Gsx400x Impulse problems

[Leblowski]

Mucho problemo's with my sons Impulse.

This bike stood for about two years and needed some work.

So i did valveclearence, ultrasone the carbs, new needles and seats, new pilotjets. Adjusted floatheight checked compression wich is just above the limit. Inletrubbers checked also they are fine.

I have some problems with it.

Yes it starts direct on the button but only runs perfect idle once it warms up a bit It starts only without the choke if you pull the choke it stalls.

I did a testride and it runs very good once warm. But if you let it stall it does not want to start, only if you start long enough it comes up again with hesitation.

If it's cold it start's much better.

I checked the plugs they where burnt clean not Black so looks very lean.

So i think it runs very rich cold and once warm it runs very lean.

 

I checked everything on the bike and kind on in the dark here.

 

What am i missing ??

 

 

 

 

[MeanBean49]

3 hours ago, Leblowski said:

Mucho problemo's with my sons Impulse.

This bike stood for about two years and needed some work.

So i did valveclearence, ultrasone the carbs, new needles and seats, new pilotjets. Adjusted floatheight checked compression wich is just above the limit. Inletrubbers checked also they are fine.

I have some problems with it.

Yes it starts direct on the button but only runs perfect idle once it warms up a bit It starts only without the choke if you pull the choke it stalls.

I did a testride and it runs very good once warm. But if you let it stall it does not want to start, only if you start long enough it comes up again with hesitation.

If it's cold it start's much better.

I checked the plugs they where burnt clean not Black so looks very lean.

So i think it runs very rich cold and once warm it runs very lean.

 

I checked everything on the bike and kind on in the dark here.

 

What am i missing ??

 

 

 

 

Have you tried some new spark plugs in it? The 400's are terrible for plugs going off and affecting running, particularly idle and when warm. You will see a spark at the plug but they go weak really easy. After having similar issues with a bandit 4 years ago and wasting days going over everything else, its always the 1st thing I try when my 400's start running shit

[Leblowski]

No i havent installed new plugs yet, an easy fix to try i'll order some.

Thanks for thinking along with me !

[johnr]

same engine as the 400 katana, carbs are a bit of a nightmare. you need to replace every o ring in there and make sure the needles in the slides arent worn, (they get ridges in them and never fuel properly again. its also worth pulling the ht leads out of the coils, cut a half inch off the ends and refit, they vibrate loose and loose contact making them run a bit rough.

[Leblowski]

For those wich are interested...

I have solved the issues on this bike and it runs perfect now.

What was wrong ??

I almost threw the towel but decided to give it one more try,  as i thought it was an electrical issue i started measuring al elektrical components including the coils once more just to be shure.
In all those years i am spannering on old Suzuki's i thought this aint gonna win from me.

So after measuring and testing the only problem could be the coils, but the resistance from them where spot on hot and cold.
I have about 5 sets of coils so i tried another set wich where measured and tried them still the samen issue.

After trying 5 sets wich all gave factory spec resistance hot and cold i still had the same issue.

So i thought wtf is going on here, i rembered having a set of 750 stick coils somewhere > sourced them installed them..

Damn the issue was gone !! so now we have a good running bike wich starts on the button hot and cold.

So dont believe what you measure and never ever use old coils, i can tell you i wont ever again! this bloody bike stood about 1,5 year because of this.



 

[TonyGee]

glad its sorted  

i had a similar problem on a customers GT750 a while back, according to the temp gauge it was over heating, stripped out the cooling system and everything was good, so tried another gauge on and still the same, tried another 3 gauges on and still the same, (all used by the way)  so into the harness i went and nothing seamed wrong ?????  I was at a loss, so i said to my boss can we try a new gauge on so he ordered one and it fixed it.    3 fecking days trying to fix it when it was just the gauge.  such is life.  

[Gixer1460]

So you changed multiple sets of coils and no doubt plugs also but problem was cured by using stick coils  . . . . . . which don't have . . . . . 

Plug wires ! Probably, there be yer problem? Its always the bit that can't be faulty, but usually is.

[Leblowski]

6 hours ago, Gixer1460 said:

So you changed multiple sets of coils and no doubt plugs also but problem was cured by using stick coils  . . . . . . which don't have . . . . . 

Plug wires ! Probably, there be yer problem? Its always the bit that can't be faulty, but usually is.

 

 

Well if thats the case then of all the 5 sets the wires and or caps would have been faulty wich could be the case but i think not.

Thing is all of the sets where old and came from bikes i took apart in the past.

As i mentioned all of the sets where measured and gave proper resistence as prescibed in the workshop manual

I even testend leakage from the leads and caps in the dark spraying with a plantspray wich did not gave any suggestion that would be the problem.

[Gixer1460]

Possibly the other thing to consider based on your reply above is that stick coils will fire using lower input voltage ie they'll work in series for a 4 cyl using a 12v input but effectively only getting 6v each . . . . . so maybe there is an issue in the coil feed line? Whatever if the bike is working!