Ahh I'm going crazy '89 GSXR-250R

**juddnz** · 7th January 2009, 19:32

Took my bike into a well known mechanic about 4 weeks ago to see if he could get it going. Rode it home today, got my gear on and got 500m down the road and it stopped. would idle at full throttle and the rpm would come back up as i decreased the throttle, would rev for a bit then do the same thing when i tried to move.

Got it home and let it sit for a while. started sweet and rev's up but when you start moving it does it's weird rev thing.

I'll call the mechanic when i can but has anyone got any ideas?

I feel that it's like the bowls in the carbs fill up and are sweet but the fuel tank doesnt keep up when you go to move.

The fuel hose is pretty long, do you think if i shortened it up so it wasn't in a big 'U' shape it might help?

Cheers,

**juddnz** · 8th January 2009, 14:52

blocked tank vent?

Im gonna give it a go when i get hme

**MSTRS:Me** · 8th January 2009, 15:21

Originally Posted by juddnz

blocked tank vent?

Not in isolation. Would take quite a while for the vacuum to build up to the level that would give your symptoms. That long hose is a possiblility...kinked?

**juddnz** · 8th January 2009, 16:48

and now it wont even start. just turns over and over then occasionally backfires MASSIVELY and a whole lot of vapor stuff comes out the tail pipe. I'm ever so pissed.

**tri boy** · 8th January 2009, 16:50

Starting to sound like a ign pulser coil or CDI.

**White trash** · 8th January 2009, 16:51

Carb diaphragms are fucked.

Price em up, you'll blow your fucken brains out.

You're welcome.

**juddnz** · 8th January 2009, 17:00

the carbs just got pulled apart so it's unlikely, plus it's quad carb

**White trash** · 8th January 2009, 17:10

Originally Posted by juddnz

the carbs just got pulled apart so it's unlikely, plus it's quad carb

Are they CV or flat slides?

**Katman** · 8th January 2009, 17:13

Possibly recessed inlet valves.

**juddnz** · 8th January 2009, 17:14

Originally Posted by White trash

Are they CV or flat slides?

Slides, started sweet as yesterday.

**juddnz** · 8th January 2009, 17:15

dunno, the guy said he sused out all the valve clearances because thay were too tight apparently

**Katman** · 8th January 2009, 17:19

Originally Posted by juddnz

dunno, the guy said he sused out all the valve clearances because thay were too tight apparently

That's what happens when the inlet valves lose their metallurgical (is that even a word?) integrity. In other words - they go soft. They start to recess into their seats and close the valve clearance up. Adjust the valve clearances and they just recess further. It's not uncommon with those engines.

**juddnz** · 8th January 2009, 20:24

Anyone in new plymouth wanna fix it for me?

**xwhatsit** · 8th January 2009, 23:20

Originally Posted by Katman

Possibly recessed inlet valves.

How does that cause this effect? Do they heat up or something and change once hot?

**mister.koz** · 8th January 2009, 23:46

I had a really similar problem with my GN250, i know it doesn't have allot in common with this bike but it might help.

Replaced the carb, no change.
Replaced the coil + spark - no change.
Re-set the tappets and it seemed a little quieter but not better.
I replaced the CDI, and the rectifier and recharged the battery and the problem went away.

Turns out the rectifiers on some bikes can start to leak high voltages as they die over time (1983 gn250) and those high voltages can cause the CDI to malfunction creating misfires and the such. I imagine if the same thing was happening in a 4 cyl bike you would have much worse trouble.

The key thing was that the problems started when i went over certain rev's, my mate explained to me that the rectifier wouldn't have faulted at low rev's because the windings wouldn't have the momentum to charge the battery so it would be inactive.

HTH