High end bogging problem.....

[Chris Daniel]

Well, after getting the bike back together from my wreck and installing the jet kit etc etc etc. It STILL acts like it is running out of gas at 7000+ RPM.

I have installed the richest jet in the dynojet kit (160) and it made absolutly no difference what so ever in solving my problem. I also installed a Pingel petcock and new fuel line.

It is driving me crazy. The bike runs great and pulls really strong up untill 7000 RPM and then it acts like it ran out of gas (this is a full throttle blast) if I try and ease it above 7000 ( half throttle or so) it will start hesitating and surging. Going from the stock petcock to the Pingel made no difference, installing the jet kit then later installing the larger jets in the kit made no difference what so ever.

I cannot get any kind of a plug chop above 7000 because it litterally acts like it just ran out of gas. Anything below 7000 RPM the bike runs absolutly great.

Is there something I am missing?

Any help anyone can give me would be absolutly great.

Thanks in advance.

 

[SqDancerLynn1]

Check the tank vent in the gas cap ? You shouldn't need the richest jets

 

[Chris Daniel]

I actually pulled that apart while I was putting it back together from the wreck. Everything seemed OK with it. It wasnt all gummed up or anything.

 

[KEITH KRAUSE]

Sure sounds like fuel starvation. Either poor venting or lack of fuel in the mixture. List what you've done to repair this.

 

[popeyeAU]

do you have an in-line fuel filter and how big is it, I have had a similar problem caused by a fuel filter that only had a 1/16" inlet and outlet. Also a partially blocked fuel filter will do the same.

 

[Guest]

Sounds like fuel vents or to lean float setting. Do you have the fuel line kinked at all? Hows fuel flow when line isn't attached? If you are running a Dyno Kit remove vent hoses. Ask Keith about mini cyclones.

 

[semerm]

check this

check this

Was the air box damaged? A little air leak will cause havvock.

 

[minutemen]

Check your coil wires .I had a misfire only at high rpms [7000-9000]. Went through the carbs changed jets and needles about ten times nothing changed .Ran great at low rpms though leading to believe it was jetting related. Finally found a broken coil wire.

 

[Chris Daniel]

Alrighty. About 6 months ago I changed the head gasket so while I was at it I went ahead and went through the top end. Basically all I did was clean the head up, make sure everything was alright, and put it back together. I did not do any valve job or anything, just cleaned everything up and put it back together (I vaccum checked all the valves and they were all sealing up great). After I put it all back together this problem began. I went back and rebuilt the carbs with a K&L kit, cleaned everything up, and set the floats per the suzuki specs (to the top of the round part of the float, not the flat part). Put it back together and the problem was still there. I then got a Dynojet kit and a Pingel petcock. I put the leaner of the 2 jets in first, still no change to my problem. I then put the richer of the 2 jets in and still no change. I also took the tank vent apart and checked it, everything was great with it, so I put it back together........still no change. The ONLY thing fuel/carb related I havent done is sync the carbs, however I never messed with any of the linkage in anyway other than hooking up the throttle cable, this is something I am waiting to do once I figure this problem out.

There was one thing I did notice while putting in the Dynojet kit, the original jet I took out which was in it when I got the bike had a physically larger head on it than the jets in the dynojet kit. Is there a difference between the large head and the small head jets? Is one richer than the other with the same number?

I have not checked anything in the way of ignition, as far as I know they are stock. It acts exactly like it is running out of gas (this was why I put a Pingel petcock on it).

Anyway, today I took it on a 100 mile round trip. Cruising it is perfect, even if I half throttle it up to around 7000 it SEEMS to do alright. But if I just flat hammer it in first gear it hits a brick wall right at 7000. I cannot get a plug chop at that speed due to the fact that it just flat will not run. Everywhere else it show to be pretty rich but it isnt fouling plugs. I have just been running it on the rich side untill I can figure this problem then I will go back and mess with everything else.

Also, I do not have a filter, I have removed the vent hoses, I have EMGO pods on it, and again, I havent messed with the ignition at all.

Thanks everyone for your help, I really appreciate it.

 

[nabrams]

Did you have the pods/jet kit on it before the wreck?
If not, I'd say the pods/jet kit are the real culprit.
There are many who've spent weeks trying to get the pod/jet kit combo to work and then just switch back to stock.
If you have the stock airbox and carb components, try them. If things drastically improve, you'll know what's what.

 

[duaneage]

Chris,

I still have an airbox WITH A FILTER for you if your interested.

Duane

 

[Sandy]

I had a similiar problem with my stock GS1000. Being the bike was stock allowed me to eliminate any major carb issues quite quickly. Like yours mine was hitting a brick wall at around 7,000 rpm in any gear as yours seems to be doing. Anyway, mine turned out to be a bad coil that was crapping out at 7,000 rpm under heavy load. At 1/2 to 3/4 throttle in the lower gears it would pull to red line but as soon as I gave it full throttle over 7,000 it would fall flat on two cylinders. It turned out to be weak spark on one coil. Just thought I'd give my 2 cents worth because I know how frustrating this can be. Good Luck.

