carb issue? bog from stop

[str8dum]

Hey guys,

I cant seem to get my off the line snap tuned right. If it crack the throttle 1/4 or so, i can accel slowly but smoothly. Anything more than that the engine load up and bogs until i close the throttle and reopen to about 1/4.

Is this bc my pilot circuit is too rich? I am running red malossi torque spring with a 3 mm shim, 4.2g rollers on a airsal 70cc/yasuni c16/oko pwk 28 with 130/JJE 2nd clip/39 setup.


After seeing Tiba's launch video, i know theres somehting very wrong with my setup.
Any ideas?

Thanks!!

 

[adas]

Aloha, so much more comes into play here, but it has to do with not enough RPM at startoff: It can be any of the following:

1: Carb issue. Not as likely
2: Need stronger clutch springs
3: You need more revs to get into the power band of a racing pipe vs muffler. Especailly if you have a good chamber, it will "bubble" just before you hit the power range rpm. If you are in this power range at takeoff (pre power range) it will be very hard to get a fast takeoff
4: Rollers too heavy
5: Do you have a gear up kit?
6: Belt is a bit too long or your pully "boss" is too short, making your bike start off in "2nd gear".
7: if you have enough RPM at startoff, then it could be the carb, but be careful as more than likely if you lean it out it will improve but not solve the problem and then you will be running too lean.
8: One last thing....Is your Airsal stock or ported? If stock, you may have it mismatched with the Yas 16. The Yas 16 likes at least 10500 rpm to start and I don't know what your Airsal is. I understand you have to wildly port the airsal to make them work any good.

9: The list goes on and on....


10: I re-read your post again and it may be the problem that Tiba described..... In my case my OKO 21 on my Evo/Yas16 (Liquid cooled) needed a fatter needle for the carb as I was on my first clip. This leaned it out and works much better, but I may need to go leaner yet. I still am at 1050F EGT and 350F CHT. , so I am still OK for now.



But I would look at your rpm vs your power range to see if you are in it or outside of it.

frank

 

[cantdrive55]

I've got a real similar thing going on with mine and have been looking into the thicker needle. The 28OKO comes with a JJH needle but you put in a JJE which is thinner according to Keihin. Might have just made the problem worse? The JJH is 2.435mm and the JJE is 2.405mm.

I am though trying to see if some shops here in the US can get the larger needle.

I've come up with these part numbers though.

2.465mm Needle
JJL/017-181

2.485mm Needle
JJN/017-182

2.505mm Needle
JJQ/017-183

 

[str8dum]

Its not a 0-10 mph problem persay. If I am at a light at twist to WOT all i get is "braaaaaaahh" and it doesnt go. Same situation but slowly twist up to 1/4 throttle it will sputter maybe once and then go smoothly.

The motor is loading up. Since going right to WOT, does that mean that the main jet is too big?

The clutch engages at 8000 rpm, the airsal is ported and runs 12.5k to 13k rpms. i have a gear up and malossi 2000 Overrange.

I swapped from a JJH to JJE to richen the midrange bc at 1/4 throttle I was getting lean crackle. It has since been cleaned up with the richer needle. I wonder if i need a richer slide and leaner needle?

If i go much lighter on the rollers, the belt doesnt ride anywhere near the top of the vario.

It drives just fine at steady throttle and if i open the throttle slowly so its metering correctly when its steady state. But big twists of the throttle bogs the motor which can be recovered from by releasing throttle and slowly opening it again.

Thanks.

Aloha, so much more comes into play here, but it has to do with not enough RPM at startoff: It can be any of the following:

1: Carb issue. Not as likely
2: Need stronger clutch springs
3: You need more revs to get into the power band of a racing pipe vs muffler. Especailly if you have a good chamber, it will "bubble" just before you hit the power range rpm. If you are in this power range at takeoff (pre power range) it will be very hard to get a fast takeoff
4: Rollers too heavy
5: Do you have a gear up kit?
6: Belt is a bit too long or your pully "boss" is too short, making your bike start off in "2nd gear".
7: if you have enough RPM at startoff, then it could be the carb, but be careful as more than likely if you lean it out it will improve but not solve the problem and then you will be running too lean.
8: One last thing....Is your Airsal stock or ported? If stock, you may have it mismatched with the Yas 16. The Yas 16 likes at least 10500 rpm to start and I don't know what your Airsal is. I understand you have to wildly port the airsal to make them work any good.

9: The list goes on and on....


10: I re-read your post again and it may be the problem that Tiba described..... In my case my OKO 21 on my Evo/Yas16 (Liquid cooled) needed a fatter needle for the carb as I was on my first clip. This leaned it out and works much better, but I may need to go leaner yet. I still am at 1050F EGT and 350F CHT. , so I am still OK for now.



But I would look at your rpm vs your power range to see if you are in it or outside of it.

frank

 

[adas]

Aloha, if you are engaging at 8000rpm and your power range is around 12k then you need to engage higher....especially with a gear up kit. Many guys here with hi rpm kits and gear up have to start their bikes off by using their legs to get moving. This is why I like midrace as it has some power for take off starts at a more docile 8500rpm, but you loose 5 hp or so that a race setup gives you. It is a trade off. frank