Gs 1000 Won't Rev Past 5000

[vitesse]

Hello, guys,

So this is the story: I bought a '78 gs thou non runner.

• Things I did: replaced points with dyna s ignition,
• set valve clearance (no clearance at all on 4 valves!!)
• rebuilt carbs and set them to factory specs,
• replaced voltage regulator ( got 16 volts on idle!!) voltage regulator was wired incorrectly also.
• replaced coils, wires and plugs.

The bike never revved past 5000 rpm in the beginning and still won't...
just need to mention i've got pods on the carbs and a 4/1 exhaust.

Anyone got an idea??
I'm puzzled since the bike runs perfectly until the 5000rpm mark.

[Dave8338]

Sounds like you're running too small on the main jets. On WOT your jet needles are over ridden by the main jets. With the pods and 4-1 pipe...my vote is the mains. Does it run smoothly through all other ranges up to 5000RPM's?

[Hap Call]

Make sure your ignition advance is not frozen up. It's located where your points are and has two springs and some weights that move outward as the rpm's build up. If it is stiff or the weights do not move freely you will get the same symptoms.

Hap

[first timer]

what brand pods you running? are you running stock jetting with pods and a 4 into 1? if so, stop riding the bike until you can either replace the pods with a air box and stock filter or rejet the carbs to accomodate the pods and 4 into 1. You will need to get a dynojet stage 3 kit for your bike and run K & N brand pods if you want to run a bike without a air box trouble free.
Some will say that the other stuff out there is good but in my experience, especailly running the dynojet stuff which was designed for K & N filters, the other stuff sucks and you will just be wasting your time messing around.

it's not running past 5k because it is running super lean (very bad), due to the pods and 4 into 1 and stock jetting.

[KEITH KRAUSE]

Another quick check to eliminate possibilities is to try running without those pods, just to test.
If they require oil, many people over oil them and the bike will starve for air, usually right about at the rpm's you describe. Up to the starve point, the bike will seem to run fine.
After some typical riding around, what do the plugs look like?
Have you verified good flow from the petcock?
Any fuel filters?
Be sure the 2 floatbowl vent lines are removed when running pods, leave the ports open.

[vitesse]

gs 1000 won't rev past 5000

Hello, guys, thanks for all your advice ,

My ignition advance is moving freely, so the carb setup must be the cause.
I will run the bike without pods and/or blank them partially off.

Hope it works!!

[KEITH KRAUSE]

Hello, guys, thanks for all your advice ,

My ignition advance is moving freely, so the carb setup must be the cause.
I will run the bike without pods and/or blank them partially off.

Hope it works!!

OK. Considering what you say has been repaired/replaced, (most of electrical/valve clearances/carbs) I'd suspect the jetting too, and we KNOW if you set the carbs to factory specs, it's lean at all 3 jetting circuits regardless of any other possible problem.
But you have to be ready to re-jet. It sounds like you've done most of the necessary tuning/maintanance already, but be sure of a few more things so you can accurately test and re-jet.
Verify the pods are flowing well as mentioned. If they are K&N's, they must be oiled properly. Their flow characteristics can even be compromised by cleaning them the wrong way, though they are permanently damaged if that happens. K&N cleaner or a mild diluted solution of water and "409"/similar, will work to cut the old oil film. Try to keep the solution on the outer side of pleats. I use a shallow pan with maybe 1/4" of solution. Round filters should be slowly rolled in the pan. Ovals should be "dipped and rotated" in the solution. Once soaked enough, you always rinse these filters from the INSIDE-OUT, and with low pressure water. Shake out and air dry only. No blow dryers, etc. I re-oil by spraying from about 4" or so. I make one fairly quick pass per approx' 2 to 3 pleats. If you oil "each pleat" as K&N says, it's very easy to over oil and air starve the bike. And no, riding it around to suck out extra oil is the wrong thing to try. Re-clean and re-oil if you over oil.
If the pods are non oil type, be sure they're flowing well.
Next, verify good fuel flow from the petcock at all positions.
Don't run fuel filters. If you have rust particles, seal the tank.
Be sure the vacuum line is good and no kinks.
Be sure the fuel line is 5/16" and no kinks.
Verify you have B8ES plugs, gapped approx' .028" works well for the Dyna S.
Verify the timing advance is working smoothly by shooting the marks with a timing gun. Very important.
Be sure you set those float levels at .94" or VERY close to.
REMOVE the two floatbowl vent lines as I said. Leave the ports open. This is also required in the various jet kit instructions.
AFTER making your JET NEEDLE position changes, bench synch the carbs. If you need help I have a detailed post at this site to help you. Remember, the bench synch must be followed by a vacuum tool synch to accurately re-jet/judge performance/read plugs. If the jet needles are disturbed/changed on VM carbs, you must synch again. You must have valve clearances and ignition timing spot on before any vacuum synch.
Now you can re-jet.
I have no idea what pipe or pods you have. That would help so I can make close as possible suggestions.
If you want to try to make the stock jet needles work, that's fine, but be aware they may not work well. It depends on how well the bike flows.
If stock needles and your pipe/pods are flowing well...the only chance the stock needles have of supplying the correct mixture is by placing the e-clip in the bottom/richest position (clip furthest from the top of needle). That's all for the jet needle. If solid 1/3 throttle position tests/plug reads still say lean, then you need to get a stage 3 DJ kit and try position 4 from the top initially.
Main jet... Mikuni 130 should work fine as long as it's flowing well. This size jet is approx' the same as a 138 DJ main and the 138 is supplied in their jet kit, along with a 142. If the bike flows even better, you may want to try a Mikuni 132.5 or even 135. Most 1000's I've jetted with pipe/pod mods are happy with the DJ138's (130 Mikuni). If you are at quite high elevations, I suggest 2.5 to 5 leaner jet. Test at full throttle.
Pilot circuit...if stock needles, you can try running the stock 15 pilot jets. Just simple richer pilot fuel screw adjustment (underneath) may be enough to assist the stock jet. Try about 2 turns out from LIGHTLY SEATED initially and test. If still lean by the time the screws are 3 turns out, I suggest a 17.5 pilot jet and return the pilot fuel screws to approx' 1 turn out and continue testing. Test the pilot circuit/get reads by running minimal throttle, steady cruise about 35 mph in 4th/5th gear uphill/level is good. Do what the plugs/performance say. If you need the larger pilot jets, be sure you get the exact same length. There are 2 sizes for these carbs and you don't want the other size.
If you run the stage 3 kit, the stock pilot jets almost always work fine. The more tapered DJ needle have a much earlier throttle position effect and they work better with the stock pilots than larger pilots. I know the pilot and jet needle are different circuits but the above is true.
Only pilot circuit change needed with DJ needles is to richen the pilot fuel screw a bit. Usually a 1/2 additional turn beyond stock setting is good. About 1 1/2 turns total. Fine tuning may be necessary.
Side air screws...are always adjusted using the "highest rpm method". They will end up approx' 1 1/2 to 2 turns out.
Don't necessarily blame any excessive decel' pop on mixture, first be sure the pipe gaskets are good/new.

