Jog-Mania

[niz76]

Tsimi, not to throw a total curveball into your tuning but have you done anything with your timing? I don't really have much experience tuning the Dellorto's but there is some excellent info from these fellas here! Kudos!
I had my carb tuned just like yours with a slight sputter down low (bit rich) and found that advancing my timing a bit cleared it up and also gave serious performance gains! I have changed so many things on my engine now (trenched, cylinder ported etc.) that I have no idea if it's a good example of what to expect, but when I set mt timing back to stock now my scoot is a total turd. If you have a temp gauge you can tune the timing fairly safely as advancing the timing can really heat things up. The timing advance is what cleared up that sputter and really unleashed the beast on my scoot!

[tsimi]

niz76

Thanks for your help.
Timing? You mean that thing on the stator side? As far I know you cannot change anything there on stock Yamahas.

Funny thing is I had the same situation with my stock carb. All was good except for that sputter at low range.
I could not find any small pilot jets for the stock carb but I could adjust the mixture screw according to tuning manual.

[niz76]

Jan 3, 2016 18:26:59 GMT -5 tsimi said:

niz76

Thanks for your help.
Timing? You mean that thing on the stator side? As far I know you cannot change anything there on stock Yamahas.

Funny thing is I had the same situation with my stock carb. All was good except for that sputter at low range.
I could not find any small pilot jets for the stock carb but I could adjust the mixture screw according to tuning manual.

You'd have to elongate either the pickup holes or the stator mount holes... I chose to elongate the stator mount holes as my pickup doesn't really move...




The scribe mark is stock and to advance, you'd rotate stator counterclockwise. This made a HUGE difference in my scoot! There are some drawback such as too high advancement can have a negative affect at high RPM's but my scoot doesn't rev that high anyway (96cc). It's a free mod to try that's reversible and now when I put my timing back to stock my scoot is just a total turd. It made that much difference!

[niz76]

 You can also get an offset woodruff key that'll achieve the same effect....

[tsimi]

Thanks niz76

I just found a topic in the Zuma forum where Corrosion helps a dude with similar issues and a few more. It turns out that the PHBG carb is delivered with a 4 stroke bushing and 4 stroke atomizer! Why would they do that?! That is beyond me...
Now my Scooter is infected with 4T parts! Terrible!
Looks like I have to get the 2T bushing with the opening on one side and the 262AU atomizer and not the 262AN!

EDIT:
Looks like the bushing and atomizer are not the reason for it. So back to the drawing board.

So we got one of the following choices;

- change timing
- try smaller main jet
- try smaller pilot jet
- bullet in the head

[spaz12]

Bullet in the head is irreversible so I'd start with the other options.


If you don't have a CHT gauge to check temps you should probably start with a smaller idle jet. Your main looks really good so i'd be careful going much lower. You can always try, just be careful. 

[tsimi]

spaz12 said:

Bullet in the head is irreversible so I'd start with the other options.

True! So let's forget about that idea, for now.

spaz12 said:

If you don't have a CHT gauge to check temps you should probably start with a smaller idle jet. Your main looks really good so i'd be careful going much lower. You can always try, just be careful. 

I do have a CHT gauge, it is just disconnected at the moment to easier swap spark plugs. But I "could" connect it once and see how it goes with a 92 MJ. But as you mentioned I have to be very careful.
What still bugs me is that I cannot setup the mixture screw correctly. Usually the engine should react, good or bad, when you turn the screw in or out. Mine doesn't at all at the moment. It first time starts to go higher on the rpms when I reach 1/4 before it sits completely in. And according to Brents tuning manual/faq that means that the PJ is too large.

I have to order a couple of parts at treatland anyway so I will get the 30s range PJ set (30, 35, 37). It just takes about 2-3 weeks until they arrive till then I will have to get used to that sputter.

[spaz12]

Yeah, that's why me thinks you should get smaller pj

You can mess with the timing later since you have a gauge to get a bit more power out of it like Niz says.

[tsimi]

spaz12

As I recall, you did warn me that the PJ will be too big and I should get smaller ones just to be sure. Well I got a 40 and 38 which was not enough small.
I need also a 36mm screw on adapter for the airbox and a gasket set just to have a spare around so placing an order at treatland is imminent.
Is there anything else I should get from them? Something maybe not for use right now but would be good to have around in case?

niz76

Any special tool required to be able to adjust that timing stuff? Except for the fly wheel puller of course.

[spaz12]

I could spend lots of your money.
Well,if you're just adding to save on shipping then maybe think about the weather changing in a couple months... You'll need smaller jets. Just one or two sizes, nothing extreme.

Of course after the shipment has sent, I'll think of something else

[oldgeek]

Jan 3, 2016 22:08:23 GMT -5 tsimi said:

......Is there anything else I should get from them? Something maybe not for use right now but would be good to have around in case?

You might consider also getting a W7 needle to try with your stock air box, and a W6 if you ever plan to try an open filter.

[tsimi]

spaz12

Good point with the MJ.
Yeah, that is what usually happens, as soon I get the shipping confirmation I remember something.

oldgeek

Good point too. Will add some needles to the order.

[niz76]

Jan 3, 2016 22:08:23 GMT -5 tsimi said:

niz76

Any special tool required to be able to adjust that timing stuff? Except for the fly wheel puller of course.

If you go with an offset key you won't need any other specialty tools besides the flywheel puller. If you opt to elongate the holes, you'd just need a grinding bit on a drill or dremel or whatever...

[Lucass2T]

Be really careful with advancing the timing! I don't like it at all but others have had good results with it.

The minarelli engines have a constant (linear) 14 degrees advance curve. So at every RPM you'll get the same ammount of advance...thats will be 14 degrees.
At the top of the torquepeak you don't really want anymore than 15 degrees. High power 2T's don't have anything more than 15/16 degrees at the torquepeak. You can look up some 125/250cc MX bike timing curves!

So if you set your current ignition at (let's say) 30 degrees with that linear advance curve you'll get that same 30 degrees in the top of your torquepeak! That would instantly melt a hole in the piston! Even if you would set it to 20 degrees temps could get outta hand. 

So be really careful with advancing the timing. Keep a real close eye to your CHT temps! I'd rather look for a CDI with a built in curve. Is way safer!

[tsimi]

Lucass2T

Thank you very much!
What you just explained makes absolutely no sense since I don't understand the basics behind it.
I will not touch the timing unless it is really, really necessary and only as last resort.
I will try simple things first. Today again I put in a brand new spark plug and again I got this nice caramel color after a couple of WOT runs with the 95 MJ so that stays like this for now.
I know from past experience that if I add stiffer clutch springs for example I could get rid of that sputter because it revs up fast and basically skips that part. But I want to get the carb tuning right this time from 0 - WOT all the way. I failed to do that with my stock carb because I couldn't find low number pilot jets for it, but there is plenty for the PHBG.

I will now fill my shopping cart at treatland and see that I can pull the trigger on a new order this week.
Thus far I have

- Main Jets #93 and #94
- Pilot Jet Set 30s (#30, #35, #37)
- Needles W7 and W6
- Gasket Set
- 36mm Airbox adapter

Ooops! Forgot to check the number off the slider. *grabbingtools* And out we go.....
Slider is a #30. What does that mean now? Good? Bad?