gsxr 750 hard starting

**slopster** · 6th August 2008, 18:19

Got myself in a spot of trouble. I have had my '96 gsxr 750 sitting round in the garage for the last few months since I got my new zx6r. The battery was about dead and it only sometimes started. I sold it yesterday and said that the battery was the issue. Unfortunately the new owner put new battery in and it was still difficult to start. He wants his money back which I guess is reasonable but of course I'm not happy about it.

Strange thing is it starts every time off a push start (cold or hot). The starter seems to crank over ok too. It usually starts ok cold but nearly impossible to start hot. Runs great at high revs but a bit snachy in the low end. But it has always been like that. Just a bit worse now. My next thought was bad fuel but he's put new fuel in and still same. Anyone got any bright ideas? Was thinking clogged carbs and stuff but it only been inactive for a about 6 months with a couple of short rides thrown in.

**slopster** · 11th August 2008, 17:15

Well I have it back now - gave the guy his money back. Trying to sort it out. I thought it was the carbs but I cleaned them out and no change. Put my spare carbs on and still no change. Pulled the plugs out and they were pretty black so maybe a weak spark? They had actually only done a few hundred km. What else can I check in the ignition system other then the HT leads and the other leads on the coils

**racefactory** · 11th August 2008, 17:51

Were they wet black or dry black? If it's oil fouled then it will be wet black. If that's the case, from my experience wet plugs have caused me all kinds of shit... miss fires and back fires and a pig to start. Wipe them down good and chuck em back in see if it fixes it.

Otherwise- isn't it a sign of low compression when it's hard to start when warm?

How much you selling it for?

**AllanB** · 11th August 2008, 17:56

If that fuel has been in there for more than 4-6 months and unused it may be as simple as draining the tank and filling with fresh petrol.

My lawnmower does the same over winter when unused (a very similar engine to a GSXR

) and a former bike I had, had the same problem after sitting for the winter- fresh fuel and WAH HOO!

**driftn** · 11th August 2008, 18:30

Plugs. Mine did the same thing so bad that it would stall when hot and flatten the battery trying to start it again.

**racefactory** · 11th August 2008, 19:49

yeah thats what it sounds like a... but the thing is he says it starts with push start so i dont get this shit- that goes against plug point doesnt it?

could it be a combination of fucked rings and shagged plugs? im thinking oil seeping past the rings and into the combustion chamber...and that would explain loss of compression, causing bike to be generally hard to start when warm right?

**slopster** · 11th August 2008, 22:09

they were wet black which is a bit of a bad sign but that was after trying to start so could have been fuel wetting them. It had a top end rebuild 15000km ago so I certainly would hope its not anything internal. It hasn't used any oil between changes at any rate. And as for cleaning the plugs - I sanded the electrodes and rechecked the gap them. Is there anything more to cleaning them then that. Have replaced the fuel and no luck infact it probably worse now though I still got it started today and it ran ok once started couldn't get it going when hot even with a push start. And the asking price by the way is $4500 + a bit more if you want all the spares that come with it, and I do have quite a few.

**CookMySock** · 12th August 2008, 08:41

pull the plugs out and heat them up smoking hot for a couple of minutes with an LPG torch or some gas burner, then reinstall and see if it starts easily. Go for a good long ride. Pull plugs again, and tell us what you see.

Steve

**Katman** · 12th August 2008, 11:15

Originally Posted by slopster

Runs great at high revs but a bit snachy in the low end.

Originally Posted by slopster

It had a top end rebuild 15000km ago so I certainly would hope its not anything internal.

Are you sure one of the cams isn't timed a tooth out?

**slopster** · 12th August 2008, 12:35

Originally Posted by Katman

Are you sure one of the cams isn't timed a tooth out?

Actually there is a slight possibility of that since I checked the valve clearances a while back and its possible I could have put a cam in slightly out. Could be worth a check - I hate putting that valve cover back on though - hard to get it to seat right.

**driftn** · 12th August 2008, 16:43

Personly i would not bother just cleaning the plugs just bite the bullit and replace the. Once they are fucked thats it they fucked.

I dont see how checking the valve clearances would bumb it a tooth out. To do that would you not have to take the cam chain off comlpetly to move the cam?

**slopster** · 12th August 2008, 18:58

Originally Posted by driftn

I dont see how checking the valve clearances would bumb it a tooth out. To do that would you not have to take the cam chain off comlpetly to move the cam?

Well when I did it I stripped the threads in the cam holders and had to remove them to helicoil them. Also replaced the cam chain tensioner at the same time but I'm still 95% sure that the cam sprockets were engaged with the chain the whole time so I don't think it would have moved. I'll check it though when I get a chance prob this weekend.

**Rob Taylor** · 12th August 2008, 19:26

It sounds like coils to me.The gsxr range is know to kill coils.Spark will look ok with plug out but no good under compression.You can check them with a meter.Mate had same problem with a gsxr250rr,Tryed everything,like you ended up coils. Give ian a text 0273291648 or email bigwoody@xnet.co.nz. He has all the info ,nice guy.

**slopster** · 12th August 2008, 20:12

I have dynatek aftermarket coils. What sort of meter do you use to test the coils? Is it one of those ones with the points that you put on the plug lead where you make the spark jump a gap and increase the gap 'til it won't jump? Or is it a proper electronic gizmo. If I was to just test the distance the spark will jump what sort of distance should I expect - 2mm?, 5mm?, 10mm?

**driftn** · 13th August 2008, 13:02

is this the red one that was on trade me? if so I know how to fix it.

Take the ohlins (if its the one im thinking of) rear shock out and sell that to me. This should get it tip top

Also still wouldnt mind the spare head light even though its broken it cant be any worse than mine