Prev: Rebuilt Petcock | Fuel Leak 20-Times Worse
Next: 1977 cb750 electrical problems
From: Paul Gustafson on 16 Aug 2006 23:53

>>Thanks again for everyone that posting meaningful advice.
>
> sounds like an airleak somewhere. are the rubbers from the
> carb to the maifold tested? even a smal leak could do it.

This is an easy thing to test.

First get it started and running without the enrichment circuit. Next spray
the boots with a non-flammable aerosol such as WD-40 with the airbox in
place. If you spray a boot and the idle speed increases, you have located an
intake leak. If not, I would check for proper float height next.

Thirdly if the problem persists, check the valve clearances. Cold valves may
not seal tightly enough if the clearances are too tight.As the bike warms up
the aluminum head expands further than the steel valves resulting in
slightly more clearance which may allow the valves to seat better. At
cranking speeds even one leaking intake valve may affect cold start
performance.

From: Robert Roland on 17 Aug 2006 04:23
On Thu, 17 Aug 2006 00:43:58 GMT, kylentz(a)excite.com wrote:

>In regards to the poster that suggested measuring the voltage off the coil,
>is that accurate? I've heard of checking the resistance (OEM manual has
>specs for resistance), but the voltage would be very high, correct?

You measure the voltage on the primary side of the coil, not the
actual spark voltage.

--
RoRo

From: MJW on 18 Aug 2006 13:20
I just wanted to thank the gentleman who advised the Berryman's ChemTool
solution.


"FB" <flying_booger(a)yahoo.com> wrote in message
news:1154830833.321980.44430(a)75g2000cwc.googlegroups.com...
> kylentz(a)excite.com wrote:
>
>>
>> The problem is that it is very hard to start or won't start - unless I
>> put a
>> very small amount of starter fluid in the air box opening. Once I do
>> this,
>> it starts right up and runs well. Idles a little slow until warm (I
>> think
>> this is normal). After 2-3 minutes, idles and runs great. Once the bike
>> is
>> warm, it will start again with no problem at all. I have tried starting
>> it
>> with the choke in various positions. With the choke on full, it will
>> sometimes sputter for 1-2 seconds, and then die. Then it seems like once
>> it
>> has done this "sputter" thing, it won't even fire until I let it sit for
>> about 15-20 minutes. One 1 second shot of starter fluid seems to fix the
>> problem completely.
>
> I have explained this a bazillion times. Your motorcycle doesn't HAVE a
> choke. It has a bypass enrichener system. It's a little valve in a hole
> that bypasses the butterfly. There is a fuel passage that sucks
> gasoline straight out of the float bowl.
>
> When the idle mixture circuits get dirty, the engine begins to stall,
> and the owner will adjust the idle speed screw to make the engine idle
> faster.
>
> This defeats the bypass enrichener. When the butterflies are open too
> far, the engine vacuum is too low to suck up enough mixture to start.
>
> The solution to your problem is to add about 4 ounces of Berryman's
> B-12 Chemtool Choke and Carburetor Cleaner to a full tank of gas and go
> for a ride.
>
> When the B-12 starts cleaning the idle mixture circuits out, the idle
> speed will increase and you'll have to turn it down.
>
> By the time you have run a full tank of B-12 through the engine, the
> carbs should be spiffy clean inside.
>
>> I have not synchronized the carbs. The previous owner said they had just
>> been sync'ed. Since it idles fine once warm, I don't this this would be
>> the
>> problem, but I am not sure.
>
> Carburetor synchronization is a moneymaker for mechanic$ in
> $tealer$hip$.
>
> When the carburetors get dirty inside, sure, the engine is going to run
> rough on one or two cylinders. Run some carburetor cleaner through the
> gasoline on a regular basis and you never need to synchronize the
> carburetors.
>
> I used my cheapie Carb Stix exactly twice and wound up throwing them
> away.
>


From: B-12 on 18 Aug 2006 15:17

MJW wrote:
> I just wanted to thank the gentleman who advised the Berryman's ChemTool
> solution.

You're welcome.

"FB" <flying_booger(a)yahoo.com> <--- (takes a bow)

First  |  Prev  | 
Pages: 1 2 3 4 5
Prev: Rebuilt Petcock | Fuel Leak 20-Times Worse
Next: 1977 cb750 electrical problems