Carburetor Questions

[lakehouse]

Thanks, Wheelman! I really appreciate the explanation. I guess I should brush up more on 2 strokes if I'm going to continue playing with them. I'm aware of expansion chamber exhaust systems, and that you can't just throw a piece if straight pipe on them and expect to gain more ponies out of your 2 stroke motor. I'm thankful that my air box is in tact, and all the pieces are there. How critical is the material that the air filter is made from, while we are on the subject? I read here someplace that one fella cut down a foam filter from a lawn mower, and I was thinking about doing the same thing. Or possibly even a ribbed, high quality HVAC filter cut to fit. Or should I try to ferret out an OEM filter somewhere? The aerodynamics of fuel/air flow of a 2 cycle motor is intriguing to me, and on paper, they don't look like they could ever run. I have been into outboard motors in the past, but that was just remove and replace sort of mechanicing. Fairly cut and dry IMHO. But trying to grab more HP like a lot of you guys are doing here is just unbelievable. So many horses from so few cc's! AWESOME!
Thanks for the shout, and I appreciate the "schooling". I owe you a cold brewski for that one!
Andy

[Wheelman-111]

Greetings:

You're welcome. It is apparent that you know your stuff from the clever strategies you invent and intelligent questions you ax-ted. I'll take that Pabst and drink to your health.

No Glory do I deserve; all the credit for amazing Specific Output goes to Signori Polini and Malossi, with the help of Phongeer. I just know how to pull it togther and apply correct torque to the fasteners. Mostly...

I cut my current filter from some foam packaging padding. Any/most Polyurethane will do, as long as it is oiled. I am using the OKO air box, modified to tuck inside Elite panels and skirt. I can do that because my OKO carb allows a proportionately much larger pilot jet choice.

Honda's PA carb doesn't easily let you enlarge the pilot, counting on the airbox. The stock Honda box has a smallish inlet, perhaps half the area of the carb mouth. That's what creates the negative intake pressure, sucking more fuel outta that tiny Pilot hole. Lose the box, lose that mist from the tiny hole. Open the throttle, vacuum drops still more, and the mixture goes too dry to burn. I think even a light spray puts the ratio way over to the Rich side.

[lakehouse]

Wheelman, I haven't even thought of PBR beer since I left Michigan almost 45 years ago. I didn't know if it was still being brewed or not. That was my fav when I was in college and "helped" me get through some courses. LOL

Thanks for the info on the technical and theoretical side of 2 stroke engines, and the compliment. Sounds like you know your stuff too. This is my true first venture into the world of playing with 2 stroke motors. I have always been a Honda advocate, as I have owned a total of 7 of them including this Elite that was given to me. It's amazing how many 2 stoke powered devices are sitting in my garage when I stop to think about it. From the chain saw, to the hedge trimmer, it now tallies five. And each take a different fuel/oil ratio. Never understood that one either. And when I had my bass boat with oil injection, OMC claimed it only used 100:1 at an idle, but somewhere between 20 and 25 to one at WOT under a load. Amazing!

Since in our chatting, you brought up (or I did) the subject of negative pressure. Do you think I would gain or harm anything by drilling a hole or two through the inside of the stock muffler? Or would that decrease the efficiency of the exhaust system? My scoot sat outside for so long that when I started to work on it, I could not get any air to flow through the system. NADA! ZIP! ZERO! Making a long story short, dirt dobbers had entered the exhaust outlet and impacted with their mud nest. A little poking and some water laced with dish soap cured that issue.

After lunch today, I'll venture out into the garage and bolt on the air box. Need the cover be in place also? I thought about doing it last night about the time you sent the latest response to me, but heavy eyes won out over anything else. I might take an early lunch, as I am dying to see if it makes a difference at all. It sure can't hurt. I'll do a follow up posting once I have tried that theory to let you know what happened.

Again, thanks for the advice and the info on 2 strokers. I wouldn't mind some day of building up a hot motor, and putting it into some kind of a frame/chassis. The engineering behind these scooters is amazing. Having owned a machine shop for 17 years, I really appreciate what went into them to appease the engineers, cosmetic designers, marketing, etc. and still comply with Federal regulations here. Smart people!

I'll keep my fingers crossed the first time I hit the start button after the air box is bolted back on. Only time will tell.

Andy

[noiseguy]

Airbox and cover need to both be in place with an element.

Now, based on above post, not sure if your idle jet is clear. If it's not, it will need to be to get running.

I sell filter elements cut to size and shipped for your bike in the For Sale section.

[lakehouse]

OK, here we go!

