Looking for a bit of help setting my delorto carb up on my gas gas 250 pro 05.

I

When did you last clean the banjo filter?

Have you set the float level at 18.5?

Have you taken the main jet out and cleaned through?

yes i cleaned out the banjo filter and tanken the tank off and cleaned out the fuel on/off tap.

i've set the float height to 18.5 mm and cleaned out all the jets ..

main jet is a 118 and pilot is a 35. the needle is set to 2nd clip up from the bottom.

fule mix is 80/1 fully synthetic with shell v power.

tank vent is bearthing ok.

my only concren is the rear donught on the back of the carb where the airbox meets the carb.this all seems tight,but could be letting air in and makeing it run weak.

the bike will not rev out cleanly at higher revs and has excess smoke from the exhaust.

could this be crank seals that are on there way out ???

thanks for any help...

I had similar symptoms where at low revs it was OK but past 1/4 throttle it would get blubbery. I cleaned out the carb and took off the flywheel cover where I found water inside. I think the water was causing the problem. It ran fine after it dried out. Make sure you seal up where the wires go in.

yes i cleaned out the banjo filter and tanken the tank off and cleaned out the fuel on/off tap.

i've set the float height to 18.5 mm and cleaned out all the jets ..

main jet is a 118 and pilot is a 35. the needle is set to 2nd clip up from the bottom.

fule mix is 80/1 fully synthetic with shell v power.

tank vent is bearthing ok.

my only concren is the rear donught on the back of the carb where the airbox meets the carb.this all seems tight,but could be letting air in and makeing it run weak.

the bike will not rev out cleanly at higher revs and has excess smoke from the exhaust.

could this be crank seals that are on there way out ???

thanks for any help...

I'm guessing that if it's a crank seal, you'd see transmission fluid level dropping as, unlike a "normal" two-stroke, the Pro inner crank area seals have tranny fluid on both sides, not only the clutch side, but that would explain the smoke.

The "donut" is on the pre-metering side of the carb, so grit getting into the carb bell is the big worry, not making the engine run weak from what I can figure. I'm also assuming that you've put fresh premix into the tank to eliminate that as a variable.

Jetting appears to be in the ballpark and premix ratio/type shouldn't be a problem so you might also want to look at carbon obstruction in the front of the headpipe. Check the exhaust mid muffler to make sure the perforated core hasn't shifted (I've seen it one time) and the exhaust has a clear shot in and out.

Electrical malfunction can mimic carb problems so you may want to do a "tune-up" by re-securing grounds, check plug gap (.024"), closely inspecting the sparkplug cap (it gets pulled on a lot) and connections, pulling off the sidecover to see what condition the stator area is in etc.

Well, that's a start....

Jon

Thanks Jon.

Been down most of the ideas you have suggested and all seems well.

I think I have found the cause and it was with the dellorto carb.

There was no washer and oring on the end of the fuel screw just a spring.

I have order the parts from http://www.dellorto.co.uk/ and hope they will be with me today/tomorrow.

Let you know how it goes

Ok a bit of an update.

Got the parts from Eurocarbs the next after the order went in, which is what I call excellent service.

I have replaced all of the orings in the carb with new. Fitted a new banjo filter and the fuel mixture screw washer that was missing. Carb is a 100% clean and all jet where removed and blown out with compressed air.

Bike fired up and all seems to be fine.

Got down to are practice sections and the bogging started happening again. First part of the throttle seems to be ok, but still fluffy at the top of the rev range.

Moved the needled up a clip and checked the plug, which was very light. To lean then.Turned the mixure screw to richen it up.

Away rode some more and the bike feels like it wants to rev out now, but its still fluffy.

I do not recommend this to most people but it has worked for me in the past. (Motor cross bikes)

I held the throttle wide open and revved the crap out of it for 20 seconds, full wide open throttle.

Lots of smoke came from the tail pipe and the engine revved out to its max.

All seem good now the bike is revving all though the rev range and throttle response is very good.

Carried on riding and did a few checks on the plug which now is a nice brown colour.

Alls well and I am happy.

Found this on carb setup. dellorto carbs might be of help to others.

How long have you had the bike?