TOPIC:

My carb tuning skills is pretty weak. My 1980 KZ1000 LTD was really having problems with the stock carbs. So I upgraded to mikuni RS flat sides. The motor has been gone through top to bottom and I'm really happy with how it turned out. Because I bored it out a bit I went with the 36 mm carbs at the recommendation of KZzone.com. I put them on and the thing idled perfect. But as soon as I apply a little throttle it sputters and dies. I'm a little lost on where to start. Like I said my carb tuning knowledge is a bit limited. The documentation from mikuni both makes it even more confusing and only slightly helpful.

Is anybody willing to give me a little hand-holding advice?

I can offer you a basic setting diagram to start with.

Cool! So is this settings that I should have to get started? I'll pull jets and stuff and compare to this.

I don't know anything about the carbs you have, but wait for a little bit and I am sure others will jump in with some pretty darn good advice for you.

Rick H.

Personally, I would call APE Racing and speak with them. They sold them to you and will/should provide customer support.. They should have "notes" on what jetting should be for your particular motor set up .

So I got out my handheld AFR meter and welded a bung into the 4:1 collector that is on the bike. At idle it was off the chart lean. Like greater than 25:1. I'm surprised it started. I got on the pilot screw and reset them all to the same place. For reference these are the RS36-D3-K's. So starting to back out he pilot screws, it didn't get down into good range until the screws were 3 full turns out. That seems like a lot especially since the documentation seems to suggest it should only be about 1/2 turn. Do I need to be adjusting the pilot screw and the pilot air jet? Is it this just how it is?

Getting the pilot screws down into a good AFR fixed all the reving problems for sure. But now my upper RPM's are super lean. We'll fix that next.

I don't know much about those carbs but in general I think it's a sign of too large a pilot jet when they have to be screwed out much farther than normal.

Changed carbs from factory BS34's to a set of RS36's based on the Mikuni sizing chart. But according to fellow member recommendations, the 36's were "too big" for my engine, so I swapped them out for RS34's when prices were right on ebay.
I'm happy with that decision, but the variety of jetting options have nearly driven me cra...Z!

Yeah so if the jet that comes stock is a 17.5, which direction do I need to go? To a 15 right?

Hello what size pistons , cams are you running. ? Ported head. ? I'm having the same problem. I have newly built engine , 1075 12.5:1 . Ported head . Oversize intake & exhaust valves. Open Kerker header. Seems have to choke carbs for about minute before engine will idle , then around 4k rpm , engine pops and seems doesn't want to take the gas . Hard to run it over 4k rpm . Did you have to reset your carbs. My engine builder told me the carbs shouldn't need syncing or jetting.

Funtimes wrote:
My engine builder told me the carbs shouldn't need syncing or jetting.

So why he didn´t do the carb tuning right? If your engine pops and doesn't want to take the gas your engine is running very lean.
What´s your pilot and main jetting set-up?

Hello , I guess the jets are the same ones that the carbs came with . I don't know a whole lot about carbs . I may have to take my bike to a good carb person . Thanks for your reply .