Mirror Image Carb?

[lakehouse]

After fighting carburetor issues for the past month and a half on my '89 Elite that I "inherited", I ordered a brand new carb and it finally came in today. Much to me surprise, it looks like a mirror image of the one I had. (It's the OEM carb and not a performance type of some kind.) No problem with the fuel inlet or vacuum port being on the opposite side, but the bistarter interferes with the shock/spring on the rear wheel, and won't allow the carb to bolt up flush with the intake manifold. In searching the internet, all the carbs shown to allegedly fit a 1989 Honda Elite E (sb50),show the bistarter on the right front side of the carb as viewed from the intake opening. Mine is on the left rear when viewed from the same direction. Even the photos in the service manual show exactly the same carb that I have. (It has a "jumper hose" on the left side of the carb body.) The carb I bought came with a new bistarter, which I was going to replace, so it's not like I am out a lot of money or anything.

My question is what gives, or, what do I really have? The decals and title call it an Elite E, so I feel like that is what it is. Also, is there any way of easily plugging, or doing away with the bistarter, and still have it start fairly easily? I know it will be lean when cold, but better than rich all the time. This thing has me baffled to no end. It's keeping me awake at night even! I'd appreciate any thoughts on this subject.

In advance, thanks for your input.

Andy

[noiseguy]

One is spree, one is elite 50

[lakehouse]

So which is which? I find it hard to believe that marketers would label a carburetor to fit an Elite when in actuality it is for a Spree. Don't you? If that's the case, then Honda must have sold a ton of Sprees and very few Elites judging on the amount of replacement part available. It's the old law of supply and demand which always governs aftermarket parts.

Thanks for the comment though.

[mousewheels]

I find it hard to believe that marketers would label a carburetor to fit an Elite when in actuality it is for a Spree. Don't you? If that's the case, then Honda must have sold a ton of Sprees and very few Elites judging on the amount of replacement part available.

Double check the sellers listing. On my scan, they show Elite SE50 or SA50, which is not your model.

-- History
Honda Elite models in the 80's are subject to confusion. There was the Elite SE50, Elite SA50 and Elite SB50.

Your model, the SB50 was roughly a repackaged Spree. Its entire powertrain is close to an 87 Spree with a single speed drive. The other Elite 50's have a variated drive, basically from the Aero50. So be careful with any part saying 'fits Elite' to check it works with SB50.

-- A carb for SB50
Since you already have one mis-fit carb, I'd point out SB50 is not a exact "Spree" carb. SB50 has an added oil injection tap. Honda as the '80s closed moved oil injection from the intake to the carb. The other Elite 50 models got an oil tap too.
--

Spree_Elite_Carbs.jpg (71.76 KiB) Viewed 12166 times

[noiseguy]

Yep. Spree has bystarter on outboard side, Elite is inboard.

And no, I think most ppl on Ebay that sell the carbs have no idea what they're selling. Honda OEM, yes. Reputable online shops, yes. Ebay, not so much.

[mousewheels]

And no, I think most ppl on Ebay that sell the carbs have no idea what they're selling. Honda OEM, yes. Reputable online shops, yes. Ebay, not so much.

Uh oh -- boss is after me. Posted info is correct. Doesn't mean it will always be so, but the current batch of clone carb sellers do say which Elites the carb fits, and SB50 is not in the list.

Intended take away for the poster is SB50 is a different model. Be careful in general about "Elite" parts

---
I did verify my statement before posting:

Double check the sellers listing. On my scan, they show Elite SE50 or SA50, which is not your model.

-- Verification
1) Search on ebay for "new Honda elite 50 carb"
2) Evaluate results

Result: All sellers post detailed model info, and SB50 is not in the set for currently sold 'new clone' carbs.

