Sudden and repeated loss of power?

[Milts]

So I recently had my ZZR250 serviced - full tune up, carbs balanced, etc. I got it back on Friday, took it for a test ride around town, no issues. Later that day I took it out on the motorway.

About 2ks onto the motorway I rev it high in 4th gear to change up to fifth and move into the right hand lane - but just then, the bike loses all power. Revs drop to about 5k and nothing I can do will give it any more power. So I put my hand up, indicator on, and pull onto the shoulder of the road. As soon as I close the throttle and pull the clutch in the engine dies. The bike won't start, choke or no choke, throttle or no throttle, etc, for a good 10 minutes. After that it finally starts.

I pull off at Ngauranga gorge, head back along the old hutt road, no issues. I figure it was an air bubble or similar in the fuel line which has now cleared. Today I did some more riding - again, bike is fine through town and around the bays. However once I got onto the motorway and started playing with the gears it did the same thing after a few Ks, and the same on the way back. It did it again thisevening in a 70 zone when I rev'd it hard enough for a bit and tried changing up.

One of the times it did this it backfired a few minutes after starting; another time there was a bit of smoke but not very much. Once the power dies nothing I do with the throttle seems to make much difference, other than that closing it completely results in the engine dying. If I put it on full the engine sounds different and maybe slowly builds in revs up to about 6k RPM but no more. The engine also sometimes seems to lack power around town if I try to suddenly build revs all the way up (that is, lacks in power more than usual). It doesn't seem to have any problem reving in neutral.

Any ideas what the issue could be? At first I thought it might be some gunk in the fuel line, but the fact that it's done it repeatedly and only under certain conditions makes that seem unlikely.
I intend to take it back to the shop on Monday, but it's tricky - I don't see how they can easily test for this... and it's pretty difficult to explain. What should I be doing now? Just tell them to take it for a ride on the motorway and try to repeat the problem so they can have a go at tracking it down?

[quickbuck]

Take it back to the shop, tell them what it is doing, and they will pull your bike apart and Reset the Float Levels to the correct level this time!
FOR FREE!

OR, as they put your bike back together, they have kinked a fuel hose.
This only becomes apparent when you are demanding more fuel than usual... Like on the motorway.

BTW, you will never really detect any engine issues by reving the nuts off it in neutral... unless it really is about to go BANG.

[shafty]

Had a similiar prob after getting my Sube back from a service - found a cleaning rag left in the Air Cleaner..... turned out to be the final straw and the young Guy in the workshop doesn't work there anymore...........

[The Baron]

Just on the off chance - check the battery leads are on tight.

[Katman]

I would be looking at getting the carbs cleaned - particularly in behind the needle valve seats. Shit from the tank can build up over the mesh screens preventing fuel from flowing into the carb bowls fast enough.

[CookMySock]

rule of thumb - "backfire" almost always means "lean". Take it back to the shop - they've done something funny with it.

Steve

[cowpoos]

Just on the off chance - check the battery leads are on tight.

Ditto

and check the rubber manifolds around the carb and air box to the carb are sealed and fitted properly..

to my mind being a sudden failure...it could be anything, fuel,electrics....but most likely simple...because it does operate most of the time.

[Milts]

Thanks for the responses. I'll check the battery leads in the morning when there's a bit more light.

It happened again today but it was harder to induce and wasn't as drastic - that said I avoided the motorway this time because having your engine cut out with cars behind you doing 100km/h is not my idea of fun. I'll take it in to the shop tomorrow and do my best to explain it, see what they think. When they did the tune up they did the full deal; engine tune, checked engine compression, replaced spark plugs, fuel filter, stripped cleaned and balanced carbs, and they say the idle mixture O rings were perished and so were replaced. So really it could be anything...

Hopefully nothing major, be good to get my bike back within a few weeks - my father just bought a bike after being bikeless for nearly three decades, keen for some family rides!

[Laava]

Check and top up the indicator fluid!
Actually there are so many things that could be wrong but you should take it back to the shop that tuned it, If they made it worse than it was before, then they should fix it. Simple.

[The Pastor]

Also check the coils for any broken wires, unlikely but it just happened to me :P

[quickbuck]

Okay Milts,
have you got your bike sorted yet?
Can you please tell us what it was, so we know for the future?

Regards
QB

[Milts]

Okay Milts,
have you got your bike sorted yet?
Can you please tell us what it was, so we know for the future?

Regards
QB

I'll let you guys know when I find out - I dropped it in to the shop early last week, waiting for a text telling me I can go in and pick it up. Hopefully that will be sometime this week.

[Crasherfromwayback]

The fuel tank breather hose may've been squished!

[CookMySock]

The fuel tank breather hose may've been squished!On the same theme, make sure the fuel line from the tank to the fuel pump is secured properly or it will suck air.

Steve

[cowpoos]

The fuel tank breather hose may've been squished!

Bloody good call!!! and I'll put a wager that they won't find that in the workshop

[Milts]

ZZZZ update time.

So the shop adusted the valves I think, can't find the printout at the moment. Took it for a ride shortly after in the pissing rain from Wellington to Palmerston -> gorge to Woodville and back. It seemed to fixed, I had a partial loss of power once just south of Shannon but the bike didn't stop, and recovered after about 30 seconds of crusing at lower RPM - hadn't done it since. It did, once, on the way back sort of bunny-hop. By that I mean the engine cut for a split second and came back.

It then started doing that a small amount just when you sat on 6k RPM. Didn't think it worth taking it back to the shop and paying to get it looked at again, so I figured next time I took it in I'd just ask them to check, it wasn't a big issue, only happened rarely at 6k rpm. Yesterday I parked it outside work, then trying to come home at 8pm it was spluttering the whole way - off on, off on. Hardly got it back in the garage, had to pull over at one point and let all the cages past. Tried it again today in the sunshine after it had been parked in the garage all night (instead of in freezing cold weather having sat in the rain for hours). Same story, unridable really. Called the shop, booked in again for this week.

Something is seriously off with this motor. Expensively so, too.

Oh, sidenote - it even does it (too a smaller extent) when idling. Some of the time, anyway.

[NJ83]

I had the exact same thing happening to my bike for the longest time and the shop couldn't track it down, but the air vent in the fuel cap had blocked,

next time it does it, open the cap and replace with one of those emergency caps from the gas station,

[glegge]

was the bike fine, ie did not have these problems, when you took it to the shop the first time? if so and it just went in for a normal service, then this shop needs to fix your problems for you - and return the bike to you working as it should. no cost to you. you have already paid for the service that you wanted, and they made the bike worse by the sounds.

so take it back, tell them you want your bike back working as it should. perhaps suggest they could try test riding it for a bit (some use it as a 'shop bike' to see if it plays up when they go to get parts - or lunch - or what have you) then they will know first hand the problems you are having.

anyway - i sympathise, it sucks when your bikes not running right.
if you give up on the shop - perhaps try another, if money is no problem.
Or, it's time to start looking at things yourself with a engine minded mate.

bugger.