GSX 250 spluttering over 45 - 50 Carbs ? elecs ?

[ukjules]

I am making notes of all the suggestion and will do them in sequence.
All much appreciated - Be assured i will never stop until this bike is going sweet !

NOTE: i didnt say before but it has a 2 into 1 motad thing on it. I hate it but
i need to find someone who has or can make the 2 into 2 like the original ....
(The issue still is it has gone ok in this setup)

I have stripped the carbs countless times. Top and bottom and have put them back carefully.
I am 100% positive the cv diaphragms are back ok.
However
- the needle i have not recorded its setting.
This i will do next.
Haynes says 3rd groove for my gsx 250 et 1980

ordered:
new plugs
ebay'd petcock

I was possibly incorrectly thinking coils ? would / could they produce this type of fault you think ?

 

[Guest]

Ok, well, I went back and listed things



There were also petcock troubles in the mix but that can now be worked around....The first is the very important- Something has changed since you got the bike. Otherwise given new info of bike running ok above 6500, perhaps the slides are sticking or there is trouble with the cv diapragm. DID you take care to replace it correctly? You can test for proper operation of CV slides by lifting slides with your finger and plugging the lozenge-shaped hole on the air-box end with your thumb. Slides should fall very slowly. At least that's how mine work on two well-running bikes and the spare carbs I have. It is a pretty ez test if you can get at them. On my bike airbox can be wobbled back aways especially if I unbolt the section of rear fender there and shift it off the knobs...hard to explain but the bodywork on my GSX400E is identical to yours, I think.

and John Park mentioned needle settings a good possibility especially if people have been in and out of there a lot. I have a set of spares so I can check out what is stock setting if my 400's carbs are identical, but given they are identical , is there a possibility 250's would be set a step leaner or richer? to allow the same carbs to be used? (Beyond my paygrade,this... )

The carbs are 30mm rather than 34 and look a bit different - not that I've ever had a set in hand.

Sometimes you can have leaky float needles and such and the bike will run okay because the float levels are higher than stock; when you get that sorted, the settings that worked end up a bit leaner. Just did that one last week. Finally got rid of some leaky and worn needles and seats and set the float levels and ended up having to raise the needles a notch.

I just replaced the stock clamps - so called - on the intake boots with hose clamps and I swear it runs butter. Even new, those things were a bit of wishful thinking, not to mention flimsy and asking to be stripped.

 

[Gorminrider]

I am 100% positive the cv diaphragms are back ok.

Ok. I had one that was not staying up after reassembly so It's a pet of mine I always lead out when I can

I was possibly incorrectly thinking coils ? would / could they produce this type of fault you think ?

I wouldn't think so Wierd spooky gremlin stuff like a leaky plug lead getting a resonant wobble at 5000rpm and shorting intermittently to the frame is possible but electric faults I've experienced are not so particular in rpm. Even a "stiction" problem at the advance weights is much rarer than not re-assembling them correctly. I think I've reassembled everything wrong at one time or another!

I just replaced the stock clamps - so called - on the intake boots with hose clamps and I swear it runs butter

Smooth as butter you mean? the threads get loose alright...taking mine off when rusty half-wrecked em...I think too the rubber must be shrinking as it gets older and harder -my stock clamps almost marry ends right together I suppose it's another sign I should fork $ out and buy new boots some day.

 

[Guest]

You need new O rings in carb & double check diaphrams

 

[ukjules]

Still awaiting parts. Will post when fitted sequentially and tested.
I got my carb rebuild kits off eBay.
I could do with new needle valve bucket seals having taken them to bits
so many times.

I am in UK , where bar eBay can I get carb kits ?

 

[fastbysuzuki]

I am in UK , where bar eBay can I get carb kits ?

You could try Technical support: tech@allensperformance.co.uk.
Your bike is not listed however it's worth a email.

 

[ukjules]

Right I will do a recap as i am forgetting how this issue started and what has been done:

Overview:
I am convinced although can barely remember now that the bike has worked on a long run
prior to these issues with the same setup - carbs, tank, petcock, plugs and exhaust.

so i am starting from scratch:
All i have done is clean the tank out ! (I have done this many many times with zero issues)

Added new plugs today and took it for a test ride:
ISSUE: Perfectly tuned up to 5000 revs and then started hesitating almost as if
it wasn't even sparking or it was on reserve ?
Basically the exact same issue as before.

