Having trouble identifying my carbs, Please help.

I have a 1980 1000 LTD manufacture date 2-80. All stock as far as I know, owned it 20+ years. Looking to up the mains a step or 2. I have read 2 different posters here with 80' 1000 LTD's and one states 102.5 stock and the other states 127.5 stock mains. Appearently I have the latter because my main was stamped 128. Where there 2 carb sets for this year model? What do I have? They have a pump on #2 and angled drain plugs on the bowl.

Edit: forgot, side air adjustments on carbs.

My 80 LTD had the 102.5 jets with the accelerator pump orignally

The 80 LTD has a VM28SS w/pump #102.5 mains #15 pilots 0-4 needle jet and 5CN29 jet needle (no clip adjustment). The #128 mains came from some carb kit that was meant for a BS34 assembly, most likely. Some BS34 assemblies use #127.5 mains and Keyster, who makes almost all the main jets for any of the kits sometimes rounds up the numbers.

Sorry still confused, do not know what the BS34 is. I ordered some 105 and 107.5 mains but they are of course smaller than the 128 I found in my carbs. George are you saying the 128's are not stock on some setup's of the 80 1000 LTD? There was an old post of another 80 1000 LTD rider that found 128's in his carbs too. I am just trying to go up a size or 2 for K&N filter and a big bog after 5000 RPM, stock pipes, pump working. I have had the bike 20+ years, stock setup as far as I know. Would the bike not be running horrible if a 128 jet was installed for the 102.5?

Here is a link to an old post that is confusing me. kzrider.com/index.php?option=com_kunena&...=43359&catid=3#43359
He is stating his 80 1000 LTD has VM33's 127.5 main stock.

BS34 is a CV carb {constant velocity}stock 81 and on. No bike ever came with VM33 smoothbores from the factory. They also never came with 128 main jets from the factory in 1980. George told you what it came with.

I am not all that interested in aftermarket racing carburetors such as the VM33. Not particularly relevant for your application. In 81, the KZ1000J replaced the earlier KZ1000 models for the most part. The J engine is a different engine with different displacement and uses BS34 constant velocity carburetors. It has NOTHING to do with your bike nor do the carburetors. I was pointing out that the main jets are very incorrect if they are indeed #128.

Not sure what the point of this thread is unless you are trying to rejet the bike for some reason. I guess you have a K&N drop in replacement filter? I would recommend a #110 main jet as the #102.5 is small anyway but the K&N isn't flowing air much different than a stock filter.

Again, #128 main jets are not stock on any pre-1981 KZ period nor anything nearly that big. Largest main jet used was a #115 on the 76 KZ900 VM26SC carburetor assembly. When Kaw started using constant velocity carbs in 81, they used #122.5 main jets on the J model or #127.5... those two sizes were used on about 2/3 of the BS34 equipped models on the bigger bikes and somewhat smaller main jets on the 750cc models.

If you have a K&N drop in filter, reduce the size of the main jets to #110 and report back in after doing so. One more thing... read their instructions on cleaning and oiling those things. MOST if not ALL K&N owners tend to OVER-OIL the darn things causing rich operation. They need to be cleaned with K&N's cleaning spray and air dried then MISTED with K&N spray oil. Most people use the "more is better" principle and drench the things.

George you were right of course. I guess many years back I did hire someone to clean the carbs and I guess they botched it. Odd though the bike did not run that bad, maybe dirt and old gas buildup compensatated for the larger main over the years.

Anyways cleaned the carbs again last night and installed 107.5 mains and holy cow that woke up the ole girl. Did pickup a slight hesatation of idle. Does it take a while for the air to work out of the accelerator pump circuit? It was working before the tear down.

Thanks for steering me the right way to lower the main size.

Actually, the pump circuit won't work the first time, even if primed... it takes several pumps; that is, several throttle openings to get gas through the circuit where it will come out the nozzles. The main jet situation shouldn't affect the off idle transition... that issue should adjust out by adjusting the air screws... shut them a 1/4 turn and try again. If that doesn't help enough, perhaps another 1/4 turn. They are probably out farther than they should be to compensate for the bit of gas getting through on main jet which does add a bit even at idle. That is why there is an air jet associated with the main jet... it supplies air at idle with the slides all the way down. The slide cut out also contributes air at idle.