Transformation of a Chinese scooter

[jackrides]

Capacitor discharge ignition advantges (to me) are to eliminate points and their timing changes, which don't amount to much in a thousand miles, possible electronic advance curve adjustability, possible higher discharge voltage allowing for larger spark gap (valuable in a 2T), and the validity to apply really cool stickers. Points problems are a hell of a lot easier to diagnose and fix when first firing up. I used points on a 2T racebike once for that reason.

[rollingbender]

Today, I welded a bung in the exhaust pipe for an A/F sensor





I thought that overall it was running fairly well except for that bog which has developed at WOT. According to the gauge, I’m very wrong. Figured as much… I’m not an engine tuner. It’s off-the-gauge rich at idle. Off-the-gauge lean at WOT and at cruising speed, just a little rich. I may mess with the idle screw and cruise around a bit after dark tonight. The bigger main jet is going to have to wait at least one more day due to this…

[br4inl3ss]

be sure you dont have an exhaust leak.
been there done that in the car performance world.
those can fuck up the reading either way.

[rollingbender]

Aug 23, 2023 21:50:15 GMT -5 br4inl3ss said:

be sure you dont have an exhaust leak.
been there done that in the car performance world.
those can fuck up the reading either way.

I did a pretty good job on my welding (the second time) so it’s leak-free!

Adjusted the A/F mixture at idle until I had it hovering in the high 13’s through 14’s…. Cheap sensor seems to jump around a lot. Went for a cruise. Really easy starts. Jumps off the line and cruises at 35 in the 12’s - 13’s. Slower cruising and it is too rich for the gauge. 38 to WOT is too lean for the gauge.

Even though it will be too hot to work on this tomorrow, I’m being left unsupervised for a few hours so I will brave the heat, install a larger main jet, and once I get the WOT issue resolved, I will work on the needle clip position.

[br4inl3ss]

its not about your weld, it's about those damn terrible flange.

duno what you mean by cheap sensor... but if you think bosch sensor are good, you're never been so wrong.
they are like 3% more precise, thats about it. so a bosch sensor wont fix that.
your cheap sensor will last YEARS, bosch wont last over 2 years.

i ised to be in the car performance world ( working at Turbo Expert.. we had the woeld most powerfull drag racing hyundai accent ). on over 150 install in 15 eyars, NOT a single bosch sensor lasted more than 2 year. we had so many problem with customers saying we are bad and the job was trash.... we knew it wasnt us. but we finally discovered the problem.
we started using cheap sensor ( like ultra power from rockauto and the like ), finito problemo. on over 40 other isntalls we NEVER heard of any problem anymore. there is 3 of them i personally know and they're about 10 years on the same cheap sensor.

we had basically the same story with AEM wideband gauge ( and sensor because they comes with bosch ). so when someone say "buy THIS brand they're the best" you can transform it to "buy THIS brand im a braindead fanboy and keep replacing it but i dont say it just buy it".

there is 2 type of wideband sensor. LSU 4.2 and LSU 4.9. the 4.2 was lasting a bit longer but on a overly rich condition the carbon would kill them earlier. the 4.9 handle much more carbon before dying, but die prematurely earlier.

the trick is to find a STOCK car that use a LSU 4.9 wideband sensor ( 90% of cars after 2010 ) with enought wire lengh from aftermarket brands ( the ONLY difference between honda dodge or whatever sensor is wire lenght and SOMETIME the connector but that was a very rare occurence ).

at the shop we were using honda civic wideband sensor because it was the longest we found and the same connector as the glowshift wideband kit ( we ended up selling only spartan and glowshift we were done with aem crap ). so on my truck ( 1999 dodge dakota v8 360 magnum swapped + megasquirt 2 + heavy mods including 454 pistons with 340 rods and 318 head that flow betetr than 360 head ) i used the same setup we were selling and installing. quality wideband kit from glowshift and QUALITY sensor from ultra power for a honda civic. could use one froma dodge journey, but in my head they would be the same fiat peice of crap, since dodge = fiat. and i had easier acces to the honda model ( my friend still working there had a box filled with them ).

maybe you got a bad sensor or an exhaust leak at the terrible flange, but i can tell you its not because its cheap. they are in fact better than bosch sensor. really better.
possibly the gauge itself too.
i worked with about 10 aliexpress cheap gauge and they're very good but doesnt seems to last as long as quality one ( glowshift, spartan, and others, just not aem ). my friend have one and its 8 years old. i have no experience with them myself.

about the flange, even italian scooter use this flange so its a well known problem in the 50cc 4t community. eh nope italian didnt do any better here, once again.

there seems to be 2 model of gasket. a flat one like car, and a ring. mine use the ring ( cannot use the flat one because the heads using the ring model arent flat ). does your use the ring or the flat gasket ? doesnt change much about the problem tho.

[rollingbender]

I goofed around with everything on the carburetor that can be goofed with and as soon as I’d get one circuit operating correctly a different circuit would act up.

