2-Stroke Exhaust Question

[redroptop]

Ok, so this is way way way trickier than first thought.

Basically, what everyone has been saying from the start, straight pipes will work. However, for the power loss/reliability/coolness factor, it's not worth it.
So this brings us to the next chapter.

I want to build the smallest possible expansion chamber, so the pipe looks relatively straight.

In the reading, it explains that it must be 3.25~ times the size of the inlet pipe.

To keep going, I need to know the port timing on the exhaust. How do I find this info?

And xb33bsa, could you post a link to the software used to give me the info I need. If you have it. Or if someone else has it.

Once you get your head around it, it's interesting. I think it's brilliant how its all been figured out.

On the Pawn Stars husky, that's the only picture I've found of a 2stroke with a straight pipe.




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[xb33bsa]

you use a degree wheel to find port timing it is a simple procedure
the programs are quite common i googled this but cant speak for it
http://www.dragonfly75.com/motorbike/ECdesign.html

 

[redroptop]

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[Walms]

I want to build the smallest possible expansion chamber, so the pipe looks relatively straight.

In the reading, it explains that it must be 3.25~ times the size of the inlet pipe.

To keep going, I need to know the port timing on the exhaust. How do I find this info?


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I've built skinny pipes for a 400 triple that worked great. They only had a 63mm belly and make an excellent torque pipe.
Transfer duration is 115deg and exhaust is 168 deg on a stock Kawi 100

 

[deputy865]

Well, you guys might kill me.

Went to do some welding with a friend the other day and weigh some options on my exhaust. For fun, we threw up the old stock exhaust to see how it would look and I kind of fell in love with it. So I think I'll be going that route after all! I'll most likely put a different tip on at the end and the current exhaust you will see in the pictures below will NOT be used. The factory exhaust is filled with some sort of sludge, is rusty and just plain nasty. I'll be getting a new one from a new model. I'm wondering if the exhaust being this nasty is what was causing my bike to foul plugs out so much.. Hmmm..

Anyway, here is a picture since some of you were inquiring. This isn't the final stage, but you get the idea. The exhaust will look a tad different, the seat will be set in it's final resting place and of course I'll have some lights on there. Other than that and some touch up paint work, here it is!

My other project in the background (Lexus SC300, big single turbo) looking at the bike all jealous since it's been getting all the attention...

Shane

 

[xb33bsa]

cool ! once you get your new shocks and forks finished rebuilding it will have a much better stance as well
yes a plugged exhaust will foul z plug

 

[deputy865]

cool ! once you get your new shocks and forks finished rebuilding it will have a much better stance as well
yes a plugged exhaust will foul z plug

No shocks for me. I know it isn't traditional for a cafe bike, but I enjoy the stance it holds right now. The forks will be raised up ever so slightly though. I really like how low it is to the ground and as mentioned before, I won't be riding it far, so comfort was sacrificed a tad. The seat sure is comfy though! lol

Kind of a cafe bike/bobber/rat rod. Definitely different, but should turn some heads either way.

Shane

 

[xb33bsa]

you must have smooth roads ???
zero suspension on a short wheelbase bike with skinny tires will be very painful and really slow you down, literally, every bump/pothole or trying to avoid them will suck
hey but ride your own ride, i would suggest one of those plastic teeth anticracker deals to put in your mouf whenever you ride

 

[deputy865]

The area I will be frequenting with the bike is very smooth.

Still have all of my factory suspension though if I ever decide I want it!

Shane

 

[xb33bsa]

you could proly get away with 20psi or so in the tires just be sure and use some talc powder,liberally
glad to see you like the stock pipe
check the oil pump adjustement

 

[deputy865]

you could proly get away with 20psi or so in the tires just be sure and use some talc powder,liberally
glad to see you like the stock pipe
check the oil pump adjustement

You just brought up a great point....

If you notice, I don't have an oil reservoir. It never came with the bike when I got it in the first place. Going off of that, I didn't even know this bike had oil injection. Fancy stuff. Didn't even cross my mind!

Question is.. If I don't have the tank, can I just premix the gas and run it that way?

Shane

 

[xb33bsa]

there are some oil injection 2 strokes that do not do well with the pump removed they have a specific port to feed oil to the crank bearings
if your little bike has been running fine without one then i would say it is ok
get you some maxima 927 castor and run it 4oz to the gallon 32-1, you may need to fine tune the jetting, just be sure and do some proper full throttle plug chops

 

[deputy865]

there are some oil injection 2 strokes that do not do well with the pump removed they have a specific port to feed oil to the crank bearings
if your little bike has been running fine without one then i would say it is ok
get you some maxima 927 castor and run it 4oz to the gallon 32-1, you may need to fine tune the jetting, just be sure and do some proper full throttle plug chops

Will do.

The bike ran alright before, but I never rode it much at all before it got the tear down. Hasn't ran since, but I see no reason why it wouldn't.

Wondering if I should just buy or make an oil reservoir for it.....

Shane

 

[xb33bsa]

all that is missing is the tank ?
oil injection is def a better way to go
you can make the reservoir/tank just be sure it has a vented cap
you will need to use oil injection specific oil

 

[VonYinzer]

Jeez... As a guy who's owned and is finishing a hardtail chop... That seat w hard struts is going to kill ya. Better never hit a corner at speed that has any bumps.

 

[deputy865]

all that is missing is the tank ?
oil injection is def a better way to go
you can make the reservoir/tank just be sure it has a vented cap
you will need to use oil injection specific oil

I'll need to double check, but I'm pretty sure all that is missing is the reservoir. I'll take the cover off and check to see that the rest of it is there. Worst case, I can get a whole new pump and everything for under $30.

I jumped on a KE100 forum and asked to see if it is okay to run without the reservoir. Again, I'm thinking of aesthetics and I'm not so sure if I'll like the idea of a big ugly reservoir stuck on the side of my bike. If I have to, I'll suck it up and do it...

Then again, I didn't want the stock exhaust and look what I fell in love with haha

Shane

 

[xb33bsa]

heck 8-12 oz res is plenty big as long as you remember to top it off every time you put gas innit
you could disguise it as a can of PBR ;D

 

[VonYinzer]

Look up "turbo catch can" on ebay. All kinds of cool spun aluminum cans with multiple fittings. Very easy to convert into a small oil tank.

 

[VonYinzer]

http://m.ebay.com/itm/400699429276?nav=SEARCH

For example. Small, under $20 and even has a sight glass. Ill be using a similar one on my R5.

 

[VonYinzer]

One note... The plug you'll have to use as a fill is tiny, so carry some cheapo paper funnels in your pocket on longer rides.