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 Post subject: Two Stroke Development
PostPosted: Tue Feb 07, 2012 6:42 pm 

Joined: Mon Feb 06, 2012 12:08 pm
Posts: 22
Location: New Berlin, WI
I first want to thank Jim Hobbs as I emailed him the other day looking for advice on welding expansion chambers and he was kind enough to supply me with a good bit of knowledge on the subject. I don't normally post on forums much anymore and sort of lost track of this one as I didn't know it had moved but in our discussion he thought some of you might like to see what I'm working on which brings me to my first post on the new board.

I'm currently going to school in Swansea, Wales and am studying motorcycle engineering and engine design. I'm in my second year of a three year program and have always loved two-strokes. I joined the KTW board in 2009 when I was 20 and got my first Triple, a 1975 H2C. That bike taught me a lot as I restored it and I still have it. Unfortunately it fell over a couple fourth of July's ago and the tank was dented so I need to repaint it. The engine isn't tuned to my liking either and I'd like to make a new set of pipes for it, machine the heads, add some piston coatings to the pistons, and do some port work to it so it hasn't gotten ridden as much as I had thought it would in the past couple of years. In other words its been sitting.

Here's what that bike looked like after I finished it.
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During my first year of university last year I decided I wanted to design a bike and attempt to build it over the summer so in my spare time I did a lot of reading on the subject, CAD work, and brainstorming. I've always liked the KR750s and wish I could have one so I decided to design my first bike to resemble the KR. I started ordering parts before I came home for xmas and when I got home I modeled all the parts I'd bought in my CAD program. I have a spare H2 that is in parts so I was able to model the engine components from that as well. What I ended up with was this.

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I've got all the jigs designed for it and know exactly how to go about making it however the molds for the tank, fairing, and tail would have cost a lot to make so I decided to put this build on hold until I've graduated and have more money. I originally intended to race the bike as well but the class structure was not all that favorable for the old H2 engine. That got me thinking and I looked into the class structures closely to see where I could get the biggest advantage. I race in the CRA (Central Roadrace Association) and the ultralight class seemed like a good choice as it was open to unlimited singles no matter two or four-stroke. In the GP class I would be facing supermoto type bikes and Ducati Monster 620s for the most part. I could also bump up and run in the lightweight class (SV650s, Ninja 650s) and maybe even middleweight (600c I4s) if I'm lucky.

So I started the design process again! This time I made sure every component I designed I could make for myself. I chose to use a KX500 dirt bike engine as I have ridden the dirt bike and was quite impressed with the power they produce. With the modifications I intended to make to the engine I was expecting around 80-100hp in a bike that will weigh around 200lbs. I've had the engine running however I haven't tuned it or dynoed it yet so the power output is still a secret. Fortunately, where I'll be working over the summer there are an abundance of dynos so I should be able to get it tuned pretty well.

I've done an entire build thread at kxriders.com if anyone is interested in the whole process however you'll probably have to sign up as it is in a members only topic.

Here is where I'm at now. As you can see my pipe welding skills are not quite as good as Jim's yet, however I think Jim and I have figured out the problem (mostly cone fitment, some small changes to welder settings) so hopefully the next one will be a bit better. I think I've got about 2-3 weeks left of work on it before it's finished and ready for racing.

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As you can tell a lot of changes have been made from the first CAD rendering to what's near enough the final bike. I originally never intended to make my own fairings or swingarm. Things just sort of turned out that way so I did quite a bit of hasty CAD work over the summer to incorporate those new components.

All the build photos can be seen at: http://s1133.photobucket.com/albums/m58 ... e%20Build/
You'll have to start on the last page of the album and work forward in order for it to make sense.

I've also got a website (it's no longer very current) where some more H2R photos can be seen.
http://olesenmoto.com/

When I'm not busy with school work my current little project I'm getting ready for the summer will be to convert the 500 single to fuel injection. I originally thought I wanted to take the leap to direct injection right away however after learning quite a bit about it I think I'll be going to port injection first. A full on big bore race motor is probably not an ideal candidate for my first direct injection project as parts are becoming more expensive and with over 200 degrees of exhaust duration it will never be all that clean. I plan on getting the port injection figured out and then converting another engine to DI. I'm not sure what yet but it will certainly be something that has more market potential and is more capable of passing an emissions test.

