Dell'Orto Carbs - anybody know about them?

[CRM]

Had this starving and bogging thing on my Gas Gas, then at idle it would build up revs until it screams. Took the carb apart as I figured there was something sticking or a blocked jet. It's running much better now but still but haven't quite got it right. Anybody had this problem and know how to set up Dell'Orto's?

[cheese]

ask rupecop,he talked to some guy down south that sorted his one

[raptorex]

Almost sounds like an air leak.Check the inlet manifold and maybe even the base gasket.

[F5 Dave]

Bit more info. Was it always like this? What has been done recently?

Only the Trial engines have Dellortos, the Enduro range have Keihen. Pampera is derived from TXT trials bike hence Dellorto.

Check for blocked pilot jet (smallest) & float jet is not leaking (take apart & check for hairs etc). Check float height & that the floats aren't leaking.

How many miles has it on it? They do wear emulsion jets.
Has the airfilter been cleaned/replaced & oiled with real filter oil?

Try turning the idle mixture screw in progressively whilst blipping (the small flatblade screw one in recess, not the speed adjuster). Does it get better or worse? Other way?

Delorto jets can be obtained as genuine Honda parts. Yes you read that correctly.

Rereading that, idles then screams? What do you mean by that? more info required, does sound like airleak or running out of gas, but confusing symptom/description. Don't be afraid of more words.

[CRM]

Bit more info. Was it always like this? What has been done recently?

Only the Trial engines have Dellortos, the Enduro range have Keihen. Pampera is derived from TXT trials bike hence Dellorto.

Check for blocked pilot jet (smallest) & float jet is not leaking (take apart & check for hairs etc). Check float height & that the floats aren't leaking.

How many miles has it on it? They do wear emulsion jets.
Has the airfilter been cleaned/replaced & oiled with real filter oil?

Try turning the idle mixture screw in progressively whilst blipping (the small flatblade screw one in recess, not the speed adjuster). Does it get better or worse? Other way?

Delorto jets can be obtained as genuine Honda parts. Yes you read that correctly.

Rereading that, idles then screams? What do you mean by that? more info required, does sound like airleak or running out of gas, but confusing symptom/description. Don't be afraid of more words.

Thanks for that. It's an 05 Pampera - one of the last ones made so not huge mileage. I just swapped it for my DRZ400 but it was going fine the first couple of rides. I suspect it was a blocked jet as it came right after I took it apart and blew out the jets. I really just need to to know how to tune the carb - so thanks for the tips.

By screaming I mean it would gradually build up revs from idle until it was at full revs - without touching anything. Restarting it and putting it in gear it would idle and chug in first gear but as soon as opening the throttle it would die.

[F5 Dave]

OK sounds lean. This could be an airleak, or it could just be lean.
Erm are these premix like the TXTs? More oil than usual will make it lean. Air filter ok & oiled? Any oil residue behind the flywheel? Indicates LH crank seal leak (plastic cover might leak in chainlube making it hard to be sure).

Base gaskets residue? Air boot or reed block leaks?

It does sound like an airleak if it races like that - so be sure about it. Ideally a leakdown test, but not many people have the equipment. Is easy & cheap to make a test setup. You have to take off the carb & exhaust & block them on a 2 stroke by means of a bung in the carb manifold & a plate with some rubber over the exhaust, my TXT is bolt on from memory. Then one pumps it up with a bicycle pump through a hollowed sparkplug with a gas fitting & low pressure gauge. About $40 worth of parts required.


Once pretty sure of above;
Turn the idle mix screw in. When blipping it you have it so it won't stumble then turn it in a bit more as will require a bit more rich when under load & experiment. If you run out of adjustment you need the next size jet, but that would surprise & concern me. Usually they are set rich.

[CRM]

Thanks for the tips. Also found some good info at http://www.trials.com.au/techtips/carb3.html and http://www.trialscentral.com/forums/index.php?showtopic=15911 for anyone that wants more help. This does seem to be a problem with dell'orto's. I think there also the air filter was over-oiled which made it run lean. Sorted that out but in the meantime I'd screwed up my carb settings when I took it apart so took a bit of tweaking as per the link above. Went for a ride Saturday and it was going pretty sweet.