DelortoCarb on Grubee

Discussion in 'General Questions' started by Manic Hy-per, Nov 9, 2011.

  1. Manic Hy-per

    Manic Hy-per Motored Bikes Sponsor

    Has anyone mounted a dellorto carb on a grubee 66/80cc motor?

    I have the right [delortto carb 16.16 ] and the proper [custom made / billeted] manifold, just trying to figure out the jet...

    Factory rep (Dellorto) says it comes with a #68 (5mm thread) I tried screwing in jets from older style carbs I had laying around that I was able to thread in, but seems to be TOO RICH. I did not see any numbers on the jets I took from chinese kits.

    Has anyone of you been successful with a delorto upgrade? I have ordered several jets various sizes coming down from #68. If anyone has done this and hit on a jet that works to save me some trial and error - let me know what number worked best! Thanks!

  2. vincevandal

    vincevandal New Member

    Dellorto Carb

    Dellorto PHBG 15 mm AS Carb (Clamp on Style) for 2 cycle
    With a #56 Main Jet.
    I went with this because Pirate Cycles had some on their site and one of their custom builds listed the carb and jet size.

    Still trying to figure this thing out...

    Got it to start and pull a little but it bogs down under load and stalls. Not sure if its carb tuning or vacuum leak yet.

    I also made a custom intake with copper piping and the standard intake clamped together and sealed with a fuel hose. (maybe a bad idea I dont know)
    This increased the diameter to fit the carb and allowed me to curve the pipe for space. Any one feel free to tell If I shouldn't have done this. Needed something quick. Dont know where to find a custom billet intake.

    I live 1400 ft above sea level and I weigh 200lbs. I also ordered a high compression header and have the stock black cat pipe.

    Any advice would be appreciated. I'll keep you updated.

    Last edited: Jan 19, 2012
  3. vincevandal

    vincevandal New Member

    Just ordered larger jets

    58 60 62 64
  4. motorpsycho

    motorpsycho Active Member

    every carb will run differently on each engine.
    what jet works for joe schmoe's carb and engine. may not work for Johnny come lately's carb and engine.
    Trial and error is the best way to dial in a carb because even the air temp and humidity can effect the fuel - air ratio.
    Jetting /tuning a carb can be a long drawn out process or it can be really easy and quick if you get lucky and happen to start with a jet that is close to what you need and tune up-down from there.
    normally a bog at w.o.t. indicates that it's too lean.
    4 stroking indicates that it's too rich.
    NORMALLY on a nt carb the stock jet size is .70, but that's not saying that they are all .70.
    so if your dellorto has a .68 in it, and it's too rich...holy cow!
    see i had to richen my nt carb up to .74 on one engine, and .76 on another.
    if 68 is too rich. wow, you will have to drop down to an even smaller jet (.68 is a very small jet).
    I still say trial and error is the way to go when jetting / tuning a carb. it isn't that difficult.

    by the way, since this is a cns carb are you sure that you have the choke working the right way?
    the choke on a cns carb works the opposite way of a standard style choke. on a cns when you choke it (for cold starting), you actually open the choke(which allows more fuel to enter the air fuel mix, and makes a richer air-fuel ratio) and when you un-choke it (engine warmed up ) you are actually closing the choke to cut off the extra fuel supplied for cold starting.
    I know it sounds crazy, but that's how they work, and if you have the choke physically open (thinking that it's off) it will run way too rich.
    just a thought.
    Last edited: Jan 19, 2012
  5. gothicguy64

    gothicguy64 Member


    yes i run a dellorto carby on my 48cc motor .

    Mind u it is a full rse motor an bike

    if u email rse or pirate cycles both should have the jet that ull need for a 66cc motor ..

    if u do use a dellorto ull need to mod the carby end of throttle cable to fit the dellorto

    50cc_HP_Stage_2__4ed99d46b8ece.jpg what my motor looks like but has a sbp shiftkit an sbp exhaust fitted .

  6. BoltsMissing

    BoltsMissing Active Member

    What is the GENUINE Dell'Orto Carb? with the inscriptions?
    The genuine real deal, not a clone.
    Or has the Italian company shifted it production to where else but, China?

    I ordered what I thought the ad meant was a "Dell'Orto" carb and it ended up in the "one day I might use it" drawer.
    When I re-read the ad, it said, "like a Dell'Orto" carb.

    Due to a specific build I am working on, I need the genuine item.

    So, has anyone got a pic of the GENUINE Dell'Orto carb for the 66/70 cc , and where can it bought from in Australia at a un-inflated price?

  7. vincevandal

    vincevandal New Member

    This may help you BoltsMissing... don't know if they supply to Australia at an un-flated price: I got mine from here just cuz they looked the most legit. They have a Facebook page too.

    motorpsycho, thanks for the advice. I'll keep cranking on it. I don't think its the choke. I do pull it for cold starts then close it when it warms up. It does perform even worse when the choke is wide open and at WOT.

    I'll have to take pictures of my hacked together intake to get your opinions on whether you think its my problem. Till then I'm gonna check to make sure its all sealed up, try to level out the carb more, and mess with the mixture screws. It only starts fine when turned out 1.5 turns. I haven't adjusted needle height either.
  8. BoltsMissing

    BoltsMissing Active Member

  9. vincevandal

    vincevandal New Member

    Dellorto Status

    Turned the main mixture screw almost all the way out and felt like I got a bit more torque. Then the screw fell out. Luckily I found it. Idle screw doesn't really do much if anything at all. Not sure if this means I'm too lean or too rich.

    So I decided to see what happens when I move the clip on the pin up to lean. Up to lean... bike would only run with choke open. Engine dies if closed.
  10. vincevandal

    vincevandal New Member

    new jets coming soon

    I read that if you turn the mixture screw out its enriching the mixture increasing fuel on this carb. Opposite of what I thought. And I turned out this screw so far it fell out, but torque increased before it did.

    So I think the bigger jets that are coming in will do the trick. And putting the clip back where it was on the needle.
  11. vincevandal

    vincevandal New Member

    no luck

    so i messed around and didnt get too far.

    I dropped in a 64 main jet and noticed more torque at first, but still not enough to go up a mildly steep hill under load. I noticed that if I put the choke on it would kill the engine.

    What does it mean!?!

    Anyhow I decided to jack around with different jets going down to a 60 where the opposite happened and it would only run on choke - not cool considering before I had a 56 and I could get it to run without the choke but no torque. For curiosity sake I then dropped in the original 70 and it was similar to the 64.

    I thought maybe increasing the richness in the needle would help but it really didnt do much.

    Now I have put everything back to where I had it with the 64 main jet and it runs even crappier than before. Barley idles unless choked.

    One thing I've noticed is a very small whistle as I begin to start the engine.Perhaps a vacuum leak coming from my hacked home made intake?

    Another thing is the exhaust that leaves behind a wet oily residue on the floor of my garage. Is this an indication that its running rich?

    I looked online to find that in order to figure out jet size you need to run WOT with the choke on. If it bogs down at WOT then your jet is too big. at WOT it runs well regardless even w/ 70 main jet.

    So I've ran into a few contradictions in my conclusions and don't know what the heck is going on.

    Any help would be appreciated.
  12. vincevandal

    vincevandal New Member

    got it going. Not super stoked with the power though. I can barely make it up a hill.
    it looks like the engine gets pretty hot. the gasket sealer bubbles on the intake.

    is it the motor?