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Valve clearances

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ranton_rambler View Drop Down
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    Posted: 31 Dec 2015 at 13:40

I've always set my 850GT loop valve clearances to the factory manual - 0.25mm exhaust and 0.15mm inlet. The factory book that came with my Spada shows both inlet and exhaust should be 0.22mm, as does my Haynes manual for the Tonti frame bikes.

Does anyone know if the loops are different for a reason, and if it's a good idea to adopt the later clearances in the earlier engines?

Ian

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Amboman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Amboman Quote  Post ReplyReply Direct Link To This Post Posted: 31 Dec 2015 at 14:39
Later engines have a few differences in the valve train, one of them being the radius of the ball-ends and sockets of the pushrods, lifters and adjustment screws. There's also a slight change in geometry due to different design rocker arms. 

Personally, I stick with .006" and .010" for Loops, .09" and .09" for later engines. 
Charlie
'69 Ambassador,'71 Ambassador,'73 Eldorado,'75 Eldorado police,'76 Convert,'77 Morini 3 1/2 Strada,'81 Ducati 500SL Pantah

http://www.AntietamClassicCycle.com
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ranton_rambler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ranton_rambler Quote  Post ReplyReply Direct Link To This Post Posted: 31 Dec 2015 at 16:02
Thanks Charlie - if you're sticking to the clearances in the manuals that's good enough for me! Pleased to see you've stayed with our Imperial measurements in the US, even though you kicked us out 200+ years ago.
 
On a slight deviation - do you have a proven fix for generator brackets on loops? I've just welded mine up and put a second plate in the middle to add a bit of strength round the 2 fixing holes. I've also measured it up and might get it drawn up as a laser-cut profile and have a replacement made at work, but would be nice to incorporate improvements.
 
Ian
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 31 Dec 2015 at 17:38
Hi Ian.Have you seen the mod' on Greg Benders site which ads a"Torque stay " to the generator bracket which ties it to one of the distributor bolts? I've been intending to use the mod on the V7 but haven't got around to it yet.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Amboman Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jan 2016 at 02:39
On most measurements, I think and use metric, but for some reason on valve clearances I prefer Imperial. Smile

Here's a link to the page Dave P. was referring to: 

I prefer to start out with a new "heavy duty" bracket, weld on the extension back to the distributor bolt, but also make a shim for between the generator and "saddle" of the engine case, install studs with large o.d. flat washers and nylock nuts.  




Edited by Amboman - 01 Jan 2016 at 04:00
Charlie
'69 Ambassador,'71 Ambassador,'73 Eldorado,'75 Eldorado police,'76 Convert,'77 Morini 3 1/2 Strada,'81 Ducati 500SL Pantah

http://www.AntietamClassicCycle.com
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ranton_rambler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ranton_rambler Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jan 2016 at 17:58
Thanks Charlie. My original bracket has done 43000 miles in 43 years, so I'll see how long my current repair lasts.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jan 2016 at 18:16
Hi Charlie,could you clarify the shim business,it's form and purpose.

Thanks,Dave.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Amboman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Amboman Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jan 2016 at 14:41
The shim fits around the locating pin at the underside front of the generator where it sits in the "saddle" of the engine case. It's very common for the generator to have a "divot" worn into it around the locating pin and for the case to be "wallowed out" as well. The saddle is an important part of the generator mounting and a gap there causes undue stress on the bracket and bolts. 

Once I fit a new generator bracket, I test fit the generator and measure the gap between it and the engine case with feeler gauge blades stacked. A shim is cut out of aluminum sheet of appropriate thickness, a hole drilled for the locating pin and fitted during installation of the generator. 

You can see the gap in this photo:


Here's the shim I make:


Blurry photo of it in place:


Better photo from another project:


Hope that clarifies it. 


Edited by Amboman - 02 Jan 2016 at 15:07
Charlie
'69 Ambassador,'71 Ambassador,'73 Eldorado,'75 Eldorado police,'76 Convert,'77 Morini 3 1/2 Strada,'81 Ducati 500SL Pantah

http://www.AntietamClassicCycle.com
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Amboman Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jan 2016 at 14:49
I still have the original bracket on my '69, up until 96,000 miles it still had the original bolts holding it to the block. One Sunday ride, I heard what I thought was gravel being kicked up by my tires. Turned out to be both bolts heads had snapped off. The generator flopped around a bit, but was still charging and I made it the 30 miles home without issue. The broken off bolts were sticking up enough that I could grab them with pliers and they spun right out. Replaced with hardened studs, large o.d. flat washers and nylock nuts, fitted a shim between the generator and engine case, and it's been all good for the last 12,000 miles. 


Charlie
'69 Ambassador,'71 Ambassador,'73 Eldorado,'75 Eldorado police,'76 Convert,'77 Morini 3 1/2 Strada,'81 Ducati 500SL Pantah

http://www.AntietamClassicCycle.com
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jan 2016 at 19:04
Thanks for that.I was completely unaware of that mod'.It makes perfect sense and I shall see to it tomorrow.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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