Help with 1984 kz700 bs34 carbs not revving over 5k rpm when in gear

Hello recently removed and cleaned the carbs adjusted floats. Bike idles goods with 3 turn on the air mixture screw. Bike has stock pipes but came with 4 pod filters. The jetting stock is 37.5 pilot 105 main so I used the same pilot and 110 main. The problem I have now is the bike runs good and all but when I hit the highway bike will not go over 5k rpm. It's cruising 60mph at 5k rpm and will not go over that at all. What could be causing this. I read other forums here I tried certain things such as running with gas cap open but nothing. The thing is it will rev ALL THE WAY to redline on neutral but not when in gear. What could be the cause of this. Bike has 4000 miles. What should I be checking?

Kz700a1user wrote: Hello recently removed and cleaned the carbs adjusted floats. Bike idles goods with 3 turn on the air mixture screw. Bike has stock pipes but came with 4 pod filters. The jetting stock is 37.5 pilot 105 main so I used the same pilot and 110 main. The problem I have now is the bike runs good and all but when I hit the highway bike will not go over 5k rpm. It's cruising 60mph at 5k rpm and will not go over that at all. What could be causing this. I read other forums here I tried certain things such as running with gas cap open but nothing. The thing is it will rev ALL THE WAY to redline on neutral but not when in gear. What could be the cause of this. Bike has 4000 miles. What should I be checking?

Most likely carb jetting related due to the pods. I'd look for a Dynojet kit and make sure you have real pods, not those Emgo (or similar) chippies.

I would install the stock airbox w stock air filter. New airbox ducts are still available at Z1Enterprises.com.
The KZ700 uses the same airbox as several other models. see diagrams at cross-reference at Partzilla.
KZ750-L3. KZ750 Spectre. KZ750-F1 Ltd Shaft. ZN700/750. et al.
An airbox from a different 750-4 might work, but you'd have to do some comparisons >> the airboxes can have minor differences, but some are shaped differently at the shoulders or maybe around the cap.

Ok, could be an overly obvious question here, but is the throttle opening up all the way and is the choke function completely off when running down the road? Are you certain nothing is in one of the pods restricting air flow? Are you dead certain you have the floats adjusted correctly? Carb sync is spot on? Running an engine to redline standing still means almost nothing in the big scheme of things. How did the bike run before you started this project? You sure you are at 5,000 rpm at 60 mph?

Rick H.

Double check the basics. Valve clearances? Fuel levels? Throttle cables properly adjusted, lubricated and smooth functioning? Carbs sealed to the carb holders? Carb holders sealed to the head? As already mentioned, cheap filters can cause all sorts of problems. Fuel valve clean and functioning properly? Fuel line kinked or clogged? Fuel filter clogged? Carb diaphragms cracked or torn?

Ok guys few things while working on the bike. I've read all the replies. I check the throttle and seems to be opening all the way. Check the slides if they were not stuck by removing the pods. Btw these pods are those cheapo pods from eBay. PO said he doesn't have airbox anymore. Been searching for stock airbox and cross reference ones on eBay but couldn't find one. When I first got the bike jetting on that main was 115. At that time, the bike will atleast rev up to 7k rpm. But when I changed it to 110 main now it won't go over 5k rpm. Bs34 mikuni is the carb btw. Could the pods be the problem?. They look like garbage pods from what I can tell. Should I go up on the mains? Maybe go 120? Isn't that too high cause stock main on this bike is 105. Pilot is untouched at 37.5. bike idles well and has great pull down low but once on the freeway is feels like trash with no power. Really wish I could find stock airbox setup. Maybe I should also consider getting kn pods if I can't find stock airbox. Can someone point me to which one pods are compatible with my bike? Thanks for the help also pipes are stock btw also adjusted float with clear tube

The pods are the problem, no matter how well the bike is set up there is a sacrifice at one end of the throttle opening, the manufacturer's spend millions of $ to get optimum running, CV carbs need stable air flow that cannot be achieved with pods, your best way forward is stock airbox or one from the list provided, ebay will unearth one eventually, be patient, you will get there..

I would be surprised if the main jet is the problem. It may not be ideal, but it should not be holding the engine back like you describe.
The problem with cheap filters is that some of them are designed so that they cover the air passages that are at the mouth of the carb. Sorry, I don't have a pic.
You can experiment by cutting away some of the rubber on the inside of each filter in that area. If the problem gets better, buy some different filters. I have used both APE and K&N. They are both very good, but I prefer the APE filters as their mounting flange is a bit better design and they are considerably less expensive.

kzzone.com/carbs.html

Was there ever a conclusion to this problem motorcycle?

Rick H.

Hello guys I finally fix the problem. And also NEVER TRUST PO when you buy a bike. Guess what the issue was. The freaking carb had dynojet kit installed with MIKUNI JETS IN IT instead of the required dynojet jets. What the hell. I only figured this out by seeing the jet needle having a clip and slide was drilled since the OEM needle is not adjustable. Purchased the required dynojet mains and boom the bike flies. I don't know why PO did that. So sad and such a waste of time and money on my side.

Thanks for the update. That is some crazy chit right there. I can't imagine why somebody would go to the trouble of installing the needles and drill the slides, but not put in the jets that work with the needles. Duh.