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Heads and Cylinders All about your porting, compression, rings, cylinder and piston modifications to your bicycles engine

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  #21  
Old 08-15-2016, 01:49 AM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

The port arrangement with more thought out ports topped out at 49.25 on the same hill. But my tire pressure is kinda low in the front though tonight, has been leaking a bit , but has much more mid range and can actually sustain better flat ground speed. Average speed on flat ground is about 45 -46. It's a success I'd say since I'm definitely getting more useful power. As for VMB getting 54mph.. no idea how that's done because I've done everything I can think of.

EDIT: I totally forgot when I was putting her together I took note of the piston at BDC and the crown was blocking litterally half the transfer port. So I need to try Sbest suggestion of the second base gasket, also going to put maximum ammount of ramp on the piston I can get away with, anything to get that transfer port more open will likely give me a top end boost. Maybe even go as far as 3 base gaskets and no head gasket.

Last edited by StevenMain; 08-15-2016 at 02:05 AM.
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  #22  
Old 08-15-2016, 09:24 AM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Quote:
Originally Posted by sbest View Post
For a novice, that is very good advice Venice. Typically things only get worse if you touch the height.
This guy is clearly a novice.

Only experienced engine builders (who know how to use a degree wheel) should attempt altering the port heights.


Also to the OP... There have been lots of heated debates here over the use of JB Weld in the ports!!
The chances of it eventually coming loose & destroying the engine are almost certain!
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Last edited by Venice Motor Bikes; 08-15-2016 at 09:28 AM.
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  #23  
Old 08-15-2016, 01:48 PM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

VMB You're absolutely right I did not use a degree wheel while experimenting to find the upper rpm limit of the engine. WHY? Because if I picked a set of port durations and timings out of a book it wouldn't be experimenting! If I find what works I may find a way to adapt one of my automotive degree wheels to a 66 crankshaft so I can duplicate the port windows on a new cylinder which still has its chrome lining in-tact.

I think its funny that you take so much pride in knowing such a basic skill lol.

As for a "Novice" you likely have no idea who you're talking to. Here is the "Main and Martinets" 3,500 HP Blown Alcohol Dragster
Video:https://www.facebook.com/steven.main...6887954826695/


This car was co-owned and Operated between my Father Howard Main & Driver: Darvin Martinets. My job was to perform between round bottom end engine rebuilds each in under 2 hours.

Here is my personal Novice-Mobile my personal "street car" an 1,100 Rear Wheel Horespower LQ9 2002 Trans Am.




Video:https://youtu.be/cNnjzNPE058

Last edited by StevenMain; 08-15-2016 at 02:01 PM.
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  #24  
Old 08-15-2016, 03:39 PM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Sorry if I offended you, but I have to call BS!

I find it extremely hard to believe that someone who builds engines for his fathers Top Fuel team would have so little knowledge of how to make a simple engine like this go faster.

I also find it even harder to believe that someone with the skills (& access to tools) you're bragging to have, would ever do engine work that looks as bad as yours. (It looks like you did it with a hammer & chisel). :/


There's info all over the internet about port timing for 80cc engines. (Yamaha timing is what I used).

There's no big secret to making a 2-cycle engine go fast... Big carb, big ports (that are properly timed), proper ignition timing, properly set squish band, properly tuned 80cc expansion chamber pipe & proper gearing... (all of which my bike has).



I'm more than happy to help you & point you in the right direction, (we were all newbies once), but please don't brag about your 'big dog engine building skills' while asking newbie engine questions & posting pics of engine work that looks this amateur...

Quote:
Originally Posted by StevenMain View Post


This one is just to show the windowed piston, I have since ported the intake as pictured above.
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  #25  
Old 08-15-2016, 09:36 PM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

First off you cant identify that is NOT a Top Fuel Dragster. That is a Top Alcohol Blown Alcohol Dragster (B/AD), distinctly different. No Nitromethane, only Methanol, Screw Type Supercharger Vs Roots, Single Magneto and one plug per Cylinder, also we ran 460 Cubic inches on this particular Hemi. The opposite side of the same class is Nitro or A/Fuel dragsters which have No supercharger and run nitromethane, Dual Magnetos, and 16 plugs per cylinder. (A/Fuel). Neither of which are Top Fuel dragsters, our car covers the 1/4 mile in 5.2X seconds at 27X mph on a good pass, if it doesn't tire shake or pop a blower panel (we run 61PSI boost)

Much more affordable to run doesn't require all the full fledged maintenance of a Top Fuel dragster. Google Main and Martinets and find that **** all day.
Check my facebook.
https://www.facebook.com/steven.main.391

As for the dremel work on the cylinder yeah dude we don't a CNC machine, if we did I wouldn't drive 4 hours to use it on a 100 Dollar Chinese engine with a cylinder that has its bore all but wiped of Chrome plating and ready for scrap anyway, Im not going to get all DiVinci with the ****.

