www.zxrworld.co.uk

I thought I had a unique problem ..

Turns out this guy has it too:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :middle:uk

here is a slight problem when its hot it wont start on the button but will bump start

Same as me.

Only thing is, he's talking toad re: the 'problem'. Yes on some L's there are evaporative issues re fueling but on the H's its starter/electrics related. The problem is it won't turn over fast enough to start the engine off the starter. Sounds like a flat battery, when the battery is in fact fine.

Haven't found out why that is yet ..

Obviously something to do with heat/resistance in the electric circuit.

Must be a well known issue, I just wish I could get hold of someone who's had one for a few years or had one years ago and figured it out.

Thats the problem, as far as we know no one has worked it out, we have that post in the workshop section to see if we could find a common factor between these bikes that dont start when hot. The search goes on......

Well if it only happens when its hot there can only be one root issue: heat.

Now whats getting so hot it can't function?

The loom.

Increased heat, increased resistance through the circuits as all the components expand.

Thats dropping the voltage below what is required to turn the starter motor over fast enough to spin up the ignition/engine.

The fact the engine is hot compounds the issue, as there is more friction on the crank, so the starter has to work even harder with less juice.

Its an electrical problem ..

Probably solved on later bikes by a rectifier/loom upgrade or starter motor revision.

But even the later bikes do it, by later i mean L model. There was theory of evaporating fuel due to heat some time ago, but how do you prove that? and more importantly how do you fix it?

RobB wrote:But even the later bikes do it, by later i mean L model. There was theory of evaporating fuel due to heat some time ago, but how do you prove that? and more importantly how do you fix it?

No, the H symptoms are NOT endless turning over of the engine and no ignition.

Its specifically the starter motor not turning over fast enough.

Ever had a flat battery? Thats what it sounds like.

I just need to go over the whole bike with a multimeter and measure the resistance when cold/hot and find the weak points ..

Can't be _fecked_ with that tho.

The L issues, I have no idea about ..

I would imagine those people with evaporative problems could probably do with putting their heat shield back on, or making one up from baco foil.

more than likely a corroded/crapped out white live wire, the section where it joins from the two front looms join the main loom, there is a junction there, that just has so much moisture the wires inside will be green, this should be the constant live wire.

I used to have a similar hot starting problem on a car i had (Honda CRX)
The problem was put down to some dry joints (Bad solder) on the ignition relay.
When the solder joints were redone the problem was solved.

Im not sure whether the bikes have something like a starter relay but that would be my first port of call.

Re-solder all joints in the relays and see how it goes from there.


But like i say im not a mechanic and not even sure they have relays for the starter

Hmmm, ive just had a thought, some of the import bikes have carb heaters, could that be a related issue?

RobB wrote:Hmmm, ive just had a thought, some of the import bikes have carb heaters, could that be a related issue?

Most of the UK bikes have carb heaters too, its just the coolant flowing through to stop carb icing, it wouldnt heat the carbs that much to cause fuel evapouration problems.

If the starter is turning over slowly it wouldnt be this. My moneys on the constant live connection in the loom being corroded/dried out.

mongo wrote:

RobB wrote:Hmmm, ive just had a thought, some of the import bikes have carb heaters, could that be a related issue?

Most of the UK bikes have carb heaters too, its just the coolant flowing through to stop carb icing, it wouldnt heat the carbs that much to cause fuel evapouration problems.

If the starter is turning over slowly it wouldnt be this. My moneys on the constant live connection in the loom being corroded/dried out.

^ I have stated that already but Rob's on a mish to make it a carb issue. Mine's an import anyway, wasn't imported till 2001.
No heaters on the Baby-Sendai.

Cheers for the head's up mongo, I'lll give it a going over tomorrow and report back, probably with some photos. Just wondering but how would getting hot cause corroded/dried out wires to no longer pass current? Just resistance against an already low throughpout?

f17th wrote:I used to have a similar hot starting problem on a car i had (Honda CRX)
The problem was put down to some dry joints (Bad solder) on the ignition relay.
When the solder joints were redone the problem was solved.

Im not sure whether the bikes have something like a starter relay but that would be my first port of call.

Re-solder all joints in the relays and see how it goes from there.


But like i say im not a mechanic and not even sure they have relays for the starter

Thats on my ToDo list as well.

Good tip!

interesting comments guys i'm with RobB on this one cos when i had my zxr400 it would spin forever as it would when cold i would say its not the starter motor.

Well im not saying its definately this or that, im putting ideas that have come up in the past.

It seems to be clear tho that the H and L have the same problem of hot starting just different issues to resolve them.

The slow spinning of the starter motor is quite possible the constant live in this problem.

The issue of the L models with the starter motor spinning at the same rate as when cold, thats a different issue and one that seems to always lurk out there.

Gubbs to do this, you can either take back all the electrical protection (plastic and tape) and scrape off the residue and unhook all the wiring from each other and try and get a nice connection again. Or buy some new wire and re-wire the constant live. Before you do this, make sure you CHECK the voltage on the starter to make sure its a low volt issue when the motor is warm and when causing the issue. If the voltage is good, its gotta be the starter motor itself (could be the bushes in it).

gubbs wrote:Well if it only happens when its hot there can only be one root issue: heat.

Now whats getting so hot it can't function?

The loom.

Increased heat, increased resistance through the circuits as all the components expand.

Thats dropping the voltage below what is required to turn the starter motor over fast enough to spin up the ignition/engine.

The fact the engine is hot compounds the issue, as there is more friction on the crank, so the starter has to work even harder with less juice.

Its an electrical problem ..

Probably solved on later bikes by a rectifier/loom upgrade or starter motor revision.

sounds feasible apart from the friction on the crank - surely there's more when it's cold due to the increased oil viscosity?