Summer Build: '96 SA50

[Dbroogs]

I am not going the heat cycle route technically on my break in. Let it warm up for a bout 2 minutes then killed it. Did that again except did a very light drive around keeping the rpms under 6k. Then let it cool then did another run. The last run had a max temp of 325 and i went third throttle one time for a bit. Throttle response seems good through idle and a third but we will see for more than that once she is broken in a bit more. I am not going to touch 3/4 throttle until i burn through my first tank.

Did another short run but got the speed up to ~25mph and the max temp jumped to 370.
Edit: This temp was without the shroud over the engine

[Dbroogs]

I am going to install the shroud and fit the new spark plug location tonight to see if the temp will go down. Spark plug looked like a nice cardboard color, maybe a little on the light side but I haven't ridden it much.

Rode it around for a bit, 20 min or so, not going over 6.2k rpm and the max temp was 268. That is with the shroud installed and i macyver-ed together a better fit for the spark plug with the old metal gasket.

I used a soldering pen to melt it into the plastic and then laid a bead of solder above it and it held it in pretty good.

sparkplugweld.png (98.81 KiB) Viewed 8425 times

After the moped was warmed up I adjusted the air/fuel screw to the highest rmp which turned out to be around 1 turn out, maybe a little more. This must mean that my pilot is lean but that could be a product of the 32:1 oil ratio I am using for break-in. I assume it will be a bit richer when I go to my usual 50:1 after break in. Needle position feels good through half throttle so far. I have only tested the main jet by going WOT for a split second and it feels great.

Went for another 20 min run this time letting the rmps hit 6.5k and kept it there. Went 42 and the max temp was 286. There was definately some * on the end of the exhaust so it must be rich, but that will be fine for this first tank of gas. Only a third tank left and I am almost ready for a bit past half throttle. It takes off a bit slower but that is fine with me.

[Dbroogs]

So i was running it a bit today and i went WOT for a few seconds but it didn't seem to be generating that much more power. Is this an effect of my rich main jet? I pulled the spark plug and it look decent but did have some gas/oil on the threads. What do you guys think, should I go down to 88 or keep it at 90 main with a little over 1 turn out for the a/f screw.
Also, cold idle and warm idle has a difference of around 700rpm on my scoot! She doesn't like to idle cold at all.

[Cmoped9]

How's this coming along? Anymore updates or anymore tuning?

[Ben L.]

I'm currently breaking in my Malossi Cast kit also. The #88 jet was too small with stock carb/exhaust. Tonight I went to a #92, it seems a bit rich but has been staying cooler. Max temp 364. Plug is a dark cardboard color.

[Ben L.]

So i was running it a bit today and i went WOT for a few seconds but it didn't seem to be generating that much more power. Is this an effect of my rich main jet? I pulled the spark plug and it look decent but did have some gas/oil on the threads. What do you guys think, should I go down to 88 or keep it at 90 main with a little over 1 turn out for the a/f screw.
Also, cold idle and warm idle has a difference of around 700rpm on my scoot! She doesn't like to idle cold at all.

Really sounds like an air leak. Take all the guards off and spray it down really good with carb clean while it idles cold. Take the variator cover off. Any crank play? Spray some carb cleaner at that seal.

[Dbroogs]

I am pretty sure it is a small airleak that is opened up at higher temps. At idle I couldn't find a leak with the carb cleaner. The temps really take off around 250 so I am pretty sure thats when the leak opens up. I just took it apart and am cleaning everything and putting it back together this week in the hopes of curing the leak. The piston had some deposits on the head already so I was definitely running rich.

[Dbroogs]

So I am back with a great running moped. Max temps are like 370 going up a hill after a long wot run so its doing fine. However, my max speed took a hit from when i was running red hot. I am guessing that is because it was super lean but my max speed before was 57 and now i am lucky to hit 51.

[Dbroogs]

57 was with 9g weights and less than 150 miles on the bore. Maybe it was leaning out and gaining power? I will put the tach back on it today and check the rest of the week. I live by a 3 mile straight level stretch of highway so its ideal for max speed runs

Edit: Just hit 55 today with 3 6gs and 3 9gs. Vary noticeable when the 6g rollers finally push the belt to the top. At like 32ish the rpms drop quite considerably.

[Wheelman-111]

Greetings:

Either a much stiffer Contra spring or go way down on roller weight. Like 30 grams total. A big spread in weights like 6es and 9s tends to run weird. As Graphie said, the juice is all at 8K or more.

[Dbroogs]

I will put the tach on and tune with what i got first. If i don't like it then i will buy 7g rollers and then maybe get into clutch tuning. Next summer will be the heavy tuning probably.

[Dbroogs]

Put the tach on and got 7900 rpm during acceleration. Drops to 6200 at like 35 or 40 then climbs back up to 7900 at top speed.

What do you guys think? this is with 4x6g and 2x9g

[Wheelman-111]

Greetings:

It sounds like your engine's best power is produced at around 8 K. The weights/spring combo are forcing an upshift too soon, it' not even in the ballpark.. Lose the 9s and see. 36g.

[curtis966]

9g rollers are to heavy even when mixed. And you always want to mix evenly when mixing rollers 3 and 3. Throw all 6s in and she will be hitting 8.5-9k and be a beast.

[Dbroogs]

Well the next summer moped season has arrived and the scoot ran like a champ all year. I am going to tune the transmission now seeing as the engine is running so well.

Because I do so much city driving I am thinking the polini blue clutch springs will be a bit much. I might just buy the malossi kit off of G9's site.

Thinking of throwing in a stiffer contra spring and then retuning the variator as well. Pretty sure i have 7g rollers in right now.

Should be fun and will let you guys know how tuning goes. Oh and if anyone who has a stock setup with a bbk wants to chime in on their transmission tuning I am all ears.