pegscraper

I say that reaming the jets out, or basically richening the idle mixture, is just exactly what was causing the idle trouble. If the idle circuit is so daggone lean that the engine can't get enough gas to run on just the idle circuit, it will get it from somewhere. When you turn the idle speed screw in far enough trying to get it to keep running, it will start to pull gas from the main jets, in which case it won't idle at all, or at best it will be extremely rough. The solution is to richen the idle circuit so it can actually feed enough fuel for the engine to idle. I've seen this many times before in cars, but hadn't yet seen it in a bike. The GM cars starting in the late '60s and all through the '70s were really bad for this, especially the ones using the Q-jet carb. It was an early first stab at emissions controls - lean out the idle circuit. But they went way off the deep end with that. These cars would idle rough, and there was no way to adjust the carb to smooth it out; no usual way, that is. If you looked down the top of the carb there was liquid gas dripping right off of the boosters. The idle circuit was so lean that it couldn't supply enough fuel for the engine to run, and it would pull fuel from the main circuit, the boosters. Turning the mixture screws out could not fix the problem, because the idle circuit was choked down elsewhere in the carb body. In fact, turning the mixture screws had almost no effect at all on the way the engine idled. The only way to fix the problem was to open up the idle circuit, and it was designed to be very difficult to modify. The idle jets weren't designed to be changed. The orifice that needs opened up is at the end of a long, thin tube in the main body. A drill bit about .039 and about 2 inches long is needed, and they are hard to find. Once the idle jets were drilled out, suddenly the engine ran smooth, gas no longer dripped off of the boosters at idle, and the mixture screws were responsive. It is this characteristic of the Q-jet that earned them such a bad reputation, and many people threw them out and replaced them with a Holley or something else that was tunable. In my own experience with late '60s Cadillacs, before I fixed them, they would blow a pile of carbon out of the tailpipe every time they started up, and the exhaust at idle stunk so badly it would burn my eyes and drive me right out of an open garage. I used to keep cardboard behind the cars to keep the wall and floor clean. After fixing the idle circuit, they no longer blew carbon out when they started up, I no longer needed the cardboard, and I couldn't smell the exhaust at idle at all. Ironically, leaning out the idle circuit not only made the car idle like crap, it also made emissions worse, because they took it way too far. Richening the idle circuit back up to where it belonged made emissions better and the engine ran better too. Mechanics who have been working on cars for a long, long time and have observed what happened to cars since the start of the emissions era know this kind of stuff. Even with our current bikes, those who are really tuned in to the way the engine runs, know that when they richen the pilot jets, the engine will run smoother. It wasn't all that bad to start with, not like the cars I just described, and most folks won't notice enough roughness to complain about it. But they are on the borderline of it. Richening the idle circuit up where it belongs makes them run smoother. Even my wife, who knows nothing about tuning an engine, suddenly noticed a difference in her bike one day. I had richened up the idle circuit a bit and removed the AIS crap. I didn't tell her that I had done anything at all. I just did it, out of principle more than anything, and then rode around the block to make sure it was good. Within a few days she asked me if I had done something to her bike. I asked why. She said it was running a lot better, and smoother. She said that she wouldn't have called it bad before at all, but something was definitely different. It took a few seconds for it to sink in with me, and then I started laughing. I wasn't familiar enough with her bike to notice a difference in the idle smoothness myself when I rode it, but she, without knowing that I had done anything to it at all, could tell something had happened for the better. I like breathing clean air as much as the next guy, and I wouldn't want an engine to run too rich and make the exhaust dirtier than it needs to be. But leaning the engine out too much causes just as many problems, if not even more, than it solves.

Pics always help. Do you have larger versions of those? They're a bit small to see what's happening. I also have a mill and a lathe at home. I had wondered about turning out some flanges to go against the carbs. I can mill out some aluminum to use as bases on the heads. But I couldn't figure out a way to connect the two.

Interesting, interesting. I have had a few carb swap ideas, but didn't have any idea how to make a manifold. It sounds like a big project making them, but I still think there's more performance lurking in this engine than the current size carbs can deliver. I see how you connected the manifold to the engine, but how did you connect the manifold to the carb?

