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This is the list of things i have done.
Basics first
- changed air filter
- cleaned fuel filter
- changed spark plugs
- checked clutch switch
- checked battery

More in depth
- changed vacum lines and conections
- sync throttle boddies
- checked atmospheric pressure sensors
- checked valve clearences
- checked both throttle position sensors
- checked ISC vavle hose and conections
- checked ISC sensor
- swaped CDI box


All the sensors checked out and swapping the cdi did not help. I am going to see what value the isc valve is giving the computer next weekend to see if it is incorrect just need the software and computer hookup.
All i do to get the bike to start is use my PCV to lean the fuel 40% on cold start using the startup fuel program and engine temp hook up. With out the power comander i have to hold the bike at 3500 rpm till 70° or it will stall. But that is not a real fix to the problem. I am really frustrated but not willing to give up.....there has to be a solution.

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Can I ask if you have tried starting the bike cold with the IAP electrical plug unplugged and Power commander unplugged.
If not doing this will make the bike run on a known working setting stored in the ECU.
if it Runs ok then there is a problem with your Vacuum lines or your IAP sensor!
If you have already replaced your Vacuum lines and T-ees then I would suggest swapping your AP sensor with your IAP sensor they should be the same, and leave the AP sensor unplugged so it uses the Default Value and not use the IAP sensor in case it's giving a Faulty output.
If this still shows the same result.
I would then remove the vacuum lines and dislodge the throttle bodies so they are not sitting over the intake and using a thin wire or an Oxy tip cleaner make sure the the small tubes the vac lines connect to are not Blocked but if you synced the throttle bodies then these should be ok.
If the problem is the same when trying to run cold with the IAP unplugged look to your ISC valve this was Suzukis 1st port of call when guys started bringing their bike is complaining about this problem.
Rest the ISC 1st then replace if it still has the problem!
 

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This is the list of things i have done.
Basics first
- changed air filter
- cleaned fuel filter
- changed spark plugs
- checked clutch switch
- checked battery

More in depth
- changed vacum lines and conections
- sync throttle boddies
- checked atmospheric pressure sensors
- checked valve clearences
- checked both throttle position sensors
- checked ISC vavle hose and conections
- checked ISC sensor
- swaped CDI box


All the sensors checked out and swapping the cdi did not help. I am going to see what value the isc valve is giving the computer next weekend to see if it is incorrect just need the software and computer hookup.
All i do to get the bike to start is use my PCV to lean the fuel 40% on cold start using the startup fuel program and engine temp hook up. With out the power comander i have to hold the bike at 3500 rpm till 70° or it will stall. But that is not a real fix to the problem. I am really frustrated but not willing to give up.....there has to be a solution.

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did you recently change out your exhaust or go with a new setup?
 

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i have a k8 750. the idle issue started happening. so i did all the basic oil change, air filter change, and spark plugs. All of that didn't fix the problem.
 

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I also tried changing out the vacuum lines. Changing out the ISC sensor etc etc. Finally I decided to check out my exhaust system. I found out there was a leak between the header and the exhaust. I got some copper exhaust gasket seal sealed up the leak and the idle issue has been gone ever since.
 

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If that was the case you wouldn't have been having cold start problems with blowing blue smoke out your exhaust until the bike warmed up and then everything running like normal it should of been idling bad all the time.

Unless the exhaust was sucking in air and the O2 sensor was then picking up the extra oxygen in the exhaust and thought the bike was running lean so it put more fuel in to make the mixture rich again.
Will have to remember that one.
 

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Bocce you fixed my problem, my dealer charged me $400 to diagnose and did not find a solution, I did what you said removethe IAP and the bike started perfect, waiting on a new IAP now to arrive. Thank you.
 

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Bocce you fixed my problem, my dealer charged me $400 to diagnose and did not find a solution, I did what you said removethe IAP and the bike started perfect, waiting on a new IAP now to arrive. Thank you.
Before you get carried away installing a new IAP, replace the vacuum hoses. It will cost you about $3 in parts. Removing the IAP from the circuit won't confirm that the sensor is the problem - it will just confirm a problem with the circuit.
 

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To confirm your IAP is good or bad swap your AP with your IAP they are both the same sensor.
The AP is located under the seat it Doesn't have a vacuum hose on it as it sensors atmospheric pressure.
Leave the AP unplugged the ECU will use its default setting.
Connect the AP sensor into the plug for the IAP and connect the vacuum hose, do a cold start If it's the same problem then it's not the IAP just replace your Vacuum lines and tees that go from the IAP to your throttle bodies
 

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OMG! I finally found this thread!:punkMy k9 750 has been doing this cold start issue for months now and I too just like everyone else spent tons of money and dozens of hours trouble shooting this issue. I was going to seafoam the vacuum lines to see if that would clear her up, however now I'm thinking that I'll just go ahead and replace the vacuum hoses. Great tutorial on how to replace the vacuum hoses, pics are excellent too!

I want to say thank you to every single person in this entire thread who posted their views, opinions and helped to figure out the source of this cold start demon that seems to puzzle dealers. I'll post my results after I change hoses and seafoam her real good. Might not be till next week tho.
Cheers bros!:cheers
 

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I posted in a different thread and just noticed this, so thought I would add to this thread instead of my new one.

