Has anyone run into this before?

I have put the engine back into my 850 and everything works (test rides went well!) except for the stud alignment for the primary chain case cover.

I did not touch the stud and when, before rebuild, I put the primary chain case cover on, the outer cover aligned perfectly with the inner primary chain case housing.
Now, the stud is positioned lower to the ground (in direction) so that when I put the cover on, the cover is misaligned towards rear of bike and cover is too low by about 2mm or more.

It seems that the reason for this could be that my engine's rear is sitting too high in the cradle compared to when I took it out.

Has anyone run into this?

Perhaps a cure is to loosen the cradle nuts, ride the bike, crack the throttle and hope that the torque of the engine rotates the rear of engine down?

Thanks
Dennis

I don't understand...there are/should be two locating dowels in the periphery of the primary casing... it should not be possible to mis-align the two halves.

Tornado said:

I don't understand...there are/should be two locating dowels in the periphery of the primary casing... it should not be possible to mis-align the two halves.

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Yes . The 2 primary cases should line up for the fit . The inner primary is an issue if the central locating stud is not shimmed well , but it can only be a guess for now . Can you rephraise the question , also what year make and model would help the thread . Enjoy .

Thanks for your replies and sorry to not be clear.

The crankcase halves are assembled with the two dowels and are perfectly aligned. No leaks!

In the photo (from web), the stud (bolted to the engine cradle) that the primary cover bolts to is touching the bottom part of the inner chain case hole it passes through. The hole (it passes through) normally had about 1 to 1.5 mm of space around the stud before rebuild. After rebuild with engine in and out of cradle, the stud is no longer centred in the hole and touches the bottom of the hole. So when I put the primary cover on, the primary cover is not aligned with the inner primary case

The way the inner primary bolts onto the crankcase, there is no way to rotate it to centre the stud in the hole.
It seems like the engine rear that is mounted in the cradle is (say) 1 to 2 mm too high and that I need to lift up rear of engine relative to cradle.
This relative movement would make the stud locate centrally in the inner chain case hole

I hope this helps explain??
Dennis

1973 850.

Mine is the same way. I don’t think it makes any difference to be a few microns off.

The engine to cradle bolts, as well as the 3 bolts holding the inner primary to the crank case all have some clearance in them. This can affect the alignment that you are observing.
Easy to loosen and adjust.

Perhaps the engine to cradle bolt holes are slightly wallowed out due to running while loose at some point in history. That might mean some misalignment upon reassembly. Try slackening all the cradle bolts, applying some leverage or jacking the engine position in the cradle as tou see fit before retighening things. May also try same on the three inner cover to crankcase bolts. I lkke some locktite blue on those three small bolts as ive had them come loose depsite the lock tab washers in place.

DennisMo said:

In the photo (from web), the stud (bolted to the engine cradle) that the primary cover bolts to is touching the bottom part of the inner chain case hole it passes through.

Click to expand...

Have you tried moving the stud, perhaps it's slightly bent?

DennisMo said:

Thanks for your replies and sorry to not be clear.

The crankcase halves are assembled with the two dowels and are perfectly aligned. No leaks! Tornado asked you if the two dowels in the primary case inner to outer case are present, Not the crankcase dowels

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Are the two dowels present? If not you can get the case alignment off, The photo (off the web) shows one dowel missing at the bottom.

DennisMo said:

In the photo (from web), the stud (bolted to the engine cradle) that the primary cover bolts to is touching the bottom part of the inner chain case hole it passes through. The hole (it passes through) normally had about 1 to 1.5 mm of space around the stud before rebuild. After rebuild with engine in and out of cradle, the stud is no longer centred in the hole and touches the bottom of the hole. So when I put the primary cover on, the primary cover is not aligned with the inner primary case

The way the inner primary bolts onto the crankcase, there is no way to rotate it to centre the stud in the hole.
It seems like the engine rear that is mounted in the cradle is (say) 1 to 2 mm too high and that I need to lift up rear of engine relative to cradle.
This relative movement would make the stud locate centrally in the inner chain case hole

I hope this helps explain??
Dennis

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Sorry about that. My primary inner case is from Alton and has one dowel only.
If it had two dowel. I would not be able to get the cover onto the second dowel.
But before my rebuild, had there been two dowels (like stock) it would have fitted perfectly

I will loosen bolts and try to move the engine in the cradle

Thanks to all
Dennis

One of the problems with Commando's is the holes in the engine and the gearbox frame tend to flog out. So if you bolt one of these up tight, then it could be misaligned when you try to bolt the inner cover to the engine, as you have described. Mine was like that. I decided to shim the inside of the holes in the engine with brass shim, and also use shorter pieces of brass shim inside the corresponding holes in the gearbox frame. I then had to wind the studs through bothg because they were tight. Better than original. when I went to fit the primary chain, I had to release the tension on the rear chain quite a lot to then get the primary together.

This told me the wear had made a big difference to the required alignment, it also ensured the bolt you mentioned, lined up with the inner primary.

That's your problem. Not an easy fix, but easier than drilling out for larger bolts, which would have been the only alternative.

Mine wont work loose again.

PS. the reason dowels are used is to ensure correct alignment and also to prevent miss alignment during use.

The commando design fails in quite a few aspects, mainly isolastics [ the inner rubbing plate flogs out on the inner tubes ], swing arm king pin, where the instructions say it is an easy push in fit. [ bloody dumb thinking ] and the weak centre stand. [ also everyone should use a head steady like Jan ( AKA Ludwig ) designed ]

Hi Dennis, mine is around 4mm down, I have raised this matter with Alton without an answer...
When I had that serious primary leak last year, I thought this matter was to blame.
In the end I have left the single dowel completely out, and the covers align perfectly.
The only issue I can see is that by removing the dowel it moves the timing marks... so time her up with the stud in.
And to be honest this is a minor issue as I have EI and the covers look so much better aligned

DennisMo said:

Sorry about that. My primary inner case is from Alton and has one dowel only.
If it had two dowel. I would not be able to get the cover onto the second dowel.
But before my rebuild, had there been two dowels (like stock) it would have fitted perfectly

I will loosen bolts and try to move the engine in the cradle

Thanks to all
Dennis

Click to expand...

Dennis, when you re installed the Alton, did you follow the steps in the install guide ?



And did you fit new ISO rubbers? If so, they would probably alter the angle the engine sits at (more upright if the old ones were worn).

With only one dowel in the Alton case, it is down to the engine to cradle bolts to keep everything in line, if you have too much play in the engine to cradle interface either do as Kerinorton said and use some thin shim to sleeve the bolt holes or use 10mm long bolts in the top two positions and an 8mm long bolt in the lower one.

One other point worth checking...is there a 3mm spacer/washer between gearbox top lug and the left side cradle? If this is missing, the cradle plate will distort when torquing gb mounting top bolt. The distortion may cause trouble with the primary case stud alignment.

Another point to consider it to make sure the plain section of your bolts protrude so that you have to space the nuts out with plain washers. I have seen where the shorter bolts threads have worn into the gearbox frame.

I installed the Alton a few years ago and alignment was fine with primary cover then. It's just changed given I have the engine out.

I will loosen the cradle and see if I can move the engine rear up within the cradle.

Dennis