Starting an 850 MkIII after, um, 10 years

Failed to start it today. It keeps almost catching, then doesn't. I kicked it until I got tired, twice. Haven't tried starting fluid yet.

Front brake master cylinder doesn't hold pressure, so that's that. Rear brake unlocked itself since the last post so I'll proceed with whatever needs to be done there.
 
Starting fluid washes any lubricant off the cylinder walls. Try to avoid excessive use if possible. It should start on its own. Check and see if you are still getting fuel to the carb bowls.
 
I'm
batrider said:
Starting fluid washes any lubricant off the cylinder walls. Try to avoid excessive use if possible. It should start on its own. Check and see if you are still getting fuel to the carb bowls.
Click to expand...
Yes, I'm trying to get this correct and not lean on starting fluid. I got visual confirmation of fuel to the cylinder while I was checking the spark a few weeks ago, in the form of fuel mist shooting out of the plug hole. That was exciting. Will try again tomorrow.

[edit] If a 5 count is the standard tickler time (according to the video I just watched), I'm definitely not tickling it enough.
 
Last edited:
Just gave it a try. Fuel runs after about 2, which is how I normally do it. If I went to 5 I'd be standing in a puddle. I'm not brave enough for that just yet.
 
jh850es said:
Hey it started! Sounds amazing. Idle, not so much.

No starting fluid, just kickstart and tickle.
Click to expand...
After a few trips around the block in first gear I called it a day. Right hand cylinder isn't firing right; the header measured 150f while the left header was 350f.
 
jh850es said:
After a few trips around the block in first gear I called it a day. Right hand cylinder isn't firing right; the header measured 150f while the left header was 350f.
Click to expand...
Are you sure the bike was warmed up ?

Kinda futile trying to problem solve fuelling issues on a cold motor…
 
L.A.B. said:
If fuel runs out after 2 then there's no reason to hold it until 5.



What was wrong with the other gears?
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I think I did get into second gear at some point but the limit is 25 here. Also the brakes, while they do grab, are not ready for prime time. This as intended to be a slow ride and never leave sight of my house.
 
jh850es said:
I think I did get into second gear at some point but the limit is 25 here. Also the brakes, while they do grab, are not ready for prime time. This as intended to be a slow ride and never leave sight of my house.
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A proper sorting of OEM brakes SHOULD result in ample stopping power for the average rider obeying posted speed limits.

Never mind the "wooden" feel (if present); you'll get used to it and still be able to brake properly.
 
grandpaul said:
A proper sorting of OEM brakes SHOULD result in ample stopping power for the average rider obeying posted speed limits.

Never mind the "wooden" feel (if present); you'll get used to it and still be able to brake properly.
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Yes, the brakes will be fine once sorted. They are not currently sorted, at all. The external seals don't seem to be leaking but the internal seal does not hold pressure reliably. It bites initially, then the lever sinks.
 
jh850es said:
So starting is a non-issue at this point. It started pretty easily with the kick starter.

I noticed it's got a Boyer Bransden ignition. I saw the spark with my own eyes so it seems to be working.

The big question mark right now: is the master cylinder OK? There's a bunch of gunk around it so I'm a bit worried, but I haven't had it apart yet. I'm going to bleed first and see what happens.

I rebuilt my Goldwing's calipers a few years ago and learned a lot about non-destructive scraping of machined aluminum surfaces. It was a real pain but had great results. The trick? I had a bunch of aluminum spindle spacers that came out of an old hard drive. These could be filed and bent into shape to reach all the channels where the seals fit, to scrape off the crystallized brake fluid without leaving scratches. Hopefully that won't be necessary here.
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Well played on your scrapers. In uncle Sam's jet engine school taught us a good practice, your scraper darn well better be softer than the item being scraped. As for o rings, break a wooden Q tip for a pry instrument...good learning! Good luck
 
wildbill56 said:
Well played on your scrapers. In uncle Sam's jet engine school taught us a good practice, your scraper darn well better be softer than the item being scraped. As for o rings, break a wooden Q tip for a pry instrument...good learning! Good luck
Click to expand...
I looked up Rockwell and Mohs hardness data for various scraper material candidates to make sure I was in the clear for that project. It went well. I'm not joking when I say you should grab any old junk hard drive, tear it to pieces and have a box of the parts and magnets on the shelf. Dozens of ultra high precision machined bits are in there, in all kinds of shapes.

For the o rings, I have a nice set of nylon scrapers, pokers and hooks.

Master cylinder rebuild kits and float bowl gaskets are on order.
 
L.A.B. said:
The rear master cylinder is often rusty inside so if it won't clean up fit a new stainless steel one and piston.

andover-triumph.co.uk

Andover Norton - Barrel and stud SS (99.7027) - 99.7027S

Barrel and stud SS (99.7027)
andover-triumph.co.uk
andover-triumph.co.uk

Andover Norton - Piston master cyl 5/8

Piston master cyl 5/8
andover-triumph.co.uk

The return spring may also need replacing.
andover-triumph.co.uk

Andover Norton - MASTER CYLINDER PISTON SPRING - 06.1906

MASTER CYLINDER PISTON SPRING
andover-triumph.co.uk
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Noted. Also covered earlier in this thread.
 
Got the right side bowl gasket in. Easier to kick start today, but still running on one cylinder. The carb slide/choke lever is on the left so I visually verified which way lowers the slides while the airbox was loose. I rode around the block for long enough that it was as warm as it was going to get but it didn't improve.

Next step is to put a timing light on the plug wires to see if it's getting consistent spark, then do a rough carb balance to see how the vacuum is doing on the right side. Plug wires measured ~5k ohm; plugs are Bosch Super [something]. I think "R0 191" but it was hard to read and I didn't want to pull them from a hot head; the main takeaway is they are not the well known BPR7ES. I went over the "what plugs for a Boyer ignition" thread and no one seems to think the Boyer needs a special plug.
 

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