Advice on Uni and Jets Please. By Bashan (Read 2,652 times)

[Bashan]

I've got your standard 1P57QMJ and I' about to redo it. I want to know recommendations on which unifilter to get and which jets I should get that I'll probably need to experiment with, I don't mind ordering a few jets at a time if necessary. Rich

[zugzug]

What are the mods you plan on doing? Just the filter? Exhaust too? port n polish or better flowing head? Hotter cam? I havent hopped up a scooter yet. (notice I said yet lol) But the general rule of thumb on a motorcycle is at least one jet size per mod. From all the info I have read on mumerous forums its closer to 2 jet sizes per mod for the scooter. Its better to go big and work down in size. Theres something most modders seem to forget. There are 2 jets in the carb. Most just change the main jet and forget the idle jet or about changing the height of the needle.

Heres my short answer. If your just changing the airbox out for a foam Uni (oil type) go 1 or 2 sizes up on the main. If your using the lil chrome filter pod go atleast 2 sizes. Your stock main is probably a 107. So thats a 110 or a 112. I would suggest changing to the metal intake manifold also.
-Zug

[Bashan]

Thanks Zug, do I have to dismantle the carb to determine what jet I have now by inspecting it?. I thought I'd start with just a uni and jet and see how it goes. This is my first real mod so I'm duh. I like the look of the chrome manifold, the only thing that concerns me is no give to it. It seems like the carb, engine are designed to move and flex. Rich

[zugzug]

You can use the original manifold but with the air-box off there's nothing supporting the carb on the other side so the manifold is going to take all the stress from the flexing. That's why yo hear about so many of them cracked after a Uni is installed. You could always make a mount to support the other side but the metal intake should work just fine and be less trouble.

As far as the jet issue, your just taking a educated guess when you first change it and then adjusting from there anyway and some of the stock jets aren't even marked. Just throw a 112 in there, take it for a short run and check your plug. Then if you need to adjust it then just buy what you need from there. If you know your going to do more mods in the near future then buy a range of jets.

Personally I fight the urge to mod/tinker with my scoot. I told myself I was going to ride it for a season before I would do anything but its hard not too. hehe. If I knew I was going to do something I would pull the carb already. But that's me. It only takes a couple minutes to pull the seat/bucket out and a few more to get the carb off and open.
-Zug

[Bashan]

Actually my main focus here IS to get rid of the accursed airbox, I hate the way it looks, I hate the hose, it's always in the way, I hate everything about it! THAT's why I'm going to a UNI, appearance and acceessibility to the engine bay. So numero uno is the Uni, the jets follow suit. Your description of the chrome manifold makes perfect sense, I'm going with that, jets are cheap, I'll get a few, I'm about ready to go, thanks Rich

[mthomas]

Rich,
I was actually thinking about the exact same mods today. I would like a little more zip and better up hills. Let me know where you get your parts, how much ballpark and what kind of benefits you see.
Thanks Mike.

[Bashan]

Hey Mike, actually I ordered from Rick at Scrappy Dog (vendors section) yesterday (sorry Dave, he had the manifold) and I'm stoked. I got a Uni, chrome manifold (thanks Zug), and jets. I got a bunch of other stuff so it came to $80.00 with shipping. But the manifold was $25.00 I think. He said it was great, you lose the stupid spacer and gasket, it bolts right on. The jets were $5.00 each (cheap), I got all he had, #115, #117, and "the guzzler" #130. He said start with the #115 and go up if necessary. I'll let you know how it goes. Rich

[speedracer]

May 9, 2010 3:21:45 GMT -6 Bashan said:

I've got your standard 1P57QMJ and I' about to redo it. I want to know recommendations on which unifilter to get and which jets I should get that I'll probably need to experiment with, I don't mind ordering a few jets at a time if necessary. Rich

I changed to the UNI and added a 40 pilot jet and a 125 main jet. So far this combo has worked well. My scoot came with a 103 main jet, which I changed to a 110 then 112 and now 125. It runs great and has plenty of kick to it.

[speedracer]

Bashan, When you put on the new chrome manifold let me know if you can still get the UNI filter on. I could not and went back to the old manifold.

[mikebpnw]

The aluminum intake manifold is has a different angle to it than the stock black intake, and sometimes there is a crossbar or engine mount in the way when the carb is at a different angle. This can prevent you from being able to install the UNI filter directly to the carb.

Also, if you remove the stock spacer and gasket when going to the aluminum intake you might not have enough vertical clearance from the plastic engine cover to mount your carb (the bowl hits the plastic).

There's any number of things that can happen, depending on your vehicle.

[Bashan]

Actually the carb hit the engine mount big time with the chrome manifold, there was NO way to squeeze it in. Then the Uni would not fit under the engine mount even with the old manifold. I'm not sure why this wasn't addressed when I ordered. I gave them the engine number and no more info was asked. Here is the manifold, the carb fits right on the end and jambs right into the mount:



I ended up improvising this:



Not exactly what I had hoped. Anyway, it's a 115 jet and it's bogging and popping, not so much a backfire, at mid-throttle. I'm thinking needs more gas. I was going to lower the needle clip one notch and adjust the A/F screw tomorrow. Maybe I need a new pilot jet too. Any thoughts would be appreciated. Rich

[speedracer]

May 16, 2010 22:09:49 GMT -6 @zugzug said:

Why couldnt you get it on?

Like mentioned before the chrome intake is at a different angle and when I connected my carb it moved the carb back making the UNI and the starter motor in conflict of each other.

[epdowd]

Hey Bashan,, It looks like we are both pointed in the same direction..Remove Air Box, Replace filter, modify intake,, re jet..
%&*!#^Air Filter #$%%&^ my recent posting and grumbling..
Harv.

[Jon C]

Bashan, did you re-jet above the 115 you put in there? Or did you get your problem solved?

I bought a 115 and a 125. I can't read what the original was, it looked like 105 or 115?? Not sure, so I'm going to put the 125 in now and see how it goes with that and a uni from scrappydog.

*edit*

Got the jets and the uni on, but what do you do with the hose that goes from the valve cover to the filter box after you add a uni filter? I don't h

(I'm trying not to start a new thread here).

[Bashan]

This thread will show back up at the top anyway but start a new thread anytime you want Jon, you're not a highjacker. Fact is, I can't think of anybody that is around here, very polite, well spoken people...nice. You're original jet was probably around a 103, mine was. I tried to go up the the 125 but it kept bogging and turning the plug black. Of course during all of this I was unaware my coil was malfunctioning which put a huge wrench in the works. Long story short, I ended up with the 115 jet and the carb needle on it's leanest setting (clip on highest notch). It does run great I must say. Dr. JR contends that if if dremel out the intake manifold spacer to match the port and beburr the inside of the exhaust pipe that it will probably take the 125 due to better flow. I used to think the crankcase breather (valve cover hose) had to have a partial vacuum on it to work. NOT TRUE! You can feel a lot of air coming out of it when you ride and oil collects in it, so I just stuck an old fuel filter on the end of some clear tube and put a downward U on it so it would collect oil, and it does! (thanks Oot!), (this picture is from a later project, this post edited 10-30-10):