Topend rebuild complete.....now for the questions :)

[Chris Daniel]

Alrighty, the topend went back together very well. I flushed the dirt that fell into the crankcase out with solvent.....I just washed it out of the drain plug instead of pulling the sump, then let it sit overnight to let the solvent evaporate.

Anyway, got it all back together, she fired right up with a little priming and choking. Took it for a few spins to warm it up, topped off oil level, made sure of no leaks, and took it for some more rides.

Now, after getting it nice and warm I went ahead and gave hell in first gear.........at around 7000-8000 it just flat out hits a wall......I can shift into 2nd and it will do the same thing at a slightly lower RPM.....so I quit. The bike also feels just a tiny bit slugish almost like it is rich, however there is no smoke to indicate a rich condition.

Now, it had none of these problems before the rebuild. The only problem related to this it had before the rebuild was after sustained high speeds 100+, when I let off the throttle it would die. Then it would take an act of god to get it to start again. After that it would pitch a fit for about 5 minutes untill it returned to normal running.

I have long suspected the petcock due to 2 things:
1. The petcock constantly ticks, it is very loud when the tank is near empty, but with a screwdriver against the ear it can be heard all the time.
2. The petcock has begun to show signs of leaking, not a drip, but a constant covering of residue.

I have full intentions of replacing the petcock with a Pingel, I just want to make sure I dont have any other problems that I need to take care of before I buy a petcock.

Thank you very much in advance.

 

[KEITH KRAUSE]

Sounds like fuel starvation to me. I'm guessing the bike will easily rev past 7-8 K if in neutral? Did you service the carbs or do anything to require a change to the jetting? Your test description/problem suggests too small of mains/possibly dirty passages/low float level...

 

[Chris Daniel]

Well, all I did to the carbs was remove them, set them on a shelf with a rag over the top of them, then put them back on the bike. Other than that I didnt even touch them.

It has the same filters on it, same exhaust, everything is exactly the same as when I took it apart. I just basically cleaned the carbon off of everything while I had it apart. I didnt even mess with the valves. I checked them out, they looked great, so I just put them back in the same hole they came out of. I tired to minimize as many variables as I could.

I am wondering if at full throttle, since there is no vacuum (or very little), if it is actually closing the fuel valve???

I have tried running it on Prime, but it has never liked it at all. If I put it on Prime it will spit and stumble and just generally run like crap.

If need be I can check float levels, ect, I just didnt figure that would be causing it due to the fact that I didnt even so much as drain the fuel from the carbs when I took them off.

Keith, also, I have been looking at the Pingel website. I am assuming that I need a 3/8npt fuel valve with reserve? They make a ton of different types, I cannot figure out what the differences are between them. I believe they are using genereic pictures for the part descriptions.

Any help would be great as to which one I need.

Also, would the carbs possibly being out of sync cause the brick wall at those RPM's?

Thank you very much in advance.

 

[Chris Daniel]

Also, yes, it seems to rev just fine in neutral.

 

[Chris Daniel]

Alrighty, I found the page that tells you what is what when it comes to the Pingel valves.

 

[Chris Daniel]

Alrighty, I put about 50 miles of riding on it today and all is well in the oil leak department.

About the brick wall thing. It only happens when I go full throttle. It will happen in any gear, at any speed, no matter what.

I did find that even at lower RPMS when I go full throttle it starts surging a little bit and then when it gets up to around 7000 it just acts like it completely runs out of gas, when I shift into the next gear it will continue doing this as long as I am full throttle. If I back off the throttle a little bit it will return to normal.

Also, if I just blip the throttle it will stumble, this will happen ever so slightly at idle (like blipping the throttle from idle), it is more noticable when I am just cruising along and blip the throttle it stumbles then goes.

Just cruising around town using less than roughly 1/2 throttle it runs almost perfect however it does seem slightly sluggish from the way it was before the rebuild. It will cruise down the highway all the way up to roughly 80-90 MPH without any problems, no bucking or surging.....again just a tad bit sluggish when I try to accelerate. As soon as I try to roll into full throttle it starts its surging and bucking. It also sounds "rougher" than it did before.