 

[Jethro]

mine turned out to be a bad coil that was crapping out at 7,000 rpm under heavy load. At 1/2 to 3/4 throttle in the lower gears it would pull to red line but as soon as I gave it full throttle over 7,000 it would fall flat on two cylinders. It turned out to be weak spark on one coil.

I was gonna suggest a electrical problem, I have learned quite a bit about this in the past week. Make sure you thoroughly test the charging system, and have a battery that rests at 12.7 volts or better. Check your voltage drop at the coils.

Another thing to try is getting the bike to act up and applying a the choke lever. If that makes it pull harder, then you are still running lean.

 

[Chris Daniel]

Alrighty, to start with, yes, the bike had pods before I owned it. It did not have the jet kit but it seemed to run fine. It was after I rebuilt the engine that it started this problem.

After doing a little more riding I tried to just ease it up there using as little throttle as I could.....it was still hesitating slightly, however I was able to make it past 7000 RPM but as soon as I would give it full throttle it would start acting up again. This sounds alot like what you are talking about Sandy, therefore I am going to going to try the coil/electrical route to see if I am having any problems in that area. What is the best way/How do you test the coils? If indeed I am having problems then what ohm coils do I need to replace them (I will go with dyna if I have to replace them). What else electrical can I check and how?

Thanks again for everyones help on this, I really appreciate it.

P.S. Duane, if I cannot get this resolved, I will be giving you a call about the airbox. Thank you.

 

[duaneage]

I've also got a few sets of tested coils....

 

[Sandy]

The easiest way to confirm whether it's coils or not would be the swap in a set of known good coils to test. If you've got a spare set around or can borrow a set the would be great. There is still a possibility that it is carburation but symptoms do seem to be pointing towards electrical. It would be too bad to fork out the money for new coils and still have the problem. I'm not sure of proper testing methods for coils but if you checked resistance between the 12V and ground connectors the readings should be the same on both sets, as well as checking the plug wire to ground the readings should be the same. Do this with the coils unplugged of course. This could be a start, although the way it's behaving they could both check out good. Maybe somebody else has a good way to check the coils.

 

[semerm]

similiar problem

similiar problem

I have a gs850 that i bought with pods on it. I had EXACTLY the same problem only mine would only get 5000 rpm. I yanked the pods out, installed the factory airbox and now it runs like a different machine and I get 8000 rpm easily. My bet is it is the airbox/jetting. Please let us know what you determine it is.

 

[morbidphil0622]

Is your petcock vaccum operated? If so, try changing the settings to reserve and if that doesnt help run it on prime and see if that helps. I have had a problem with this on a bike that I had once before. I swapped everything electrical, coils, ignition box, plugs, wires, etc.. it was expensive and did not work, but hey at least I got it all out of the way. If your petcock isn't vaccum operated then just shoot me the finger... Jason

 

[BadBillyB]

Alrighty. About 6 months ago I changed the head gasket so while I was at it I went ahead and went through the top end. Basically all I did was clean the head up, make sure everything was alright, and put it back together. I did not do any valve job or anything, just cleaned everything up and put it back together (I vaccum checked all the valves and they were all sealing up great). After I put it all back together this problem began.

This would make me highly suspect that you might have the cam chain on wrong. One tooth off on one sprocket can wreak havoc on your tuning. Re-check your valve timing........BadBillyB

 

[Chris Daniel]

Well, after digging a little deeper into the wiring and coils I found 3 things.

#1. The coils only have 9.7 volts going to them (with the bike not running).
#2. The number 1 plug wire right at the coil has a rather large crack in it facing the fuel tank. I was able to stick my mulitmeter probe into the crack and the other probe at the end of the plug wire and get an ohm reading........so the core of the wire is exposed. This is also the plug that I have intermittent problems with it fouling out.
#3. I pulled the plugs and 1-4, the plugs are black except for the very tip of the porcelin and the tip of the electrode, which are very dark grey. Now, 2-3 the porcelin is white and the electrode is light grey.

Now would either of these cause my problem?

If I decide to go with the dyna coils do I need to 3.0 OHM green ones?
Is it OK to run the wires with no resistor in them with a plug with no resistor in them (I am assuming that a D8EA NGK is a non resistor plug)?
In other words, do I have to have some type of resistor, be it the plug or the cap?

About the cam chain, that has been a passing thought. However, I checked and double checked when I installed it. As far as I could tell, and according to my climers manual, I was spot on with the cam timing. I am not ruling that out, I just want to cover all other bases before I go pulling the cam cover off again.

Also, I replaced the stock petcock with a "racing" petcock (no reserve) from Pingel, along with nice pretty yellow fuel line and a quick disconnect fitting......which has come in quite handy with diagnosing this problem.

Thanks for everyones help.