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My brothers bike has been having serious issues over the last year, and he never could figure out what the problem was, So I decided to take it on.  The issue started out as it wouldnt idle when cold.  You would have to hold the throttle half open and crank it, then turn up the idle to let it warm up.  once warm it would race, and you would back the idle down and it would be fine.  if you killed it and started up fairly soon it would start and idle fine.  but once cooled down, same as begining.  Anyways, he's changed tps sensor, iat sensor, complete throttle bodies, and a number of other things.  tried it with and with out the powercommander.  Its at the point now, that I have to hold the throttle wide open to even get it to start.  once started I have to maintain 1/3 to 1/2 throttle to keep it running.  if I back off it just dies.  It acts like it is loading up.  It's been pouring here for a week, so I havent been able to tear it down, but I thought I would post the symptoms, and see if anyone else has had similar problems in the past.

Oh and if I put it together and do get it out to the highway, it sputters on low end but once its up above 2-3k rpm it runs pretty good, till you let it drop back down.

EDIT:   It turned out to be valve clearance.  4 of the intake Valves were open and the other 4 were to tight for spec.  After putting it back together, re-measuring and doing it again I finally got it to spec and now it idles when cold no prob.

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

Well I replaced the map sensor this weekend and got it to run better.  It still floods out on startup sometimes, but generally it will start pretty easy but it wont idle on its own till it warms up.

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

I hope your issue gets cleared up.  I'd offer more but I don't have anything worth saying.  I just didn't want this post to die in case someone else can help.

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Never follow, Never lead

www.myspace.com/nyansapo

Well it still could be a map sensor issue I guess.  It was his original sensor I put back on.  He had put the one off of a second set of throttle bodies he had bought and it wouldnt run at all with that one.  Now it will start but I have to hold the throttle half open to get it to start and then keep it cracked a little to keep it running while it warms up.  once it is really warmed up, like 160 degrees or so then it will idle just fine.  otherwise it low idles and dies.  I think it may be the start valves needing sync'ed but he says he did that and it didnt make a difference.  Any other thoughts?

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

How does the cold start system work on these FI bikes.  I've never had such a problem out of my old F4.  I've narrowed it down to its flooding out when its cold.  You have to crack the throttle wide open to get it to start and then hold it open till it warms.  then it will idle.  however until there is a temp reading adjusting the idle screw does nothing, which tells me its electronic.  Im wondering if it is a temp sensor or if the ECM is just junk.

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

i had similar problems with my f4i except i had problems after the bike has been running for a bit and nice and warm.  but same issues there after.  sometimes it would cut out and i could only get it running again if i held the throtle open a bit.  my fix was the fuel pressure regulator.

when you fixed the throtle body, did that include the fuel rails and regulator?  check your plugs for fouling.  that could lead to flooding.  also, check the vaccum tube on the pressure regulator.  it should be completely dry.  if it looks dry, try this.  with the vaccum hose off and the run switch off, turn the key to on, then flip the run switch to run.  when the fuel pump primes, keep an eye on the vaccum side of the regulator.  nothing should be coming out.  if its bad, youll see some gas drip out, or in my case, squirt out. 

if it has problems at a cold start, you might have a injector stuck open and fuel is constatnly just dripping into a cylinder which would explain a poor cold start.  for mine, as the bike cooled, the exccess gas evaporated and a cold start was perfect.  as the bike ran, the cylinders slowly started to flood so my warm starts sucked balls.  whats the gas milage like?  also, if fuel is dripping into the cylinders, check your oil to see if gas has gone into the crankcase.  just look at the oil window and see if you notice the level is higher than before.

good luck

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blah blah blah

Its not the pressure regulator.  It runs great after it warms up, plus it was just replaced new as well.  The only thing we havent replaced with a brand new one is the map sensor and the ECM.  This morning I cranked it till I heard it try to fire, and then cracked the throttle and held it.  I got it to start but it was hovering about 800rpm. I was able to keep it running but barely till it warmed up a bit, then it would accelerate on up.  This time however, I got the map sensor error while it started, so Im fairly sure that both the map sensors we have are crap.  Either that or the ECM just isnt working right.  My brother is working on getting both of these replaced so hopefully one of them is it.

