minarelli tune up?

Miguel Centellas /

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Jun 21, 2002 10:05PM

after my long trip to chicago and back ... i want to check on a few things on my bianchi (minarelli engine). here goes ...

my bike won't idle and sometimes dies if i bring it down to low rpms (i have to nurse the throttle at stop lights). it does this if i ride it for 5 mins or if i ride it for 5 hrs (or anything in between). why is this?

could it be a timing issue? my bike starts up really easy, so i don't think it could be taht. but maybe?

i've adjusted the idle screw on the carb (dellorto 15.15) all the way in. it helps a tiny bit, but not really much. could it be jetting? i have a #55 in it. should it be smaller/larger?

the spark plug is brand new. it also does it w/ older plugs. basically, my bike has never idled. at least not in about a year or so.

could it be that i need new piston/rings? my rings are about a year old or more.

i can't think of anything else. if you do, please post it here adn let me know. i'm willing to try anything. i want my bike to perform better. also, i think a top speed of 40mph is a bit low for a bike that has every imaginable minarelli performance upgrade on it (short of a 60cc or 75cc kit, which i don't want).

thanks.

Re: minarelli tune up?

Fred /

Jun 22, 2002 01:36AM

Keep in mind I don't know your bike or carb.

If it makes you feel any better... my Honda will only idle for about 10 seconds when hot... so I give it a little 'goose' every 10 secs or so... If I turn the idle up much more it starts to engage the tranny at idle when cold... I don't like that so I just leave it as is.

but if yours won't idle hot or cold... it doesn't seem right... I imagine you have already adjusted BOTH idle mixture AND speed screws?.. (if it has both?)

I doubt its ign timing or piston/rings if it runs good at mid-range and higher speeds.

On the 40mph... If your cylinder and head are stock you could have the typical 2 stroke mods done to them.

You'd gain maybe 5mph... with the same low end.

(I could do it if you wanted).

I am about at the same point with mine... I hope further changes don't make the low end weaker.. (the faster you go... eventually they will)

Re: minarelli tune up?

Ron Brown /

Jun 22, 2002 12:22PM

> my bike won't idle and sometimes dies if i bring it down to

> low rpms (i have to nurse the throttle at stop lights). it

> does this if i ride it for 5 mins or if i ride it for 5 hrs

> (or anything in between). why is this?

>

> i've adjusted the idle screw on the carb (dellorto 15.15) all

> the way in. it helps a tiny bit, but not really much. could

> it be jetting? i have a #55 in it. should it be smaller/larger?

>

Miguel,

I think you may have answered your own question here. If you answer the next two questions with a yes, then the problem is...

Is the idle screw that you turned all the way in, the idle speed screw?

At a stop light, can you maintain a reasonable idle speed with the throttle twistgrip?

...your idle speed screw is not working for one of the following reasons...

The screw is too short or is the wrong screw.

The spring is too long and will not allow the screw to turn in far enough.

There is a groove worn in the bottom of the slide preventing the tip of the idle screw from supporting it.

Any of these problems should be easily visible if you take off the carb and just look at it.

If you answered no to the above questions, maintain an idle by hand for a minute or so, then let it die, then pull the plug and see if it was too rich or too lean.

Ron

Re: minarelli tune up?

Miguel Centellas /

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miguel OP

Jun 22, 2002 02:14PM

the dellorto carb only has one screw for idle, unlike the bing carbs. i have that screwed in all the way. it might be that the screw is short or the spring long (never thought of that).

i'm also going to check on larger jets.

Re: minarelli tune up?

Ron Brown /

Jun 22, 2002 03:06PM

Miguel,

If the idle screw is easy to access, take it out, remove the spring, screw it back in gently until you feel it toch something, then twost the throlle and screw it in another turn. If you can then adjust the idle speed, get a shorter spring from the hardware store.

Why the bigger jet? Are you running lean?

Ron

Re: minarelli tune up?

Miguel Centellas /

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miguel OP

Jun 22, 2002 06:10PM

ron:

when i twist the throttle, do you mean all the way? or just part of the way? or twist it back to "no gas"?

my bike's not running lean, but i just wasn't sure if maybe it was not getting enough fuel through the smaller jet.

Re: minarelli tune up?

david f martin /

Jun 22, 2002 06:16PM

Another possibility... the clutch may be catching too soon, bogging the engine so that it won't idle. I experienced this last week with an improper, substitute variator belt.

david

Re: minarelli tune up?

Miguel Centellas /

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miguel OP

Jun 22, 2002 11:51PM

i don't think the clutch is a problem for me ... i don't have a belt. the minarelli is a single chain drive system.

another problem is that my bike did idle before ... but at very high rpms ... i want it to idle at low rpms ... the way it's supposed to.

Re: minarelli tune up?

Chris Rice /

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chrisr

Jun 23, 2002 03:48AM

And you say minarelli is the way to go.....My Grande idles at low RPM's all day long. :)

Re: minarelli tune up?

Ron Brown /

Jun 23, 2002 10:24AM

Miguel,

As you turn the screw in, it exentually contacts the throttle slide. Twisting the throttle simply lifts the slide out of the screw's way instead of moving it with the screw. Then, when you turn the screw in and lower the slide again, it will be resting on the screw tip.

It probably makes little difference, but I like the idea of parts being moved the easy way.

The main jet makes close to zero difference to the idle mixture.

The fact that you mention a new jet, leads me to ask if the answers to my 2 questions in my first post, were really "yes".

If they were not, please say so or I am pissing in the wind here.

Btw, when did your ped quit idling?

Ron

Re: minarelli tune up?

Miguel Centellas /

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miguel OP

Jun 23, 2002 04:20PM

no, the bike's not running lean. so i'm inclined to agree w/ you, ron, that it's not the jet itself. i'll try to adjust that screw the way you suggest in a few minutes.

MOPED ARMY

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