Right now Im away from home finishing flight training for my commercial pilot rating. I have nothing but the most basic hand tools with me and a dremel at the moment. This is my old certificate back in 2012 when I got my private pilot rating.


As for your running 56 MPH on a 30 tooth, there is a REALLY simple answer for that. You're full of it. It would have been more believable if you had done some radical port configuration which require fabrication on the jug and case, and had more like a 40 tooth or up and was spinning something like 14,000 RPM but the stock port configuration can never achieve that RPM due to the awfull version of Schnuerle system ports employed by the HT engine. This engine cannot produce the torque required at 9,500 ish RPMs to push a bike to 56 mph on level ground with a 30 Tooth sprocket. You can keep your "advice".

Last edited by StevenMain; 08-15-2016 at 09:53 PM.
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  #26  
Old 08-15-2016, 10:56 PM
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sbest sbest is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Actually Steve, I did get 41mph out of the 44t sprocket, and no gain even if downhill. If you figured through ratio and proportion, 60mph might actually be possible. I think there would be some losses along the way. I did it with a stock pipe as well. It took some careful jetting and adjusting. 35mph was easy, 40mph was not.

I'm with you on no need to polish to mirror smooth. I've done it and seen no gain over rough finish.

These motors are a wonderful place to try it to prove what works.
I hack and slash to try something new too.

I thought that crankcase stuffing job looked pretty good. I've used Devcon and JBWeld for years in 2 and 4 Stroke intakes with no problems.


My port work is not artistry but I get good speed and low end torque out of it. Lots of window area and aimed the right way. These picts are with stock base gasket and BDC and yeah, the ports are still covered:




It is like the motor is designed for a 41-43mm crank.
Extra basegaskets helped probably by increasing port area rather than timing.

Steve, keep plugging away, taking photos, and reporting results.
There is stuff to learn.

Steve (Best)
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Last edited by sbest; 08-15-2016 at 10:58 PM.
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  #27  
Old 08-15-2016, 11:02 PM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Oh im absolutely with you on there is stuff I could learn about. Im addicted to learning and this is my first two stroke project, but given advice like dont adjust port timing from that other member is just bad advice for someone who is obviously willing to yank apart a motor 25 times a week trying to eek out extra speed and rpm in his spare time. Yeah I remember we had a conversation a while back when I had a 44 tooth and 41 mph was my best as well at 9,733 rpm. It wasn't the rpm I couldn't believe, it's that a bicycle could cut through the air at 56mph on level ground. When speed is doubled, drag increases at a square (it's not linear) and aerodynamic drag is about 90% of the resistance applied to the bicycle that's like saying he has made 85% more torque at the same rpm with the 66cc HT. That's highly suspect. (Unless he was drafting a vehicle which makes it highly likely, but then not a true top speed.)

Last edited by StevenMain; 08-15-2016 at 11:25 PM.
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  #28  
Old 08-16-2016, 09:07 AM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default Re: 34 tooth swap, down hill, new personal best!

I've been building these engines since 2007, & there's plenty of proof all over the internet of bikes going even faster than mine... (so don't doubt someone just because you can't do it too).


Good luck with your experimenting 'big dog'.
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  #29  
Old 08-16-2016, 09:48 PM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default Re: 34 tooth swap, down hill, new personal best!

StevenMain... I want to offer a genuine apology for my rudeness... I'll be glad to give you some good tips on how to reach your goals.

The biggest single thing you can do is get a genuine 65-80cc motorcycle pipe (& be careful to keep the factory length)!
A good pipe will literally turn a properly built 5HP engine into a 9HP engine!




Again, my apologies!
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  #30  
Old 08-16-2016, 10:04 PM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

I had pretty much come to that conclusion earlier today when I put more ramp on my piston transfer sides, increasing even more duration, lowering compression, ruining proper squish and turning it into a dog. I'm going to port map my cylinder on paper and transfer all the measurements to a brand new cylinder (this one has 1,200 miles of very hard wide open all over riding and there is no chrome left)

This is my first two stroke project, I've never messed with such a small engine but my itch to tinker is getting the best of me while I'm stuck away from home.

Being called a novice really angered me because all of those thing I showed you are real. I am not a liar nor do I exaggerate. Even though a 2 stroke is rediculously more simple the principles which is uses to operate are much more complex, pressure differentials, blowdowns, and pressure waves have no place in 4 stroke operating principles.

Apologies accepted if you will accept mine.
My chamber is very long and narrow, It begins expanding quite soon after the exhaust and I figured it to be good for top end power but honestly I think it performs about as well as a stock pipe. I would like to replace it. Not having any way to fabricate stuff here is killing me.
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