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Technical Discussion Forum / Re: 1928 Model 9 engine in a 1928 Model 8 frame?
« Last post by Tom Snow on December 11, 2018, 04:29:37 PM »
Hi, the '28 Model 8 engine is 20.50 inches from the bottom of the crankcase to top of the rocker plate, say 22 inches overall for good measure. As previously stated the 8 and 9 were scaled up or down depending how you look at it , even the petrol tanks have a different depth; about 4 inches for the model 8 and 4.50 inches for the model 9. I would look for model 8 engine pieces or swap the 9 engine as it would make a better job at the end of the day as all of the other parts like primary chain cases would fit and not need modifying.

Regards,

Tom.
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Technical Discussion Forum / Re: Model 90 mainshafts
« Last post by singleminded on December 08, 2018, 08:04:33 PM »
Alpha think mine could top £1000..But hey ho if I want it on the road!!
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Technical Discussion Forum / Re: Model 90 mainshafts
« Last post by Rick Parkington on December 08, 2018, 06:44:36 PM »
With you there, brother. My '35 crank just cost me £650 from Alpha but they had to make a custom pin and machine the big end eyes as well as sorting the D/S mainshaft bore (I've swapped the splined shaft for an earlier tapered one to make it suitable for a 1931 crankcase) which they oversized, plating/grinding the shaft fit to suit. It's a lot of work - but without doubt I find that as soon as a job leaves my workshop it starts getting frighteningly expensive very quickly. 
That 0.500" crank is a Lion one by the way but not sure of year. I did wonder if the feed hole was smaller due to the lack of top end lubrication diverting some of the supply but I can't imagine why Marstons would have made a different bush - I THINK all the cranks I've seen have had the same size nose. Mind you it doesn't need to be diameter, maybe it's something to do with rocker feed take off - like it has a hole in it somewhere; but then the '31 doesn't have a rocker feed...oh I dunno!
Cheers R
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Technical Discussion Forum / Re: Model 90 mainshafts
« Last post by singleminded on December 08, 2018, 05:42:26 PM »
Thanks Rick..You've just about confirmed what i was thinking anyway..
I checked my 1932 parts list,I have a '32 9A as well, and the timing side bushes are the same for all models. On checking the '31 parts list the Lion has a different mainshaft bush, my guess would be that the inside diameter may be smaller. At least as the spare bush I have is smaller then I can machine it to fit the new mainshaft.
This is not going to be a cheap repair though :-[..John
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Technical Discussion Forum / Re: Model 90 mainshafts
« Last post by Rick Parkington on December 08, 2018, 04:21:04 PM »
Hi John, I have two cranks out of engines at the moment so they're easily measured. One looks very good and mikes up at 0.500" the other also looks pretty good and is 2 thou down (0.498") so I would guess half inch is standard. Interestingly the bore is approx 1/8" on the first - which I would say is probably about '32 (bolted mainshafts and small big end) but more like 3/16" on the second which is probably '35 (bolted main and large big end).
As you say, steel  doesn't sound right - all the bushes I've seen have been bronze.
Maybe your undersize one was made for a crank with a reground nose, Triumph used to do a 10 thou undersize timing cover oil seal for the same reason. I doubt these bushes were ever supposed to be a particularly close fit. Roller big ends aren't too fussy about pressure delivery and the oil seems to syphon through, to a degree aided by centrifugal force and crankcase vacuum I think.
Just out of interest, when I first stripped my 1932 9A (which was the most comprehensively knackered bike I had owned up till then) I found both roller bearings had broken up and the rollers were rattling about loose in the crankcases leaving the crank entirely supported on one sloppy drive side ballrace and that little bush in the timing cover. As if that wasn't bad enough the magneto shaft was broken, suggesting that it had been running like that for who knows how long up until the magneto happened to break!
Cheers Rick 
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Technical Discussion Forum / Model 90 mainshafts
« Last post by singleminded on December 08, 2018, 10:57:58 AM »
Hi everyone.
I have found someone to repair my 1932 90 crankshaft.
Question--What is the correct size of the portion of the timing side mainshaft that goes into the timing side oil feed bush.
The bush that is in mine is 503 thou inside diameter which would make me think that the mainshaft should be 0.500 thou.
The problem is that I have sent the flywheel assy to the repairers who are going to make new mainshafts and after going through my assorted bits have found an unworn bush that measures 490 thou. So which is correct?.
Even worse the bush that is in there is made of steel,must be wrong.
I really need to get an idea of what is correct so that I can now send either the bush or correct dimensions to the repairer..Here's hoping someone knows the answer..John
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Parts Wanted / Wanted oil pump plunger and sight glass
« Last post by shorrog on December 06, 2018, 01:27:33 PM »
Wanted an oil pump plunger and sight glass for a 1927 long stroke petrol tanks?
Please Contact raymond.albeson@blueyonder.co.uk or phone 0131 669 9219.
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Parts Wanted / 1932 parts
« Last post by singleminded on November 27, 2018, 04:49:50 PM »
Hi Everyone..I'm looking for a hand change tank lever for a 1932 Model 9, also a rear (foot) brake lever assy  or at least the the lever for the same year.
Here's hoping..John
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Technical Discussion Forum / Re: 1928 Model 9 engine in a 1928 Model 8 frame?
« Last post by wessex_man on November 23, 2018, 06:51:10 PM »
Sorry I can't help re-height as I don't have my M8 now. You could try fabricating some temp engine plates in wood or aluminum to drop the engine and see how far out the other alignments are. A case of suck it and see if it's possible. Best of luck.
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Technical Discussion Forum / Re: 1928 Model 9 engine in a 1928 Model 8 frame?
« Last post by priormuir1 on November 22, 2018, 05:44:34 PM »
Many thanks for the reply. I wonder if any kind Forum member might measure the height of a 1928 Model 8 engine? Clearly, I have the choice of either trying to fit my Model 9 engine to the Model 8 frame I have  or I can try to find a 1928 Model 8 engine.
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