special about it right?
This farce head... Can find anything about it. Was this something where you would ship your stock head somewhere to have it CNC milled? Does the concept actually work? Where are the power gains for it?
Thanks so much blaner. Cant wait to learn more about this theoryI:I
Blaner
Your Friendly South African Ambassador
ya the Vesrah rod is a stock replacement, stock stroke etc, nothing special.
If you read the info I posted there carefully, you will notice that acoording to the info I posted from Graham Bells tuning book, that the port timing of a stock blaster is equivalent to that of a well tuned single cylinder 400 cc two stroke!! this is why blasters have that tendancy to die out at high RPM and dont perform as well as most 2 strokes of the same engine size.
Then if you look at the port timings I posted which result from the 1mm spacer plate, you will notice they are within the range of what Graham Bell suggests are good port timings for a performance 200cc motor.
The only way to see if the deck has been skimmed is to measure the total cylinder height and compared it to a known stock one.
If you read the info I posted there carefully, you will notice that acoording to the info I posted from Graham Bells tuning book, that the port timing of a stock blaster is equivalent to that of a well tuned single cylinder 400 cc two stroke!! this is why blasters have that tendancy to die out at high RPM and dont perform as well as most 2 strokes of the same engine size.
Then if you look at the port timings I posted which result from the 1mm spacer plate, you will notice they are within the range of what Graham Bell suggests are good port timings for a performance 200cc motor.
The only way to see if the deck has been skimmed is to measure the total cylinder height and compared it to a known stock one.
What do you think about spacer only being .8mm. Is that alright?
Also where can I find info for this farce head?
Also where can I find info for this farce head?
Blaner
Your Friendly South African Ambassador
Well its probably compressed due to the torqueing of the base gaskets, it is also likely that it was originally 0.9mm thick as that is standard issue rolled aluminium plate, you dont get a 1mm unless its machined, my plate is actually also 0.9mm,
As for the head, im not sure if you understood, but what I meant by farce is that it is a scam, farce=joke/untruth. I dont see how that swirling/rifling helps. Im not sure where to find info on it either.
read this carefully: 1989 Blaster Engine Rebuild - Two-Stroke Software Review - Part 1
Also if you interested, search for Performance Tuning by Graham Bell and Two Stroke Tuners Handbook by Gorden Jennings, on google give them a read through, you will need some patience but they are very interesting!
As for the head, im not sure if you understood, but what I meant by farce is that it is a scam, farce=joke/untruth. I dont see how that swirling/rifling helps. Im not sure where to find info on it either.
read this carefully: 1989 Blaster Engine Rebuild - Two-Stroke Software Review - Part 1
Also if you interested, search for Performance Tuning by Graham Bell and Two Stroke Tuners Handbook by Gorden Jennings, on google give them a read through, you will need some patience but they are very interesting!