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

Curious as to whether you ever found the problem with this.  I'm having very similiar issues with both my f4i and my 954.  f4i has idle and running issues warm or cold and has a miss at all rpms and is loading up the 2 center cylinders.  The 954 idles great warm or cold but has a miss at all rpms and is loading up the 2 outer cylinders.

no never found the problem.  My brother took it with him to Alabama when he moved and hasnt been able to figure it out.  Im in the process of buying it from him right now, so as soon as I get it back I'll continue working on it.  On a side note he's replaced everything electrical from sensors to the computer and it still does it.  I believe it is something to do with the wax thing on the cold circuit.  I cant remember the correct name right now.

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

Hate to ask this, but has the O2 sensor been replaced?

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_____________________________________________
2008 Triumph 675
My Website = http://www.3knucklesracing.com
BSS #88
TTC #88

DucRacer748:

Hate to ask this, but has the O2 sensor been replaced?

 

Non-Cali bike. Doesnt have one.

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

JonLD:

no never found the problem.  My brother took it with him to Alabama when he moved and hasnt been able to figure it out.  Im in the process of buying it from him right now, so as soon as I get it back I'll continue working on it.  On a side note he's replaced everything electrical from sensors to the computer and it still does it.  I believe it is something to do with the wax thing on the cold circuit.  I cant remember the correct name right now.

The wax unit is controlled by the temp of the coolant.There's air bleeds in the top of the throttlebodies, and as the cooland warms up the wax unit, there's less air moving through the bleeds.  This is also how you set up/sync the throttle bodies, so maybe When they were sync'd, might have something to do with it.  Engine load is engine load regardless of what the engine temp is, so map sensor shouldn't be the problem.

Jeff

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My bike-2002 F4i-With OEM CCT......And no rattle
"Life would be boring if everyone was perfect"

Thanks Jeff,  Thats kinda what im thinking but wont know till I get my hands back on it.  My bro is pretty good with things, but not quite as persistant as me.  He replaced all that stuff and he synced it but when it didnt fix the problem he quit messing with it.  He also had a cheap alarm system on it for awhile, so Im gonna check all the wiring and make sure nothings bare.  I had that issue with my cousins bike that he had also installed an alarm system but later had to remove.  I probably wont be able to get ahold of the bike till around the first of the year, but when I do, I'll let everyone know what I find.

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'99 CBR 600 F4 Silver, Carbon Fiber Grips, Levers, Mirrors, Stainless Steel Muzzy Slip-on, 520 Stealth sprocket set 15/47, Factory Pro Stage 1 TI jet kit, Reverse Indiglo Guages, Goodridge SS Brake lines, Custom Carbon Fiber Seat, rear turnsignal eliminator, rear brake LED Bulbs, F4i Rear Shock

'87 Yamaha XV1100 Virago Black/Red Fireball, Mac slash-cut pipes, custum air filter, clear turn len's, Lots of Chrome

I had actually tried to sync my throttlebodies awhile back, but the bike didn't seem the same afterwards.  I had bought a spare motor, and used the throttlebodies off that.  I don't know what it was, but something wasn't right with the old ones.  i had used the Motion Pro gauges filled with Mercury(sp?).  I'm not sure if the gauges were NFG, but throttle response wasn't the same.

It's just wierd that this problem only happens when the bike is cold.  I'd definetly be looking at the Wax unit.

Jeff 

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My bike-2002 F4i-With OEM CCT......And no rattle
"Life would be boring if everyone was perfect"

Any updates yet Jon?

Jeff

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My bike-2002 F4i-With OEM CCT......And no rattle
"Life would be boring if everyone was perfect"