who else ran u4.1 in a bike mapped for u4?

A few of the people I was pitted with and myself have our bikes mapped for u4. We ran the regular U4 that we had and then when we ran out we put in the new U4.1 and all of us felt the bikes ran poorly. They had off idle stumble and felt really lame in the midrange where with the regular U4 they were pulling great.
Obviously the mapping needs to be addressed for the new fuel. I just figured I would share. I will be remapping this week to see how different the maps are.

 

Please keep us updated. My SS motor is done this week and I have to map it for U4 as the west coast wont be getting any U4.1 until the end of the month. I guess I'll have to have it remapped when they finally get it in.

 

I'll Mook tell the story, but he had a hateful moment this last weekend with a Carb'd 99SV on U4.1......

 

I just saw this post.

I had my 01 carbed SV jetted to run U4. I also ran pump with no problems for a year. I put the U-4.1 in for my second race and by the end of the 1st lap it was coughing and running like poo. That cost me 3rd place for sure.... i was running down 2nd! Oh well. I know it's not the same problem you modern folks have with powercommanders and all, but obviously it's not as easy as just switching fuel.

I thought it was just me and i had a bad can. I never had jetting issues with the SV before at all. I guess it will require more attention than the VP guys originally told me at Indy. They said it's a direct replacement for the regular U4.

I still have a full can and i'll be taking the bike to my tuners to run on the dyno. I guess he'll be able to sniff it out.

 

Mine was fine this weekend.

 

what are you running and what was it mapped to?

 

had some slight glitches on Maintenance throttle and some stumble while picking it back up. Bike was mapped for U4.1. Issue went away with pump gas. DJ guys worked on it a little at the track but not 100% smooth. Will se what local guy can do with more time.

 

we found that you have to really run the bikes rich on that stuff ,, and it really goes fast .. a few poeple where running out of gas before the end of some of the races ...

 

right...I am thinking the regular u4 maps are not going to work very well with this fuel and that a remap will be required. Like I said, on U4 my bike was a beast...as soon as I switched fuel it started loosing power

 

So people with U4 map were running too lean with the U4i in their bikes? Sounds like the U4i is more oxygenated and hence could produce more power.........

Good thing no one blow their motors running too lean (guess not lean enough to cause detonation). :up:

 

ya .. i dont think it's enuff to melt a piston ...... just not getting enuff fuel over tha 0/2 .. and rumore has it that you can leave it in the bike a little longer than u4 ,,,i may be wrong ,, would not be the first time

 

Guess its back to the Dyno.

 

you can get away with goin pretty lean. when we mapped my sv for u4 last year it was around 14:1 on pump and with the u4 was at 16:1 a/f!! it ran best around 13.2:1 IIRC. this was done about halfway through the season, not to mention the year it ran before i purchased it.

 

04 GSXR 750. Mapped to U4.

It pulled strong, on/off throttle was good. There was another here, same basic bike, same basic mods, mapped to U4, and his didn't run right with the 4.1.

 

Roger...where are you getting the U4.1? I'm having my motorwork done right now and they are about to tune it so I'd love to get a pail of 4.1, but my distributor doesnt have it. I'd love to have it tuned right off the bat with the 4.1 so I can take it out to FBE with no probs

 

My local distributor is Dick Harrell's in Las Cruces, but I bought his complete stock last weekend for resale. Any VP dealer should be able to get it within a week.

 

Just called a few places...looks like So Cal is lagging behind the rest of the country. Guess I'll have to spend another $250 to have it remapped once I'm able to find some of the new stuff :down:

 

I'll be getting a new map made some time this week for U4.1 from U4 on my K6 600. I'll post up how much richer (or leaner) we had to go to get peak power.

 

my R6 is mapped for U4 and i ran the 4.1 this weekend. it had a really bad deadspot at about the 4-5k range. gonna have to take it in and get it remapped i guess. looks to be a new fuel issue.

 

the guys from VP said to run it a little richer