K6 600 to k7 750 motor swap issues...! | GTAMotorcycle.com

K6 600 to k7 750 motor swap issues...!

GixxeR_IaN

Well-known member
Hi there. I just recentley did the k7 750 swap in my k6 600. I have run into a few issues. (STOCK MOTOR)

Before I start I will tell you that I have tripple checked timing, valve clearance, compression, spark and made sure everything is connected properly.


Issue 1- the bike starts but it takes a few cranks then dies. After a little bit it warms up and runs but very poorly. I get a nice little flame in cup 3 thrttole bodies the odd time, which I cannot understand because valve clearances are on spec.


Issue 2- I got the c14 fi light (tps) and adjusted it but the line on the gauge cluster does not move no matter what way I turn tos. It stays at the bottom- _c14, I the. Replaced sensor thinkin it was bad and same problem. This problem just started yesterday randomly.


Issue 3- which probably relates to issue 1, as soon as I open throttle the slightest bit it does out.


Issue 4- there is a slight burning rubber smell comming from valve cover area when it starts to warm up. No wires or hoses are touching anything, also not my stator or rectifier they are workin I have tested them both and there is no over heating of the r/r, so I'm lost on that as well.


Any help would be much appreciated.


Thanks Ian
 

GreyGhost

Well-known member
Site Supporter
you've checked spark on every cylinder or just one?

I have had problems with an engine (assembled by someone else) where the spark was way off (they had keyed the distributor 90 or 180 out, its been a while) so timing seemed reasonable but it was actually firing way off. It surprising could start but obviously barely ran. Connected the spark plug wires up in the new pattern and it fixed the problem.
 

GixxeR_IaN

Well-known member
Which throttle bodies and ECU are in the bike?
The k7 750 throttle bodies. And I borrowed my buddy's 750 ecu and same problem as with my 600 ecu. The ecu can't be the full problem tho. It almost seems I am getting way rich than lean if anything. Isn't the only differance on the 750 ecu is the fuel map to compensate more fuel to the more air due to the bigger throttle bodies?


And GreyGhost. What were the exact steps you took to fix that?

Thanks, Ian
 

ZX600

Well-known member
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I had the same issue on my GSXR 750 (no motor swap)when it got cold out. I added a Power Commander, changed the slip on and changed the fuel map and the problem went away.

There is a lot written on the web about that problem, most point to the TPS but mine got solved by the PC.

The k7 750 throttle bodies. And I borrowed my buddy's 750 ecu and same problem as with my 600 ecu. The ecu can't be the full problem tho. It almost seems I am getting way rich than lean if anything. Isn't the only differance on the 750 ecu is the fuel map to compensate more fuel to the more air due to the bigger throttle bodies?


And GreyGhost. What were the exact steps you took to fix that?

Thanks, Ian
 

GixxeR_IaN

Well-known member
Ya but when I adjust my tps it doesn't move the line on my gauge cluster and I've even tried with a brand new one. And can I run a pc 5 with the 600 ecu with the 750 motor?
 

GreyGhost

Well-known member
Site Supporter
The k7 750 throttle bodies. And I borrowed my buddy's 750 ecu and same problem as with my 600 ecu. The ecu can't be the full problem tho. It almost seems I am getting way rich than lean if anything. Isn't the only differance on the 750 ecu is the fuel map to compensate more fuel to the more air due to the bigger throttle bodies?


And GreyGhost. What were the exact steps you took to fix that?

Thanks, Ian
It was a long time ago, I can't remember exactly. Judging by others comments (that know much more about bikes than me) I would investigate fueling first. Will the bike fire on propane?
 

frekeyguy

Well-known member
Are they used plugs or new?
 

ZX600

Well-known member
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What exhaust system are you using? I bet you don't have a full system and still have the cat on it. Fuel management system? do you have any?
 

frekeyguy

Well-known member
Can you post a video of the motor turning over / running ? if I can hear it I might be able to help with some input.

But that motor should fire right up and get going if it does not have any issues ? have you done timing / valve cleareces before ? or was this the first time?

**Was the 750 motor intact when it was pulled and put into your frame ?
** is the wire harness a 2006 600 harness?

Bike was 2006 600, and the new one is from a 2007 750 ?
 
