Jog CV50R 70cc Polini BBK Install

[iwiketuddlz]

Wow I love details but not typing them!!!!!!cudos good sir... Investigate!!!!

[tsimi]

Thanks for being straight forward. Appreciate it.
You are right it is not ideal not knowing exactly what Carb that is.
Carb has been cleaned already when i was installing the BBK. I never paid really attention to type number or maker name stamped somewhere on the Carb.
I did some research and found the Carb type. According to this site

global.yamaha-motor.com/jp/news/2003/0122/jog.html

It says Y16PX1 which would indicate to be a 16mm Carb.
Still even i gathered this info i will follow your advise and remove and take appart the Carb and write down all the necessary infos.

[fe53series3]

Jul 21, 2015 19:01:22 GMT -5 tsimi said:

I did some research and found the Carb type. According to this site

global.yamaha-motor.com/jp/news/2003/0122/jog.html

It says Y16PX1 which would indicate to be a 16mm Carb.

If 'Y16PX1' is correct..... it looks like you are breaking entirely new ground.

I right click searched it.... and there were only 2 pages of links (from the entire global internet)!!!!!!
... and all of them in Japanese!

That's rare.
OMG also rare that you can only gain performance, specific to a lean plug.

Let's hope that your investigations produce referenceable data.

[tsimi]

Had a "little bit" time today and put in the MJ #82 and went for a long(er) drive. About 2km.

I went through all throttle positions.
Idle, 1/4 and 1/2 are very smooth and steady. The acceleration on half throttle is.....WOW, man it is very fast. Way faster then when it was a 50cc stock engine at WOT.
Anyway, at 3/4 and WOT again bogging and sputtering. If I go WOT from the start it bogs down. If I go half throttle first and then slowly to 3/4 and then WOT. It bogs a bit and then the power comes. Brutal acceleration.

So even with a #82 i got no perfect result yet.
Still Snorkel is in place.
Here the pictures of the spark plug.




What you guys think? Is the color with the #82 OK? or is it too lean?
If it would be OK why is it bogging? Would it help if i drilled small holes into the air box? Maybe starting with one hole and drilling more and more until I get the desired result?
Maybe even go back to a #84 and drill holes?
To remove the Snorkel seems to be a PITA and I doubt that I can put that back in since the rubber is pretty old. Holes can be closed by tape if necessary.

Or could it be that I have too much oil in it that's why the bogging? I have the stock oil pump still running and I am adding 50ml 2T oil to 3.5l gasoline that's around 70:1 ratio.
Overkill?

Yes I know, i just didn't had time to take apart the whole Carb yet.

[90GTVert]

IMO if you're going to be reading plugs then do nothing but WOT first and dial that main jet in. Then worry about the rest. Figure out what works holding WOT. No sense in playing with the needle or anything else to figure out throttle transitions till WOT is good as long as you can ride it to test. Also look at the mixture ring deep in the plug other than just taking cues of if the plug is wet or dry. Still I prefer using MPH, RPM, speed, and general observations with jet swaps to trying to read plugs.

[tsimi]

90GTVert

That is what i am trying to achive.
If i can't get good performance with WOT then it makes no sense to tune the rest.
I am just giving info about the lower speed stuff so that people won't say that the slow jet or needle is the issue.

So you mean no matter what the plug looks like i should change jets until i found the one that runs best? Even if that would mean that i run too lean?

[90GTVert]

You said it's sputtering WOT which is usually rich and the lack of color on the base or splotch of color looks like what generally happens when the plug is being washed. It doesn't appear that you're at a great risk of being so lean it's going to seize within the next couple of jet sizes at least. Hard to know and I make no promises. Tune at your own risk and so on.

If you're going to put the money into a bunch of plugs then I'd be doing it this way :
49ccscoot.proboards.com/thread/1727/spark-plug-reading-tuning-info

I still tune mine just by simple trial and error mostly though. Can't say I've never had a seize, but usually if I keep the tuning pass short and don't make big jumps in jet size I can get away without a soft seize. I still like to do a long WOT run before calling it done though... at least a couple of miles without letting off... because I'd rather have it show me any imminent issue while I'm prepared to tune vs while I'm headed somewhere or out on a casual ride. Also keep in mind that once you start to figure out whats what, you can keep it on the rich side for better cooling. Sometimes there's not even much discernible difference in the max power jetting and a step or two richer that will be safer.

[tsimi]

Roger that Brent!

I'll just keep going down jet by jet until i get the best result at WOT.
The engine didn't make weird noises and also didn't got too hot either so i guess I'm still doing OK there.

Thanks.

[tsimi]

Which of the following is considered a "correct" WOT test drive?

1. Strong take off version.

Scooter is standing still.
Crank the handle and go instantly to WOT.

