250 Rebel idle problem

[shoester5]

Hi everyone! I’m new to this forum and new to Rebels but not new to motorcycles. I have been riding and working on motorcycles since I was 16 years old (now 46) but had a bad accident in 1998 involving a motorcycle and hadn’t been riding since until recently.

About 2 weeks ago, I bought a 1996 Honda Rebel 250 with 1600 miles on it. It had been ****ting in a barn for 13 years. Heck, with the price of gas and the great deal on the bike, I couldn’t resist.

Preparing the bike
I dumped the old gas out of the tank and cleaned the inside with mineral spirits and an old bicycle chain. There was a lot of rust inside the tank. After words, I let the tank completely dry in the sun. I then, tore down the petcock, cleaned and reassembled it. I did the same with the carb with special detail to all the little passage ways inside the carb. I have also put on a new chain, sprockets, tires, spark plugs, fuel line, fuel filter and a battery. I also adjusted the brakes and cleaned the air filter. Before trying to start the bike, I squirted a small amount of light weight oil in each cylinder and turn the engine over several times by hand to loosen up the rings and to coat the cylinder with oil.

Starting the bike
I filled the tank with fresh gas and 1/3rd can of SEA FOAM to help clean out anything I might have missed (and the inline fuel filter will catch anything before it reaches the carb). I put the choke on and then cranked it over and it started right away. The bike idled fine but couldn’t take any throttle until fully warm (about 15 minutes). As it starts to warm up the idle will increase slightly letting me know that I can gradually let the choke off but I can not shut the choke all the way off. By doing so, it always dies. If I keep the choke on about 1/8 amount, the bike runs good and strong and will run all day like that.

Now, I have gone through 3 tanks of gas, all with SEA FOAM in them and the bike runs the same. The bike runs good and pulls hard till red line. I can get the bike to 80mph on a straight road and almost 90mph going down hill. It has very little power below about 3000rpm but pulls hard from then till red line. But, I still can’t shut the choke fully off.
I took the plugs out and they are light tan in color. I also changed the oil.

The fact that the choke on the Rebel is actually an enricher and not a choke as pre say, tells me the bike is running a little lean but the plugs indicate the bike is running just right. The air/fuel mixture screw is turned out 3 ¼ turns. I know that Honda recommends 2 ¼ to 2 ½ turns but I can’t get the bike to run at this adjustment.

Maybe someone out there might shed some light on what I am over looking if anything or has experienced the same thing I am. I’m open to any and all suggestions. I know this is a 21 year old bike that has been sitting for 13 years and may never run like a new bike but I would like to get it as close as possible.

I realize this is a lengthy post and I apologize for that but I want to give as much information as possible.

[GearJammer]

Welcome aboard, Eric & congrats on the primo "barn fresh" score!

Please don't apologize for the lengthy post, it's an EXCELLENT one with a lot of valuable info for others to read.

You've done a LOT of the right things & that's commendable. That Reb has obviously found a good home! ;)

As regards the choke not shutting all the way off & the 3 1/4 turns out on the air mixture screw. Is it possible that these specs are related ? What I'm getting at is.......with the air mixture screw allowing more air in, the choke being engaged slightly & acting as an enrichener, could they both be compensating one another ?

If you're able to allow the bike to fully warm up as you usually do, then you might try adjusting the air mixture screw along with the slight choke engagement & see if you're then able to fully back the choke off as well as have the air mixture screw at the manual spec.....

[b4v4]

It had been ****ting in a barn for 13 years.

I thought my cows were the only thing that did that!
Eric, although you carefully blew all the orfices out, I gotta think that maybe the idle jet, which has a hole so small only a wire-brush tine can fit through, is plugged. It is a VERY common thing on Keihin carbs that have sat for a while. If you haven't already, I would actually remove the jet, and ream it with said wire brush. Seafoam is awesome stuff, I must say, but that chunk of varnish will probably take more than that.

[shoester5]

Thanks for all the replies…very helpful!

b4v4, you are right about the varnish build-up in the tank, petcock, and carb. Not only did I take the carb completely apart and after removing all the o-rings and all rubber or plastic pieces, let the parts soak in an ultrasonic parts cleaning machine for 24 hours. I then used a combination of a piece of broom straw and a bread wrapper tie to help clear all the little passage ways and jets. I also used compressed air to help aid the cleaning process. After all that, it is very possible that I did miss a hole or two and maybe another cleaning is warranted. If one of the small holes in the idle jet is still plugged, I can see how that would affect idle and low rpm power.

GearJammer, you are also right about the air mixture screw and the choke being related. The choke is probably trying to compensate for the lean mixture. I thought about that already but I just can’t get the bike to run very good with the air mixture screw set at factory specs. The bike will idle at 2 ½ turns but starts to die as soon as I give it any throttle at all. It almost acts like it’s flooding out. As soon as I start backing the air mixture screw out, the more throttle the bike can handle.

I think the best thing for me to do right now, would be to tear the carb down one more time. I’ll wait till this evening when the temperatures start coming down, tear the carb apart and let it soak over night in the parts cleaner. I’ll keep you all updated every step of the way.

[shoester5]

Well, here’s a quick update on the bike.

