Ivans jet kit AFR and popping

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born riding

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Hey Guys, as you can probably see i am fairly new member. This is my second motorcycle but do a good amount of engine work building Jetskis. Building a 500hp, 100mph turbo boat at the moment. everything i do is fuel injection so this is odd for me. The only carbs i mess with are on old 2 stroke jetskis and fourwheelers. I have never seen a carb like this one, but figured a carb is a carb.

I need help figuring out an issue or two. the first is that after i installed ivans jet kit i got the usual issues but were resolved easily with the search button here. Bike is super fast now. I made a deep tail pipe sniffer to get some afr readings to be safe. Everything over 4,000 rpm is fine like 12.5 AFR. ANYTHING below 4,000 rpms is still lean. lean between 15 to 18. any one else have the lean problem below 4,000 rpms after install? followed ivans instructions step by step.

the second is the popping on decel and letting off at high rpm. I have new intake boots and rechecked for leaks in boots and exhaust, none. AIS has been removed and plugged. TPS calibrated and carbs synched. never had 1 pop till i removed the AIS. now 10 times worse after ivans jet install. i though maybe too much fuel so unburnt fuel is burning in exhaust then thought about octane, wonder if i should lower my octane and see if that makes a difference? maybe a quicker burn in cylinder will yield less unburned fuel in exhaust.

other than AIS removal and Ivans jet kit bike is stock.

i will continue to read and troubleshoot but before bothering Ivan I thought i would post. thanks, Barrett
 
born riding said:
Hey Guys, as you can probably see i am fairly new member. This is my second motorcycle but do a good amount of engine work building Jetskis. Building a 500hp, 100mph turbo boat at the moment. everything i do is fuel injection so this is odd for me. The only carbs i mess with are on old 2 stroke jetskis and fourwheelers. I have never seen a carb like this one, but figured a carb is a carb.

I need help figuring out an issue or two. the first is that after i installed ivans jet kit i got the usual issues but were resolved easily with the search button here. Bike is super fast now. I made a deep tail pipe sniffer to get some afr readings to be safe. Everything over 4,000 rpm is fine like 12.5 AFR. ANYTHING below 4,000 rpms is still lean. lean between 15 to 18. any one else have the lean problem below 4,000 rpms after install? followed ivans instructions step by step.

the second is the popping on decel and letting off at high rpm. I have new intake boots and rechecked for leaks in boots and exhaust, none. AIS has been removed and plugged. TPS calibrated and carbs synched. never had 1 pop till i removed the AIS. now 10 times worse after ivans jet install. i though maybe too much fuel so unburnt fuel is burning in exhaust then thought about octane, wonder if i should lower my octane and see if that makes a difference? maybe a quicker burn in cylinder will yield less unburned fuel in exhaust.

other than AIS removal and Ivans jet kit bike is stock.

i will continue to read and troubleshoot but before bothering Ivan I thought i would post. thanks, Barrett
Click to expand...

So your still running the stock airbox and filter? Also, do you have an aftermarket slip-on or are you using the stock can?
 
Billy, didn't you have some sort of issue with yours and realized the EXUP wasn't working properly? Or am I confusing the EXUP issue with another?
 
FZ1inNH said:
Billy, didn't you have some sort of issue with yours and realized the EXUP wasn't working properly? Or am I confusing the EXUP issue with another?
Click to expand...

No, no problem with mine. I was just curious as to whether he had a slip-on which I believe the jet kit is made for. I never had any popping afterwards but I was running the D&D can on mine. I'm thinking if he freed up his exhaust whether it would make a difference.
 
stock intake and exhaust

Hey forgot to mention it is a 2002 FZ1 with 13,000 miles.
air box and filter are stock and exhaust is stock. from what i have read the Kit can be used with stock exhaust. I have had the popping before (not this bad) the carb jetting but not when the ais was on. i will check the EXUP and see what I can find. I will read about this style of carb and see if there is a low speed jet or something i can replace.
thanks, barrett
 
Currently on the road without main computer to be able to direct to right info on "how to", but if you have not already found, I think on the "rehto site" (fz1oa) under the links in the right hand corner (pat's page) gives you a lot of info.

Sent from: GS4
 
No box mods

No air box mods, filter is stock, but just got in a performance filter for stock box, but like to do one thing at a time to measure results. Yes pats page is basically my home page.
 
not really sure, should i adjust or replace the pilot air or pilot jet or what. don't think i need to adjust total mixture just a t low rpm / throttle opening. could spend all day trying different combos, but gonna keep looking for some guidance to minimize amount of time and work necessary
 
found this post from ivan in 04:

There is nothing wrong with the air fuel ratio of the pilot circuit on the FZ-1.....in fact 99.9% of carbureted bikes have nothing wrong with the airfuel ratio...
There is usually a volume problem which is inherent on the FZ-1 (all FZ-1's) ....

Fuel ratio is determined by a combination of the pilot jet and pilot air jet...the mixture screw just varies the volume of this pre-mixed fuel and air......
The problem with the FZ-1 is that there is too little volume at the very small throttle openings, and this is what causes surging and excessive leanness at cruise.....

Using a larger pilot jet will not get rid of all the surging, in fact since the pilot outlet holes are so far apart, using a larger pilot jet with less turns out will cause even leaner running at very small throttle openings and excessive richness just before fuel delivery transitions onto the needle.

Here is how it works....

When only one outlet/bypass hole is uncovered....

(During cruise - 4000 rpm, and there is no signal at the needle yet, because you haven't opened the throttle that far)....

At this throttle opening, the engine loses volume from the mixture screw, because it is turned out less turns, and will pass less volume at the same throttle opening as it did with more turns out with the stock pilot jet...
(which had the correct fuel ratio anyway)
The one outlet/bypass hole is too small to supply what the engine needs at the throttle opening that I am talking about.

There is actually less volume......
Because if you haven't uncovered the next outlet hole....where is the fuel going to come from?

Using a larger pilot jet will usually give a small stumble/rich spot at around 1/8 throttle opening after you have uncovered the other 2 pilot outlet/bypass holes.

Because this isn't correct, another symptom which will show up is poor on/off throttle response (it will be a bit choppy and will not come back smoothly...especially at high rpms.

Will it run better than stock?....not much
Not compared to the methods that I have done

Ivan


also found these illustrations. i am a visual lerner and stuff like this is priceless for me. simple
 
called ivan's, but don't think it was ivan that i spoke with. the guy was very knowledgeable about the bike and kit, but did not really care about my info just the info he asked for. Everything he said i have read on this forum, so i'll just keep on trying and following the directions, but if i cant get this fixed soon i am going to have to go for a fuel injected bike, maybe newer FZ1? dunno, too much money tied up in a turbo build.
 
drilled out #15 with #77 bit lean spot dropped to 3500 rpms. then replaced #15 jet with 17.5 jet and no lean real lean spot, but on road when cruising at steady throttle around 5000 rpms slowly gets lean then Very lean, trying to see why, maybe reversion from using my deep throat tail pipe sniffer? but the lean spot was very consistent, so looking into this.
 
I have Ivan's in my '03 with a MIVV GP slip-on. Mine pops on decel below 3K. I've always just accepted that it was normal given the state of tune we're running. I'll be interested in reading what you do. Keep us posted.
 
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