GPZ 500 difficult to start

[nigel_robbins]

Hi,
My GPZ 500 occasionally starts using the electric start but most of the time I have to bump start it (which works every time).
I've checked the following and all seem to be okay:
- fuel tap - fuel flowing when I disconnect the larger black rubber pipe (not reserve pipe) from the fuel tap
- battery - full charge, even tried jump starting via car battery (with engine running) to no avail
- starter motor - motor rotates and turns engine over
- air - does not seem to be an air lock (same electric start issue when petrol cap open)
- plugs - new plugs with good sparks from both plugs
- bike runs fine when started
Any thoughts anyone ?
My bike is a GPZ 500 1995 N Reg (D2)
Thanks,
Nigel

[jaffa90]

Are you testing and using jump leads at the battery terminals ???

[nigel_robbins]

Yes, I'm using jump leads at the battery terminals.
I'll charge the battery overnight and see if it starts in the morning.

[JackDG]

Going off of 'runs sometimes', 'is ok when started' and 'always bumpstarts'

Is the choke operating correctly?
If you bump start it, get it up to temp, turn off engine, would it then start under the starter?
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1992 GPZ 500

[jaffa90]

[MarJay]

Have you done a compression test? Could be valve clearances.
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[stinkwheel]

I'd go with faulty ignition switch. They can fail in such a way as they give you the starter and lights but no ignition.

I would also have a really good look at the solenoid, its wiring and the main fuse holder that attaches to it. Particularly the fat white wire.

Another possability is an idiot switch issue. Try the electric start with it in gear and the clutch pulled in.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[B5234FT]

What is the actual problem? Is the starter turning over slowly (which is why it starts when bumped) or does it whizz over fine and then just fail to start?

With mine, unless the battery is full, it winds over just too slowly to start in anything less than ideal conditions.

I've also experienced a cracked spark plug terminal which leads to it trying to start on one cylinder until you get some heat into it.

[bikenut]

Post a wiring diagram.

You do not say battery voltage when fitted to bike fully charged, when ign turned on, and finally voltage across battery when cranking.

Do any of the heavy starter wire connections get hot when cranking ?

Next, you know whats coming don't you, do you have ht when cranking? red noen plug caps will prove this. See the pic of the red neon plug caps and adaptors in the 125 thread.....Keeway RK 125 Running Issues
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nuts about bikes

[nigel_robbins]

The issue was a badly corroded connector (at end of fat white wire) where it joined the solenoid.

Thanks for all the replies (especially stinkwheel).

Apologies for my delayed reply but not been on bike due to the Xmas period.

[jaffa90]

I did state follow the battery leads.

[nigel_robbins]

Yes, thank you jaffa90