I removed and disassembled the carb last night and let it soak overnight. I reassembled and installed it this morning. I set the air mixture screw to factory specs. I started the bike as normal with the choke on. After fully warmed up, I started to slowly shut the choke off and found that the bike stayed idling with the choke fully off. I went for a quick ride around the neighborhood and find the bike responding very well. So, I got my riding gear on and went for a more intense test. The bike pulls hard from idle till redline now and is a lot smother taking off. I don’t have to use as much clutch to get the bike moving. It seams to have more power in the lower rpm’s. It looks like the carb still had some dirt or varnish in it that I didn’t get the first go-around.

I did find some reddish/rust color staining in the bottom of the bowl. Does anybody know what can cause this? I do have an inline fuel filter installed with new fuel lines.

[GearJammer]

Far out! b4v4's advice & your determination got ya back in business & that's totally right on! ;)

Not exactly sure about the reddish deposits in the float bowl. Have heard that any reddish coloring found on spark plugs are simply a by-product of an additive in today's fuel & nothing to be concerned about.......this may apply to the coloring you've found in the float bowl as well ?

[shoester5]

Just another quick update:

This morning I adjusted the chain, checked the tires and took the bike for a 100 mile ride in the mountains. The bike runs fantastic! It pulls hard from idle to redline without any coughing, hesitation, or loss of power. It sure makes for a much smoother ride. I can get the bike to 73mph in fourth and near 90mph in a half-a-mile. Not bad for a 250. I also averaged 67mph and 68mpg for the trip.

[b4v4]

Sweet, Eric! Another rebel on the road! As far as the reddish deposits, it's gas tank rust. I've seen it too many times!

[shoester5]

I was afraid of that... How's that going to affect my engine in the long run? Should I invest in a new tank? I was thinking about changing the colors of the bike anyway. Maybe, a new tank is not a bad ideal. Can any year Rebel 250 tank fit or do I have to stick to the eighties series?

[b4v4]

Naw... A little red powder is nothing to be afraid of. Prolly got there when the bike sat for a long time with little gas in it. I would install an in-line fuel filter, simply because that stuff can clog a needle-and-seat in the carb, and hold it open. Most likely, if it wasn't stored out in the weather, it's fine. But if you find a tank, yes, all years of Rebel 250's work on 250's. Prolly wouldn't hurt to drop the little sediment bowl off the petcock and check & clean it, too. That will also tell you if there is any moisture in the tank.

[GearJammer]

Some sediment in an older tank would be expected. Your in-line fuel filter will keep your carb safe from that junk. If there's enough of it in the tank, the first place to actually clog would probably be the Reserve setting of the petcock as the access for fuel flow on Reserve is at a lower position on the "totem pole", LOL! You can do as b4v4 suggests & drop 'n clean the petcock bowl & keep on truckin'......if the petcock ever gets funky with sediment, THEN you could give the inside of the tank a good cleaning with mineral spirits and an abrasive such as plumber's chain or regular nuts 'n bolts......it's the ol' shake & drain cleaning method & works very well. You'd also remove the petcock from the tank, disassemble entirely & clean that out as well.

[shoester5]

Here is another update:

The bike is running strong and is very enjoyable to ride. I almost forgot how much fun motorcycles can be. But the transmission seemed to develop a problem. It has slipped out of gear twice on me now. Both times it has slipped out of second to neutral. The first time it happened, I was shifting from 1st to 2nd. When I released the clutch and started to accelerated, the engine just revved. I looked down and saw the neutral light was on. So, I shifted back into second and figured it was rider error. The second time it happened, I was in second and half way accelerating through the powerband when it slipped out. Again, the neutral light was on. I checked the clutch to make sure it was adjusted properly and it was. The oil was changed 220 miles ago and I used Honda GN4 oil. Could there be a problem developing in the transmission or is it possible that when I shifted, I didn’t get it fully in gear and it just pops out? Ever since it has happened, I pay special attention to each shift.

[b4v4]

Of course the first thing I'd check for would be any obstuctions with the shifter and its linkage. It could possibly be a bent shift fork, but that would be the other extreme.

[GearJammer]

With 1600 original miles, the previous owner would have had to work hard to mess things up in that fairly bullet-proof motor. Not impossible tho'.

It could be a matter of paying more attention, as you've mentioned, to insure a more positive shift. I've done the same thing on the chop & thought for sure I was gonna have to tear the gearbox down to fix it. It'd seem to hit "false neutrals" on the downshift. Took it for one more test ride & discovered that it was me being a bit too casual after not having ridden the chop for awhile. Got back in the groove & no problems after that.

Now that you're mindful of it, if the problem definitely returns, just give us a shout, but let's hope that it's just the "lazy shift" syndrome, LOL!

[shoester5]

Sorry it took so long to get back to the forum but I’ve been very busy the last couple weeks and just didn’t have the time.

Gearjammer got it right when he called it the “lazy shift” syndrome. It seems that after sometime in the saddle, my shifts would get a bit sloppy. It also helped when I moved the shifter lever down one notch.

[GearJammer]

Thanx for getting back to us on that, Eric....it's always good to know how things work out (or sometimes not) and it sounds like you're good to go! Right on!