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TwistedKestrel

King of GTAM
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Issue 1, 3 & 4 could all be the same problem. I know nothing about this motor swap but it sounds to me timing is off or firing order is wrong. Mixed up ignition leads is a d'oh moment but it happens, and the motor will sometimes run (poorly)
 

GixxeR_IaN

Well-known member
I'm almost finished my motor cycle technician course so I have quite a bit of experiance with building motors lol. But this is a whole new problem that I've never encountered. And the I have the cat on still but set valve is removed. And no I don't have a pc yet for fuel managment. And the 750 was intact when I got it. But I've compression tested all 4 cyl and tripple checked all hoses and connectors are in proper locations. I'm using the k6 600 wiring harness but the k7 750 harness is exact same. And the harness is good since I was using it with the 600 motor without any problems. I will try and get a video asap.
 

ZX600

Well-known member
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I'm almost finished my motor cycle technician course so I have quite a bit of experiance with building motors lol. But this is a whole new problem that I've never encountered. And the I have the cat on still but set valve is removed. And no I don't have a pc yet for fuel managment. And the 750 was intact when I got it. But I've compression tested all 4 cyl and tripple checked all hoses and connectors are in proper locations. I'm using the k6 600 wiring harness but the k7 750 harness is exact same. And the harness is good since I was using it with the 600 motor without any problems. I will try and get a video asap.
When I had this issue I spent months researching on the forums and speaking to various techs.

In some cases was the TPS - some bikes got it replaced and it worked
IN Some case was the harness - Some bikes got it replaced and it fixed the problem
IN some cases the TPS and Harness were replaced and it didn't fix the problem - Their issue was they installed a slip on without removing the cat with no fuel management (this was also my case)
IN other cases it was valve clearance, they got their clearance adjusted and it fixed the problem.
IN other cases was the ECU but mostly because of other issues (this one wasn't common)

The screwed up thing is that the symptoms are exactly the same for all those issues above.

You checked ECU and TPS and Valve clearance so I would recommend doing the rest on my list. I am not a mechanic, just someone that spent 2 years hunting for gremlins
 

JohnnyP636

Well-known member
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Issue 1- the bike starts but it takes a few cranks then dies. After a little bit it warms up and runs but very poorly. I get a nice little flame in cup 3 thrttole bodies the odd time, which I cannot understand because valve clearances are on spec.

How are you seeing the flame in the throttle body? Are you trying to run the bike with no airbox or with the top of the airbox off?
 

GixxeR_IaN

Well-known member
No air box but shouldn't cause a back fire in the throttle bodies. They only cause of that should be valve timing and clearance. But both are right on spec. The air box only controls intake air temp and filtering of air has nothing to do with backfire. I'm completely stumped. I've never had a problem I couldn't fix but this is a whole new ball game.
 

JohnnyP636

Well-known member
Site Supporter
No air box but shouldn't cause a back fire in the throttle bodies. They only cause of that should be valve timing and clearance. But both are right on spec. The air box only controls intake air temp and filtering of air has nothing to do with backfire. I'm completely stumped. I've never had a problem I couldn't fix but this is a whole new ball game.
Running without and air filter or an airbox can affect your A/F and cause the bike not to run properly, yeah you can get them to start and even idle but any throttle input and they usually don't like it. Not saying it will cause an FI code like your having but generally I have never found a bike to run properly without them. And Ive also done the 600-750 swap more then once....Ive also had to deal with the stupid Suzuki TPS problem in the past, pain in the *** I dont know why still after all these years they couldnt fix that issue for good
 

GixxeR_IaN

Well-known member
Ya man I agree. When I open up the throttle it bogs right out. And I've just tried adjusting the tps again and still nothing I've looked for pinched or torn wires so now I'm even more stumped. I have it idling a bit better now but blowing more white smoke out the pipe then a bond fire lol. I checked plugs and they're soaked with fuel and the odd time I'm still getting a nice little piping flame in the throttle bodies but it's only happening once every 5 minutes or so.
 

GixxeR_IaN

Well-known member
Progress update! Okay so I grabbed a beer, a few cigarettes and sat down and stared at the bike and thought about everything I have done so far. I figured that since valve clearance and timing is on spec that it has to be a fuel problem. So I primed my fuel pump a few times and figured out that fuel is not the problem. So I then figured it had to be electrical. I started by testing ignition system, charging system and all were good. I then did a voltage drop test on the TPS and found .3 parasitic resistance. So I tore into the harness finding that someone had butchered by soldering and not knowing what they were doing. I attached new wires and bam, set tps and she ran like a beaut. I used the harness before without any problems but I guess taking the other motor out disturbed the garbage soldering job.

I am still getting a lot of white smoke from the pipe and the burning smell from the valve cover area, but as for now I'm happy lol
Thought I would give everyone an update.

Thanks everyone for your help. Much appreciated.
 

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