Date: 19-01-20  Time: 09:53 AM

Author Topic: Shop says new piston rings required. Am I being conned?  (Read 695 times)

Whomightyoube

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Shop says new piston rings required. Am I being conned?
« on: 16 October 2019, 09:29:35 PM »
Bike shop just diagnosed new piston rings required. I put it in because it is still misfiring on cylinder 3 intermittently. Chap suggested that it may not be economically viable to repair. It is a 2001 FZS Fazer, They seem to be going back up in value. Is this guy trying to rip me off?


I had previously dropped the bike off at the same place about three weeks ago but it was running fine then and they tried it through the day and it was fine when I rode it home.


Next time I tried it it was lumpy as shit, stalling at junctions or lights, with a terrible smell of petrol.


Thought it might be sticking carb piston. What would be the symptoms of that? If I started without any throttle either with or without choke it had run fine. Might a start with throttle lift the carb piston before it had chance to lubricate with some fuel. ( or how are these pistons supposed to be lubricated?


Previously I have had the carbs off three times to clean but using carb cleaner and air. Perhaps a clean in an ultrasonic bath is required.


I had done a compression test from cold which gave 14,5 barg for 1,2 and 4 but 12 for 3 but that might have been due to unburnt fuel washing lubrication from the piston rings.


I have swapped over coils and leads to eliminate electrical problems. Spark is healthy.


I have been very busy with work so not had time to sort this out. Also I think I am a bit prone to a reaction from petrol vapours which make me feel ill. Hence I tried the bike shop.




Any one got any ideas/comments?

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Re: Shop says new piston rings required. Am I being conned?
« Reply #1 on: 16 October 2019, 09:56:03 PM »
Spark may be fine, but have you tried new plugs at all, or even swapping plugs around to see if number 3 is still the issue?
Air filter okay?
Do a check on the TPS as well to make sure that's not breaking down.
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Whomightyoube

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Re: Shop says new piston rings required. Am I being conned?
« Reply #2 on: 16 October 2019, 10:02:16 PM »
Hi


Yes new plugs. Also re-prepared lead ends.


I would have thought the air filter would affect all cylinders. It is now new but I have cleaned it with a vacuum.


I am not really familiar with the TPS. How is that checked?


Bike is still at shop so cannot look at it now.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #3 on: 16 October 2019, 11:27:21 PM »

It’s quite easy to get a misleading compression test result, particularly on cylinder 3 since that plug well tends to suffer more from corrosion… if the tester doesn’t seat quite as fully the extra space will result in a lower reading. That said, have the valve clearances been checked?


The carb slides are teflon coated and stay dry in normal operation. After a high mileage (80k+) the coating can wear and they don’t move so freely. That’s not likely to cause flooding though.
The float valves and the rubber o-ring round the brass body of the float valves can leak, quite common now these bikes are getting on a bit. Checking the fuel levels in the float bowls is slightly fiddly, but can be done with the carbs in-situ.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #4 on: 17 October 2019, 12:50:34 AM »
What mileage is on the engine?Bore wear on the FZS600 is rare as the bore is nikasil coated, however on a very poorly maintained engine it can happen.

Bore washing from a leaky Float valve seal is the most likely issue as you have alluded to yourself and Fazerider also suggested..
Faulty TPS will not cause a misfire in just one cylinder as it changes the ignition timing at different throttle openings and would effect all four cylinders
Was the bike idle for a long enough period for the pilot jets to be clogged from evaporated petrol. If it was, then replacing the seals on the float valves would be wise.
I would suggest that the first thing to do would be remove the carbs again and replace the float valves and seals on all 4.The pilot jets are difficult to clean as the have a star shaped web internally and the only way to clean them if you do not have access to and Ultrasonic bath is to poke the jet with a fine brass or copper wire as this will not damage the jet. I have found soaking the jet in Cellulose thinners to be very effective and using a brass wire to dislodge the most stubborn crap.