Code: Select all

Search string "Carburetor Honda SA50 SA50P Elite Scooter Carb" 

Example Results:
"Carburetor HONDA SE50 SE 50 ELITE 1987 1988 Scooter Carb NEW" 
"1994 1995 1996 - 2001 Honda Elite SA 50P SA50P Carburetor Scooter Moped SA Carb (Fits: Honda Elite 50)" 

3) Now change the search to "new Honda elite SB50 carb" -- zero hits for a carb, only bystarters

[lakehouse]

Thank you so much for all of your valuable information and the pictures. The photo of the Elite E SB50 1988 - 1889 is exactly what I took off of the scooter, and what I have been trying to replace. I've seen a couple of used ones advertised on EBay, but most were for parts and not rebuildable (per sellers). I guess that I'll have to go through mine for the 5th or 6th time, and try to find out where the problem lies. In reading your threads, it sounds as if the air/fuel adjustment is super touchy on where it is set. Also, I have been doing all my adjusting without the air box off and sitting on the bench. When I do put it on, it starves the engine for air and kills it. I still find it hard to believe that enough air can find its way through the few, and small, openings. It goes directly against all 4 stroke theories that I have used for over 50 years of tinkering with engines of all types. I know 2 strokes are a different animal altogether, but every engine needs air to run. Gearhead friends of mine keep telling me to look in other directions, and to get the carb thing out of my head as the source of my sporadic running conditions. But when you have good compression and spark, where else would a person look? (The stock exhaust can easily be blown through with no restrictions noticeable.) Do I need to get a shaman to perform an exorcism to rid the evil spirits out of this creature? I am at a loss. Would a 750cfm 4 barrel Holly be a bit of an overkill on this application? LOL (Just kidding, of course!)

Back to the drawing board for me I guess. Maybe my old carb with the new bistarter installed would shed some light on the issue, but I doubt it. But I am desperate enough to try it though. What would I have to loose but time and a little effort?

Again, thank you so much for your time and thoughts. I'm open to a phone conversation with anyone at most any time if you think you can help me. I have too much into this scooter to scrap it at this point. I DON'T want it to have to come to that!

Andy

[mousewheels]

Also, I have been doing all my adjusting without the air box off and sitting on the bench. When I do put it on, it starves the engine for air and kills it. I still find it hard to believe that enough air can find its way through the few, and small, openings

The airbox is probably not the issue, openings are sized fine for a stock bike. Pluse starting/idling is not pulling much air. Yet dying rich is a clue.

Couple ideas:
1) Check float level - there's a spec in the service manual
2) Check the actual fuel level in the bowl. A poor float needle/seat seal can make the level too high. Some use a clear tube on the carb bowl drain to visually see the fuel level.
3) Bystarter air valve issue, where when cold, air flow is restricted, but fuel is not.

[lakehouse]

Thanks for the clarification on the air box question. It still seems way too restrictive to me for maximum performance even for an all stock engine. I know these little motors don't draw that much air, but I'll bet Honda did flow tests before putting this design into production. Some posts claim that the air box MUST be in place to troubleshoot tuning issues. Maybe?

I have checked the float level more that once, but only statically with dial calipers. The clear tube idea is a neat idea, but would take some rigging to hook up. But then again, I am desperate! LOL

I have bench tested the bistarter and found it to have 5.2 ohms with a meter. When hooking it up to 12VDC, it extended about 1/8". Maybe that's not enough? My plan is that since a new bistarter came with the new carburetor, I'll try it after rechecking (again) all the passages in the body and bowl. I'll also compare resistance of the new one vs. the old one just to satisfy my curiosity, and see how far it extends when voltage is put to it.

What has me puzzled is that upon initial starting when cold, the motor starts up just fine. However, it has a rough, fast idle, and is very slow to accelerate. I have to "feather" the throttle to keep it running after about 3 to 5 seconds. Then after running for maybe 15 or 20 seconds at various RPM's, and holding the throttle at a given position, the motor accelerates considerably (and sounds good and clean), and then dies. The only way I can get it to restart is to put a finger or two across the intake opening of the carb. To me, it sounds like it is set too rich initially (maybe because of the bistarter working?), and then it runs out of fuel. That could mean that when the fuel gets low, it leans itself out, accounting for the increase in rpm's and sounding like it should. However, when I remove the bowl drain screw, fuel still flows out. A low float setting might cause it to die like it does, but then I would be running lean all the time. Right?

