[dvnr] Mechanic Help

[Daniel Sellers]

Jack Lyons

Actually many of our members like to hear about your problems as they learn from your misery. Some, I might admit, may also chuckle uncontrollably and be glad that YOU are having the problem and not THEY!

Well if it ran before it will run again. From what I read I would start with the carburetors. When you over tighten the mounting flange you warp the base and distort the bore in the throttle body making the slide hang up just as you observed. Loosening will relieve some of the bore distortion but it remains out of shape (round). The EXPERTS who think they know it all believe you can remove the warp of the base of the carb by sanding it on a glass plate. While this will flatten the mounting surface it will not fix the distortion of the throttle body bore. Air leaking around the carburetor base and leaking around the throttle slide will reduce the vacuum when you are starting (and running at idle) to the point that the engine won't pull the fuel from the bowl. Engine won't start and if and when it does start it is too lean to remain running. Having the choke slides removed exacerbates the problem even more.

Without studying the Mercury parts manual in detail, I don't know what parts are used to attach the carbs. I know that the Triumph Amal Concentric carbs of the same era use a hard heat spacer against the engine and use the "O" ring in the carburetor groove against the spacer. To reduce the over tightening of the nuts there is a shouldered stud and combination of steel and rubber washers to fasten the carburetor.

We have a member who is somewhat of an expert at getting the carb body bores back into shape but he works on motorcycles for a living and doesn't do charity work. If the carbs are the only problem then perhaps new bodies would be the easy way out. But of course, how can you be sure that's the problem until you fix it.

Dan Sellers


-----Original Message-----
From: John Lyons <thelyonsden at yahoo.com>
To: Daniel Sellers <dsellerspa at verizon.net>
Sent: Tue, Feb 18, 2020 9:58 am
Subject: Re: [dvnr] Mechanic Help

 Hi Dan-
Thank you very much for reaching out. I did not want to drone on about the bike in the general forum and bore folks to death. 
Bike brought in the shop with the same complaint and wanted it to be gone over to remedy the problem and also fix anything else that needed attention. Motor rebuilt on 9/2017 and bike ran  (better) but tough to start and would stall out when coming to a stop. I think I was able to ride it around the block on a few occasions (maybe 2 or 3 times) with the latest this past June 2019.
Coincidently i had it started and noticed my throttle cable was stretched to the point and needed to be replaced. I received several cables from a Norton parts company in CA and i believe finally I have the right size installed (travel of the throttle valve (slide) in the body). One odd thing that I can not figure out is when I tighten the carb mounting nuts down to tight the cable gets bound or xxx throttle valve caught up in the body due to distortion and will not move. I have to back off a bit on the nuts. It seems tight but wondering if gaskets is making a proper seal. Since this point the bike will not kick over and only backfires on occasion. 
The ticklers work but as far as the rest of your questions such as Ignition and timing, I am a frustrated mechanic (always have been) despite being a hands on guy with tons of things - construction, plumbing, electrical but mechanics was never my strong skill for me.
Any tips or help is very appreciated. 
Regards,
Jack+1.908.672.7328
Bike ran but never started  
    On Tuesday, February 18, 2020, 08:49:00 AM EST, Daniel Sellers <dsellerspa at verizon.net> wrote:  
 
 Jack Lyons


Why not give us some more information.

 The Mercury looks like an excellent restoration and I wonder why you restorer didn't make it run right. So what is the problem. I presume it turns over easily and has compression (at least 120psi). That leaves only three other necessary functions. Ignition, timing and carburetors. Does it have spark? The ignition is VIA magneto? Is the magneto original or rebuilt? Has it ever run since you got it back? Do the carburetors have choke slides in them? Do the ticklers work? Have you reviewed your start procedure with another British Bike owner? Answers to these questions tell us where you need to start.

Let us know
Dan Sellers
DVNR Treasurer


-----Original Message-----
From: John Lyons via DVNR <dvnr at casano.com>
To: Bob Katz via DVNR <dvnr at casano.com>
Sent: Mon, Feb 17, 2020 5:22 pm
Subject: [dvnr] Mechanic Help

Hi-
1968 Norton Mercury 650

Located in central NJ and looking for help in getting my Norton on the road. Spent some serious bucks at Classic Cycles getting bike serviced (rebuilt including machined, crank, bearings, valves, cam, piston, etc) but never ran right and rode. I can probably situate a trailer to travel to travel.
Frustrating but want to get her road worthy this spring.
Regards,
Jack Lyons


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