My Daily Driver

[vwine]

This bike is my daily driver, it is a fully stock setup. I did drill the hole in the carburetor as reccomended by somebody on this site. That is the only modification I did. I love it. I have been driving this bike for about 3 weeks. I am on my 3rd gallon of gas, so Im around the breakin stage still.
It tops out at 23 mph and then makes a wierd bogging sound. IT sounds like it could go faster, but not sure ( may be the crappy stock sparkplug), I have ordered a cone airfilter, inline fuel filiter, and Gorrila bars, which are on the way right now. I will get an NGK sparkplug soon (stationed in germany, nothing here is convenient) My exhaust is rusting.. (salt on roads) I do also plan on getting an expansion exhaust from whoever ships APO. I know its not as great as most peoples, but its my first build and it runs great.

 

[2door]

Curious. How do the laws treat motorbikes in Germany? I assume you're American military? If so, does that make a difference in the legality of motorized bicycles in 'der Father Land' ?
By the way, that's a good looking bike and congratulations on a successful build. What fuel mix are you using? If over 32:1, try lowering the oil content and see if it doesn't start to run a little better for you. Keep in touch.
Tom

 

[vwine]

hey tom,
Well, I found out these are for sure completely illegal here.
On post, the MP (military police) can care less, as long as I am not acting a fool.
They see me all the time and wave, or check out the bike. I do live off post, but only about .5 miles from the gate, so I make it to work safely without worrying about Polizie. There may be a way to get a license for this thing, or register it legally, but I honestly am not worried about it, As military we ALWAYS get warnings... And Ive yet to be warned.
I dont know my mixture ratio, I just put one of the little bottles of 2 cycle oil into 1 gallon and shake it. lol....However accrording to my spark plug its running Great. I was shocked to check my plug and see the color was perfect. a few minutes ago, i added a performance plug cap, Dunno if that will make a difference, but it was cheap so i figured why not... Thanks for the comment. I like my bike too.

 

[vwine]

Curious. How do the laws treat motorbikes in Germany? I assume you're American military? If so, does that make a difference in the legality of motorized bicycles in 'der Father Land' ?
By the way, that's a good looking bike and congratulations on a successful build. What fuel mix are you using? If over 32:1, try lowering the oil content and see if it doesn't start to run a little better for you. Keep in touch.
Tom

I came across this on wikipedia..

German law has two categories for mopeds. The first and slower category is the so called Mofa, with a maximum design speed of no more than 25 km/h (16 mph) and only the driver is allowed on the bike, no passenger. Minimum age is 15 and no license is required, but a written test has to be completed.
The second category is the Moped, with a maximum design speed of 45 km/h (28 mph), mimimum age is 16, a drivers license is required, one passenger is allowed if the moped or scooter is certified for a passenger. Both types need an insurer issued license plate, which is much smaller than regular state issued plates, which have to be renewed every 12 months, changing the color of the plates every year. Since a 16-year-old can now drive a 125 cc (7.6 cu in) (80 km/h (50 mph)) bike, and scooters in the "moped" category allow for transporting a passenger comfortably, mopeds, since they have less power, appeal, and space, have almost disappeared as a result of the new E.U. laws. Most teens that don't have the money for the costly A1 driver's license (1st step towards the full motorcycle license), which allows them to drive a 125 cc (7.6 cu in) (80 km/h (50 mph)) scooter or motorcycle, go for the less expensive AM driver's license, which allows them to drive a moped or scooter with a maximum speed of 45 km/h (28 mph), but less than 1% chose a moped over a scooter based bike. Modern scooter design and amenities have effectively changed how teens chose their first set of wheels in Germany

 

[vwine]

Four US fl oz to one gallon is 32:1. Not sure if you're getting bottles in imperial or metric units there. Here's a good calculator: Gas Oil Mixture Ratio Calculator

I bought a gallon of 2cyc oil a while back, so I don't even remember what size the "little bottles" are. From looking online, it varies depending on the brand. Even if your engine runs perfectly on what you're mixing without measuring, it's good to measure what you have mixed, so you know in case you want to tweak one way or the other. Little tweaks like fuel mix can have a very noticeable effect on engines this small.

hey, thanks for the information. That makes since. The oil bottles i put in are 2.6 ounces of oil to 1 gallon of Gasoline.... so by the calculator link you sent me that would be...50:1......oo.. sounds off huh... would that explain why it boggs out at high RPM and speed? So what is recommended exactly?

 

[wheelbender6]

Cool. Looks like a great way to get to the hofbrau.

 

[vwine]

vwine, a 2 cycle will run absolutely great on straight gas with no oil - just not for very long before it seizes. For these, I generally see recommendations of 32:1 to 40:1 when using generic 2 cycle oil. High performance synthetics can offer good lubrication at smaller ratios, and there's threads around with people running 100:1 with the expensive stuff.

Bogging at high speed ... I have to put some thought to that. Any little thing you change - fuel mix, needle setting, jet size, exhaust flow - all that is going to change the fuel-air mix, and how much of that is able to get into the cylinder to be combusted, and how much of that stays in the cylinder to be combusted.