I did mount the new carb, minus the bistarter since there is the clearance issue, just to see what would happen. Obviously, it was hard to start, but once I got it running, it never did die on me, as long as I was "feathering" the throttle, like it does with the old carburetor. It too was difficult to restart without finger choking it. I really couldn't do much tuning to it, as I had to keep one hand working the throttle, one hand to finger choke it to keep in running, and that didn't leave any free hands to adjust screws!

It is quite difficult to get motivated to go out into a cold garage and tinker with this, as we have been having temps in the teens here in north Texas lately. I may just walk away from it for a day or two to think on it some more, and hope the temps will come up over the weekend to at least 30 or 40. With a heater, I can live with that! But my game plan as of this moment, is to tear into the old carb again, and install the new bistarter and see what happens. While I have it apart, I'll compare float levels between the two carbs and see if there is any noticeable difference. Would you by chance know what the "rubber jumper tube" on the side of the carb body deals with? Is it part of a vacuum circuit, or fuel, or maybe just static air? Could that have any bearing on my problems, since the new carb doesn't have that rubber tube? It's rather difficult to follow the flow path. You'd probably would have to have one in your hand in order to figure it out, unless you've had prior experience with this particular carb. Just thought I would ask.

I'll post my findings and results when I can muster up the time and desire to be out in the cold again. Again, thanks for your input and help, and taking the time to do your postings. I really appreciate it. Have a good one and try to stay warm!

Andy

[paulpauly7]

have you done a compression test??

[lakehouse]

Yes I have. I'm showing 115psi with a cold engine and the throttle closed. After I put everything up, I read in the manual that the throttle should have been wide open though. That's the first time I have ever run across a connotation like that. But I cranked it long enough for the pressure erading to stabilize out. Considering that this has been sitting around for 8 - 10 years without being started, I was quite impressed.

Next question?

[mousewheels]

I know these little motors don't draw that much air, but I'll bet Honda did flow tests before putting this design into production. Some posts claim that the air box MUST be in place to troubleshoot tuning issues. Maybe?

Spree's are sensitive to a missing airbox. Lot of them wont start/run lean without the airbox present. That's why dying rich with the airbox presentis a clue for starting/idling issue, rather than the airbox is restrictive.

upon initial starting when cold, the motor starts up just fine. However, it has a rough, fast idle, and is very slow to accelerate. I have to "feather" the throttle to keep it running after about 3 to 5 seconds.

That's rich at startup

This to me is one more point towards the carb level is too high at startup. Do you notice a faint gasoline scent in the garage or near your scooter?
--
I have had a scooter with similar symptoms.

It took a slightly leaking petcock and a compromised float needle seal as pre-conditions for a too high fuel level. Will post a more info on the carb seat shortly...

Then after running for maybe 15 or 20 seconds at various RPM's, and holding the throttle at a given position, the motor accelerates considerably (and sounds good and clean), and then dies. The only way I can get it to restart is to put a finger or two across the intake opening of the carb.

It may be your mixture screw is turn way out to get past the rich start issue.
1) Once running, fuel excess is drawn down.
2) With excess fuel removed, normal conditions for the carb and bystarter circuit are present.
3) A re-start is not rich, because the bowl is no-longer overfilled.
4) Finger over the intake required for re-start -- item 3 below is worth a check

Some common causes for dying lean
1) Plugged pilot jet
2) Air leaks
3) Bystarter fuel inlet is clogged Check the carb bowl, there is a tiny jet in it feeding a smaller well on the bowl side. Wiki Link --
4) Bystarter needle is broken loose. In that case, it will plug the fuel circuit. In this case, the system just gives extra air.

Would you by chance know what the "rubber jumper tube" on the side of the carb body deals with? Is it part of a vacuum circuit, or fuel, or maybe just static air?

I do not currently have an SB50 carb to look at. Never thought about the tube, but *now* am curious Will look for info...

[lakehouse]

Let's see if I can provide an answer to your questions and add a few comments too.

