1978 cb400f2

[10tenmen]

I have sent my Carburettor set to Gerben in Holland for a full overhaul take a look at the pictures below of my slides and the residue on them god knows what has caused it Gerben said he has never seen anything like it in over 300 sets lol.

[K2-K6]

I have sent my Carburettor set to Gerben in Holland for a full overhaul take a look at the pictures below of my slides and the residue on them god knows what has caused it Gerben said he has never seen anything like it in over 300 sets lol.

A similar effect accumilates on cars with oil breathers recirculating through the intake system,  usually higher mileage examples.

Whether this one has been blowing oil mist into the carbs maybe worth investigating. What condition is the engine in?

[Nurse Julie]

Wow...they look awful, defo something not right there ( no disrespect to your carbs 😊).

[10tenmen]

Wow...they look awful, defo something not right there ( no disrespect to your carbs 😊).

Well Gerben has no idea if you recall Julie I reinstalled the breather system has it had bits missing, the float bowls are also effected with quite spectacular pitting. I have only ridden the bike for 180 miles and it ran well but flat spotted around 80 mph, it outran my friends new Royal Enfield on acceleration and it doesn’t smoke at all.
Needless to say it’s having new float bowls lol

[10tenmen]

I have sent my Carburettor set to Gerben in Holland for a full overhaul take a look at the pictures below of my slides and the residue on them god knows what has caused it Gerben said he has never seen anything like it in over 300 sets lol.

A similar effect accumilates on cars with oil breathers recirculating through the intake system,  usually higher mileage examples.

Whether this one has been blowing oil mist into the carbs maybe worth investigating. What condition is the engine in?

It runs really well pulls throughout the gears but bogs down at the top end, the plugs were very sooty originally until I adjusted the mixture screws now look a lot better, it doesn’t smoke at all so I’m quite happy with the engine. The carbs were an unknown quantity and I kept getting a leak on no 4 from the drain pipe, I’m expecting them back at the end of the month so I’m using the time to clean and polish up the engine etc, I will post up pics later on their return. If it helps it had been stood for a few years in Colorado before coming to the UK in 2016.

[PHILIP2908]

Interesting point about a bike from Colorado - the elevation there is 7,000 feet so the air is a lot thinner. My DK special was from the same state and the needles were set to provide a richer mixture. So when it got to sleepy old Cheltenham (elevation 247ft) it ran rich and blew black smoke out the back. I have yet to fix this but have managed to jigger up one of the screws holding the needle in place by not using a JiS screwdriver. But that another story...

[Lobo]

Phil... I’m confused here as surely you’d install smaller jets when operating at higher altitudes? The airmix ratio must be kept constant, and if less air avail .... then correspondingly less fuel.

On returning the modified bike to sea level, my guess is you’d then be running it VERY lean and so setting yourself up for some expensive trouble?

Simon