Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Jin don't know whats going on with emails as all others are getting through.
Can you try this one instead shirleywhirley62@icloud.com.
Thanks Trevor

We still can't send mail to your mailbox! Are you restricted?Jin

Last message should have said that I have used the Microcosm contacts page to send a message.
Would it be possible to list the items on Ebay ?.
Thanks
Trevor.

Thanks for that Jin,could you let me know when you put them on ebay.
Cheers Trevor.

Thanks for that Jin,i've ordered one straight away.
Trevor.

Hi Trevor,
That doesn't sound good, the loose flywheels will make the engine stop abruptly but it should not sieze.  Is it 20 seconds from cold?
If it were mine i would strip it and find the component that is picking up before any more damage occurs.
Kind regards
Ade

Hi Trevor,

I have had the issues with the loose flywheel burring the crank so they don't want to come off. 
The flywheels distort very easily and the outer rim is just pressed on, to be honest if you can tighten them up without removing you will save yourself a lot of grief, i think a puller would buckle the flywheel before it pulls it over the burr, and the twist and pull method just gouges out the inside bore of the flywheel and it usually does not run true again when refitted... i know from bitter experience.

Hardened grub screws stop the loosening and the hexagon rounding out, i have some from RC helicopters that do the job.

I'm glad nothing is seizing :-)

Kind regards
Ade

Hi Trevor,
If the engine is stopping suddenly enough to work the flywheels loose then i guess something is wrong internally, personally i would strip the engine and have a look.  I think the crankcases split horizontally on the M91?  If so try to remove the crank, bearings and flywheels as one unit, this may make it easier to remove the flywheels.  You could try a hot air paintstripper gun to warm the flywheel centre and try to twist it off, some penetrating oil helps here too, but be careful not to twist or bend the crankshaft.
The main bearings are needle roller type and so have no sideways control, on the M90 the shell of the needle bearing acts against the crankweb to limit endfloat (bearings are positioned in the crankcase to allow clearance but little side to side play on assembly).  As there is little sideways thrust this design is sufficiant.  To check the health of the bearing, once you have it apart, just look for scores on the crank where the bearing runs and check the needles are running in the shell freely, not twisted and evenly spaced.  They are normally a sloppy fit on the crank so some radial movement can be felt, this is by design.  Normally needle bearings are very reliable and require minimal lubrication, but if they have run totally dry the cage may break up allowing the needles to twist and pinch the crank which may possibly be the root of your issues though i would not bet a weeks wages on that being the case :-)
If you need and pictures of how the parts 'should' look just give me a shout.
Hope this helps
Ade

Hi Paul,

I guess the M91 suffers from its enclosed crankcase design and does not encourage user lubrication like the M90 does? no offence Trevor, i'm not saying you did not lubricate, just a general hypothesis.

Even with poor instruction and the weaknesses i still think they are good for the money.

Kind regards
Ade