GAS ODOR: Yes. I do have a smell of gasoline when I fire up the engine for the first time. But then again, I have been playing with this for so long and have the residual smell in some shop rags and imbedded into the concrete flooring. I know that fuel is very volatile and should evaporate completely, but probably not in an enclosed garage when the doors are normally closed. I just blew it off as being part of the smell of a man cave!

FLOAT LEVEL: Even though I measured the float level and assure myself that this is the setting that the service manual calls for. (0.48" in this case.) And comparing the two carbs sitting side by side, the levels look identical. But there is no telling where the factory set the new one since it supposedly fits numerous applications.

BISTARTER: The old bistarter is intact, with no broken needle, or pieces trapped in the carb body. I have good air flow through that circuit when compresses air is blown through it. But no where in the manual does it give a specification on how much travel the needle should make when it is fully extended. I still have a gut feeling that perhaps my problem lies within this circuit somewhere. I'll know more once I spend more time comparing passage flows of both carbs sitting at my desk, in the house, where it is warm! LOL

FUEL VALVE: I did replace the fuel valve, as I found the old one to have a leak between the chambers. When I orally created a vacuum with the old valve, I got a small amount of gasoline into my mouth. That accounts for my initial condition of running too rich. And BTW, I have replaced both fuel supply and vacuum hoses from the carb to the fuel valve.

PERSONAL THOUGHTS: When the engine dies and it is somewhat warmed up, I would think that it should start without having to finger choke it. But if the fuel bowl is out of fuel due to a low setting of the float, that would explain the no start condition. Letting it sit for 10 or 15 minutes until the bistarter cools off and returns to the normal static position, if starts right up. I'm not sure where the fuel is coming from to make it start that quickly, although I know the bistarter creates a richer fuel/air ratio for starting. A low float setting would require some vacuum to get the fuel flowing again, and raise the fuel level in the bowl allowing to be started again. Or am I missing something here, or overanalyzing it too much? Perhaps I need to put the air box on and start over from square one. But when I had it running and feathering the throttle, putting the air box on killed the engine instantly.....just like it was choking it to death. It's strange that no where in the service manual does it say anything about the air box having to be installed in order to properly adjust the carb. Common sense would dictate that if it was that critical, something would be mentioned.

I know that you fellas who have been working on these engines for years, probably know a whole lot more about them than the creators of the shop manuals. I found that to be true on any make or model of any type of an engine or vehicle. Ya just can't beat hands on experience. And those of you who really know their stuff are more than willing to share their knowledge. Again, I appreciate all your postings in trying to help me iron out this problem. Trying to figure this out is tough enough when I have the pieces and scooter at hand, let alone, trying to be an armchair quarterback. I'll have more time this weekend to dig into these carbs and see what I can come up with. I'll let you know then.

Thanks again, and again!

Andy

[mousewheels]

I have good air flow through that circuit when compresses air is blown through it. But no where in the manual does it give a specification on how much travel the needle should make when it is fully extended

Honda service manual uses the air test cold/hot to determine if the bystarter is open/closed.

I took a new pic and added to the bystarter 'wiki topic. Pic is a measurement of travel required from a cold bystarter to shut off the circuit. It's around 0.1" to initially close the air valve, and 0.15" would bottom out the air valve. Link to Bystarter extension measurement

FUEL VALVE: I did replace the fuel valve, as I found the old one to have a leak between the chambers. When I orally created a vacuum with the old valve, I got a small amount of gasoline into my mouth. That accounts for my initial condition of running too rich.

Good to have the fuel valve ruled out. Are you saying it's no longer way too rich at startup with the airbox on?

[lakehouse]

I only have time to comment that my old bistarter travels about 0.125" from fully retracted to fully extended. I guess that's about normal then.

My significant other had surgery this morning, and I've been running back and forth to the hospital all day. One more trip and I am done with chasing all over the country until tomorrow, when I can bring her home for good. I don't like driving her Hyundai compared to my Corvette. But her SUV is easier for her to get in and out of right now. At least, we think so! LOL

Later, my friend!