Whomightyoube

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Re: Shop says new piston rings required. Am I being conned?
« Reply #5 on: 17 October 2019, 08:18:53 AM »

Mileage 40K. I cannot say that it has had the best of maintenance, but has been garaged. Trouble started after a period of not using again suggesting carbs being the problem.

I have replaced the float valve and rubbers. Not checked the petrol level though.


I have had the carbs of 3 times and cleaned out all the varnish. Jets cleaned so you can see daylight through them. Transfer ports blown through.


Any comment on my concern about the bike shops claim that i need new piston rings? The intermittent nature of this problem with it running perfectly sometimes suggests to me that, along with my compression test, compression is not the problem. Just checked the book last night and all cylinders are within range albeit that 3 is more than 10% down.


My thinking on the carb piston was that it opens the main jet. if it sticks open, then surely there would be too much fuel getting through on idle.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #6 on: 17 October 2019, 08:48:30 AM »
Put a clear plastic pipe onto the drain of carb 3 and 4 tape them on to the side of the tank.
Open the drain screws and let them fill, turn on the ignition to let the pump fill them up. 
Now start the bike and run it for a few minutes to allow the levels to settle, leave it for an hour or two and then see if the levels are the same.
You could also swap the slider with another carb and see what happens.It is possible to pinch the float valve seals when fitting them.
« Last Edit: 17 October 2019, 08:58:57 AM by unfazed »

Whomightyoube

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Re: Shop says new piston rings required. Am I being conned?
« Reply #7 on: 17 October 2019, 09:07:53 AM »
Thanks for that.


I had swapped the slider over on the last time I had the carbs out.


The fuel pump clicking always lasts quite long compared to previously and always occurs even if the bike has just stopped for a short time.


Bike is still with shop so not able to do any more investigation at the moment.

Whomightyoube

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Re: Shop says new piston rings required. Am I being conned?
« Reply #8 on: 17 October 2019, 09:36:55 AM »
Just spoke to the shop and they said they had done a crankcase pressure test which resulted in oil being pushed up into cylinder 3 which would be causing intermittent miss fire and it definitely needs new piston rings. Cost likely to be 6 hrs labour at £60 per hour. £150 for new gaskets and £150 for Piston Rings. Plus £108 already spent. £768 +vat.


Bike probably worth about £1000 as not in brilliant condition.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #9 on: 17 October 2019, 09:49:33 AM »
Coincidence that it was running fine until you left it in with them?
It still sounds to me like one of the coils is contributing to the problem, perhaps working intermittently, giving the impression that it's still 100% when it's not. You could take her for a short run, then stop & feel the heat from the downpipes, noting which one is colder. Then swap the coils over & go for another run.  If the colder downpipe has 'moved' then it's not the cylinder compression at fault.




Whomightyoube

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Re: Shop says new piston rings required. Am I being conned?
« Reply #10 on: 17 October 2019, 10:08:23 AM »
To be fair it was miss firing badly when I last tried to run it with a very strong petrol smell that made me feel sick and gave me a headache.


I got them to pick it up as I didn't want a repeat of that.


I had tried swapping coils and leads but it was always 3 that was misbehaving.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #11 on: 17 October 2019, 11:34:41 AM »
Although I'm now on the 1000 my own went off, running on three cylinders a couple of months ago. Ran rich / stunk of petrol although eventually one of the carbs started leaking too. I had sooty / oily spark plugs in cylinders 1 & 4, both fed off the same coil. The issues you're having sounded similiar, but perhaps not.

Would it be worth fitting another set of carbs to see if the cylinder 3 problem persists?
If not, and you're unable to DIY this will become very expensive very fast  :\ Are there no Foccers nearby who could help out here?

unfazed

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Re: Shop says new piston rings required. Am I being conned?
« Reply #12 on: 17 October 2019, 11:38:01 AM »
One  reason for damage to nikasil bores on number 3 is that grit found its way in when changing the plugs.
Since 3 is the one that holds the greatest amount of junk especially on bikes left on the side stand in bad weather and drain hole blocking.Add grit and bore washing you now have an unlubricated bore ready to be worn more than normal.This is just a theory

