Back to original airbox from pods - Adjustment needed?

Actually, I just looked up my Haynes manual, and it says that the Kz900 carried a 115 main jet (same as I´ve got) (see attachment). Little confused, as this 115 is not working well at all. 

The question still remains. Will a 102,5 jet be a good option? If not, is there another jet I should try?

Unless... I´m thinking... that the PO drove some kind of wire into the jets to clean them, and they are not a 115 anymore. If that is the case, there is no way I can figure it out; except getting a new set of them.

Bike run really well with the pods and the  4 into 1 marving exhaust... so something fishy there... 
 

A 102.5 jet was used from '78 to 80 but I would not use it in your carbs.  The 115 is correct for 1976 with stock intake and exhaust.  

Is your air filter clean?

Do you have a clear pic of the mouth of the carbs.
There's a slim chance they may have my air corrector jets fitted which don't require a large increase in main jets and a 115 will have been a sufficient increase if the originals were 102.5.
I have sold a few sets to Spain.
If this is the case only the main should have been altered so removal of the air jets and a reversion to 102.5s is all that may be needed.

Yep. Filter is brand new. I agree, 102,5 is a big jump from 115. 

I strongly suspect my 115 jets are no longer 115. Have no reason to think so, other than they don´t work; and I cannot check it anyway but buying brand new ones, and installing them. 

Going back to stock should make everything work. 

 

Zed,

I have no pics of the carbs. I´m not sure if any of your kits were installed; but I really think I should try to go back to stock. 

wrote:

Zed,

I have no pics of the carbs. I´m not sure if any of your kits were installed; but I really think I should try to go back to stock. 

Yes! What i'm saying is that if my air correctors were used you would have an easy job to return to stock with simple removal of the air jets which are accessible externally and a straight reduction of the main.
If my jets weren't used then most likely you will need to change pilot jets, main jets and move the jet needle position ( which would have ALL been increased to deliver more fuel to compensate for the pods ) all back to stock specs.
If the stock main jet hasn't been drilled out there is a chance the PO just lifted the jet needle , maybe increased the pilots, fitted cheap pods which didn't offer a great increase in air flow and left the mains stock.
This would probably have given the impression of a decent running motor but would have been down on performance and top speed compared to one that had been correctly set up..

 

wrote:

I strongly suspect my 115 jets are no longer 115. Have no reason to think so, other than they don´t work.

 

 

 

You need to check the jet needle position and pilot jet size as these will likely have been changed to deliver more fuel too.
Just changing the main will not rectify the fueling on its own,particularly anything below around 3/4 throttle.
The main jet is for top end fueling so your idle and midrange etc will still be too rich causing poor running no matter what size main you fit..

Guys,

Thank you SO much for your help and guidance. The problem is now solved. I just came back from a ride and the bike runs beautifully now, going up to 7500 rpm with ease (and probably more....)

There was NO problem with the bike, or the carbs or the jets. The problem was with the owner, who´s an idiot. 

After installing the air filter box, I replaced one of the fuel hoses with another one. Not a new hose, but a used hose, whose end was a bit expanded. This hose would pour fuel all over the engine when running, and got worse by the day, as the hose got larger and larger. 

A couple of hose clamps, and there´s no more fuel being dumped and what seemed to be rich running, was really fuel starvation. 

I apologize for the time I´ve made you lost... even though, I learned a big deal about these carbs now thanks to you. 

The only thing I really don´t understand now is how on earth was the bike running OK with the 4 in 1 exhaust and the filter pods. Wouldn´t it be lean? Don´t get it.

In any case; thank you TONS for your help. See you soon.

Carlos