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Post by rcq92130 on Sept 7, 2014 19:30:37 GMT -5
Thanks again, Alley. I really enjoy learning what is what with these things and appreciate you taking the time to explain (beyond simply diagnosing and telling what to do).
Will have more info tomorrow!
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Post by alleyoop on Sept 7, 2014 19:51:48 GMT -5
Hope they have the #35 you will notice a difference. We will get that thing smoking  Alleyoop You can also do a temp but I would not bother really that 32 is just to small. But if you have to order it and it will take some time, what you can do is tape off some of the UNI. Start at the end and tape off about 1 inch all around and try it if still to much air add another strip of tape etc.. |
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Post by rcq92130 on Sept 8, 2014 11:48:37 GMT -5
Well, with the 120 main jet the scooter still BADLY stutters and falters on acceleration. With only slight throttle it's OK; any more and it is pretty lousy.
But I'll go find an idle jet and get that resolved first, then see what else needs to be done.
Thanks again for helping with this ..........
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Post by alleyoop on Sept 8, 2014 13:36:06 GMT -5
Well, with the 120 main jet the scooter still BADLY stutters and falters on acceleration. With only slight throttle it's OK; any more and it is pretty lousy. But I'll go find an idle jet and get that resolved first, then see what else needs to be done. Thanks again for helping with this .......... Have to remember the MAIN JET does not come on until your up on speed and rpms( about the last 3/4 of the throttle). That stuttering and bogging is caused by the Pilot Jet not by the Main Jet right now. Once you get the low and mid-range fixed with enough fuel to get to the main jet part of the throttle you will then know if the 120 is good or not, that is around 40+ mph. |
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Post by rcq92130 on Sept 8, 2014 15:44:53 GMT -5
Just got a 35 and a 38 pilot jet. One thing --- Alba racing said mine was "not really a Kehein style" jet ... theirs protruded down into the bowl about 3/8 inch more than my OEM jet. I'm thinking that is OK, since the pilot jet was recessed into it's hole about that much. The orifice side seems identical - it's only the slotted end that is longer. That sound OK or not? Also - should i just go to the 38, or try the 35?  |
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Post by alleyoop on Sept 8, 2014 15:56:34 GMT -5
#35 should be good that is a lot of fuel from a #32.
Alleyoop
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Post by rcq92130 on Sept 8, 2014 17:12:15 GMT -5
OK, have the 35 pilot in and it makes a HUGE difference at idle. Now have it idling nice and smooth at 1,500 (didn't try lower; don't care if it's lower or not).
Tried to adjust idle mixture ... not clear what is correct. I'm used to adjusting OUT until RPMs start to drop, then back in 1/8 turn. But engine speed never seems to drop. So, not clear where to leave the screw.
CURRENT PERFORMANCE (other than idle):
Acceleration: Still have really poor acceleration. Bucking and surging, unless I use VERY slight throttle increases. Difficulty getting speed above 45 or so.
Deceleration: Now have a very frequent popping (backfiring?) out the exhaust on coast. If I go downhill with closed throttle the popping isn't continuous,. but damned near.
Thought of trying to do an audio recording for you, but don't know how to post and AND not sure it would tell much (on acceleration) since the bucking does not make much of an audio difference - mostly feel - and RPMs don't drop (or they drop and then are restored too quickly for my tach to register).
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Post by alleyoop on Sept 8, 2014 17:24:57 GMT -5
How many turns is the Fuel Mixture out?
Idle should be 1500-1800 on the 50s and150s, 1800-2000 on the 250s, so it is ok to raise the idle a little.
Also Popping and Backfiring are two different things, Popping on De-cel little Lean on the Fuel Ratio Mixture or you have a Leak on the ACV valve Vacuum hose or the 1500 idle is to low and the butterfly cutting to much fuel, mine idles at 1600-1650.
Backfiring you have a bad AIR LEAK.
Did you follow the procedure on how to adjust the carb?
If it is surging still you should see the rpm gauge bounce. You can take a Video and use Youtube then copy the link and post it.
Alleyoop
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Post by alleyoop on Sept 8, 2014 18:28:07 GMT -5
You always test on the center stand first by giving the throttle a quick twist to see if there is not a problem before you jump on it for a test ride. If it revs up good no bogging or hesitation and comes down to idle nice and quick then you can test ride it. Alleyoop Did you follow this procedure to adjust the carb? itistheride.boards.net/thread/12/4ts-carb-tuning |
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Post by rcq92130 on Sept 8, 2014 19:06:00 GMT -5
OK - have some things to report and a video of the (bad) performance I still have.