There have been a few cars with Nikasil problems The most notable early XK8 Jag V8 and the early  BMW V8 engine, but this was finally traced to high sulfur cheap fuel.
The sulfur reacted with the Nikasil de lining the bores.
most fuels not have low sulfur virtually eliminating the problem.
I have my serow stripped at the moment to replace a leaking base gasket, it has 35000 km on its air cooled engine and the nikasil bore still has the original honing marks with absolutely no determinable wear.My last serow had enough bore wear at the same mileage to cause its oil burning issue, cured by a rebore and oversized piston and rings,

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Re: Shop says new piston rings required. Am I being conned?
« Reply #13 on: 17 October 2019, 01:23:38 PM »
Given that the workshop have explained how they came to think it's piston rings, I'd be inclined to accept that's what the problem is. 

We know from your own compression tests that there was a problem in that cylinder, and with unfazed saying that the bores are rarely an issue, all that remains is the rings. 

For that much money, you might be better off buying a replacement engine to swap in, then selling yours for spares/repairs to reduce the overall cost.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #14 on: 20 October 2019, 08:26:58 AM »
Mine is kind of in a similar situation.  It's running fine, but I'm loosing oil, no blue smoke, no puddles on the floor.  I took it to a trusted bike shop the other day and they said that it wouldn't be in my financial interest to repair whatever seal is causing the issue.  They also quoted about £800 as a fair representation of what I'm likely looking at cost wise.  They said the bike is running fine and a litre of oil per 1000 miles is acceptable on older bikes.




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unfazed

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Re: Shop says new piston rings required. Am I being conned?
« Reply #15 on: 20 October 2019, 08:42:40 AM »
Sounds like Valve seals.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #16 on: 20 October 2019, 08:59:55 AM »
That's what I suggested to them.  And they agreed that it sounds about right, but still silly money to repair at a garage compared to the cost of the bike so I said not to bother even investigating because I can't pay £800 to fix.


Bike runs lovely, especially having just re-balanced the carbs so I'm going to keep going as is and be aware of oil loss.
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unfazed

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Re: Shop says new piston rings required. Am I being conned?
« Reply #17 on: 20 October 2019, 09:10:44 AM »
Sounds very expensive, considering OEM valve seals, head and base gasket are about £200

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Re: Shop says new piston rings required. Am I being conned?
« Reply #18 on: 20 October 2019, 09:26:59 AM »
How many hours labour to do you reckon?  5 hours?
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Re: Shop says new piston rings required. Am I being conned?
« Reply #19 on: 20 October 2019, 10:06:36 AM »
Difficult to say really as it depends on whether they lap the valves or not. 5 to 8 hours would not be unreasonable.
Much depends on the experience of the mechanic with 16valve heads as an inexperienced mechanic  could spend 2 to 3 hours doing the valves alone.

Head can be removed without removing the engine.


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Re: Shop says new piston rings required. Am I being conned?
« Reply #20 on: 20 October 2019, 01:03:58 PM »
Taking the head off and replacing valve seals is doable at home.  You need a suitable torque wrench and a valve spring compressor.  Read the manual a few times so you know the procedure and how to time the engine. If you go slow and careful you should be able to do it. The hardest part would probably be getting the exhaust off without shearing studs.

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Re: Shop says new piston rings required. Am I being conned?
« Reply #21 on: 20 October 2019, 04:15:46 PM »
This is WAY above my skill level! Trust me!  :\
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Re: Shop says new piston rings required. Am I being conned?
« Reply #22 on: 28 October 2019, 11:15:18 PM »
People mentioning washed out worn bores and valve seals...has the OP said the bike is smoking?

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Re: Shop says new piston rings required. Am I being conned?
« Reply #23 on: 23 November 2019, 10:37:14 AM »
Hi went through the same thing with my fzs600 --even had the carbs cleaned at shop no change--havin been through the electrics etc still convinced it was fuel i borrowed my mates carbs off his bike and was up and running on all four in no time --bought a set off fleabay happy days good luck-
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