Tested the coil:
I am going to continue another thread on this as even though this coil tests
fine the only bike i have that it tests right on (this one) it doesnt work is this one and all the other
bikes test fail but work perfectly ? (they fail on the secondary giving "1" on 20k setting.
On both coils Primary - 4.2 ohms Sec 16000 ohms

Put on a new (second hand) fuel tap:
Took it for a test ride and exactly the same issue - hesitating ....

took carbs off for the 20th time:
Cleaned and think the needle jet a few holes were blocked or was it just petrol residue ....
anyway all cleaned up.
I could not check the height of the needle as my circlip pliers are not good enough to get the circlip out !
(If anyone in the uk knows where i can get a "good" set tomorrow let me know !)

Vacuum piston - the big thing i n the mddle:
These moved freely but one did stall coming down.
Cleaned and they are now fine.
Took it for a test run and exactly the same issue.

Diaphragms:
No tears or pinholes and seat perfectly.
Testing with pushing up the piston and blocking the oval inlet they both come down slowly.

So thi is where i am - the bike runs perfectly at idle and all the way
up to 5k revs.
Over that is splutters and i cant be sure now about it being fine over 7k revs.

so that is the status, something that i simply cannot understand or fix.

 

[Gorminrider]

Well, I've shot my bolt too, as to things that are simple and at a distance from my own spatulates but there's always things to try....to find the cause.

Here's one that hasn't been tried. Warm up the bike first so you are sure it's running as described, then before it goes entirely cold but after it's so hot as to vapourise gas fumes ,
Disconnect your fuel line to duplicate "running out of gas". Now, can you then rev beyond 5k as the fuel level drops? It's the opposite test of applying choke/enricher.


Your coil testing process sounds a little indefinite...I don't understand it. The numbers you get seem alright. The rest I didn't get.

I do not know how good this is for you or anybody but from a pdf per Ignitors =TCI (transistor controlled ignition) I have downloaded from http://ridersofvision.net/
Really, the first thing is "bad connections" and "voltages". It calls to mind that a voltmeter across the suspects when this stuttering is happening can be a clue.
Both cylinders misfire,
Engine runs real erratic,
May run fine high RPM but not low, (or visa-versa)
May not start or spark at all,
Worse when hot=
Most likely TCI problem or bad connection to TCI
Check connections and voltages
TCI -> power on tests
TCI -> Inspection
Ignition good till under load Bad Battery=
Connections - Voltage drop somewhere
Ignition good some days not others=
Bad Connections
TCI -> Open Inspect for obvious flaws / moisture

Also go here and look for help
http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html

there's an intersting pdf per ignitors and more

 

[ukjules]

Coils tested to be fine.
What I am saying us the only bike that tests fine is the one that doesn't work.
All my bikes that work perfectly fail the coil test.
I am at a total loss to explain this.
This is not the forum for this though.

Anyway next is :
- clean second petcock
- check for fuel starvation
- find some aftermarket coils in same range.
- drain out all petrol and use new
- check needle height , poss lean out.
- another atu
- atu pickups

It really is depressing , a bike in perfect tune but only until it
gets to 5 k revs.
I really need someone with another gsx to swap parts out
to test.

 

[Guest]

I had similar problems when i 1st got mine. O rings were rock hard as were carb to airbox rubbers. Diaphrams holed choke cable not shutting off properly. Then it didnt help when i got the cam timing one tooth out which is easily done. Have you change all o rings ? They will probably be 35yrs old now &rock hard

 

[ukjules]

All inlet and air box rubbers fine ! I have a way of sorting old rubbers.
Carbs are fine.
Remember the engine runs like a dream to 5k revs.

O rings: (What o rings ?) O rings on the carbs were replaced. Hard to get all of them with the kits available
but i got one from japan with most of the carb bits.
HOWEVER having taken them to bits so many times i am not 100% on the state of them now.
thing is there is absolutely no change to the issue whatsoever !

Todays test:
I re did many many connections around the battery. Earths all cleaned up.
Warmed up the bike not going over 5k. Went like a dream as i remember it many years ago when
I had a new one.
Over 5 k immediately the hesitation.
(I now cant be sure if over 7k it is fine. mid to high range throttle is where the issue lies.
If i stopped and simply revved the bike 1,2,3,4,5,6,7k all no hesitation on the engine i could hear at all ??
The second i move off and go over 5k immediately the hesitation again.