1. Thought I might have a bad air leak at the engine/manifold joint. Saw their was no gasket under the (?) heat or vibration spacer between the manifold and engine. So I added one. Also saw the o-ring on the bottom of the manifold looked TERRIBLE! Got all excited thinking maybe I had found the problem. Didn't have the right sized o-ring so I siliconed (hi temp copper silicone) the bottom of the manifold, and also both sides of the gasket under the manifold. I know this stuff is not great in a fuel environment, but at least it will be OK to test and see if I've ID'ed the problem. So now I'm pretty confident there is no air leak there.
2. Went back and readjusted the idle as follows:
- screw out 1-1/2 turns. Idle ~1800. Sputtering/hesitation on accel; popping/backfiring thru exhaust on decel.
- screw out 1/4 turn more. no change
- screw out 1/4 turn more. Idle maybe slightly higher. bad hesitation; pauses at high RPMs before dropping
- screw out 1/4 turn more. no change
- screw out 1/4 turn more. Slight RPM drop maybe. Very bad hesitation. Popping / backfiring.
turned screw in 1/2 turn.
3. Still have very bad hesitation / stumbling as throttle is quickly opened. Still have popping or backfiring out the exhaust. Took and published a youtube video, though it's very hard to capture what is going on. I think on a few of the more extreme "hesitations" you can hear or see how the engine is not responding properly. Tried 3 times to get a decent video; this is the best of the lot. Maybe if I just placed the camera on the ground near the exhaust?
Anyway, here is the video:
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Post by rcq92130 on Sept 8, 2014 19:39:05 GMT -5
Just read your tuning tutorial. Maybe I need to strip the carb and clean it. Seems odd after total of 800 miles on this scooter ... but maybe something clogged the carb last ride and that's why it suddenly went bad.
Is there a tutorial on carb cleaning?
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Post by alleyoop on Sept 8, 2014 20:20:52 GMT -5
That sucker is STILL TO LEAN bogging and also notice how the RPMS do not drop quickly they slowly come down, it needs more fuel.
What size carb is on there?
Now when you turn the fuel ratio screw in EITHER DIRECTION does it change the RPMS up or DOWN if not the PILOT JET passage and or tiny holes by the butterfly are probably clogged. But I thought you got a new carb?
Also try this turn the fuel ratio screw clockwise 1/4 at a time and see if it kills the motor. It should kill the motor about 1 turn left before closed.
Alleyoop
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Post by alleyoop on Sept 8, 2014 20:29:00 GMT -5
You can also for testing cover some of the UNI up with some tape to cut some air off. To clean out the carb, get a spray can of carb cleaner they come with a long thin straw. Stick it in the holes of the jets and spray. Alleyoop   |
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Post by rcq92130 on Sept 8, 2014 20:46:35 GMT -5
If I turn the screw almost all the way in (maybe within 1/2 turn of closed or so the engine DOES die. But, starting with the needle 2 turns out, there is very little RPM change. Up to 1 turn in no big change. 1 or 2 more turns out no big change.
I only have the analog tach installed, so can't give a real accurate RPM reading, but within 100 RPM or so (what I can see on the analog tach) there is very little change.
I'll pull the carb and clean it tomorrow. BTW - it's not "new" - came with the scooter, which now has about 800 miles on it. To my knowledge, it's a 24mm.
Was thinking of getting a 30mm carb since i now have a bit more engine (163cc instead of stock 150cc), a bit more cam and a bit more compression.
Should I?
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Post by geh3333 on Sept 8, 2014 21:37:21 GMT -5
If I turn the screw almost all the way in (maybe within 1/2 turn of closed or so the engine DOES die. But, starting with the needle 2 turns out, there is very little RPM change. Up to 1 turn in no big change. 1 or 2 more turns out no big change. I only have the analog tach installed, so can't give a real accurate RPM reading, but within 100 RPM or so (what I can see on the analog tach) there is very little change. I'll pull the carb and clean it tomorrow. BTW - it's not "new" - came with the scooter, which now has about 800 miles on it. To my knowledge, it's a 24mm. Was thinking of getting a 30mm carb since i now have a bit more engine (163cc instead of stock 150cc), a bit more cam and a bit more compression. Should I? How's it going, im helpin someone out right now with his 30mm setup . I sent him the uni setup " that setup lets in a ton of air " and he is having the same prob as you . He was using a 35 pilot which is to small and a 122 main . He has the accelerator pump and it revs fine until after the pump sprays after about an 1/8 turn or so . And it pops and hesitates " Boggs" I advised him to go to a 39 pilot and see how it runs . He may have to up the main jet also " time will tell" he has the 61mm engine . You will not be disappointed with a 30 mm carb . His plug was blackish but it's sometimes hard to go by the plug when u have an accelerator pump . |
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..BAD TO THE BONE..