Here is a recap of my first post

Just went to fire up the bike and it couldn't stay at idle. Only way to get it to start is with a bit of throttle, so thought maybe its just cold so kept throttle on to see if it would idle when warm. It wouldn't. Got it operating temp, looked at my exhaust and noticed a flame sitting ontop. Like a butane torch! So I shut it off and a flame popped out. Looked down the pipe and it was glowing orange.
Started great few weeks ago. No throttle needed. Only thing I did at that time was add fuel stabilizer and filled up the gas. Bike is stored in a dry clean garage.
27,000km, just had valve job done. Only mod is aftermarket exhaust.

That was least week. Just went to fire her up today and same thing. Except it started right away and then dies. So I assumed bad gas to start with, drained tank and refilled with new gas, no stabil this time. Ran rough for about 3 min then smoothed out and now holds idle. I ran some seafoam through IAP and ISC hose, puffed out some smoke and still running great. Will see what happens tomorrow with another cold start.
I noticed when I about to grab the ISC hose it wasn't even plugged in, just floating there, so that is now connected. Not sure but maybe that's why I had a FI light come on Cpl months back? No idea
 

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The problem this thread has been addressing is a cold start problem which then disappears once the bike is warmed up.
The fix is to clean out or replace the vacuum hoses that connect to the IAP sensor.
To quickly check if you have this particular problem wait till your bike is stone cold.
Then unplug the IAP sensor electrically and then start the bike
If the bike runs ok then your vacuum lines need cleaning or replacing.
I have written a how to with pics on this thread a few pages back.
The reason you bike runs ok with the IAP unplugged is because the ECU knows it's unplugged and uses a known working default setting.

If your bike still runs bad with the IAP unplugged then you have a different problem which could be related to your ISC valve if it only happens on cold starts.
Good luck.
 

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Discussion Starter #1,355
Wow I can't believe I started this thread so many years ago and it was still going strong with so much input from everyone. I have long since sold my 750, but I remember starting this thread and thought I would see if we came to a solution.

I hope checking of the vacuum lines works for those with this problem, wish I had known this years ago..might still be riding her to this day.

Thank you all for your contribution :)

Dex
 

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Your welcome mate!
I felt so bad for you guys who had this problem and had not long brought your bikes from new even and not even the so called experts could fix the problem.
I'm glad to say there are many from this thread that have permanently fixed their rides buy replacing or cleaning the Vacuum lines.
 

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Wow I can't believe I started this thread so many years ago and it was still going strong with so much input from everyone. I have long since sold my 750, but I remember starting this thread and thought I would see if we came to a solution.

I hope checking of the vacuum lines works for those with this problem, wish I had known this years ago..might still be riding her to this day.

Thank you all for your contribution :)

Dex
I'm grateful you posted the video! It demonstrated perfectly what the problem was, and I was able to find some like minded people who could work on discovering a solution with me. Otherwise, I don't think I'd have figured it out.
 

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Ha ha a your kidding right take a look at post 971 this is the one where I got my bike to display the same symptoms as bikes that have this problem buy just removing the Vacuum line from the IAP and then it all went away when I plugged it back in.
There buy proving the problem was Vacuum related.
I then convinced Bocce to replace his Vacuum lines when we were checking his bikes valve clearance and wow he never had the problem ever again!
 

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Hey guys, I am a new user to gixxer.com and the reason is because I was searching the Internet for my idle problem during cold start and I think I found the resolution to my issue on this thread.

I went ahead and decided to pull the trigger on switching my vacuum lines. I ordered the 3mm tubing, t fittings, and began by taking off the air box. However, it was a pain in the ass to get the tubes off of the tb's. I honestly tried for an hour trying to pull the old lines off and they would not move. So instead, I decided to blow into the lines starting from the line that plugs into the iap. I started to blow until I head a thud, to which it was much easier to blow afterwards. So I'm guessing that that was the blockage that was causing my problem.

I still want to change the lines though, just to be sure. Did anyone use a technique to get lines off?
 

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Ok I wouldn't recommend blowing into the lines while they are still connected to the bike as what ever is blocking the lines will end up inside your intake or block the vacuum ports on the intake.

To remove the lines it's best to remove the air box and loosen and just pull the throttle bodies off the intake they are only held on with the same type of clamps as the air box.
You don't need to disconnect the throttle cables but you might want to unplug the injector plugs so your not pulling on the wires also unplug anything else which has very short wiring.
Once you lift off the throttle bodies just leave it sitting on the intake follow the vacuum lines to the intake ports, with a small flat screw driver use it to brake loose the hose buy working the screw driver under the hose from 3 - 9 0'clock this should be enough to brake the rubber seal so the line will just pull off.
Their is no actual seal on the end of the hose but over time with the heat the rubber sort of bonds to the intake fitting and that's why it's hard to remove.
Once you replace the hose and tees just slide the vac lines back on as far as it will go on and replace the throttle bodies be sure to check no dirt or anything has fallen in the throttle bodies before assembly and when fitting the throttle bodies make sure you push them all the way home they shouldn't rock at all but feel firmly in place they may take some wiggling to get back into place.

PS because you blew air into the lines I would check the ports on the intake where the vacuum lines connect all 4 of them to make sure nothing has blocked them up use a small strand of wire or an Oxy tip cleaner to check the ports are clean before you put the new Vac lines on.

Also get some shop Paper Towel or a clean rag that doesn't fray or have lint all over it and cover the intake air ports before you clean the Vac ports so if there is anything in there it doesn't end up in your engine

You can do the above without taking the throttle bodies off but access is much better with them off and you can clear any possible vac port block age without it falling into the engine.
 
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