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Anthk7: thanks man. Yeah blowing into the vacuum lines was probably not the best idea, but it did solve my problem temporarily. That is, until this morning when I tried to start the bike up the morning after a rainy night and the problem came back. I'm guessing the blockage was blown right back into the vacuum lines after a couple dies of riding.

I was able to get access to the vacuum ports without taking off the throttle bodies, but the lines wouldn't budge. However I didn't break the seal around the vacuum port so I will definitely try again this afternoon by using a small screwdriver and hopefully I have better luck.

Appreciate the reply! I will report back my success or failure.

PS. I hope this issue solves my idle issue. My bike is idling high around 1.8k at times then it will go back down to 1.5k at times.
 

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Ok so I was finally able to get the vacuum hoses off using a screwdriver to release the seal. I then checked the vacuum ports with the end of a safety pin and did not feel any blockages. There was however an oily substance in and around the vacuum ports that I tried my best to clean out. The same oily substance was found inside my old vacuum lines and t fittings, so I'm guessing that this was the source of the blockage. I then made new vacuum lines and placed them back in. All together from start to finish only took me about an hour.

Time will tell if this is the solution to my problem. This weekend is supposed to be rainy and cold so I will post my results. I'm just hoping that I did not blow the blockage deep inside the vacuum port because then I will have a larger problem to deal with.

PS: my idle is the same after replacing the lines. Every time I pull the clutch in when riding, my bike goes from 1800 rpm and then quickly settles down to 1500 rpm. Don't know if this is an ecu issue or perhaps the isc sensor, but it is something that kind of bugs me.
 

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This thread's problem doesn't effect the idle when the bike is warm.
So if you have any problems when the bike's warm you have a different problem.
Replacing the Vacuum lines will only solve the cold start problem because the lines were blocked the IAP sensor could not send the correct message to the ECU
Once the bike wormed up the heat from the engine would melt the blockage and the bike would be like normal until some cold weather made the lines block again.
This is why when guys took their bikes to the dealer they could never find a problem because they would keep the bike inside out of the cold so the problem wouldn't show up.
To reproduce the problem of the blocked vacuum lines just pull the Vacuum line off the bottom of the IAP sensor and start the bike cold.
The bike will start but run very ruff blow a bit of blue smoke out he exhaust then most likely stall.
Now connect the vacuum hose back up to the IAP and if they are clear the bike will run as normal!
 

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Is there a part # for these vacuum lines? Like can I order this from the dealer?

I'm not mechanically inclined... I'm trying to tell my mechanic to do this for me because I have the same symptoms described in this thread.

I don't want to go to a hardware store and just buy random vacuum lines because I'm sure they'll be the wrong ones, or wrong size, etc. Unless someone can tell me exactly what length / width I need, how many, etc.

Thanks!
 

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Is there a part # for these vacuum lines? Like can I order this from the dealer?

I'm not mechanically inclined... I'm trying to tell my mechanic to do this for me because I have the same symptoms described in this thread.

I don't want to go to a hardware store and just buy random vacuum lines because I'm sure they'll be the wrong ones, or wrong size, etc. Unless someone can tell me exactly what length / width I need, how many, etc.

Thanks!
Yep! Take a look at this: Suzuki Motorcycle Parts 2008 GSX-R750K9 THROTTLE BODY HOSE-JOINT Diagram

The hoses and t-pieces are parts numbered 14, 15, 16, and 17. You can use standard 3mm vacuum hose from an auto parts store, and T or Y pieces that fit them. If you buy about 80cm - 100cm of hose you should have more then enough length. Then you just cut each piece to match each of the hoses you are replacing. Total cost of parts should be about $4.
 

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Yep! Take a look at this: Suzuki Motorcycle Parts 2008 GSX-R750K9 THROTTLE BODY HOSE-JOINT Diagram

The hoses and t-pieces are parts numbered 14, 15, 16, and 17. You can use standard 3mm vacuum hose from an auto parts store, and T or Y pieces that fit them. If you buy about 80cm - 100cm of hose you should have more then enough length. Then you just cut each piece to match each of the hoses you are replacing. Total cost of parts should be about $4.
Thank you. So far my problem has been alleviated by blowing through the vac lines and fittings. Hopefully the issue doesn't resurface.
 

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It will come back!
It's due to the lines being lined with a sticky substance that when the engine gets hot it clears, then when the temp drops the lines become blocked.
blowing them out is a short term solution unless you put some degreaser in the lines to actually remove the stuff that's stuck to the tube walls.
When a friend of mine had this problem we removed the lines and blew them out, nothing came out but air and it seamed they were clear anyway.
As it was so cheap to replace the lines we did so anyway and the problem never came back.
You don't have to buy OEM lines and tees just remove you lines take them to any auto shop and ask if they can supply the same size hose and tees.
1m of hose is more then enough.
 

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After owning my 2010 gsxr750 experiencing the same problems as in the video in the first post. Managed to read first 10 pages and jumped to the last one reading about blocked IAP vacuum line.
Is that the solution to the problem with rough cold idle and start up problems?
 

