engine removal

Moto Rumi technical problems or solutions
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jmensch
Posts: 17
Joined: Sat Feb 03, 2018 3:48 pm

engine removal

Post by jmensch » Thu Mar 12, 2020 1:45 am

Hello from Miami, Did do a crankcase pressure check on my formichino sport as suggested and there is indeed a crankcase leak! I would to remove the engine to further investigate. Any tips/ suggestions to make this chore easier? Thanks

hugomez
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Re: engine removal

Post by hugomez » Thu Mar 12, 2020 10:22 am

Hi,

Luckily you have a Sport motorcycle model. Removing the engine of a Formichino is much more complex than at your model, muuuuuch more. So, start removing screws and you will have it over the table in no time.
My little Formichino here: http://www.formichino.com/pictures1.html

jmensch
Posts: 17
Joined: Sat Feb 03, 2018 3:48 pm

Re: engine removal

Post by jmensch » Sat Mar 14, 2020 1:15 pm

HI, I do have the formichino scooter model and not the motorcycle. Soooo please send advice. Thanks in advance,

arthur lewthwaite
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Joined: Fri Dec 28, 2012 7:03 pm

Re: engine removal

Post by arthur lewthwaite » Sat Mar 14, 2020 9:59 pm

take the footrest /crash bars off,remove carburettor and also drain petrol tank.stand on a large wood block or sturdy box under engine,so wheels are just of ground,also remove clutch cable under engine first,then remove left hand engine side cover, then split chain and remove flywheel and back plate so wiring free from engine and tie to handle bar.ithen undid the cylinder heads and removed,if you then slightly loosen bolts holding front casting together from one side only just enough to allow a little movement of casting this will allow castings to slide of engine when you do next operation undoing top and bottom front engine bolts,get help to do this ,remove font end complete,then remove rear engine bolts top and bottom and pull back gently again with some help.should leave engine on block.also as have not done this since 1964 am going from memory,you will have to be observant as you disassemble, there are the stand and footbrake pedal to remove/disconect.and any little bits i have forgotten over 56 years.also if heads difficult to get of because of front mudguard get help and slide of studs as you pull front assembly of and put back on studs as you put assembly back on.this is how i used to do it when i repaired rumi back in 1964 in stoke newington,london.refit is the reverse of taking apart.sounds a lot of work but quite quick and easy to do.

jmensch
Posts: 17
Joined: Sat Feb 03, 2018 3:48 pm

Re: engine removal

Post by jmensch » Tue Mar 17, 2020 2:10 pm

Thanks Arthur, I have another question for the forum. I had checked for a crankcase leak by pressuring through the air intake manifold and found a serious leak. Yesterday, before removing the engine, I blanked off separate cylinder intakes and found that the leak was in the left cylinder. Not only that but the air escaping was coming out of the oil intake plug on top of the transmission. (I had previously removed the oil from the transmission).
The engine only had about 50 hours on it after being dissembeled and bearings/seals inserted by a Miami mechanic. It has never run right after that with hard starting and no idle. Any thoughts as to the cause? It seems that the problem is a leak between the crankcase halves?

UHJ200
Posts: 525
Joined: Mon Aug 17, 2009 1:37 pm

Re: engine removal

Post by UHJ200 » Wed Mar 18, 2020 11:56 am

In the bottom half of the crankcase there are little pins that are there to prevent rotation of the crankshaft seal carriers. The seal carrieres themselves have notches that are meant to locate over the pins.

It is all too easy when laying a crankshaft into the crankcase to not ensure that the all the seal carriers are properly located.
It is also all too easy, if not properly located, to crush the pin(s) into the seal carrier(s) when tightening down the top carankcase half. The pins are small and the carrier material soft, if not properly located the lip seals will flex giving the impression that everything is in order so be really careful.

The result if misplaced will be an imperfect seal. I have seen evidence of this on more than one occasion.

A further possibility is that a seal has been installed the wrong way round.

I'd be very wary of rebuilt crankshafts, I had the advantage of a university mechanical engineering workshop when I did mine and it still anything but easy. I would certainly have the existing crankshaft checked for alignment and if more than a thou. or so out I'd bite the bullet and buy a new one (Parmakit?). You only really get one chance with pressed-in crankpins, any misalignment will bruise the hole in the web and from that there is really no way back.

greasy-fingers
Posts: 513
Joined: Thu Jan 07, 2010 11:36 pm

Re: engine removal

Post by greasy-fingers » Thu Mar 19, 2020 8:20 am

for many years I have removed those pins carefully with a dremmel, and used a good quality silicone sealant to retain and seal the seal holders, frankly if the seal holders are loose enough to require the pins to stop them rotating your chances of having good crankcase compression are zero.

jmensch
Posts: 17
Joined: Sat Feb 03, 2018 3:48 pm

Re: engine removal

Post by jmensch » Thu Mar 19, 2020 2:25 pm

I may be over my head in this project! Thanks for the information. I have sent an email to Parmakit and have been waiting for their response. Is their a place where I could send the engine to get it properly fixed?

UHJ200
Posts: 525
Joined: Mon Aug 17, 2009 1:37 pm

Re: engine removal

Post by UHJ200 » Thu Mar 19, 2020 5:47 pm

DO NOT weaken! I presume you took it apart, if so you can bloody well put it back together! Think thrice, measure twice, cut once! If you have ANY doubts we are here.

While I have some sympathy for Greasy's method, (they are after all sneaky little buggers hiding down a hole), I am not entirely comfortable with it. It' is after all just a matter of being aware of the danger and then taking care to position the seal carriers carefully --- all of 'em :!: :twisted:

In the days of yore it would have been a smear of Hermatite to ensure a seal betwix case halves and carriers, today we have Loctite. Check carefully around the slotted locating ridge on the carriers for any signs of bruising and carefully dress any suspect spots.

I really would like to see the crankshaft checked for alignment. What facilities do you have available? A surface plate, dial test indicatoor, "Vee" blocks, etc?

Still, if you think this is "interesting" just wait until you try getting all four gears . . . Plenty of reading about that on here too. :lol:

jmensch
Posts: 17
Joined: Sat Feb 03, 2018 3:48 pm

Re: engine removal

Post by jmensch » Sat Mar 21, 2020 2:16 pm

Thanks UHJ200, Just removed the engine, " Stay Strong" makes sense! I have both surface plates and dial indicator. In as much as the air " escaping" through the vent hole on top of the transmission when tested through the left air intake port, it would appear to me that the loss may be through the locating carrier ridges??

UHJ200
Posts: 525
Joined: Mon Aug 17, 2009 1:37 pm

Re: engine removal

Post by UHJ200 » Sat Mar 21, 2020 11:58 pm

Being from the "colonies", (nobody's perfect :lol: :roll: ), you probably don't know about thruppenny bits. Every Rumi owner should have one to demonstrate just how smooth the Rumi engine can be.

Anyway, you have a surface plate and a d.t.i., good start! All you need now is three matching "Vee" blocks that are no wider than the width of the main bearings. Set the bearings in the "Vee" blocks and measure the run-out all over the crankshaft. Failing "Vee" blocks parallels to lift the crank webs clear of the surface plate would serve particularly if you can stabilize things, long cable ties over the two outer bearings and under the surface plate, maybe neodymium magnets to act as blocks, even "gaffer" tape, time to dive into the "Hope Chest", imagination is your friend!

Note that I say the two outer bearings, doing all three at once might mask an error, indeed it would be best practice to do three tests on all three bearings two at a time. That is to say two outer bearings, left and middle, right and middle.

Look at it this way, it'll give you something to do while you are hiding from this pesky virus :!:

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