So after all other tuning/above is done... jet change, bench synch, start up and warm up fully, set air screws, then vacuum synch. Test. Good luck!

[KEITH KRAUSE]

Oh, one other thing.
If your pipe is one of those "Motad"(?) types, I hear they are quite restrictive. Poor flowing. I have no experience jetting with those. Leaner jetting at all 3 ciruits would be needed.

[vitesse]

gs wont rev past 5000 rpm

Oh, one other thing.
If your pipe is one of those "Motad"(?) types, I hear they are quite restrictive. Poor flowing. I have no experience jetting with those. Leaner jetting at all 3 ciruits would be needed.

Hi, Keith,

My exhaust is a period Micron 4/1 and doesn't sound restrictive.
As for the pods, they don't carry any brand.
I'll change the pods.
Yesterday i tried the bike with partially blanked off pods and it gained about 1000 rpm.
So i'll follow your advice to set the carbs differently when I'll find the time.

Anyway thank you for the professional advice, I appreciate greatly

Johan

[KEITH KRAUSE]

OK. I'll assume the pipe flows well, so my previous advice should cover everything, depending on if you try the stock needles and separate Mikuni jets, or the stage 3 DJ kit.
I hope you'll get back to us with the results.

[vitesse]

Gs 1000 Won't Rev Past 5000

Hello, there,

It's been a while, but changing jobs, home improvement an child conceiving, not to mention lack of money put me off my bikes for a few months8-[.

Well, i've put the Dynojet stage 3 kit in the carbs, set the needles at 2nd groove and gave 2.5 turns for the fuel mixture.
Just came back for a test blast and wow, that bike flies!!!!

I just have to fine tune the carbs, because the exhaust is too black to my taste.
When I'll have the time i'll check the plug color to tune the carbs, do some balancing (just bought some vacuum gauges off Z1 enterprises).
Finally i'll have to tune the front forks, since they are way too soft for the performance that is on hand now.

I would like to thank Keith Krause for the tremendous help he gave me via this site....Cheers, Keith, wish I could offer you a beer over here in Belgium!!!Thanks mate!\\/

[KEITH KRAUSE]

Hello, there,

It's been a while, but changing jobs, home improvement an child conceiving, not to mention lack of money put me off my bikes for a few months8-[.

Well, i've put the Dynojet stage 3 kit in the carbs, set the needles at 2nd groove and gave 2.5 turns for the fuel mixture.
Just came back for a test blast and wow, that bike flies!!!!

I just have to fine tune the carbs, because the exhaust is too black to my taste.
When I'll have the time i'll check the plug color to tune the carbs, do some balancing (just bought some vacuum gauges off Z1 enterprises).
Finally i'll have to tune the front forks, since they are way too soft for the performance that is on hand now.

I would like to thank Keith Krause for the tremendous help he gave me via this site....Cheers, Keith, wish I could offer you a beer over here in Belgium!!!Thanks mate!\\/

Thank you too.
Just be sure to check the performance and plug reads at minimal, 1/3, and full throttle.
I know you say the bike seems to be running fairly well but from my past experience, setting the jet needles at "the second groove" as you say doesn't usually work. I don't know if you mean the second groove from the top or the second groove from the bottom of the DJ needle, but the second from the top is too lean and the second from the bottom (5th) is too rich, based on past experience.
I just want you to be sure the bike is truly running right and not just impressing you even with an incorrect mixture. Good luck and let us know if you need further help.