Feel free to ask any questions or post any comments you may have. I'll do my best to answer them when I have time as the board has been very helpful to me over the years. I wish I had more time to mess with triples now but my interest in improving the cleanliness of the two stroke and developing new bikes has taken up the majority of my free time. I truly believe that with a little development the two-stroke could make a comeback to the streets.

Paul


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PostPosted: Tue Feb 07, 2012 6:56 pm 
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Joined: Wed Jun 08, 2011 11:34 pm
Posts: 10000
Location: North Central NC
Thanks for posting the photos and description, Paul. I know I won't be the only one following your progress.

Why is the expansion chamber so convoluted?

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PostPosted: Tue Feb 07, 2012 6:59 pm 
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Glad you found us, although Jim is a questionable cohort..... :lol: (J/K)

Great post, please keep us updated! :thumbup:

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........


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PostPosted: Tue Feb 07, 2012 9:47 pm 
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Really good stuff.....thX for sharing !

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Busy doing more riding than wrenching.......


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PostPosted: Tue Feb 07, 2012 10:46 pm 
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Location: Just north of Toronto, Ontario
Very nice work! What are you using for cad software?

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PostPosted: Wed Feb 08, 2012 4:12 am 

Joined: Fri Aug 19, 2011 3:15 am
Posts: 224
Location: Kingdom of the Netherlands
Very impressive project! Re injection, this site may give you one or two ideas, even if it's about a Yamaha RZ350: http://www.smcomp.com/~smurph/RZ-EFI/index.html
The Yamaha 600 throttle assembly may be a tad too small for a KX500 though and you may have to find something larger. I've thought about doing something similar to an H1 engine (about same cylinder size as the RZ's) but it's been nothing more than thinking so far.


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PostPosted: Wed Feb 08, 2012 9:22 am 
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Joined: Wed Jun 08, 2011 10:04 pm
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Location: Just north of Toronto, Ontario
Also wondering if you have done FEA on the frames you have created? I'd be interested to see some results if you have! I've done a bit of work with the stock 400 frame and it would be interesting to compare results.

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PostPosted: Wed Feb 08, 2012 12:58 pm 

Joined: Mon Feb 06, 2012 12:08 pm
Posts: 22
Location: New Berlin, WI
Jim wrote:
Thanks for posting the photos and description, Paul. I know I won't be the only one following your progress.

Why is the expansion chamber so convoluted?


Your welcome. Curving the pipe back and fourth came down to a packaging issue. I made one before that was pretty much straight and the widest part of the pipe stuck out to the side too much for my liking (see below). In the CAD model it looked like it had plenty of lean angle and in real life I wasn't sure so I decided to redesign it and try to fit the majority of the pipe right under the center of the frame. I'm a lot happier with the new one and the foot peg will scrape before the pipe. I think I can lean the bike over 55-60 degrees before I have any issues now.

Image


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PostPosted: Wed Feb 08, 2012 1:01 pm 

Joined: Mon Feb 06, 2012 12:08 pm
Posts: 22
Location: New Berlin, WI
Gerrit wrote:
Very impressive project! Re injection, this site may give you one or two ideas, even if it's about a Yamaha RZ350: http://www.smcomp.com/~smurph/RZ-EFI/index.html
The Yamaha 600 throttle assembly may be a tad too small for a KX500 though and you may have to find something larger. I've thought about doing something similar to an H1 engine (about same cylinder size as the RZ's) but it's been nothing more than thinking so far.


Thanks for the link, it was a good read! I can't say for certain what I'll be using yet as far as parts go but the more info I have the better. Fuel injecting the triples has also crossed my mind.


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PostPosted: Wed Feb 08, 2012 1:04 pm 
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Location: North Central NC
PVO22 wrote:
I think I can lean the bike over 55-60 degrees before I have any issues now.

Definitely post photos of you doing that while actually riding. :P

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