Changing the throttle needle height isn't going to lean/rich the fuel much at WOT; that's for idle and midrange. I'm going to hazard a guess that you're too lean at WOT; if you were too rich, I'd think it would four-stroke instead of bogging.

The stock exhaust is restrictive. You can get a little more power out of the engine by drilling some holes in the stinger tube inside the end of the pipe, or through the end of the pipe cap if you have a flat pipe end. If this bike has a bunch of miles on it, and this condition has gotten worse over time, pull the silencer out of the muffler and see how gunked up with carbon it is. You can clean it with hot hot fire, or try and knock some of it out.

From the looks of your pipe, you've been riding this machine a while. I'd look into opening up that exhaust a bit, either by cleaning it, drilling it out, or both.

NOUGAT, thanks for putting so much thought into my bike.
The exhaust does make it look old.. but its about 3 weeks old. lol Germany uses ALOT of salt on the roads.. I have however recently sanded it and repainted it.. so it lookds better.
I also removed the baffles and muffler cap... bored the exhaust and intake and got an NGK spark plug. I did a pretty clean job on the boring it out., took it out for a spin yesterday, It topped out at 29 MPH... Thats Great compared to my 23.. I think 29 mph is where my engine is ment to ride. Even though it still does that bogging out noise... it strange... but 29-30 is fast enough for me.

 

[vwine]

If it's only three weeks old, do change your fuel mix to 32:1. You're probably past the point where running extra oil for break-in would matter, but 32:1 will ensure that you'll get more miles out of the engine than 50:1.

As far as the muffler cap is concerned, I would put that back on. Baffles out should help. If you're still not quite happy, you can drill a couple holes in the cap. You do want some backpressure. If you really want to play with the exhaust, see if you can get an expansion pipe, and wrap the whole thing in heat tape to keep the rust away from it.

Edit: that bogging out noise ... can you describe it? If it just feels like the engine drops in revs, that would be lean. If it sounds like the engine is running rough, that's four stroking, which would be rich. And you'll get four stroking if you open up the throttle all the way when you're not going very fast, because the engine doesn't rev up fast enough to use all the air-fuel that's coming in.

hey,
I will change the oil mixture next time i ride out what I have in there. I will also put the muffler cap back on, I wasnt thinking about backpressure. I am getting an expansion muffler as soon as i find someone that sells them to ship APO (military address in germany) piston bikes ships apo, but dont have them... It drops in revs... with a wierd constant lower rev sound........but then it will gain back up for a second, and then bogg out again.... It can go faster, it wants to, i can tell. (this only happens at max speed.

 

[Vistaman73]

Im with Nougat, that engine does not look flush to the tube. Make sure its flush or else you will have problems later on. Nice build by the way. Thank you for serving in the military.

 

[pre-war Schwinn]

Since You do often drive your bike, and it is a short hop to work. plus You wish not to show off... It well be smart to run leanl(Less product in your gallon of gas).
I imagine that if you had an rpm gauge, you would be able to calculate the exact point of bogging to an rpm number.
EPA and CARB approved motors are "retarded" so there is a trade off in performance. I'm pretty good at hearing the difference in the rapid recovery of a motor when stomped on. Which can lead to the optimum point of spark vs tdc. X rpm. a well tuned engine takes a hint and tugs at the bit a little,.causing the driver to allow it to pull out from a stop without much throttle. If a motor bogs at a low rpm, it would be rich or dirty, Alias, not enough air.
If a motor bogs out at high rpm on a flat road, it is starving out.
That Hole drilled in the carb will ensure a extra bit of Air to be present at all times. but if its too big of a hole it deters the compression needed to suck the fuel in. Gravity feed.
I am going to propose a solution of which I have first had experience.
I had a JAWA two stroke bike made behind the Iron curtain in the 1960's. Guys loved the super pick-up and ability to run in filthy dirty conditions.
I on the other hand, wanted to ride long distances and TRAVEL!
I would start out fine but bog and nearly kill the engine at the ten mile point, while Riding down Venice Blvd.
I'd have to pull over and take off my carb to look in there and check for dirt. I sensed that the fuel was restricted at certain rpms
I was only 17 and had driven other bikes, like the Honda 90,,plus my Dad sold Bike's in Hollywood,
So I was stumped every time that issue came up ,yet I could only make it run-right by dis-assembly
My Headlight bucket was broken so I needed to find a Jawa Parts place. To get a few things when there I asked the guy about my situation.
His answer was Spot On!!!!!!!!! he said " You have no other end (ventilation)" So the gas flow slows down during continuous operation and eventually stops due to Vapor Lock.
He told me to Drill a Hole in my Gas Cap. This I did and $Poof$ I eliminated that issue.
I've never looked back. That was 43 years ago, but I bet You it is a strong possibility in your case. I hope YOu will look into it , drill a pin hole in your gas cap! just because of my first person story, I left out the cussing the Throwing things and the fact that the tank caught fire one time.As I matured inside the mechanical check lists I run in my head always start with Fuel Flow