It will fire right up and idle without any problems what so ever, if I roll on the throttle from idle (like taking off from a light) it does great, just again seems ever so slightly sluggish compared to when I rode it before the rebuild.

Would doing what I did (cleaned all carbon from everything, installed all new gaskets and put it back together) change things enough to cause the jetting to be different????

I also tried the petcock on all settings Reserve, On, and Prime it did the same thing on all settings.

Anyway, any help would be great.
Thanks in advance.

 

[Chris Daniel]

One more thing.

Seeing as how I do not have a millimeter measuring tape or stick........which adapter am I going to need for the Pingel fuel valve the 44 mm one or the 46mm one? They are so stinking close in size I cannot tell which one I need by using a regular tape measure.

Thanks.

 

[KEITH KRAUSE]

Just read this on my way out. Will try to answer after work.
If the problem happens at full or nearly full throttle only, then it's the main circuit. Main jet, primary air jet, or float levels. Carb synch should always be done as basic maintenance.
Does the idle increase as the motor becomes hot?

 

[Big Dog]

44MM * .0394 = 1.7323"
46MM * .0394 = 1.8110"

 

[Chris Daniel]

No, the idle stays right around 1100 RPM. When it is very cold it idles slightly lower, but once I make it about a block it will idle at 1000-1200 all day long.

I road down an extremely bumpy road after work (old down town brick roads) and then got up on the highway, I took it to full throttle and it seemed fine.....although a little sluggish. Once I got off the highway I did a first gear blast and it went right to the redline, when I shifted into second gear it acted like it was running out of gas slightly, it didnt buck and surge very badly but it was noticable. It is also noticably rougher when accelerating, and the exhaust note is not smooth....kind rough sounding. Although I am sure that has to do with the carb sync.

Also, again when I am cruising along for 30 seconds or more at a normal speed then blip the throttle to wide open it has a pretty noticable hesitation. Other than that, idles great, fires right up with full choke to start and then about 1/4 choke for maybe 1 minute then turn the choke off and it idles great.

I have not done any plug chops as of yet. But it isnt smoking, and my buddy said it is not smoking upon acceleration that he can tell.

I did notice after riding yesterday I had alot of little black specs all over the gas tank coming from the gas cap, almost looks like it is coming out from around the key hole. It has always done this, but I added a small fairing so it maybe just splattering it around more making it more noticable.

Just for reference, the engine is stock except for EMGO pod filters and a MAC 4-1 exhaust. Other than that she is stock as far as I can tell.

That is about as much info as I can think of at this time.

P.S. Thanks Big Dog, the best measurement I could get with a pair of dial calipers from work today was 1.71-1.73, measuring from center of bolt to center of bolt, so it has to be the 44MM one.

 

[KEITH KRAUSE]

Pods and pipe require jetting changes to all 3 circuits. I won't get into that because you say the carbs were not changed during the rebuild and the bike didn't have this problem before. I just hope they were re-jetted correctly or you'll have more difficulty troubleshooting.
Generally, a bike that revs fine in neutral (no load) but doesn't rev well in gear is a classic fuel starvation problem. The problem generally worsens as the load increases (higher gear/same throttle position).
I always check all basics before troubleshooting.
Some basics here would be a clean gas cap vent, ignition timing/advance check, carb synch, the 2 floatbowl vent lines REMOVED for pod filters and the ports left open, CLEAN CARBS, attention especially to the air jets/main jets/float valves and any float valve screens. I don't know how long the carbs sat but the small passages everywhere inside can varnish up quickly when not used. Gas tank must be rust/dirt free.
You suspect a bad petcock. Your petcock should flow well in prime position and successful testing on prime would also expose a leaking petcock diaphragm or leaking vacuum line. But you say the bike runs bad on prime. The only way it would run bad on prime is if dirt/rust is clogging it.
You say you'll buy a Pingel. That's fine but a CLEAN petcock on PRIME should flow well, at least for performance testing. Also new/correct size vacuum line to #2 carb. If not, poor fuel flow is not the fault of the petcock or vacuum line.
If the bike does run well with a known clean petcock/new vacuum line on prime but not the on or reserve positions, then the diapragm is failing.
You are using a 5/16" fuel line, correct?

