hi all
just bringing the old girl out of winter storage
some problem between idle and low speed eg 1000 rpm to ca 2500 rpm
will start ok with choke
cold idle difficult
will idle ok at ca 1000 rpm when warm
will run ok on the high way eg pick up and cruise are ok
problems is when pottering about in town on a crack of throttle the pick up and running at between 1500 and 3000 rpm feels like its running on 3 or 3.5 cylinders ( you can hear a " missing " beat )
or rather lean( missing )

as i dont want to bother you without already having put in some own effort:
i checked/ did already

- new gas in tank
- took off carbs and removed float chamber
-checked / cleaned main and secondary jets
- removed brown powder from the bottom of the float chamber, looks like bits of gas varnish accumulation over the many years in use
-checked / cleaned the little carb inlet filters
- checked fuel tap vacuum line no loss of vacuum fuel flows ok
- balanced carbs with a carbtune device( better but not perfect )
- removed pilot screws and cleaned up the points , re-set at 2 turns open
- removed plug on nr 2 and nr 3 cyl and replaced ( seems to be the most affected )
- swapped ht leads

so a fair bit of time spent to no real avail
the bike is rideable but not fun
can it be that the carb itself is bunged up on the low power fuel port?
your critical thoughts and advise are appreciated

cbr paul

 

Is the bike getting quite hot when going around towm? could be one of coils or the wire fo the coil.. trust me I have been there ...

 

Sounds like you've done it all and just stopped short of the goal. You'll need a RPM
guage that will read to +- 50 RPM accuracy. After it's warmed up, and the carbs are
sync'd, it's time to set the idle. Go through, each carb in turn and turn the pilet jet till
the engine slows and just starts running rough. Then advance it back till it just runs
smoothly. Grab the main idle **** (on the end of the coiled-spring shaft), turn it
up/down to the specified idle-RPM for your make/model. Go to the next carb in the bank,
adjust the pilot screw, in the same manner. Re-adjust the main-idle **** back to target,
go to next, etc.

Hope this helps, Ern

 

put a good dose of seafoam in a half tank of fresh premium gas and ride the living
**** out of it - all the way past 10k and back until the tank is nearly empty ....that'll
flush out those carb's bigtime

 

i would also check for a vacuum leak on one of the carbs. those can cause poor signaling in the carbs which lead to low idle issues.

 

hi guys
many thanks for your swift replies
I have contacted the seafoam cy to see if it is sold in europe, if not ill try to find a generic carb cleaner to try to do it
i will also try to change again the ht leads , and perhaps buy 2nd hand another coil set
i have found a 2nd hand carb set in the uk for ca 40 gbp and may try that as a last resort when i go there in next 2 weeks
a question is the following:
about the rec about the dynamic ( whilst running )pilot screw adjustment
it easy the access the pilot jet screws of the outer 2 cards when in situ, and did that outer 2 already
the question is how to do a adjustment of the inner 2 without having to remove the f--- carbs again and again as the access to the screws is horrible ....
your advice is appreciated
thanks
cbr paul

 

Seafoam : can be purchased on EBay UK not sure if it can be shipped a little further
west to you though. (Regs on shipping flammables within the EU that is !)

 

I'd be interested in this as well, do you need one of these? eBay - The UK's Online Marketplace

 

Seafoam will clean what you already did a through job of cleaning. If you hear hissing, a cap has come off a vacuum tap. If you don't have that "snap" of the throttle, the tops of the carbs may have to come off. You can easily test how sticky the piston/needle slides are.

With the engine off, slide the airbox back off the carbs. Stick your finger into a carb inlet and lift the piston to the top. It should slide up with slight resistance. Let it go and it should drop with a nice plastic thunk. Do all four. If anyone of the pistons sticks at the top, comes down slowly, or drops with no resistance, you have to take the tops off the carbs. For the sticky ones, you have to clean the piston and walls. For one with no resistance, you may have to repair or replace the rubber diaphragm. Avoid getting carb cleaner on the rubber diaphragm.

Lagging acceleration could also be incorrect ignition timing. You would need a timing light to check it.

 

To adjust the pilots, you need to get a right-angle adjuster similar to this....

Motion Pro - Pilot Screw Adj. Tool

They make a more expensive version that uses a helical gear set instead of a coiled spring, that's what I got for myself. I wanted to show you the low and high-end choices, so you could fit to your budget. The geared ones rotate and fine adjust smoother and easier than the spring versions, but you definetly pay for the ease.
Here's a link to the pricier version...

Motion Pro - Carb Tool 90 Degree w/Bits


Ern