What have you done with your bike/s today?

[jhg1958]

Took the bike on a run to the leisure centre to play badminton. Nice to be using the old girl (and the bike). Ran sweetly over the 10 mile round trip. I need to get a better bag or better bungies as I nearly lost the bag on the return journey mainly due to the heavy lock and cable. I wonder if I need to lock it up out here in the sticks.

John

[Black Sheep]

Took the 1913 Douglas for a test run after the engine rebuild. Not good with partial seizures. Photos of scuffed pistons have been sent to the engineer. Damn.

What a real disappointment BS after all that work.
Will the pistons (and bores) polish up do you think or are they scored / smeared in areas that really matter? I don't suppose they are bits that grow on trees either.
Here's hoping a polish and a hone will get her running OK again  . . . .
Good luck!

The damage isn't too horrific. After discussions, the plot is to put it back together and keep running it in. We'll see how that works out. Not going to the bi Early Bicycle Event this weekend after all - but have you seen the weather forecast?   

[groily]

Fingers crossed for you.
Doesn't seem too deep, but it's certainly picked up over a goodly area.
Still see the machining marks though, in many areas, and the ring lands don't seem to have been smeared over, which is something.
Good luck with the polish!
Weather forecast here not good either from tomorrow. I'm hoping to do about 300km on Sunday with the like-minded on one of mine, but not too sure just now  . . . . got a pretty decent 250km in this past Sunday with another group under mostly sunny skies so not whining. It's been a quite good year for using oldies as daily transport in fact, so I have.

[chaterlea25]

Hi All,
The piston looks to have grabbed all round?
My opinion is that the bores are too tight!
If those pistons are JP they need a ridiculous amount of clearance 
Martyn Adams (Serco) got some JP's made for Blackburne 350's (71mm) and experienced seizures until he left 7 thou clearance   
And that is how he finished the cylinder on my yet to run engine

John

[Swarfcut]

 Lucky escape there. A check of the running clearance for a start, but in any case a light hone to smooth any pick up on the barrel. Can the piston be reversed so the less scored face becomes the thrust face?

 When faced with such a situation, a home fix is worth a try in any scenario before replacing with new parts.

 I've certainly seen far worse, (examples where the piston is well seized and only removed by violence....)  that looks a minor problem, and with careful fettling can be coaxed back to running order. Such components are well worth a try, after all, it can't be made worse.

 On the bright side, vertical scores reduce frictional area and allow more lubricant on the sliding surfaces. If the piston rattles, you know why, and can stop agonising over a possible cause! Good chance it will run even better.

 Swarfy.

[groily]

Hi All,
The piston looks to have grabbed all round?
My opinion is that the bores are too tight!
If those pistons are JP they need a ridiculous amount of clearance 
Martyn Adams (Serco) got some JP's made for Blackburne 350's (71mm) and experienced seizures until he left 7 thou clearance   
And that is how he finished the cylinder on my yet to run engine
John

Yes, obviously bored too tight I agree. Couldn't see the make (all the JPs I've had have one piece oil rings of the trad 'slotted' configuration if that's an indicator) - and at 70-odd mm bore my ones have been good with 5 thou min skirt clearance (as provided by T&L Engineering, who've done all my recent rebores / resleeves).
JPs get a bad press on grounds of weight and this requirement for more than average skirt clearance, but the particular ones I've had, on twins with dynamically-balanced bottom ends it has to be added, have been pretty OK this past dozen or more years - and that using the rings supplied with them (which also come in for criticism quite often).

[Joolstacho]

Where did I see this recently... I think on a classic car site (and I don't recommend it but)... They sprinkled AJAX into the carbs as it was running. (Ouch!)They reckoned it did the trick! Cleaned out the thing no doubt 

[muskrat]

Where did I see this recently... I think on a classic car site (and I don't recommend it but)... They sprinkled AJAX into the carbs as it was running. (Ouch!)They reckoned it did the trick! Cleaned out the thing no doubt 

G'day Jools.
I (and others) used to do that for the race motors when a Sat night rebuild was needed for Sun races. Only 1/2 the amount of oil in the motor, warm up and rev it to 3/4 and sprinkle in the Ajax. Shut down and change the oil and carb clean in the carb. Warm up and change the oil again. Ready to race!!!
Cheers

[Black Sheep]

Pistons are Honda and the bore clearance is 7 thou. The engine man is suspicious of excess petrol washing lubricant off the bores. I'm not convinced but will strip and check over the AMAC carb. The thing is, the bike has done 1,000+ miles with the same carb setup and I think I would have noticed excess petrol pouring into the engine. Or maybe not. Oh, I do splash a good dollop of 2T oil into the petrol. 

[Triton Thrasher]

I think the scouring powder trick is for bedding new rings into the bore.

If there’s piston aluminium stuck to the bore now, hydrochloric acid fizzes it off in seconds.

[Triton Thrasher]

On the seized Douglas subject:

Determined coarse honing might get you another thou clearance.

Then there is the possibility of filing the piston where it appears to be gripping the bore.

PE Irving, Tuning for Speed:

[Black Sheep]

Spot on. A fine second cut file was carefully brought into play. The original pistons were of course cast iron. Not only unlikely to seize but they also expanded at the same rate as the barrel. It's these new-fangled alloy pistons that are the problem. They'll never catch on...

[chaterlea25]

Hi Black Sheep,
Adding a " good dollop" of 2t oil can actually lean the mixture due to increased viscosity of the mix!
On my recently completed BSA L25 ohv  I found that I had to increase the AMAC jet size
From the 32 that was recommended by other owners to a 35. I had a 33 and tried it but the bike lost power and got hot.
The spG of modern fuel is a lot higher than back  a hundred years ago

John

[Adler]

Hello together,
I had a nice ride, but a after few hours in the garage I found some drops underneath ... seems, I will have a job in the cold season and my wife always knows, where I am.
Best greetings to the best forum.
Manfred

[berger]

they all do that sir , some more than others , if you give them a good thrashing oil mist collects on the cases from the breather and drips when they have their well earned rest.