GSXR250 - leaning out?

[j_redley]

O.K.

So finally, I have my 89 GSXR 250 in a rideable state. Its taken a while, but now I'm stuck.

I've checked valve clearances according to spec. I've checked for block jets, leaky diagramph etc in the Carbs, but I still have this problem.

The bike will only run with the choke out. It starts first press of the starter everytime, and idles away until it warms up. It won't rev above 7000rpm at any time, and if I try to push the choke back in, it cuts out instantly.

I've checked everything obvious I can think of. I've sprayed "Start yah bastard" around the inlet manifold, and the vacuum pipes I can find. Nothing doing. I've checked hose connections etc, but still does the same problem. Any ideas?

[neels]

Idle adjustment?

Float levels?

Pilot screw settings?

[j_redley]

The only thing I havent checked is Pilot screw settings, would these stop it from revving over 7000?

[Katman]

The only thing I havent checked is Pilot screw settings, would these stop it from revving over 7000?

No.<hgvhgvhjv>

[Slavvy]

Sure you don't have a spark issue?

I had a basically identical problem with my bike, had to push start it to make it go, didn't want to rev, made no power etc. It turned out I was getting basically no spark on one cylinder. Does it sound rough at all? It might be mis-firing without you realising.

[j_redley]

Sure you don't have a spark issue?

I had a basically identical problem with my bike, had to push start it to make it go, didn't want to rev, made no power etc. It turned out I was getting basically no spark on one cylinder. Does it sound rough at all? It might be mis-firing without you realising.

This is an interesting thought... I'm going to replace the spark plugs, which haven't been done yet, and take a good look at the coils. I vaguely remember one of the leads pulling off a coil when I first assembled it. I don't suppose you might know where I can get another coil?

[tigertim20]

that might well be your issue, but go through all the other things first like idle and pilot screws, and new plugs, theyll be alot easier (and cheaper) to check than the coil.

You can probably test the coil on the bike couldnt you?

[j_redley]

that might well be your issue, but go through all the other things first like idle and pilot screws, and new plugs, theyll be alot easier (and cheaper) to check than the coil.

You can probably test the coil on the bike couldnt you?

The only way I know to check a coil is to check the resistance through it, which I'd need to find out the factory specs for anyway. As has been mentioned before, the pilot screws wouldn't give my problem, so I might focus on checking the plugs first. If I take them out and they don't show obvious signs of leaning out, I might have to look closer at the spark issue.

[Slavvy]

The only way I know to check a coil is to check the resistance through it, which I'd need to find out the factory specs for anyway. As has been mentioned before, the pilot screws wouldn't give my problem, so I might focus on checking the plugs first. If I take them out and they don't show obvious signs of leaning out, I might have to look closer at the spark issue.

The other thing you can do is take a plug out and fit it to the lead. Crank the engine over while holding the plug thread or electrode to a grounding point (like the engine for example) and see if it makes sparks. Granted that wont tell you if you have a particularly strong or regular spark, but it'll tell you if there's a break in your lead somewhere or your coil is stuffed.

As for where to get new coils, if I knew I'd have bought them already :pinch:

I had the exact same issue with a lead pulling off a coil, but I managed to bung things back together enough that it all works properly. I'm investigating gj73a coils, theyre shaped differently but I suspect they'd plug & play just fine.

[j_redley]

The other thing you can do is take a plug out and fit it to the lead. Crank the engine over while holding the plug thread or electrode to a grounding point (like the engine for example) and see if it makes sparks. Granted that wont tell you if you have a particularly strong or regular spark, but it'll tell you if there's a break in your lead somewhere or your coil is stuffed.


I'm aware of how to check for spark :-p I know I have spark there, but need to make sure its a good spark, or not.

[Slavvy]

I'm aware of how to check for spark :-p I know I have spark there, but need to make sure its a good spark, or not.

Sorry, just making sure :)

According to this:

http://www.gsx-r250.com/down/Suzuki_GSX250F_Service_Manual.pdf

Primary coil resistance: 2.0-4.0 Ohms
Secondary coil resistance: 36-56 K.Ohms

That's the closest I've been able to find to any kind of workshop manual for the gsx-r250. Also has info on plug gap etc.

[ducatilover]

Are your carb slides lifting?
What colour are the plugs?
Does the power go flat and "dry", or boggy, stuttering and "wet" feeling?
Is is better hot, or better cold?

[Katman]

Are your carb slides lifting?


Could be something well worth checking.

I remember the GSXR400 (with twin carbs but four diaphragms) can be put together incorrectly with the diaphragms not hooked underneath the slides. In doing so the diaphragms will operate but not lift the slides.

[ducatilover]

Could be something well worth checking.

I remember the GSXR400 (with twin carbs but four diaphragms) can be put together incorrectly with the diaphragms not hooked underneath the slides. In doing so the diaphragms will operate but not lift the slides.
it took me multiple tries to get the diaphragms on the ZZR600 carbs to seal, I ended up resting the slide on a spanner (Down the carb throat) to lift it up and stop it pulling on the rubber, now they lift happily.

(Still cannot get it running right :facepalm: but that's another story )