VHB setup

I tried 50 pilots yesterday. Didn't leave the garage. Obviously too small.

There's a small local outing tomorrow, will monitor carefully how the bike reacts.
Everything in those carbs apart from the slides is new.

It has been suggested that I lower the float level. I'll try next week.

The bike is bog standard.

Paul
 

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Stock DMC Pipes and Dellortto 30A's - You should be fine with 25 main jets and stock needles. Don't expect any more then 7000 rpm with that setup.

From what I see is a late model 750S approaching the SF0 Model about the same time the Breganzie factory was developing the 750SFC.
 
DMC/DCM Mufflers - What's the difference, that's what the Breganzie factory used on the S and early SF models - Not Conte's.

My 70 SF0 came with the exact same setup - Except it had BREV Drums, the SF Tank, Dual Seat and complimentary Letter Box single seat.

Plus I had to assemble the bike from a parts kit in a crate.
 
Paul Marx said:
I tried 50 pilots yesterday. Didn't leave the garage. Obviously too small.

There's a small local outing tomorrow, will monitor carefully how the bike reacts.
Everything in those carbs apart from the slides is new.

It has been suggested that I lower the float level. I'll try next week.

The bike is bog standard.

Paul
Click to expand...

Paul, you need to set it to the correct value. sure, a to high float setting makes the lower end rich, however, a  to low level will result in a leaner mixture more at higher revs.

when the bike is warmed up and you pull throtle and close it right away - does the engine take a while until revs drop or does it return right away to idle?

if it returns right away, mixture is either OK or to rich. if it takes a while until the engine drops to idle, mixture is to lean.

A standard engine MUST run with a standard setup of the carbs if the carbs are OK, else something is wrong with the carbs or elsewhere. changing the setup of the carbs might only mask the route-cause of the issue...

Have you checked valve clearance/adjustment meanwhile and all sides for air leakes?
 
The engine hangs onto the revs with 50 pilots Lothar so I put the standard 55 back in.

Everything has been checked apart from the obvious. Ignition, valve clearance, cam timing. Intake flange gaskets are new.

Paul
 
Didnt someone use a metal Gitar string up the carb passages, I also thought someone else used a number drill, available is hair like sizes, don't snap it off, gently by hand to clear obstructions on the passages. Risky but as a last resort. Someone drilled these holes when the carb was built, one size down from the original hole size might shift the crap. I think these holes arrive via different directions meeting in the middle so don't go too far.Dramals have chucks small enough but don't power these bits, hand use only and at your own risk.
 
I have used guitar strings and they are great, but my favorite 'digger' is to snip off a nylon bristle from my stiff yard brush. Nice 'n stiff, but no damage. Chisel cut the end. Twist as you go like a drill (don't push).

Actual twist drills? That's a no IMHO. To aggressive I feel, especially if powered by anything more than finger tips.

But as Vince says, you can only get as far as the turns/corners with a probe. So it becomes a solvent and air flushing task. Backwards and forwards.

When using compressed air to flusg through the circuits, I first soak with white spirit or turps (i.e. a solvent that does not quickly evaporate). The compressed air pushes this liquid through the channels and I find it better than air alone. If you can't accept getting white spirit squirting all over the place, use water. Carb cleaner is OK, but evaps too quick when flushing with air.
 
My favourite carb cleaner is made by Nulon, it even cleans the tarnish off the outer skin of the carb. Probably your skin as well.
 
"Piet: I sure Wolfgang told me his early model 750S came with Amals !"

no reason why Wolfgang could not have had an early bike with Amals, easily fitted by a skilled engineer if that was his choice, For extra money the factory might have even done it as a special request, although I doubt that, it doesn't mean that all 750's of the same era were factory fitted as such. Please be careful Ron, members on here never cease to amaze me with their knowledge, and I have been "put in place" a few times as well, you are getting it on a daily basis.
CLEM
 
Hi Paul,

FWIW:

I'm with Piet on this one.  Every time I've had a mixture screw not responding, it's been due to a poor air feed in the pilot/idle circuit.

I can't now remember how the VHB gets its air at idle - and I'm too lazy to go down to the garage to look  :D ; but on a PHF carb,  it's this drilling (see attached piccie).  Which as you can see narrows down.  And can therefore be very inclined to stay blocked, even with ultrasonic cleaning.

Just saying, as I feel sure I'm 'Telling my grandmother how to suck eggs'.  Mais au cas o? ...  :-*

Craig
 

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Paul Marx said:
What is a DMC pipe?
Click to expand...

Sometimes we need to cut Ron a little bit of slack ...  :-*

DCM = DGM, as in Direzione Generale per la Motorizzazione

Conte = Conti

Breganzie = Breganze

Dellortto = Dell'Orto

etc.


Btw, Ron:  'BREV' is just a shortening of the Italian word, 'Brevettato', meaning 'Patented'.  It's not a manufacturer's name or nuttin'.  Anyone who has designed something for which they have registered a patent can put it on their product, whatever it is.
 
I've blown the bejaysus, Joseph and the virgin Mary out of those carbs with a compressed air nozzle and things appear to be passing through. (Not your Grandmother Craig)

Too high a float level has been suggested. Wrong mixture needle as well.
I'm sure I've been through all of that but will have another look next week.

I've even changed all the ignition including the auto advance.

Paul
 
keep at it Paul, it so easy for us, because it aint our bike, you pissy offness is aparaent, it will be a great moment when you solve it, just think of an idiot dealer trying to do it in 3 hours and charging you for six..... yeah right, and you pay and get ABSOLUTLEY NOTHING, play it again, war, what is it good for......
CLEM
 
CLEMTOG said:
keep at it Paul, it so easy for us, because it aint our bike, you pissy offness is aparaent, it will be a great moment when you solve it, just think of an idiot dealer trying to do it in 3 hours and charging you for six..... yeah right, and you pay and get ABSOLUTLEY NOTHING, play it again, war, what is it good for......
CLEM
Click to expand...

Bike dealer is a job I would never have done. I like my motorcycles and tinkering with them too much to put up with a lot of money tight, impatient, demanding, ignorant arseholes.

I've done a couple of bikes for others, I was very pleased to see the last one go.

Doctor is a much better job. People are mostly polite even if they think you're a right cunt but a cunt with the power of life and death.
Ideally, one would want a couple with one doctor and a pharmacist, or undertaker.

Paul
 
Good luck with the search, Paul. I think it may be wise to put a '1' in front of Ron's suggested main jet sizes ... unless I'm wrong a 25 to 34 main jet would be problematic!

It is sounding like some sort of blockage in the air feed for the pilot system to me. Don't suppose you have access to another pair of carbs to try?

If a carb was REALLY blocked a last resort (before tossing in the bin) would be to drill out the plugs that are used to seal a system after a 90 deg turn in a passage has been drilled (ie drilled from two different angles) - no big deal to reseal the passage with Loctite epoxy or JB weld.

I've used wire from the brushes I use on my drum kit as a cleaning prod ... but RH corners are still a prob.
 
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