For the oil leak, it sounds to me like a gasket under one of the cam covers may be out of place. They would have had those covers off when they torqued the head bolts. When I did my cam swap I did the same thing. A cam cover gasket slipped out of place and didn't seal, and it created a major oil leak down the side of the engine. The spot couldn't be seen with everything assembled. I had to take it all back apart again to see what had happened. It is a little tricky to keep that gasket in place when putting things back together.

I kinda wondered about the carb size thing. I understand about the airflow not being constant. Now how did you go about making the manifold?

I'd be VERY interested in knowing how you went about making your own manifolds. How did you figure how much bigger to go with the carb, since it needed to feed both cylinders?

Yeah, but the first time out of the box that engine made 290 hp. And they detuned it what, five times to get down to only 210? Let's put this engine in the Venture now and kick the crap out of the 'wing. It appears you've found the new V Max site.

I'm also one who can't leave well enough alone sometimes. But this would be - a real project. Here is a what a Royal Star airbox looks like. It won't fit your carbs at all. The hole spacing is wrong, and the rubber boots are the wrong diameter. These carbs are angled in towards the center at the top and the airbox is designed to match, where yours are vertical and plumb. And this is only the beginning. It would be easier and probably cheaper too, to just buy a Royal Star and hop it up a little. Mine is making a dyno proven 90 rear wheel hp.

The RSTD does have a bit smaller tank, but you might double check the tank bib fit anyway. It still may or may not fit, or maybe could be made to fit without much trouble.

Wow, it must suck to have to live in CO. Here in northeastern IN these last couple weeks, we are tying and setting record highs. I broke down and turned the AC on last night. It was just too stuffy in the house. I can't remember that I have ever turned the AC on in October. Today is supposed to be another really hot one. It feels like July around here.

Unless I'm way off, there aren't any 20W50 oils that will be "energy conserving". To my knowledge, nothing any thicker than 10W30 is.

Yes, 200X is what I meant. Freebird threw me off with his number up there. I had a 200X before the 350Xs, but I couldn't remember that headlight.

Watcha got in mind, there, dragracer? I always like hearing others' custom ideas.

Congratulations on the anniversary! Is that the 250X? It's been too long since I've seen one. Several years ago I had two of the 350X three wheelers, the ones that were only made for two years before they got cut off. They were mean. When I quit riding and went to sell them, I got more than I paid for them. And now I see them priced at nearly double what I sold mine for ten years ago. They must have quite the cult following. The prices just keep going up.

Before you pull the D3K out, you might check out what the LEDs are showing. One of them, I forget which one, should come on when the throttle is about halfway open. Or maybe it goes off, I don't remember. The status of it should change at about half throttle. I'll put it that way. If it doesn't, it indicates a problem with the TPS somehow, maybe a connection that got dirty. I know firsthand that if the TPS is not connected or doesn't work right, that gas mileage will be in the mid to low 20s. Spark advance can make a big difference in gas mileage.

It's a Delphi forum. They call them an Ultra Star. Here you go. Do you have another idea up your sleeve? http://forums.delphiforums.com/ultrastar/start

Just how bad is your gas mileage? My vote is for a carb problem. Have you checked them out at all? I wonder if it's possible for a throttle valve to stick open. Usually they stick closed.

Charlie, that's hysterical! Only you could take a picture like that.

Wow, there's a whole lotta white on that thing. And someone is going to get a very sharp looking Royal Star.

Yes, but for what? That thing wouldn't be good for long distance riding.

I'm with you Freebird. I didn't think that bike looked too bad, if one likes the Sportster look. I'm not one who likes Sportsters though. But I'd take a Heritage Classic if I were given one.

I'm rather glad to hear you say that. If you build something that custom, you had better like it, because no one else wants what you built and you'll never be able to sell it for anything. Check out this custom V Max that someone is trying to sell right now. Ebay item #280158011462.

Another one sees the light. His eyes are opened. Come into the light, my son. Come into the light.

Boy, that has to feel good to have it running again and be riding again, just in time for cooler weather.

It is kind of a goofy situation. I don't know why Y can't stamp the correct model year on the bike. My '96 Royal Star has a tag on the neck stamped with "1995". There is no model year of 1995 for the Royal Star. The model was first introduced in 1996.