2. Increasing speed style.

Scooter standing still.
Slowly start to drive until you reach cruising speed.
Then crank it open to WOT.

one more thing...

My tank is soon reaching the stage where I have to refill it for the first time since the BBK.
Now what fuel are you guys using over there in the US?
And does the fuel type have an impact on the Scooters performance?
We here in Japan have "Regular", "High-Octane" and "Diesel". No number regarding the High Octane fuel though.
50cc Scooters usually use "Regular" fuel here.

And one more thing...

I heard there is a difference between bogging and sputtering.
What is exactly the behavior difference between the two?

[tsimi]

No one out there that can answer the questions above?

Anyway, today again I had time to test drive and this time I got more then just "drive feeling info". I tested WOT in both variations. Power take off and slowly accelerate to top speed style.

First test run; MJ #80

Max rpm that I hit was 9200-9300rpm. Speedometer needle hit max which is at least 65kph.
I held WOT for at least 1-2 min. and engine sounded good. No sign of overheating either.
And today it is really, really hot outside. around 35 Celsius.
No bogging or sputtering through out all ranges of throttle position.

Even #80 seemed to be the winner I still wanted to see if I could drive it with a #82.

Second test run; MJ #82

Max rpm reached 8900-9000. Top speed was same as with the #80. It felt that it took a bit longer to reach top speed though. Also a slight bogging when crank it WOT and doing a power take off.

What I also tested in both test runs was when running full speed and WOT I released the acceleration a bit and then cranked it again to see if it would react fast enough and pick up speed again.
With the #80 I had good quick reaction with the #82 i got terrible bogging. The engine couldn't pick up the speed again from where it was wit the #82.
Then I thought I drive home with the #82 but then out of nowhere it started to bog terribly no matter if 1/4, 1/2 or WOT. The scooter just didn't wanted to accelerate and pick up speed. So I stopped on the side of the road and put back the #80 and instantly speed was back again. No bogging at all until home.

At last the hard test, Uphill! Around where I live are just hills so I could test it and here again. #80 performed excellent. Steady increase of speed even on steep hills. #82,....just bogging.

I didn't get the power at take off that I see from your guys videos but I think that is not a jetting matter but a CVT issue which is the next step on this journey.

So I guess my winner is MJ #80 with the Snorkel still in place. Just to make sure I also drove at WOT full speed, stopped the scooter pulled the plug out to see the color and it looked nice brownish like milk chocolate. *relieved*

I don't think it is necessary to do any Needle or Pilot Jet adjustments since I had no problems in lower throttle positions.

But just as info; Pilot Jet is a #44. And the needle...well look at yourself the pics below.
I don't know how to take that apart so any help/info is appreciated.

[tsimi]

Need to put back the champagne.
Needed to go out shopping with my Scooter and on the way back home, just when I was about to drive on the hill a slow driving %&$% car sneaking at 5-7mph was in front of me and so i was forced to drive the same slow speed which was OK "until" he left and I wanted to crank it open to WOT to climb faster it started sputtering.
And once it gets into this sputtering phase it stays even down hill until i reach speeds over 30kph.

Sputtering for me means it is not dying out but more kicking and spiting.
Bogging = almost shutting down and dying out.

So what is the issue here?
Lean?
Rich?
Needle position?
Pilot Jet?

I don't have that issue when I attack the hill with more speed.

[birdman]

It sounds like a cvt tuning issue now. It seems to me you have the jetting on point or very close. I would start looking at the cvt now, it sounds like you need a stiffer torque spring and/or lighter weights. Also if it was me I would remove that snorkle now and go with the a higher mj. Let that 70cc with the performance pipe breath a little better.

[tsimi]

Jul 26, 2015 4:09:09 GMT -5 birdman said:

Also if it was me I would remove that snorkle now and go with the a higher mj. Let that 70cc with the performance pipe breath a little better.

Thanks birdman!

hmmm..., good point. More air and more fuel thus more power. Now that I know what MJ is good for stock airbox with snorkel I could give it a go without the snorkel and see how that goes. Probably No Snorkel + MJ #86 would be a good start. And then work my way down or up from there. Just need to get a new Spark Plug first.

[spaz12]

You have what appears to be the same carburetor that comes on the American Zuma's. There is a throttle mod that can be done to it if it is the newer, restricted version.
An 80 MJ is also what comes with them stock.

[Lucass2T]

I'd suggest try some different needle clip positions. Mine runs terrible with the needle at middle position while running very strong at the lowest position. When driving 1/2 throttle (with the needle clip position in the middle) for some time and then go WOT is all but sputtering. But it doesn't happen when i put the clip in the lowest position.

Some carbs or engines are really sensitive to certain adjustments.