850MkIIa rebuild underway

possm said:

Hi b+bogus
I to have a mk2a here in newzealand engine #308408 it was imported from usa in the early 1990's

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Hey Possm, that's a VERY close relative! If they didn't come out of the factory the same week I'd be suprised.
I believe mine never left the UK.
Do you have the date stamp? What was the original colour? Roadster?
Sorry - just too curious
A photo would be good ;o)

Has anyone else got any close relatives to theirs that they know about?

Hi andy
Date stamp is 9/73, a friend of mine owned my bike when it first came into the country and it was black, i lost track of it untill i purchased it as a rusty heap and have since restored it to close to origonal condition it is now metal flake blue and i will try to post photo's but have previously strugled with photo bucket but will try again. regards Al

I am doing a similar rebuild right now. The pictures posted here are very helpfull. My bike was completely apart with some parts missing. I am building it as a cafe racer. I am not doing as nice a job as you are. By the time I am finished I won't have more than $3,000 into the bike. I have a Gus Kuhn tank, no seat yet. I have decided to use RD 400 mag wheels. They are being powdercoated gold right now.

My gearbox looked very much like the pictures. All the mainshaft gears except the sleeve gear are worn through the case hardening. None of the layshaft gears are bad. I have decided to replace just third gear right now because it is so important. (as well as the layshaft bearing) With the gearbox I got two extra shafts, and an extra sleeve gear and lots of selector forks. There is a small crack in the gearbox near the cover that has been repaired with JB weld. I will grind it out and weld it. It looks liket there was some previous blow up at that end of the box.

My bike is a 74, I think it is a MKIIb. It came with a rear disk wheel and the rear caliper as well. Is this correct, for a MKIIb or is the rear disk only on the MKIII? I am going to put it together with the rear disk anyway, it will suit the RD 400 wheels. The footpegs I got are the type for a drum brake, and right hand shift.

Welcome tricatcent,

tricatcent said:

My bike is a 74, I think it is a MKIIb. It came with a rear disk wheel and the rear caliper as well. Is this correct, for a MKIIb or is the rear disk only on the MKIII?

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The disc brake was introduced at the same time as the gearchange/shift was moved over to the the L/H side on the MkIII models.

Its probably got MkIII parts fitted? As there's no MkII 'B' model (not that I've ever heard of?)

It would be interesting to see the master cylinder assembly arrangement of that, do you have any photos?

Here's a photo of Possm's bike



Maybe I should quit now!

L.A.B. said:

Welcome tricatcent,

tricatcent said:

My bike is a 74, I think it is a MKIIb. It came with a rear disk wheel and the rear caliper as well. Is this correct, for a MKIIb or is the rear disk only on the MKIII?

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The disc brake was introduced at the same time as the gearchange/shift was moved over to the the L/H side on the MkIII models.

Its probably got MkIII parts fitted? As there's no MkII 'B' model (not that I've ever heard of?)

It would be interesting to see the master cylinder assembly arrangement of that, do you have any photos?

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I don't have a master cylinder. The bike came with some footrests that would be for a drum brake. It also had some rear sets with it. I am sure that this bike was never assembled with the exact collection of parts I have. I wonder if my bike is actually a MKII or a MKIII? The numbers on the frame and the engine are 314426. I have the very late type swing arm, that is thicker and has the separate adjusters, more like Triumph ones. But I have the right hand shift and the non electric start primary.

tricatcent said:

I wonder if my bike is actually a MKII or a MKIII? The numbers on the frame and the engine are 314426.

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314426 would make it a MkII or IIA model (MkIII engine numbers start at 325001).

tricatcent said:

I don't have a master cylinder. The bike came with some footrests that would be for a drum brake.

I have the very late type swing arm, that is thicker and has the separate adjusters, more like Triumph ones. But I have the right hand shift and the non electric start primary.

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I'd say that more-or-less confirms that it's a MkII/IIA which has been fitted with a MkIII S/arm & brake assembly.

Nice roadster possum!
Myford

No, I haven't given up altogether - just getting back into it after a too long winter lay-off.

I'm nearly finished wiring up, and I'm after some advice regarding the way the ignition switch wiring is routed...
This is what it was like when I took delivery- is this right?
The wiring going outside the frame seems a bit untidy to say the least, but there doesn't appear to be sufficient clearance between the airbox and the frame.

DonOR said:

And btw, Andy, I'm running the re-sleeved original master too, From Rabers. unless you're a maniac (as I was 30 years ago) it STOPS, progressively, and really well. "Soft" pads and stainless calipers are a real good investment too. I also replaced my stainless disk with a cast iron, drilled one. Not that my disk needed to run cooler, but it rains a lot around here... I think the pukas (holes) help keep it drier. happy wrenching! cheers, Don

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Where did you get stainless discs and calipers? Mine are chrome-plated cast iron (plating wears off) and cast alloy. (stainless bore plugs, perhaps?)

possm said:

Hi andy
Date stamp is 9/73, a friend of mine owned my bike when it first came into the country and it was black, i lost track of it untill i purchased it as a rusty heap and have since restored it to close to origonal condition it is now metal flake blue and i will try to post photo's but have previously strugled with photo bucket but will try again. regards Al

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My date stamp is 5 74 Engine Number 315014 bike rescued from Texas.

great photos
good job

Got 308-640 and 315-129 here, Roadster and Interstate.

Mick

Some more progress has been made at last!