I bolted the air box, cover, and a bit of the filter and cranked it up. That only made things worse, and I couldn't get over about 2500 rpm tops, with no idle. I removed the filter, and it made no difference. Then I removed the cover, but left the box itself in place and connected. It ran just like it did without any air box connected. Plus it didn't matter if I had the bistarter plugged into the circuit or not. Overall, I doubt that I was getting a 5,000 rpm from the motor. And at that, it took about 4 to 5 seconds to reach that range. Then just for grins, I set my air compressor at about 30 psi with a blow gun attached. I sort of "supercharged" the motor, and it grabbed the rpm's like they were going to be outlawed! Sounded awesome and very spunky. So where do I get a supercharger for a 50cc engine? LOL To my way of thinking, that pretty much changes my thoughts of it running too lean, to a condition of running way too rich. And the depth of the bluish/white color of being a deep blue/white (or even grey) color of the exhaust when I was "supercharging" it diminished in intensity to a more normal color for this motor.

Now I am at a complete loss. And there is no doubt in my mind that the jet opening is like it was when it left the factory in every way, shape, or form. Unless someone who understands these motors better than I do (which is most of the members here, I think) can come up with something else to try, all I can do is wait on the new carb coming from Hong Kong. (I got notification that it was shipped yesterday, BTW.) I even checked to be sure that the throttle needle was in the correct detent too, which it is according to the shop manual. So I guess I can watch for it around Thanksgiving. No telling what I will discover when I bolt the clone on. I'll either be one happy camper, or at my wits end over this one. Maybe after a few hours of pushing a piece of 320 back and forth over plastic surfaces, I'll regain my enthusiasm to solve carburetor problems. I don't know of any way of leaning the mixture out, other than going to a smaller than original jet size. And I don't want to JB weld the jet closed and redrill. I don't have any spare jets to fool with anyway. I doubt that Holley or Quadrajet jets will interchange with a Honda! LOL

Think I'll go take a nap and wait for the carburetor fairy to whisper in my ear while I am asleep. But I won't hold my breath on that one either.

Later, my friend(s).

Andy

[Wheelman-111]

Greetings:

There's still the question of the missing part in the carburetor. Maybe Honda-san had some purpose for it?

[lakehouse]

That was my faux pas on that diffuser tube. When I first noticed to brass under the jet, I thought it was a pressed in tube for the throttle needle to ride in, so to speak. But, I can't remember if it was you or another member who said to put a drill in it and wiggle it back and forth, so I did. And lo and behold, it came out with a little wiggling. I didn't find any contamination in it, and was able to pass a copper wire through each of the 10 (I believe) holes drilled into the sides. After reassembly and mounting, it made no difference it the way it ran.

I have been wondering if it is possible to have somehow gotten communication between the bistarter fuel circuit and the main running fuel circuit causing a rich running condition? Since there is no change in the way it runs, whether or not the bistarter is in the carb and/or wired up and hot or not, it's just the same slow revving and no idle (or adjustment). I know that all the two stroke engines that I have, and currently do own, they are very cold natured, temperamental, and will not start from cold without the choke being on. Right now, that is not an issue for me. The bistarter can be sitting on my workbench, the motor cold from not being run in 12 or more hours, and even on a 40 degree day like this morning, it fires right up on the first or second crank. Or is that common on a Honda 2 stroke? If it is, they why even have a choking device? Or should I say, a fuel enrichening circuit?

So in a nutshell, all the original parts are there, and had I not hears the engine run like it should (except for being unable to maintain an idle rpm), I would haven't torn into the carb and got this snowball rolling downhill. But what slays me is the way it sounded and performed at half throttle, when I squirted some compressed air into the carb opening from a short distance. I was grinning from ear to ear just knowing a had a rich, and not a lean condition. Everything points to that.

Need to run and kill some dragons. Will be back mid afternoon though. If you prefer, email me at ajlakehome@yahoo.com or we could do a phone chat for more detailed (if possible) information if you have the time.

Andy

[Wheelman-111]

Greetings:

So if it isn't the carb, have you checked the Basics?
Compression test, Spark plug, Reed Valve (Might be onto something there...), Vacuum leak, Plugged-up muffler, and finally the position of the rotor on the right end of the crank. Once I installed one incorrectly. It ran fine at first, but over time it started running more and more poorly until finally it would barely start. Turns out that the Woodruff key wasn't in position when I thought I had torqued it down. The ignition timing just got further and further retarded...

