ET: Engine (Twin) Leak down test

roy the mechanic

Well Known and Active Forum User
VOC Member
Gardner carbs are great on the racecourse, once you figure out how to tune them. I had two on my rocket gold star. It went "like off a chrome shovel", but was a pig to start cold, there's no cold start enrichment. I ended up with an oil squirt can of petrol in the tool box to start it. Took them off when I sold it. I guess it's the price you pay for running a hot-rod on the street.
 

Peter Holmes

Well Known and Active Forum User
VOC Member
Bill, it sounds to me like your best bet is to pay a visit to the Godet workshops with about £70k in your wallet, then you might achieve your utopian dream. I notice reading MPH, French section, that Didier is still putting in the good miles, and last year at the International Rally his big bore Green Godet Egli did look and sound fantastic.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Gardner carbs are great on the racecourse, once you figure out how to tune them. I had two on my rocket gold star. It went "like off a chrome shovel", but was a pig to start cold, there's no cold start enrichment. I ended up with an oil squirt can of petrol in the tool box to start it. Took them off when I sold it. I guess it's the price you pay for running a hot-rod on the street.
That's strange Roy I , I used them for years on the track and same Bike on the road,
Found starting good, If you open the throttle, It should be like squirting down the hole ?.
Cheers Bill.
 

Bill Cannon

Well Known and Active Forum User
VOC Member
Gardner carbs are great on the racecourse, once you figure out how to tune them. I had two on my rocket gold star. It went "like off a chrome shovel", but was a pig to start cold, there's no cold start enrichment. I ended up with an oil squirt can of petrol in the tool box to start it. Took them off when I sold it. I guess it's the price you pay for running a hot-rod on the street.
Roy, I've found cold start no problem. I routinely give 5-10 seconds full throttle which dribbles neat fuel into the venturis. Alternatively you can screw the needles out a few turns for starting. With the electric start it fires up instantly.
Cheers Bill
 

Bill Cannon

Well Known and Active Forum User
VOC Member
If I had done a strip-down of that engine with no leak test and found that much oil in the combustion chamber I would have felt that I had found a serious oil containment problem.

David
David, as ever your insight is great. You make me wonder if the stem seals are letting oil in. I'll make a point of inspecting them when the valves are out.
Cheers Bill
 

greg brillus

Well Known and Active Forum User
VOC Member
The stem seals or not great.......they are modified Harley ones so i found out, as I had to replace my ones that got damaged quite easily after the valves were removed with the middle collars on them.......doing this damages the seals unless you place a fork shaped device over the seal and then tap the valve out.
 

Monkeypants

Well Known and Active Forum User
Non-VOC Member
Are the stem seals only at 1000 miles as well?
The seals in my OZ bike are at roughly 60,000 and could use replacement now. They were good until recently but have now started to let oil through when above 4000 rpm. These are different seals to those sold by the Spares Co.
I pulled the heads to fix a loose exhaust valve guide at about the 52k mark. There wasn't a whole lot of carbon in there, even with a few thousand miles running too rich with worn out carbs.
Also took the 1360 engine apart at 1500 miles, all clean in there barely any signs of combustion on the piston tops.
Those are a different seal type again, Terry's seals. I should ask him about that! Have the numbers for the D Smith/J McDougall seals but not the T Prince ones, which Bill must have.
Terry puts seals on the exhaust as well. Doesn't seem necessary as the Vincents here on the West coast are using intake only seals and it works just fine.
When the top end was fairly new I used 8 ounces of oil going to California and back, 2700 miles.
Thats better than the 1 Imperial gallon per 1500 miles as considered normal oil consumption in 1950 ( Riders Handbook)

Glen
 

vibrac

Well Known and Active Forum User
VOC Member
I've just put a new 40 mm Gardner flat slide on my racer.......not too sure about race carbs on a street bike. I just rebuilt a Shadow with TT Amal's on it..........great carb's and very well made, but not easy to tune unless you have a good supply of slides, jets and so on.......My thoughts are that they tend to run very rich which is ideal for a racer, but difficult on a road bike. The Gardner's have very little in the way of adjustments, so you might want to re think of the practicality of using these........I could be wrong, but I'm just going off my own experiences. I've yet to find out for myself how to set up the Gardner.......once the bike comes back from having it's exhaust done, its time to fire it up for the first time.
Good luck with that Greg we tried for a year when we were on methanol we went for it because they were made starting in 1948 so were elegible in the upto 49 class and were bigger that the bigest TT (GP carbs are about1951-52 and not allowed) we borrowed the Gardener from Ronald Mettram (Mogvin) and were glad to give it back. Ron Gardner is I belive still around I did speak to him
it seems its all in the needle but we could never get it clean at the bottom end out of corners etc
1597157051438.png
 
Top