Jet Question...or something else? By tianna67 (Read 2,310 times)

[tianna67]

Hi all - my scoot is having a problem with bogging and having very little power. I changed the airbox to a unifilter. Since then, I have followed the directions on adjusting the throttle and air/fuel mixture but cannot get the setting correct. I am just wondering if mabe I need a bigger/smaller jet. The one I have now is 115. Any thoughts/advice?

Thanks!

[tianna67]

Sorry for the repeated post.....just jrryan's reply to a very similar question and I will try his suggestions and get back to you if I need more help. Thanks!!

[tianna67]

Okay, so I have been able to right the idle and the bike now purrs nicely when idling. The problem I have now is that if I am stopped and then go and pull the throttle back very far (for a nice strong take off) the scooter bogs. She also bogs if I am going over 30 and pull the throttle to go faster or to go up a hill. Rides nice and smooth if I am coasting along though. Not sure how to fix this or what the problem is....Thanks for your help.

[Bashan]

I would also check for vac leaks. The vacuum slide might not be pulling up fast enough to provide adequate fuel; after you cruise a bit it catches up and it runs fine. Check your vac lines and intake manifold. Also, pull the vacuum slide out and make sure you don't have any leaks or pinholes. Last, make sure you're getting a good seal on the diaphram when you put the cap back on.

[tianna67]

Thank you both so much. Please forgive for not understanding what you mean...

jrryan - when you say raise the needle or lower the clip - what exactly does that mean?

Bashan - what is the vacuum slide?

Thank you guys!!!

[tianna67]

One more question....

"Last, make sure you're getting a good seal on the diaphram when you put the cap back on."

What diaphram and cap are you referring to?

[tianna67]

Thanks a lot Dr JR. Today I moved the clip down one notch and went for drive. The scooter still bogged a few times but it was less than before. So I then moved the clip down one more notch and it began bogging even more than originally. Any ideas?

[ce]

You're getting too much air for that 115 main jet, and not enough fuel through the pilot jet.

The pilot jet should be a 38 or a 40 with the free flow air filter, that will help the low end bog. If you didn't change it then it's either a 32 or a 35.

Try wrapping a cloth around the filter to slow down the air and see if that doesn't balance out your air fuel ratio.

If it does, you can prolly just go back to the airbox and call it good.

[tianna67]

I suppose its a shame that I already trashed the airbox. I will try to increase the size of the pilot jet and see where that gets me. Should I also increase the size of the main jet?

[tianna67]

UH OH!!!!! I was repositioning the clip up one notch when it flung across my driveway and now I cannot find it. Short of purchasing a new needle, any suggestions on what to do? I thought of getting a small washer but not sure how I would be able to get it on there and be able to make it tight enough to stay. I am going to go look some more...wish me luck!

Edited to add - FOUND IT!!!!!

[ce]

We will repair our scooters in the sea, on the beaches, on the roads, across the fields, and every day, and every night, but we will never, never surrender.

Jolly good show, Tianna, splendid!

Yeah, just do the bigger pilot jet if you need to, the main jet is prolly good. One thing at a time.

How's it run with the lowered needle?

[jake aka:ventoscoot]

and if you loose the clip again, you can take it to an auto parts store and they usually have a selection of "C" clips for various applications and small enough ones to replace the clip on your needle. That is what I did with my old vac slide carb and it worked fine.

[tianna67]

Thanks for all your assistance guys! This morning I changed the pilot jet to a 38 (dont know what size the old one is since it has no numbers on it). Took it for a spin and it seems worse. It is fine at idle (the resting idle rose after the jet as well) but when pulling the throttle, it putters and bogs and has very little power going up hill. Should I go back to old pilot jet and try something else? I have already moved the clip down one notch, which did make things slightly better but still have bogging and not as much power as I used to have.

Should I buy a new airbox? I didnt have this trouble when I had the airbox....

[Bashan]

Here is a diagram of how the various fuel feeds come into play with your throttle:

SJ= Slow Jet, the thing you changed to 38, the other one was smaller, it doesn't matter how small it was. PS= Pilot Screw which is your A/F screw. So you see those two really don't affect the overall function of your scooter that much, just at very low throttle. Your problem is when the needle starts to, or is supposed to, start to lift out of the main jet. JNS=Straight Part of the Needle, JNT= Tapered Part, and MJ is all main jet, the 115 thing you put in. A 115 with a uni filter should at least be in the ballpark, you may have to do some tweaking, but it shouldn't be falling on its arse like yours is doing. My impression is that the needle is not lifting out of the jet, it gets the air, but not the gas. That would be a vacuum problem. It didn't do this with the stock box so something happened in the transition. You put in a new jet so you had your carb off. Are you SURE the intake manifold is tight with a good gasket and O ring, the carb is tight in the manifold, and the vac nipples are all tight including where the vac lines run? You were messing around with all that afterall. One last thing, have you pulled your plug and looked at it? If it's oily black I'm completely wrong. Rich

[Alleyoop]

Your are to rich on the Pilot Jet, usually if just putting on a free flow filter you do not need to change the Pilot jet just the main jet. Put the old Pilot jet back in. Also you don't need to take it for a ride put it on the center stand and do your adjustment there so you don't have to be taken things off and on.

While on the stand to test it out Give the Throttle a quick half twist and adjust your air fuel mixture until it revs up without bogging or hesitation. With the correct Pilot Jet and Air/Fuel mixture adjusted it should rev up to about 3/4 throttle. Past that the main jet kicks in quite a bit but first work on the low and mid range.
Alleyoop