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After owning my 2010 gsxr750 experiencing the same problems as in the video in the first post. Managed to read first 10 pages and jumped to the last one reading about blocked IAP vacuum line.
Is that the solution to the problem with rough cold idle and start up problems?
Read the other 59 and you'll find out ;)

Short answer: yes, probably :)
 

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Replaced all the little vacuum hoses with new silicone hoses and gave all the T connectors good cleaning blow o
ut with compressed air. I only experienced this issue twice but hopefully won't happen again. First cold startup was fine.
Many thatnks to all those made massive effort to get to the bottom of this problem, impressive.
 

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It will come back!
It's due to the lines being lined with a sticky substance that when the engine gets hot it clears, then when the temp drops the lines become blocked.
blowing them out is a short term solution unless you put some degreaser in the lines to actually remove the stuff that's stuck to the tube walls.
When a friend of mine had this problem we removed the lines and blew them out, nothing came out but air and it seamed they were clear anyway.
As it was so cheap to replace the lines we did so anyway and the problem never came back.
You don't have to buy OEM lines and tees just remove you lines take them to any auto shop and ask if they can supply the same size hose and tees.
1m of hose is more then enough.
I kind of expect the issue will come back too, and will post back here if it does.
 

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I kind of expect the issue will come back too, and will post back here if it does.
I replaced all the rubber vacuum hoses with new ones. T connectors were soaked in chain cleaner and blowed out with compressed air.
If the problem comes back will replace T connectors too.
I personally consider taking throttle bodies out and check all 4 nozzles that vacuum hoses connect to, just to make sure that there is no blockage too.
 

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If you ran some kind of degreaser through them that should be OK as they are not very long and it's easy to see if there is anything in there
 

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After owning my 2010 gsxr750 experiencing the same problems as in the video in the first post. Managed to read first 10 pages and jumped to the last one reading about blocked IAP vacuum line.

Is that the solution to the problem with rough cold idle and start up problems?

This problem is not just a rough idle!
There are 3 symptoms
Rough idle
Blue smoke at cold start out the exhaust.
And then bike stalls once it's been running for about 1min and will not idle at all.

If you continue to get the problem after replacing the Vacuum hoses lift the tank and start bike once it's cold again then unplug the electrical connector on the IAP sensor if the bike works runs fine and you have already replaced the vacuum lines then I would be changing the IAP sensor.
You can double check this buy swapping the IAP sensor with the AP sensor which should be under the seat they are the same part swap them over and if the problem goes away it's the sensor.
But these sensor don't really fail often.
 

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This problem is not just a rough idle!
There are 3 symptoms
Rough idle
Blue smoke at cold start out the exhaust.
And then bike stalls once it's been running for about 1min and will not idle at all.

If you continue to get the problem after replacing the Vacuum hoses lift the tank and start bike once it's cold again then unplug the electrical connector on the IAP sensor if the bike works runs fine and you have already replaced the vacuum lines then I would be changing the IAP sensor.
You can double check this buy swapping the IAP sensor with the AP sensor which should be under the seat they are the same part swap them over and if the problem goes away it's the sensor.
But these sensor don't really fail often.
Thanks mate. I read all about IAP sensor too so will keep an eye on it.
Hopefully everything will be sweet. 👍
 

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I have a K8 GSXR-600,

Just read all the pages of this thread...

My bike just started having a rough idle issue this past week out of the blue.. Had it out for a long ride running perfect.. Went to take it out 4 days later and it's running like shit.. Only difference is doesn't matter ifthe bike is warmed up to 180 still runs the same.. Tach reads just about 1K idle.. It does little revs up to about 1200-1300 RPM. The bike sounds like all cylinders aren't firing. If I try to drive off in 1st gear I have to give it a lot of throttle and roll off the clutch or it will stall out engine bogs down.. Even in neutral if I just slam the throttle engine bogs.. I can get the engine to idle on its own with a few starts but the idle is terrible. I was going to replace the plugs but came across this thread I recently created my own but now don't know what course of action to take...

But I saw someone say on here if the engine is warm and the idle doesn't correct its prob not related to the vacuum hose fix?

Here is a video of how my bike sounds.. I'm not getting any lights or codes on the LCD at all.. So no warnings just running bad..

https://www.youtube.com/watch?v=7vqmYgso4f8
First things first, check the battery voltage at idle, and at 5,000rpm. You want 13v at idle and 14-15v at 5,000rpm.

Second, check the ISC. On the K8+ models, that is what controls the idle speed.

Are you seeing an FI light on the dash?
 

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No warnings on the dash at all... All recalls have been completed even the latest Rectifier.

I'll check the battery voltages today and respond back. How do you check the ISC?
The ISC test is described in the factory service manual, get yourself a copy for sure.
 

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Ok checked the voltage of the battery,

Standing Voltage was : 12.80

Starting Dip: 10.50-11V

running idle: 14.33-14.50

The drops in voltage are in sync with the idle problem..

I had the battery on the tender all night, when I started it up a few minutes ago it actually started running normal for a bit then the idling issue came back....

One thing I failed to mention was when I got the bike back from the dealer the battery was to drained to start the bike so I put it on the tender. When I went into the garage after only like 35 minutes the green light was flashing on the tender indicating the battery is 80% charged already... Maybe my battery is faulty.


First things first, check the battery voltage at idle, and at 5,000rpm. You want 13v at idle and 14-15v at 5,000rpm.

Second, check the ISC. On the K8+ models, that is what controls the idle speed.

Are you seeing an FI light on the dash?
 
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