flying pasty
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« on: May 01, 2015, 08:20:47 AM » |
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Hi guys, I have a reliant 850 engine with a misfire on No1 cylinder, i have adjusted the tappets as they were well out, the previous owner had them gapped at 0.06 instead of 0.006 when cold.
Does anyone know what the cause of the misfire is.
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fifer
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« Reply #1 on: May 01, 2015, 09:51:02 AM » |
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Start with the basics ;
Remove the Distributor and gently scrape any hard deposits on the 4 contacts points .
Refit the Distributor .
If the lead is long enough swap the HT lead from number 1 cylinder with number 3 cylinder .
If the misfire changes to number 3 then the original HT lead from number 1 cylinder is faulty .
If the misfire does not change to number 3 then the original HT lead from number 1 cylinder is not faulty .
Fit new spark plugs and gap them .
Change the distributor cap .
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Confucious ; He say that man who take woman up hill , him not on level
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Olds
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« Reply #2 on: May 01, 2015, 10:03:44 AM » |
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As the oracle (fifer) says.
If you are sure it's only on one cylinder chances are it's -
1, spark plug
2, plug lead or connector
3, tracking inside the distributor cap
Just because there is a good spark if you test the plug doesn't mean that it works in the engine.
My V twin had a misfire on the front cylinder. With the plug out it had a great spark, so I spent days looking for another fault.
When I swapped the plugs around the misfire moved to the back.
New plugs, no misfire.
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Getting older but no wiser! Just using bigger hammers.
The answer to most problems, fire and lots of it.
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flying pasty
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Posts: 33
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« Reply #3 on: May 01, 2015, 10:21:49 AM » |
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Hi guys, I should have stated this in my post earlier, my appollogies.
ok i have a new dizzy cap, rotor arm, leads,plugs & electronic ignition i have also done a compression test, the timing re-checked & the carb setup at my local garage, the results are that i have a misfire on No1 cylinder.
The local garage changed the plug leads around as too the plugs still a misfire on No1 cylinder, the tappets were very tappety so i have re gapped them to 0.006 as stated in the manual when cold all valves are gapped at this setting.
My next port of call is to take the head off & replace the valves & head gasket, but before i do this is there any other cause for the misfire, the local mechanic says he is sure it is from the head up not bottom end.
Thanks for your replies guys.
Robbie
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Olds
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« Reply #4 on: May 01, 2015, 10:40:08 AM » |
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If you have done a compression test and that is ok, then I can't see it being the head unless you have a valve that occasionally sticks.
Is it a misfire or is number 1 not firing at all ?
When setting the gaps did you check the valves were opening fully ? It's unusual, but I have seen cams where one lobe has almost totally worn away.
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Getting older but no wiser! Just using bigger hammers.
The answer to most problems, fire and lots of it.
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kapri
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« Reply #5 on: May 01, 2015, 12:07:57 PM » |
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Also check points gap on ALL lobes, wouldn't be the first with worn inner bearings or bent shaft I've come across.
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terry t
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« Reply #6 on: May 01, 2015, 02:54:34 PM » |
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Do a cylinder leak down test. that will tell if valves or gasket. is it ok when cold
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flying pasty
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« Reply #7 on: May 01, 2015, 03:53:40 PM » |
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Hi Olds
Yes i checked that the valves were all opening fully when i gapped them also i have a bright spark on all plugs but when i remove No1 lead while the engine is running there is no difference in tick over it doesnt drop at all, where 2,3,& 4 leads nearly kill the engine dead.
I am at a loss as to what it can be, its just a feeling i have that it is the valves that are gummed up or totall burnt out.
When i bought it last year i was told by seller it was totally rebuilt but after the investigation of everything that has gone wrong on it i am in no doubt that the engine has not been touched at all.
Robbie
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flying pasty
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« Reply #8 on: May 01, 2015, 03:56:31 PM » |
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Hi Terry T
do i take it to my local garage or can i do that myself & what does it involve, i`m perfectly willing to do all the work myself in my garage but not sure what tools i need.
Robbie
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flying pasty
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« Reply #9 on: May 01, 2015, 04:03:20 PM » |
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Hi Terry T
No it is exactly the same hot or cold, no difference at all.
Robbie
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flying pasty
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« Reply #11 on: May 01, 2015, 05:03:21 PM » |
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Hi Terry T
The compression readings are 10.5 to 10.8 across all 4 cylinders, yes the rad pressurizes while running & no oil& water mixture at all, its completely bafflied me as to why it is only running on 3 cylinders.
The garage also done a pressure test & same results, could it be a slightly bent push rod on No1 rocker.
Robbie
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terry t
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« Reply #12 on: May 01, 2015, 05:17:39 PM » |
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Robbie
Have you had the rad tested for cylinder head gasket leak
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flying pasty
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« Reply #13 on: May 01, 2015, 05:18:17 PM » |
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ROD
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« Reply #14 on: May 01, 2015, 05:21:21 PM » |
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Robbie..think you may have the wrong idea of rad pressurising..if it does , theres a problem.Any mayonnaise looking stuff in the rocker cover? Does it misfire when eng is cold or warmed up? What type of plug leads are they? Carbon or copper? try running engine in the dark ,you may see a fine crack "tracking" the spark to earth or somewhere.as olds said plugs maybe new , but could be dodgy
whats the state of the rotor arm?
Are the plugs the correct ones?
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« Last Edit: May 01, 2015, 05:24:22 PM by ROD »
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