Starting issue - Head scratcher for sure....

Righty ooo, some background first to set up the story... hope you have a coffee (or perhaps something stronger!).. trust you are going to need it....

Tech bits for you: he is a 1984 XJ750D, fuel injected beast

My Walter is a rather cranky ol boy, but I do love him! And it's this reason why this ol boy hasn't ended up in the motorbike scrapheap in the sky.... so last year I was getting ready for a bike rally. I hadn't ridden him in quite a while partly due to a knee fracture but also due to lack of money etc.... so I go and try to start him, no joy. he would turn over but not catch... long story short turns out the spark plaugs were the problem, new plugs in and away he went..... very happy biker chick went to the rally, no problems. Great time had by all!!

Rode him over the xmas hols, he was a very happy puppy as was the rider. So cue another bike rally coming up, longer ride this time. Plan was do the loop of the South Island of NZ (that's where I'm from) so about 1500kms (930 miles roughly) so I knew he would need some TLC....

A few days before the ride, I fire him up, all good. Started first time, so checked the oil, half way up the sight glass, made sure the lights etc all worked. Happy ol boy was he... brought him into work, all good!

Cue the first day of the bike trip.... all was great. The weather was hot about 30 deg C and both of us were happy. I was out riding my bike.....

About 320km (199 miles) into the trip the oil light flicks on. Can't stop no where near for oil. Stopped at a town and sent a text to my friend "Oil light came on and need oil, can you help?" Thankfully he is close by (32km, 20m) and has oil for me, so topped up the oil. Now, here is where it went down hill.....

Oil put in and rider suitably fueled as well, jumped onto the bike, tried to start, it wouldn't. turning over but not catching.... cue a push start, all good fired up no worries. Ride back to friends house.... after humming and hahing decide to leave bike at friends place, go do the rally which thankfully is only 10km (6m) from his house.

Friend gets up on Sat morning has a look, spark plugs are loose, tightens them up, checks the oil and fires up bike, no issues..... so rally complete BF and I head back to friends house.... decide to go for a short ride... 80km (50m) round trip, all good... so thinking at this stage it's overheating and he doesn't like it.... fair enough....

Nope, leave on Tuesday from friends house, ride 53km (32m) to get fuel, bike dies again, have to push start (thank goodness for the hill there) all good again. Ride 262km (163m) and I don't stop the bike! The one time we stopped for a break, he fired first time..... get to our destination, too tired to think. Leave him to sulk it out in the car park whilst I go and fill up on food!

Wed morning, fires up first time, all good even on the couple of stops we do, he fires up no problem..... get to our destination and yep you guessed it, he didn't want to start again, so cue another push start....

So you see where this is headed..... what is the problem?? Got home, and pulled out the spark plugs, all good there, still a wee drop of oil in him..... so now, if you've got through that... well done....

 

Would a correct summation be; Engine starts fine when it is cold, but not at all when the engine is hot?

 

The male version of the story, yep!! LOL but it's intermittent

 

a) vapor lock on a hot day on a hot engine
b) almost classic tight valves story, hot engines don't start with tight valves
c) ?

 

You were the one with the black spark plugs back in November last year.... Polock sounds right on the money.

"still a wee drop of oil in him..... " seperate issue but a worrying turn of phrase!

I'd say its time to clean your carbs.

Pls advise a. battery condition and b. a run through on your hot engine start up regime choke on/off etc

 

c) leaky injector(s) causing low fuel pressure and leading to 'a'.

 

Yep that's me, LOL

a. Battery condition is excellent, new Motobatt about 18 months ago, although have been wondering if it has a full charge, going to get the output etc checked.
b. Damn, I have to think..... LOL

As I hit the starter, a quick flick of the gas and he's all good, usually. No choke

The bike is fuel injected, so is it the same process for cleaning the carbs??

 

When was the last time the valve clearances were attended to? Mileage-wise? They need to be checked every 5000 miles.

"Fires up fine cold, won't start warm" is the first symptom of neglected valve clearances. Put that together with your "running low on oil" episode and I recommend you get your valves in spec, then do a compression test.