[lakehouse]

Howdy again, Wheelman-111,

Always good to hear from you and your thoughts and suggestions. I'll try to cover all the basics that you afore mentioned;
COMPRESSION: Unfortunately my gage is out on loan at the moment, but I'm in the process of retrieving it. I know it may sound crude and grossly inaccurate, but placing my thumb over the spark plug hole give a good pressure indication with the electric starter. But that is at the top of my list. I believe these little engines run fairly low psi, unlike my Corvette with it's 10.5:1 rating.
SPARK PLUG: It is the correct part number, correct gap, and is brand new.
REED VALVE: Have not checked that. I didn't think that a rick condition would warrant that at all. AM I wrong here?
MUFFLER: I can manually blow through it from either end with very little, if any, major restrictions. Compressed air flows readily.
ROTOR: I have not got into that side of the motor at all. It is still virgin from the manufacturer. But I did have a Trail 70 (or maybe 90) many years ago that I bought for next to nothing b/c it wouldn't run at all. And like you said, an inexpensive Woodruff key solved that problem. I was just thankful that the keyway wasn't wallowed out. That would have been a different story all together.

I still get back to the fact that when I "shot" a bit of compressed air through an air nozzle near the carb intake, the rpm's took off like they were supposed to do. (Very impressive!) I cannot help but think, and don't know if it is even possible, that somehow, someway, there became constant communication path of the fuel channel for the bistarter, into the venturi, and is causing an over rich condition under all throttle settings, and choke phasing. I intend to let it sit for a few days, and get onto a different area of the scooter that need attention, mainly cosmetic. I just need to give my feeble brain a break, and it perhaps something will pop up. I'll take a compression test when I install a new fuel shutoff valve, and I have the gas tank removed.

But I do agree with you that I have to get back to basics, and make sure all systems are a go there. I think it will be extremely interesting to see what happens when the new carb is bolted on, filled with fuel, and cranked up. I'm almost paranoid to hit the starter button fearing the worst case scenario! Guess I'll just have to grow bigger "cahonis" at that time! LMAO

Thanks for the shout, and please keep in touch, watching for my next posting. Have a super weekend!

Andy

[lakehouse]

Just a quick update on the carburetor issue I am battling.

I removed the exhaust on the scooter to see if there is a washer tack welded into the opening of the exhaust pipe like I have read and have seen pictures of on a few threads posted here. Nope, no washer, or any signs that there ever was one. I just wanted to double check that issue, and while I had the exhaust off, I stuck my finger into the exhaust pipe. It came out blacker than the ace of spades, covered in soot! That, along with my other findings, removed any trace of doubt in my mind that I do have an over rich condition. Now the $64,000.00 question is, "Where is it coming from"? And please don't say it's coming from the gas tank! I KNOW that much! Give me a ;little credit, won'tcha please? LOL

I'll get back to chasing that demon sometime next week I think. Right now, I have too many irons in the fire to devote more time on it over the next few days. I'm still thinking on it, and won't quit until it is solved, or somehow avoided so it runs normally.

Again, holler at me if you have any brilliant theories or ideas that maybe I haven't tried yet. I think my new carb is somewhere in the Pacific islands by now on its way here. Wish I was with it! LOL

Andy

[Wheelman-111]

Greetings:

Sometimes a really bad float needle will overfill the bowl and make the mix hopelessly rich. However if that were the issue the carb would overflow and leak anytime the petcock was flowing.

[lakehouse]

And hello again to you too!

I agree. And this is not the case at all. In fact, the petcock is stuck in the open position (just opposite of what it was initially), and I would have a humongous puddle under the scooter. It is totally dry every time I have opened the garage in the past. The new petcock should be here Tuesday or Wednesday, BTW. When I pull the tank to replace it, I'll check the reed cage and reeds, and pull a compression test at the same time. I'm guessing that I should be pulling somewhere around 90 to 120 psi on the compression. Right? Also, I fired the motor up after pulling the exhaust off today, and it didn't make any difference in idling or pulling rpm's.....other than a lot of noise, of course!

Again, have a good, and safe, weekend. Keep your handlebars parallel to the road! (BIG GRIN!)

Andy

[lakehouse]

Here we go again with the fuel issues. But first, a few basic follow ups. I did end up pulling the intake off and checking out the reed valves/plate. Everything there looks to be normal with no visible obstructions or broken reeds. And while I had a few parts removed, I went ahead and pulled a compression test. With a cold motor, I got a 115psi reading. Needless to say, I was very pleased considering the circumstances of this poor little bike having to sit dormant for about 10 years. Therefore, I think I/we can eliminate those two areas as possibilities.

