1976 350 Road

[Ventodue]

Model for the seat cover. Ideally should have more packing up at the back; but they always look better with the seams, IMO.

Road seat.jpg

[George]

Would be nice to get a uplifted silencer like in the publicity material of the time. Sporty ... And your rear light is looking a bit sick

Also note how the tank filler cap is fitted with the pointy bit facing AWAY from the 'Family Jewels'. Has always seemed a wise precaution to me ...

Thanks for information. I take note about filler cap, with the recent accident I had it was the steering damper knob that brought tears to my eyes.
The rear light is complete and held in position with sticky tape, fixing screw missing.
The silencer is sound and I will clean up and spray with high temperature satin black.

[George]

I have finally started 350 Mototrans Road restoration.
Engine out, head and barrel off. Piston is standard 76mm. Barrel, piston and rings within wear limits. No play on big end and small end bush. Cam shaft is in good condition with some damage to one rocker, I will get both rockers off to Phil Joy for reconditioning. Cam bearings in good condition but I shall replace all bearings and seals as the bike as been off the road for 25 years.

The head is in good condition with good valve seats, spark plug and exhaust threads good. Some wear on valve guides, will fit new guides and valves
The valve head sizes are inlet 36mm, exhaust 33mm, with 8mm stems and lengths as shown on various seller sites. These sites show these head sizes for 250cc heads and 350 head sizes 40mm and 36mm. I won't be changing head but curious to know if anyone knows if the 1976 350 had the smaller valve sizes. The only part number I can find on head is the letter 'P'
Although valves have bucket shims fitted rockers have adjusters, makes it easier for me but is this a modification?

The head inlet tract is 28mm diameter.
The carburettor is Spanish Amal Concentric627/421 27mm inlet.The slide and bore is very worn on mine and the choke is missing. A new carb is called for. The Burlen Amal catalogue list shows the same carb as fitted to 1973/74 250cc Road with same specifications as my one. Price £200 + and not stocked made to order only.
I have come across an eastern copy of concentric. manufacture is WASSELL. 28mm that Amal jets fit and has good reviews from classic Brit bike forums. https://www.ebay.co.uk/itm/113753032004 Has anyone had experience of these or could recommend an alternative.
Sorry for long post. Positive results so far hope I am not tempting fate

[Jon Pegler]

The P head is correct for a 350 Road.

[A.I.M]

Hi George,
a couple of years ago Burlen made up an Amal 627/419 to order for me. It took 12 days from placing the order to having it in my hands, in France. It was built up with 200cc Main Jet, .105” Needle Jet and a 2.5 Throttle Valve.
My one is standard for a 250 SCR, so my superficial impression is that it would be a bit small for a 350.
Cheers,
Al

[George]

The P head is correct for a 350 Road.

Thanks Jon. Wondering now if later 350 models carbs were changed to 250 carb because of availability / emissions rules changes.

[George]

Hi George,
a couple of years ago Burlen made up an Amal 627/419 to order for me. It took 12 days from placing the order to having it in my hands, in France. It was built up with 200cc Main Jet, .105” Needle Jet and a 2.5 Throttle Valve.
My one is standard for a 250 SCR, so my superficial impression is that it would be a bit small for a 350.
Cheers,
Al

Thanks for info Al. Jetting and throttle valve sizes you give are same as the carb on my 350. Wondering if previous owner has put this carb on because he had one.
Burlen state 350 road carb for 1973-1974 as R930/417. I think I will contact them for advice.

[Jon Pegler]

The carburettor fitted to the 350 Road was a bit confusing, depending on which source of information is used.
The Mototrans parts book lists a 27mm carb on both the widecase 250 and 350.
The Mototrans riders handbook lists a 30mm concentric carb in both the Spanish and English language versions.
Maybe Mototrans were unsure themselves.
I would guess that George's bike came with the 27mm concentric from the Factory.

[Jordan]

Burlen state 350 road carb for 1973-1974 as R930/417.

From Amal carb settings list for 1973:

Amal R930-417 settings.png

Numbers left to right are for Main jet, Pilot jet, Slide cutaway, Needle position, Needle jet.

Note that the settings are not stated as being specific for any particular motorbike. In Amal's system the number after the slash just defines the combination of settings for the carb. The same number could be used on more than one make/model of machine.

[George]

The carburettor fitted to the 350 Road was a bit confusing, depending on which source of information is used.
The Mototrans parts book lists a 27mm carb on both the widecase 250 and 350.
The Mototrans riders handbook lists a 30mm concentric carb in both the Spanish and English language versions.
Maybe Mototrans were unsure themselves.
I would guess that George's bike came with the 27mm concentric from the Factory.

Thanks again Jon. More or less confirms my thoughts. Putting a 30mm carb on a 28mm inlet tract seems wrong to me. Carb looks like it has been on a long time and run without air filter giving the wear I would expect from a bike showing 20,000 miles and engine in good condition.
Life with Mototans can get confusing, now to decide on 27 or 30 carb as either will work. I will wait and see what Burlen have to say