Author Topic: Rock solid engine.  (Read 1697 times)

Offline AdrianJ

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Rock solid engine.
« on: 04.10. 2019 17:32 »
Help please with ideas and how best to proceed.
Started the plunger A10 engine with the intention of going for the first test ride.
Carb seemed to be sticking when I opened the throttle so I killed the engine. Stopped as soon as I hit the button, no overrun at all.
Now the engine seems to be solid.
Clutch is working.
I have taken off the rocker box covers and I think the push rods are in place.
Can't turn the crankshaft with a spanner.
Kick start is solid but turns when clutch is disengaged.
Have now removed the gear box cover and the kickstart mechanism is fine - didn't really think it was this.
Yes - I do have an oil return!
Unfortunately can't get back to work on it till Wednesday.
I'm mystified. Next step rocker box off, try to turn the engine?
Any ideas what to do next head and barrels off?
Regards,
Adrian.
'53 Plunger Flash, Steib S500.


Online Swarfcut

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Re: Rock solid engine.
« Reply #1 on: 04.10. 2019 18:50 »
Hi Adrian. Whoops, or a similar expletive. Sure its not left in gear in the confusion? OK, clutch disengaged, kickstart moves, mainshaft and layshaft are free.

 As a start, whip off the sump plate. A good cup of oil should be in there. Full to the brim? Hydraulic lock.  Dry as a bone? The engine has probably seized.
 Get the primary cover off, and remove the clutch springs. This effectively separates the engine and gearbox and if you find the crank now moves OK, then the fault is in the clutch.

  Crank still solid? Carb could have put neat fuel into the bore, washing off the oil, so see  if the pistons are seized in the bores by lifting the barrel which may allow the crank to move and turn slightly. Pistons moving OK in the bore as the barrel lifts but crank still locked solid? Good chance the timing bush has seized on the crank, a big end seizure or the camshaft is locked up. Something as simple as a jammed cam follower could do this, so if pistons and crank move normally with the barrel lifted an inch or so this is where to look. Seized rockers possible, easy to check but unlikely. No need to take off the head yet for these simple checks. Jammed or seized timing gears are again possible but unlikely.

Be methodical, but as it stopped without any major clank or bang it will require a bit of detective work to find the fault.

Swarfy.

Offline AdrianJ

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Re: Rock solid engine.
« Reply #2 on: 04.10. 2019 19:15 »
Great - thanks very much Swarfy.
I'll get down to it o Wednesday when I'm back.
Regards,
Adrian
'53 Plunger Flash, Steib S500.


Offline chaterlea25

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Re: Rock solid engine.
« Reply #3 on: 04.10. 2019 19:53 »
Hi Adrian
Buggershitnfuck *ex*
Oil returning is no guarantee of oil getting to the main and big ends??
Is the engine just after being rebuilt?
If so did you prime the crankshaft oil gallery?

John
1961 Super Rocket
1963 RGS (ongoing)

Offline AdrianJ

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Re: Rock solid engine.
« Reply #4 on: 04.10. 2019 19:55 »
I did but it sat a long time vefore I finally started it. *sad2* *sad2*
Adrian
'53 Plunger Flash, Steib S500.


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Re: Rock solid engine.
« Reply #5 on: 04.10. 2019 21:15 »
G'day Adrian.
Double bugga. You have tried turning over with the plugs out? Are the pistons up or down the bore?
Follow Swarfy's suggestions but have a good look in the timing chest first.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline AdrianJ

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Re: Rock solid engine.
« Reply #6 on: 04.10. 2019 22:00 »
Yep Muskrat. Plugs out no change.
Wednesday I start to take it apart
 *sad2* *sad2* *sad2*
'53 Plunger Flash, Steib S500.


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Re: Rock solid engine.
« Reply #7 on: 05.10. 2019 06:44 »
This once happened to me. Stopped for petrol and went to start and engine was solid. Was towed 100 miles home. Once the timing cover was off it was obvious what had happened. A bit had fallen off the ATD and fallen between the timing gears.
It may not be anything drastic after all...
2 twins, 2 singles, lots of sheep

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Re: Rock solid engine.
« Reply #8 on: 05.10. 2019 09:48 »
Adrian, just had another thought. A good dose of WD down the bores will do no harm while it stands for a few of days, may help free off a tight piston.  Sorry to have painted the blackest picture, other folks have a more optimistic outlook on life! I reckon it will be a simple explaination.

Swarfy.

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Re: Rock solid engine.
« Reply #9 on: 05.10. 2019 10:40 »
Lots of silly things can lock the engine solid
the dynamo can sieze
The magneto can sieze

So as suggested, off with the timing cover and pull the idler pinion to take the magneto out of the equation
While you are there watch the dynamo chain , if it is still there and see if it is straining as you try to turn the engine over.
Also pull the sump off and slip your pinkey inside the crank case feeling for metallic trash.
Bike Beesa
Trevor

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Re: Rock solid engine.
« Reply #10 on: 05.10. 2019 11:46 »
To add to Trevor's post. Only take the idler pinion out if the pistons are at tdc. If it isn't and the cam has a valve down and you take the idler out and turn the crank (if it turns) there's a good chance of bending a valve or two  *pull hair out*
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

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Re: Rock solid engine.
« Reply #11 on: 05.10. 2019 17:10 »
You mention a stuck open throttle. If the engine was revved hard before oil got to the bores a piston may have picked up in the bore. Has either (or both) exhaust header blued? An indication of excessive heat.

I know some people here do not believe in lubricating a new piston/rings/bore, as they feel it slows down the break-in period but I've always oiled my pistons on every engine build I've done. If my engine had been standing for a while since a rebuild I would have squirted oil down the plughole.

Offline ironhead

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Re: Rock solid engine.
« Reply #12 on: 05.10. 2019 22:55 »
You mention a stuck open throttle. If the engine was revved hard before oil got to the bores a piston may have picked up in the bore. Has either (or both) exhaust header blued? An indication of excessive heat.

I know some people here do not believe in lubricating a new piston/rings/bore, as they feel it slows down the break-in period but I've always oiled my pistons on every engine build I've done. If my engine had been standing for a while since a rebuild I would have squirted oil down the plughole.


With oil, too much is waay better than not enough.
SA

Online Rex

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Re: Rock solid engine.
« Reply #13 on: 06.10. 2019 09:52 »
With just a smear of oil on the rings and no more added. Always worked well for me.
I remember reading about an old bike racer and tuner back in the Brooklands days who would leave the freshly-bored barrel out on the lawn overnight to get a thin film of rust, then assemble it dry and rev it to the "bloodline" (as he termed it) a couple of times and the bike was ready to race. No gentle running in required. ;)

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Re: Rock solid engine.
« Reply #14 on: 06.10. 2019 10:23 »
With just a smear of oil on the rings and no more added. Always worked well for me.
I remember reading about an old bike racer and tuner back in the Brooklands days who would leave the freshly-bored barrel out on the lawn overnight to get a thin film of rust, then assemble it dry and rev it to the "bloodline" (as he termed it) a couple of times and the bike was ready to race. No gentle running in required. ;)
Horses for courses. A race bike might have a new engine every race. A private bike needs to go for many years between rebuilds.