 

[Chris Daniel]

OK, I tried a few things this evening to try and narrow down the problem a bit. First things first, the weather tonight was much colder and "damper" than yesterday or the day before.

I went for about a 10 mile cruise down the interstate tonight and the bike stuttered and bucked while cruising (something it hadnt done before). While cruising if I quickly opened the throttle it would stumble pretty bad then pick up. If I was very very smooth with the throttle and eased it up to just under full throttle it would take it OK.....still a little sluggish but not apparent stuttering ect. I made about a 30 second run (around 100MPH) with as much throttle as I could give it (roughly 3/4) when I let off the gas it all but died.......it had zero throttle response, it acted like I ran completely out of gas. I kept the throttle open about 1/4 for about 15-20 seconds and it bucked, bucked, bucked, then picked back up and went.

If I try to roll on the throttle too fast it will stutter sometimes, other times it just feels sluggish. I tried moving the petcock to different locations and it didnt seem to make a difference at all (it was set to ON when it died after letting off from around 100 MPH).

And again, when taking off from a light, if I open the throttle too fast it will stumble then go.

The gas cap looks clean and it doesnt have any build up anywhere on it.
Ignition timing I havent messed with at all being an 83, I didnt think there was anything you could do to it????
I am hoping to get a carb sync tool pretty quick, the mechanics around here keep telling me that a sync will make no difference :roll: :roll: so I am just going to have to get one of my own and do it myself.
The floatbowl vents are in fact removed.
Just physically looking at the carbs they look nice and clean, they are not dirty at all really. Looking down the throats of the carbs they look really clean. I have not taken them apart however. They sat for about a month on the bike without being ridden, and about 2 weeks off the bike on the bench with a rag over the top of them.
Looking down into the tank with a flashlight reveals no dirt or rust that I can see. It is still nice and shiney. I completely flushed my tank out shortly after I got the bike due to me accidently putting about a gallon of diesel in it at the gas station before I realized what I had done (stupid me). As soon as I figured it out I called a buddy and I dumped the tank out in a bucket and used fresh gas to clean the tank out about 3 times then filled it back up with gasoline. During all of that, not a single piece of rust or dirt came out of the tank, so I am confident that it is nice and clean.
The petcock has become a bit of a mystery to me. After you said something about it last night, I tried it on prime this evening, it didnt change a single thing. I couldnt tell the difference between RES, ON, or PRIME. So I am kinda scratching my head at that one, it has never seemed to like prime before, but I am starting to think it may have been something else.
The vacuum line to the petcock is still flexible and plyable. It looks good and doesnt seem to have any leaks or holes in it. Same with the fuel line......which is 5/16.....if 5/16 is stock then that is what it has.

I really appreciate your help. I am a little green at tuning bikes so I really really do thank you for taking the time to help me out.

I am trying to give you as much information as I can to help.

Thanks again.

 

[KEITH KRAUSE]

You say the bike ran fine before the rebuild, so it seems you've done something related to that. Something that presents itself mostly at 3/4 to wide open throttle.
The way you describe it sounds like carburetion, possibly due to the carbs sitting.
Other possibility is an electrical problem that could mimic a carburetion problem. Just as clean carbs are a basic part of a good running bike, so are clean/tight electrical connections. Maybe you disturbed the wiring somewhere? I've seen coil terminals down to 2 strands remaining intact, maybe something like that.
As I've said before, with any problem, you must check all the basics that can cause the problem. In your case, anything to do with fuel flow and good spark.

 

[BadBillyB]

definitely sounds like fuel starvation or loss of good spark. I would take the fuel line off at the carb and add a hose to this to lengthen it so you can put the end in a jar. Turn petcock to prime and see how much volume you get. Should fill a beer bottle in 15 to 30 seconds. If not check your fuel line for a kink. Not too hard to kink one if its not routed perfectly. Also you could have routed the plug wires in a way where a bad spot is now near a place to arc to ground. Sometimes you can see it if you check it in total darkness, with bike idling, by misting the coil/plug wire area with a spray bottle with water in it......BadBillyB

 

[Sandy]

I had a problem similiar to what you are describing on my GS1000 last year and it turned out to be one bad coil. On my mine it would constantly fall flat at around 7,000 RPM. I swapped in a used set of coils and the problem disappeared. There does sound like there is a problem in your fuel system that is either a bad petcock or floats. The bike should run properly with the petcock in the prime position. Pull the fuel line off, switch to prime and you should get a nice even fuel flow, if not there's a problem either with the petcock or a plugged strainer in the tank. If you have good flow I'd be looking at the carbs or maybe ignition. Good luck.