As I was asleep (sort of) and woke at my usual 2:00Am, give or take, I got to thinking what if there is a leak in the seal, or in the diaphragm itself, in the fuel shut off valve? (If you recall, I had written that the one that was on the scooter when I got it was stuck in the open position.) That would surely account for a too rich condition since it is exposed to a vacuum all the time while the engine is running, and has fuel in the chamber right next to it. The new one came in the mail today, and I guessed that one bigger than Dallas, as they say around here! When I pulled the old petcock off and sucked on the vacuum port, I got a small amount of gas into my mouth. Eureka, I thought! My problems are over. I couldn't put the scooter back together fast enough and get the battery hooked back up to give it a try. I hit the starter, and she popped right off and accelerated just like it should with no lags at all. But after about 30 to 45 seconds of running perfectly and me grinning like a Cheshire cat, it quit running. To top it off, it wouldn't restart. What's going on here? Am I on Candid Camera or something? Did someone cast an evil spell on this machine, or were the original builders getting even with us Yankees for WWll? First I was fighting a too rich condition, and now this? Too lean?

OK! I've got good spark, that's not an issue. Pulling the drain screw out of the fuel bowl, gas ran out, so the problem wasn't that either. But if I put one finger over the carb inlet, it would start right up again, idle (sort of), and grab rpm's quickly. But the minute I would remove my finger, it died. I remember what Wheelman-111 said about having to have the air box on with the cover. (All this was done without the air box/cover on the carb.) That didn't make any difference either. I thought maybe it needed a bit of back pressure/ choking effect that the box would create. Nope. And fiddling with the air screw and idle speed adjusting screw didn't do any good either. I also tried removing the bistarter, but that didn't help one bit. Sounds like a whole new set of problem for me.

I left my garage disillusioned, tired, sore back, but not ready to give up on it yet. I feel as if I am making some progress in the right direction. If I would have thought about it at the time, I would have done a vacuum leak check with whatever I have in the garage that's in a spray can and flammable. I have a feeling that may be the issue, as it acts like it is too lean now, and my new problem may lie there somewhere. But there isn't that many places where it could occur is what's puzzling me. Unless there is a pin hole leak in one of the two vacuum lines somewhere. And if there are no leaks, what then? Could it still be issues with the carb? The float level is correct, as I double checked that some time ago. When I fire it up, it stops running at an idle, or at WOT.....makes no difference.

Anybody have any ideas on this new subject now? I still have at least 10 days before the new carb gets here, and I'll keep tinkering with it until it arrives. My luck would be that I finally find all the bugs and issues, get it running like it should, and the new carb will come in the next day. Murphy's Law will prevail, I think.

Hmmmmm...........????????

Andy

[alexfleury]

The last post was in November !! I wanted to hear the solution

[lakehouse]

I changed the title to MIRROR IMAGE CARBURATOR? after I received the brand new carb I ordered from Hong Kong. It was the wrong carb. There are 3+ pages under that heading as of now.

Thank you for your interest in me finding a solution to the problem. Everybody points to clogged passages, which there are none. I even included a picture of light shining through a pilot that some were suspicious of. I regret to say that I have as yet found anybody that has come up with the cure. After going back and reading carburetor threads for the past 6 months or so, it seems that many others are experiencing the same, or at least similar, issues when they try going through their carbs. For some strange reason, they just don't seem to turn out like they should. But I haven't given up on my problem.....yet! And I hope I don't have to either. But these little two stroke motors are making me awful skittish, I'm afraid. Guys are frying their motors b/c they are running too lean, some just loose power for no apparent reason, some can't get them to start, and when they do, they run like crap. I guess it's just the nature of the beast when you play with 2 strokers. It's funny, as all my lawn equipment is 2 stroke, and I never have any issues with them at all. I've owned a half a dozen Honda motorcycles in the past and never had any trouble with starting or running. But they were all 4 strokers. Right now I am wondering if I could find a crashed 4 stroke scooter with a decent motor for sale. Bet I could make the swap somehow. That's getting away from the theme of this website, but if I can't get the thing to start and run like it should, what good is it? I've got a couple of hundred bucks in this scoot already, and haven't even got to the cosmetics. Now I wish I hadn't bought the new seat cover and mirrors for it! Let alone new tires and tubes too! Is it destined to become a parts bike? It's too good of a scooter to do that. Especially with less than 500 original miles on everything.

Just watch for any posting dealing with carb issues from "lakehouse" and it will be my continuing saga, if you are still interested. There has to be a solution that hopefully other will be able to apply to their problems too. Sorry about the subject title change, as I didn't mean to throw you off. I truly hope that someday in the near future, I'll be able to post how I rectified the problem so other can benefit from my trials and tribulations. And thanks for the shout! I hope you're not experiencing the same issues as I am.

Andy