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Blue right side pipes and carb weirdness

  • Thread starter Thread starter isaac
  • Start date Start date
I

isaac

Guest
Hey yall, as some may remember my 850 has had weird running since I put the engine together. It starts and idles fine, and the choke seems to do what it should, but it's got running problems everywhere else.

Getting it up to speed isn't full of drama, but it has serious bogs and surges in the powerband, depending entirely on the throttle angle compared to engine speed.

In order to accelerate faster than the average car, you have to rotate the throttle progressively as the revs rise, essentially matching the rpm with a certain amount of throttle to prevent severe bogging, otherwise it slows down. Too much throttle, slows down, too little, slows down. When I say "slows down" I mean literally. If you have too much throttle angle at any speed, it will lose speed pretty rapidly. Full throttle kills the bike at all but near redline. The range in which the throttle is in sync with RPM is a razor thin margin. It's a major art form to get it right. It pulls pretty damn hard if you do though.

I'm guessing it's running lean all the rest of the time. This is also blueing the right side pipe pretty badly just beyond the merging point of the right two cylinders, and is killing mileage. I got 30mpg out of the last tank.

I've already sealed the living crap out of the boots and tried spraying MAPP gas around them while it's running to see if they still leak, but got nothing, so I'm saying they're sealed.

That leaves adjustments. What would cause the bike to act this strangely?

Another hint: If I cover up the left most (#1?) or 3rd carb, the engine speed will rise. If I cover up only the air jets of those two, it'll do the same.

Ideas? Thanks.
 
Well I just went out and adjusted the air screws on the engine side of the carbs and they were all 3 1/4 turns out. They're down to 2 now and the bike pulls significantly more smoothly, though the underlying problem remains. Ideas? Thanks.
 
If you have not done it already, you must sync your carbs with a vacuum guage. It sounds as though the carbs are out of synch for one. There may be underlying problems but I would start with that. Did you mess with the jetting? Do you have pods? It is most definately a lean issue.

Scud
 
Scud, no mods to the engine, so I have to assume the sync is remotely correct.

Well guys, I fixed my own problem again. It turns out the air screws in the back really do help a lot. The difference between 3 1/4 turns out and 1 1/2 turns out is enormous. The bike still could probably use a carb synch for the final tuning, but the problem is almost totally gone now.

It has a flat spot below 15mph in first, but beyond that it pretty much goes. I can't go full throttle until it's halfway up the revs (by ear, tach doesn't work), but it pulls insanely now. When it hits 30mph or so, it tries to remove me from the seat.

I'll update when I make it run better than this.

I'd like to thank Scud and myself for all the help. Once again, thegsresources has proven a valuable venue in which to ask unanswered questions and then figure things out in my driveway by myself.
 
Last edited:
isaac said:
Once again, thegsresources has proven a valuable venue in which to ask unanswered questions and then figure things out in my driveway by myself.
Click to expand...

Do I smell sarcasm?

The only advice I can give besides adjusting the mixture screws (which you have already done) is to tune with the full airbox on. You mentioned that the bike runs better with your hand over carb 1 or 3. You shouldn't even be able to do this with the airbox on. And if you do get it right, once you put the airbox back on, it will be too rich.

Good luck!!
And don't be too hard on the GSR. When you ask a question you are asking a group of enthusiasts, not a microsoft help desk.

-Kevin
 
outofcontrol said:
Do I smell sarcasm?

The only advice I can give besides adjusting the mixture screws (which you have already done) is to tune with the full airbox on. You mentioned that the bike runs better with your hand over carb 1 or 3. You shouldn't even be able to do this with the airbox on. And if you do get it right, once you put the airbox back on, it will be too rich.
Click to expand...

Thanks for the help. I had the box off to diagnose, but put it back on before I started making air screw adjustments. It's been fully adjusted with the box on and everything hooked up. I'd prefer full rich instead of lean anyway. The right side pipe looks like it was anodized blue in one spot.

Good luck!!

outofcontrol said:
And don't be too hard on the GSR. When you ask a question you are asking a group of enthusiasts, not a microsoft help desk.