 

[duaneage]

If running on PRI does not solve the problem a Pringle valve won't either. I suspect you have problems with the bowl levels. How about the fuel vent tubes? Remove the two fuel vent hoses from the carbs and see how it goes.

 

[Chris Daniel]

Well, the weather turned to crap around here untill next week. SO I am going to do some testing in the garage and see what I can come up with.

Is there any way to check the float levels while on the bike?

I was going to check that, check to see if the petcock flows good in prime into a jar or something. I was also going to put new fuel line and vacuum line on the petcock.

I was going to test the coils with a multimeter and see what happens, check the plug wires and plugs.

Hopefully I will run across something.

Would the petcock have anything to do with the problem I am having of the bike dying after running high speed for extended periods of time then letting off the throttle? As long as I have the throttle open it will keep on trucking, as soon as I let off the throttle it dies (just like it runs out of gas) if I just let it coast down with the clutch out it will eventually buck 4 or 5 times then pick up and go. If I pull the clutch in and coast to a stop, it will take a good 15 minutes of sitting and cranking to get it to start again.

I was thinking the petcock was actually closing due to no vacuum, that was originally why I wanted a Pingle. However, if none of this is the fault of the stock petcock, then I will put it off untill I have a little extra money. Also, can I pull the petcock off the tank without disturbing the O-ring or am I going to have to get a new one if I take the petcock off?

Anyway, the more I investigate and think about it, it seems more fuel related than anything else. However, I am still going to check the electrical side to make sure.

Thanks again.

BTW, I removed the vent tubes not long after getting the bike.

 

[duaneage]

YOu need to get into the carbs. Winter is a good time for that. Spend you money on the carb kits and a berryman's cleaning can.

Anything else and your dancing around the real problem.

 

[Chris Daniel]

Best place to get a carb kit?

My wife will be pleased, she loves it when my projects find their way into the house, on the coffee table, the bar, the kitchen table HHAHHAHA.

Anyway, I will tear into them and clean them up, whether it solves the problem or not......it still needs to be done.

 

[KEITH KRAUSE]

As for the petcock, when it's on prime, that by-passes any faulty diaphragm. So if it's known to be clean (inspected) the petcock WILL flow freely and the correct amount.
The vacuum line is connected to carb #2, correct?
I always suggest a new o-ring if the petcock is removed from the tank but you may get away with it? Depends on how supple the o-ring is.
As for your problem of stalling after closing the throttle after a high speed run, I'm not sure what it is. I do know that backing off the throttle from full throttle creates a temporary/momentary rich condition but this richer condition shouldn't have a long enough effect to cause a stall? Not sure, though it could depend on just how rich it really is. With a sudden change in rpm under high speed conditions, the plugs could glaze over (flashing) and interrupt good spark. Trying to re-start the bike up to 15 minutes could allow raw fuel to clean the plugs and the bike would eventually start again. But I'm just thinking out loud. Funny thing is that you seem to have a fuel flow problem (lack of), that would seem to contradict a rich condition causing the stalling.
I've seen other bikes stall after a high speed run, even a fuel injected Speed Triple, and it always seems to be worse when the motor is hot, suggesting a rich condition because as the motor heats up it runs under a richer condition. All I can say is all basics would have to be checked and verified related to fuel flow, which is a lot of things to check. When something gets to the point of driving you crazy, you just have to go and check everything to be able to eliminate it as a possibility.
Also, check for correct ignition timing with a gun, while you're checking basics.
And I know you say you didn't touch the mixture screws, but where are they set? Should be around 2-3 turns out for your mods.