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Post by rcq92130 on Sept 11, 2014 10:11:31 GMT -5
Thanks, GEH & Moat, for hanging in there with me. Pretty frustrating. Ordered a new coil last night (and a new - larger - carb also ..... straw grasping here). Photo of the plug I removed yesterday - way more dirty than I have seen before.  |
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Post by rcq92130 on Sept 10, 2014 17:33:57 GMT -5
Here is today's (non) progress:
1. Tried a different CDI. No change
2. Tried another spark plug. No change
3. Tried an electric fuel pump. No change
4. Tried a 105 main. No change (previously tried 115 - back in now - & a 120)
5. Attempted to get a strobe timing check, but the timing light wouldn't fire. Checked it on my Goldwing and it worked OK. Maybe the voltage in the scooter isn't high enough of the inductive pickup ...
6. Checked vacuum with the electric pump, not the vacuum fuel pump --- still at 10 in mg
7. Tried the 28 pilot jet. No change.
8. Put a gun in my mouth. No change.
Recap: this started after installing a BBK. Drove 20 miles with everything fine -- great, really -- and then suddenly heard a stumble that, within a mile, became so bad I didn't know if i could get back home. Pulled the head and found i had bent the intake valve during installation (stupid mistake; didn't relieve the tensioner & the rocker arm pushed against the side of the valve as I torqued down the head nuts. Got replacement SS valves, installed, scooter still stumbles.
Wondering: I did NOT use lapping compound to seat the replacement valve, thinking with only 20 miles on the head it would be OK. Maybe the valve isn't seating fully?
Maybe should put the old OEM 150cc cylinder head on and see if anything changes. but would it fit on top of a 60mm piston and jug? Or would the valves hit the piston?
TOTALLY grasping at straws at this point ..........
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Post by rcq92130 on Sept 9, 2014 19:47:23 GMT -5
More frustrated than I can tell you.
You must be just sick to death of me too.
Yeah - before seeing your (and Moat's) suggestion I thought ... maybe the CDI. Have the original one; swapped it in, no improvement.
Never messed with the flywheel, and the magnet is intact. I have a timing light. Anyone know where the strobe should light the flywheel?
Yanked off a fairing section (in anger - hopefully can eventually get it back on!) and was able to do a compression test. Got between 130 & 140 , average about 135 (throttle open). I do not know if this is acceptable -- seems low given i now have a supposed "high compression piston" in there. But I don't know.
Maybe just buy another carb.
Wish I had more hair so i could pull out my hair.
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Post by rcq92130 on Sept 9, 2014 15:58:42 GMT -5
OK - what I did was to discommect the air intake pipe (from the Uni to the carb) ... just because the Uni is sticky. That way i could hold my fingers over the air inlet of the carb and vary how much I close off.
nothing i did made it any better. Fingers got wet with fuel.
Any chance this is too RICH, and i should go back to a 115 jet?
And, remember - this all started suddenly .... new BBK, was riding hills to break in, everything perfect for 20 miles, than out of the blue noticed a stumble, then within the next mile it got so bad i was not sure i could get home.
ps: was speaking about the gasket between the intake manifold and the head - making sure no leak there.
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Post by rcq92130 on Sept 9, 2014 15:45:12 GMT -5
Will try closing off some of the UNI surface.
Checked the diaphragm for obvious tears, etc and saw none. It's pretty new (800 miles), but never know. No kinks during assembly. Might be leaking under the center washer that holds it in place, but don't know how to check that.
Yesterday made sure there was no leak under the manifold (new gasket plus silicone, which should hold up at least for a while) .. so that's ruled out.
If after taping off some of the Uni no improvement, should i go up to a 125 main or a 28 pilot? Idling now is nice and smooth.
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Post by rcq92130 on Sept 9, 2014 15:20:15 GMT -5
Yes. Two vac lines off the manifold - 1 to the gas pump, the other to the carb
Reversed the cover; no difference.
Just hooked up a vac gauge - running 10 in at idle (very low for normal gas engines). Goes down normally when throttle is opened, up normally (to, maybe, 15) when throttle is let go. Checked a few weeks ago and got 13 or 14 (18 is typical of larger engines. Don't know if that's relevant.
Have 2 compression testers; one has too big a threaded fitting, the other is "press and hold", but it's way too long to fit into the compartment w/o removing all the fairings.
Pretty lost at this point.
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Post by rcq92130 on Sept 9, 2014 15:08:14 GMT -5
If by "pumper" you mean a "squirter" when the throttle is opened - I do NOT have that.
Will go fix the cover and see if it makes any difference.
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Post by rcq92130 on Sept 9, 2014 15:04:50 GMT -5
Don't know where to go from here with the horrible performance.
Drop down to a smaller jet?? Bigger main?
Arggggggggggggggg !!!!!!!!!!!!!!!
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Post by rcq92130 on Sept 9, 2014 14:56:00 GMT -5
Carb is on, adjusted. I DO have a small change in RPM with changes in the idle mixture screw (but no more than 150 rpm or so).
No real improvement. Best I could get was about 2 turns out. Still bad hesitation and popping on closed throttle. Here is a video - for some reason it didn't pick up the popping much, but you can easily see the really bad hesitation/stuttering upon quick throttle. RPMs here about 2K
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Post by rcq92130 on Sept 9, 2014 13:56:52 GMT -5
Sorry - 1 more quick question.
I don't need the fuel enricher (though i WOULD like a manual throttle adjustment - choke - if you know of one) because there is no cold weather where i live.
So - I cute a small piece of gasket material to put between the auto "choke" body and the carb body, sealing off the 3 holes.
Is that OK?
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Post by rcq92130 on Sept 9, 2014 13:49:17 GMT -5
How cool is THAT!!!!!
Thanks!
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Post by rcq92130 on Sept 9, 2014 12:10:40 GMT -5
Anyone know what the correct float height is on these (24mm) carbs?
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Post by rcq92130 on Sept 8, 2014 21:19:09 GMT -5
Just a thought - might want to try with the old cam (since that's easy). Will eliminate one variable.
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Post by rcq92130 on Sept 8, 2014 21:14:58 GMT -5
Harbor freight - couple of AAA cells should do the trick.  |
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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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