The original carbs were in remarkably good nick, so any notions of changing for a better setup couldn't be justified on the grounds of replacing worn-out components. The slides are still a good fit in the bodies, so all that was needed was to replace the nasty nylon float needles with Viton-tipped brass numbers...much better for keeping the fuel on the inside.



New banjo bolts and fuel pipe got the job done. I've held off from putting the pilot and tickover adjuster screws in as I need to order some extended ones which make adjustment without a screwdriver possible...I'm down to the last few oddments which need to be ordered, so I'm waiting until I've got a worthwhile order together.

I got a Trispark ignition from LP Williams - 20 minutes ride from here on the Devil's Bridge road and very convenient, not to mention being on the most popular Biking road in the Northwest.
The wiring is pretty much done, and just needs a little tidying once I've got the headsteady properly adjusted. This has to be the messiest wiring job I've ever seen on a production bike!



A set of TT100s have been fitted to the wheels, and after some serious deliberation, I decided to have a go at salvaging the original mudguards, which were both in pretty bad shape - this is the best shot I have pre-restoration



They both came out OK after a lot of beating, filing and polishing, and I'm pretty happy with them - I'll get a decent photo once I can get the bike outside (soon!!!)

The front brake master cylinder got an RGM re-sleeve and a braided hose. It feels very much like a proper brake should, so it'll be interesting to see how it performs.



The main reason the bike is taking so long is the weather. It's just been so sodding cold and miserable I haven't dared lifting a spray gun since I did the frame, but at last things are warming up
Today I'm in the middle of doing the metalflake blue paintwork, and it's a character-building experience!
I'd previously thought my character was well and truly built, but it seems there's more required :roll:

This is what it looks like so far...



It's fun really. I mean Really. Honest.

More soon - I hope...

B+Bogus said:

Some more progress has been made at last!

The original carbs were in remarkably good nick, so any notions of changing for a better setup couldn't be justified on the grounds of replacing worn-out components. The slides are still a good fit in the bodies, so all that was needed was to replace the nasty nylon float needles with Viton-tipped brass numbers...much better for keeping the fuel on the inside.

New banjo bolts and fuel pipe got the job done. I've held off from putting the pilot and tickover adjuster screws in as I need to order some extended ones which make adjustment without a screwdriver possible...I'm down to the last few oddments which need to be ordered, so I'm waiting until I've got a worthwhile order together.

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What did you use to clean the carbs?

swooshdave said:

What did you use to clean the carbs?

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Dave,

Some STP carb cleaner followed by a toothbrush and Solvol. A bit labour-intensive, but worthwhile.
Having 120 PSI on tap is pretty useful for clearing the passages out too.

B+Bogus said:

Having 120 PSI on tap is pretty useful for clearing the passages out too.

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120PSI, is that a single barrel Scotch?

I have an electric guitar player in my house so I use some old strings to clean out passages just did it this week as a matter of fact.
Then carb cleaner has to flow out the bottom of the carb body if the fuel idle circuit is clear.
compressed air is good as well to finish it off.
Replace the mixture screw out 1 1/1 turns and start and follow synch procedure.
Mine starts much easier now.
Needs to be done seasonally due to crud deposits.
Marshal

Looking at these pictures Amal concentric's reminds my of a old tri trident 1972 i bought...It would not tick over on three...and no amount of compressed air at 1million psi would clear the bleedin pilot jet!! and 0ne million psi is a LOT!!.....Amal deceided in there wisdom...to replace the pilot screw in jet with a sealed in one!! The brass disc under the float head hides it very nicely.

No amount of "Blowing" will remove the crusty plug that blocks the tiny hole...and the thin strand of cable wire just bends.

Answer was to drill out the blank side..carefully! and expose the jet ...then a strand of thin wire can be twiddled in. At least you can hold the jet up against a light and see the holes clear....then tap the drilling 1/4 BSF and plug with a short grub screw...The Trident now ticked over!

Hopefully I'll be finding out how clean my carbs actually are this weekend...
Yes! nearly there

After a much delayed start to the paint spraying, I made some further progress on the Fireflake blue paintwork, until I ran out of flakes...



I got about 80-90% coverage, but it isn't good enough yet, and I'm having to wait for more flakes to come in from the States.

In the meantime I got hold of a set of Interstate bodywork. The original intent was to get this done in time for the Summer hols, but as the Roadster stuff had stalled I went ahead with a candy apple red paintjob.

It's just about done, and will hopefully be OK to put on the bike tomorrow





There are still a couple of minor things to sort out on the bike; the biggest challenge will be where to put the rat's nest of electrical connectors under the top-tube - what a mess!



In among the box of bits which came with the bike were a pair of brass-bodied fuel taps which were brand new and rather nice looking, but lurking in the back of my mind were niggling doubts, based on previous experiences of these not being the most leak-proof taps around - although they didn't snap the lever off like the original nylon efforts!
So my 'final' shopping list included a pair of BAP taps, which I've used on my Bonnie for years without any issues at all.



I know I'm going to have fun fitting the tank (I generally do :roll: ), and I'd welcome any advice as to what goes where on the interstate tank.
According to the parts book, there are studs mounted in the front and rear underside of the tank, and a stack (8 or 12!?) of rubber washers. As it's a parts book it's not helpful, and the workshop manual isn't exactly filling me with confidence either!

What's the correct way to fit these - i.e. how many on each stud? Should the rear mounts be studs, bolts or silentblocs?

Final question...should I strobe the Trispark to 28 deg. or 31/32 deg? The motor is 1oo% standard with the black box filter and peashooters.

As ever, any advice gratefully received!