-Kevin
Click to expand...

Mmkay. It's just that on the car site I go to there are answers flying left and right. Here it seems more or less pulling teeth unless it's a super common problem.
 
Not trying to argue here, but regarding the sarcasm, I've read a few of your posts in the past and I sometimes just can't figure out what you're trying to say. Maybe it's just me, but I find it hard to follow you. Also, some of your repairs that you do later on that fix the problem or at least change things, simply don't make sense.
Your bike is running better you say, but the mixture screw adjustments you mention will not have the overall effects you describe. Adjusting the mixture screws correctly will certainly help the idle and minimal throttle opening performance and can have some overlap effect with the jet needle up to maybe 1/5 throttle position, but that's it. So I just find it hard to make sense of your posts sometimes. The confusion makes me not reply.
I believe your bike is showing fuel starvation. Hard to say if it's fuel flow, intake leak/vacuum, or mixture related. A classic symptom of this problem is a bike that will rev' much better in neutral than in gear and under a load.
Basic maintenance checks of the gas tank venting, petcock, carbs/manifolds, can narrow it down. Never assume something's right on an old bike, especially the carb synch or rubber parts.
Also, it sounds like your manifolds are depending on sealant to seal from intake leaks? Sealant is a poor fix. Sure, some people say they use a sealant and it works, but it's really a poor fix. Period. If your manifolds are hardening/cracking, replace them and any o-rings that they may use.
 
KEITH KRAUSE said:
Your bike is running better you say, but the mixture screw adjustments you mention will not have the overall effects you describe. Adjusting the mixture screws correctly will certainly help the idle and minimal throttle opening performance and can have some overlap effect with the jet needle up to maybe 1/5 throttle position, but that's it.
Click to expand...

Whether it makes sense or not, that's the reality of the situation. I turned the screws down to 1 1/2 turns out, and the bike runs significantly better at all throttle positions. I have so little understanding of adjusting these things that those screws are relative mysteries to me, but they gave me a major positive benefit when screwed downward from where they were.

Before I touched them, the throttle was a very delicate balance between too much and too little. Either way would kill the bike. Just right would get it going and eventually it would hit a rev spot where it would pull really hard for a thousand revs or so. Now it's got a much broader range of throttle opening where it'll pull very hard without bogging, and pulls over a much broader range of RPM.

Oh, and the boots weren't really hard or cracked, but I decided that in absence of any evidence of dirty carbs when I pulled them and opened them up, I'd put sealant on the boots to cover my bases.

I know they're probably out of synch, and the bowls might be misadjusted too, but I dunno if that adjustment would matter in this case.

As it stands, I still can't go full throttle until near redline, but it pulls hard as hell at 3/4.
 
OK. What's the jetting now? What mod's? What maintenance has been done to the bike? Compression check? Valve clearances set?...
 
Let me just tell you from very recent personal experience, these bikes aren't going to run well across the power band unless everything is just right. The float levels have to be set accurately and evenly or you can have too much or too little fuel. If a float is set too low, you can easily starve a cylinder. If the carbs are not in sync, it won't ever accelerate or even idle well and it will definitely affect the take off as you describe. If you don't have absolutely clean passages in the carbs, it's not going to run right. If you don't have the original airbox on and the filter on and sealing properly, you'll have that bogging and surging as you describe. You may also have problems with ignition including wires and/or plugs. I agree with Keith that it sounds as if you may have a fuel starvation issue. Have you tried running briefly on PRI to see if the behavior changes? You really need to go through piece by piece and ensure that everything is right. There's tons of great info here and I've seen Keith talk folks through some real crazy stuff. You just have to ask the right questions and be sure to give as much info as possible and you will eventually get the right answers.
 
I always rely on Kieths judgement on his posts.He has helped my tremenously(even though he probably doesnt know it)He knows his stuff and I look forward to reading anything he answers to and posts.he has givin me the confidence I need to work on my bike and the time to listen and answer in depth.Thanks Kieth!!!!By the way my new boots did come with new sync screws and washers and you will be the first to hear how it comes out!
 
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