I think i am going to discount fuel totally now.
(I WILL CHECK THE NEEDLE HEIGHT HOWEVER WHEN I GET THE RIGHT CIRCLIP PLIERS)
I think this is the Coil, a faulty coil.
The reason why i think this is this is the only thing i can think of what i did something too
since "i think" it was working better. I yanked the ht lead thinking it would come out ?
Of course the useless design has it fixed into the coil , all i wanted to do was check the ht leads.

That is my intention to backtrack from a coil (the left hand one), pickups from coil to atu, atu.

if anyone has any of these bits please let me know !
I simply must know what is causing this issue.
I have never ever had anything like it and been totally stumped for so long.

I do appreciate your help chaps too ! We must know why this is happening ?

 

[Guest]

Bit of a long shot, but could you use the coils from your RD250 to test?

 

[Gorminrider]

^good idea,Steve-or from the closest match on another bike that has 12v system...... or even gently wiggling (wearing your rubber gloves! and or a wooden clothespeg ) on the coil lead might do it . Inspect the HT lead closely. You might see cracks in rubber from a sharp bend.

The goal posts keep moving per high rpm (was ok above 7k rpm) but Intermittent stuff ican be very difficult.

 

[ukjules]

As for goal posts moving when testing a bike on a country road it is hard to provide the exact rpm.
4.5 / 5 ...
Lets call it 5k. What has changed is that i cant detect if it is ok over 7k - the bike is screaming at that point !!
its a 250 ! I think after listening intently it is not ok and still hesitating.

Re rd250 coils - Damned good idea ! I will do this tomorrow !
I have the rubber gloves ready for tomorrow to test and wiggle.

I really do think the "yank" i gave the ht lead on the coil is the reason .... a long shot i know
but i am done with the fuel system.
Remeber the ht lead is "fixed" into the coil and if it was damaged it cannot be changed.
(I have inspected it to ignore this but i will look again)

thanks again guys - i cant fix this alone and these ideas may be nothing to
you but each one helps.

 

[Gorminrider]

found this...click it if it's too small.

 

[Gorminrider]

View attachment 45116


found this...click it if it's too small.

 

[ukjules]

I cant get to the rd 250 coils the bike is in a place i simply cant be
bothered to get too. Stuck at the back of a shed.
Ill have to risk and buy others.
this bike was meant to be an easy fix up and run around and i am getting quickly sick of it.

I like the check list you posted !
I am now convinced it is the coil, atu, .... and will go down that route purely as i reckon when i tugged on one of them
i caused some damage.

SO if anyone has any coils, pickups , atu ? let us know.
Cant do much else until i get those now but wil inform when i do.

JUST THOUGHT OF SOMETHING ELSE:
I have had issue getting the timing right. It is right on the camshaft visibly
but with the strobe i cant get it right ? (not that there is much adjustment at all on this bike) (I did a post few weeks back)
Odd issues such as poor flashing on the strobe when on the ht leads and at one point no flashing
on one of them. This after i yanked the ht lead !!

I am clutching straws here and "think" the above to be correct although it was a while ago...

(Remeber it is "perfect" and I mean perfect at revs below 5k)

LH coil (the one i yanked) ordered.
ll then get a RH one if tha fails then a atu.

 

[fastbysuzuki]

I cant get to the rd 250 coils the bike is in a place i simply cant be
bothered to get too. Stuck at the back of a shed.
This after i yanked the ht lead !!.

Why don't you pick out the old leads from the coil being carefull not to damage the metal post at the bottom and epoxy new ht leads that's if you want to be bothered of course.

 

[ukjules]

they are sealed units - poor design ! no metal post .
to consider this i could destroy them. they test good with a multimeter.
I would have to do a wiring extravaganza and that is not to be done on coils.

I have ordered a LH coil and will go that route.
i will order the RH one if that fails .

so no i cant be bothered !

 

[Gorminrider]

...the HT leads themselves are pretty stout wire so excepting a spark jumping through cracked wire insulation, if there's an issue, it's more likely in:

the epoxied coil connection to them?

or the plug cap which has an assembly inside it? Inside it are:

the brass plug-end snapon,
a ceramic resistor with silver coated ends,
a teeny-weeny little disc!!!
and a spring that sits on the brass connector to the stout wire HT lead

lots of room for error in that cap like missing parts....

Much less chance imo at the epoxied-in end of the HT lead... I know ways the insulation can be ripped and cracked by pulling on it but getting the wire disconnected is a much much stronger pull.