The carb that came with the crate motor was removed and replaced with new because I assumed I had clogged up something with debris from the building process. Carb #2 was the one I did all the goofing with. Then I noticed that both of those carbs had an inactive feature. The nipple where the vacuum line from the intake manifold was not drilled and there were no parts behind the plate on either. I ordered a new PD24J carb from Amazon, crossed my fingers, and got lucky with the receipt of a full featured carb. Installed #3, set the idle speed, and everything is coming up roses on the A/F gauge. What a difference with the carb working 100%!!!

Then….

I broke the muffler mount for the third time😡. The original muffler was a ghetto rigged affair that I slapped together just so I could have a muffler and start riding when I first got the bike running and driveable. I didn’t sound terrible but it didn’t look the greatest. So… I installed a Harley Davidson muffler…. With a few modifications, of course. These Harley mufflers are about 3’ long! I needed something about 1’ long so I cut about 2’ out of the middle. To call these things a “muffler” is certainly a loose interpretation of the term. Inside the pipe is a large baffle at the output end and a large tube made of stainless steel screen which is wrapped in a fiberglass rope. I unwrapped, resized and rewrapped a section of the screen and stuffed it back inside (now we have 2 layers of screen and rope).

Then I made this dodad…



The part on the right slides into the part on the left and welded together then a flange is welded to both parts, that gets stuffed into the input side of the muffler and that all gets welded together. So here’s what happens to the loud sounds coming from the header: hot gasses and noise enter the muffler, hit a wall and are forced outward through 41 quarter in holes in the inner baffle. Next, thing hit the wall of the outer baffle and are forced back forward and the out through 40 quarter inch holes and into what’s left of the original Harley “muffler”. All that stuff bounces around in the new double screened glass-pack affair, through the original Harley output baffle and straight to your ears.




I like the way it sounds. At idle, I don’t think it’s any quieter or louder than before but it has a deeper/bigger tone. A friend of mine said it now sounds a little bit like a metric cruiser. At 35mph and beyond something unexpected happens. The stars line up in a certain order and cause the exhaust noise to go down a notch or two. Must be some sort of voodoo where the exhaust gas velocity causes the sound to get caught in my devious trap.

The bike is now officially a Hardly-David Son🤣

[rollingbender]

New exhaust must be slightly less restrictive also…




Down an incline with a brisk tail wind but 60mph is 60mph!!!

[rollingbender]

Another new muffler day!

You can see the build of my home-built muffler in the Build section called “Experiments in Sound Mitigation”.

Here’s the innards before I stuffed it all in the tube and welded it together.



And here she is after a coating of high temp paint and installed on the scooter.





It’s not as quiet as your grandma’s Buick and I won’t be able to sneak in and out at all hours but it is much quieter than either of the two previous attempts and it has a nice low tone (for a scooter).

[90GTVert]

Solid exhaust mounts often become a problem, sometimes very quickly and sometimes it takes awhile. Lots of vibes and no damping. If it turns out to be an issue, get some stainless steel and make a clamp that will bolt to the mounting location instead. Rubber that can take heat under the clamp is better still. SS clamps can still break, but they tend to work much better than solid steel mounts. Hopefully there's no tension built in (not forcing the pipe into place) and it will last a long time as-is, but if not maybe this will help.

The DIY exhaust below started with 1 steel tab that broke. Then I used 2 steel tabs which took some time to break. Then I tried aluminum clamps (like the one on the left) and one broke. Then I went to stainless (right) and it was fine after.

[rollingbender]

Sept 9, 2023 6:50:20 GMT -5 90GTVert said:

Solid exhaust mounts often become a problem, sometimes very quickly and sometimes it takes awhile. Lots of vibes and no damping. If it turns out to be an issue, get some stainless steel and make a clamp that will bolt to the mounting location instead. Rubber that can take heat under the clamp is better still. SS clamps can still break, but they tend to work much better than solid steel mounts. Hopefully there's no tension built in (not forcing the pipe into place) and it will last a long time as-is, but if not maybe this will help.

The DIY exhaust below started with 1 steel tab that broke. Then I used 2 steel tabs which took some time to break. Then I tried aluminum clamps (like the one on the left) and one broke. Then I went to stainless (right) and it was fine after.

I broke 3 mounts on the first muffler, 2 stainless straps like you have pictured and 1 aluminum mount that I made with considerably more substance.
I need to do something different and soon as the current arrangement has introduced a bone shaking vibration right at 30mph. I think my first attempt will be to leave the tab on the muffler but embiggen the mounting hole so that I can install a rubber bushing…sort of like a motor mount. That’s on the docket for tomorrow when I am left unsupervised.

[rollingbender]

Rubber isolation installed on the muffler hanger. Vibration Gone!

[rollingbender]

Hit a milestone today! 1,000 miles on the build!



The scooter riding is coming to an end here in the frozen northland. Between this build and the Vino125 I picked up this spring, I’ve logged about 2,000 miles of scooter riding!

[sinfull]

1,000 😃