72cc Stock Setup Concerns

[Dbroogs]

I want to go with a stock setup with my 72cc cast iron malossi kit but I am concerned,
The a/f screw is exactly one full turn out and the rpms vary by almost 700 between when it is idling from cold and warm.
Will the stock setup have enough tune-ability in it for me to squeeze out 55ish or is it really not ideal.
People really shot down this idea on a previous thread and baka was the only one to say it would be fine.
Moped is in the sig(will be changing 90 to 88 main once break in is over)

Edit: Link to previous thread http://www.hondaspree.net/phpBB3/viewto ... =4&t=22315

[ped]

hi. I have a 92 jet on my stock carb, c clip down one, stock pipe, 9to1 gears, on one of my elites 50 and it goes 50 all day long 55 mph downwind.
I recommend a CHT temperature gauge. you can monitor your engine's temperature.
I get mine from graphite 9. he has them in stock.

[ped]

[Cmoped9]

How's the acceleration on that cast kit and the 9 to 1 gears? (With that other stock stuff)

[1man8scoots]

With 9.8:1s acceleration is great. 9:1 shouldn't be much worse.
Sounds like you need to clean your carbs pilot circuit out. If that much deviation you have a carb issue.
Also before you had a polini kit, now you have a malossi cast iron? I'm confused.

[Dbroogs]

I picked up the malossi from g9 when he had the sale, when did i say I had the polini? Maybe I did, i might be losing it haha

And took it for its first more than half throttle run and the temps were too high, 385 and climbing when I slowed down. I got 50.6mph but it didn't feel like WOT gave it that much more power. By C clip do you mean needle, if not I do not know what the c clip is. My WOT and 3/4 throttle were both making temps soar so I think richer on both is needed.

Edit: Ped based on my temps and what you said I might be in the same boat.

[Wheelman-111]

Greetings:

I have the near-identical setup except for substituting Polini for Malossi Iron. Without tryin' real hard, it's posted 53MPH on the Trail-Tech. My Contra spring is a + something, but I'm running 36 or 38 grams in the vario. Acceleration with 72cc on 9:1 gears is still better than stock on 12:1.

[Dbroogs]

Sounds like i should pick up some 7g rollers

Rode it in to work today `5.5 miles and got 50.8 after going WOT for 30ish seconds. Temps were 320 cruising at 3/4 throttle and 362 max. The rmps are pretty low which is probably why I am not seeing more from WOT and why you suggested the lighter weights? It just doesn't feel like WOT is giving me all it should right now. Oh and it was foggy, 94% humidity, out so it probably rain a little leaner.

[Wheelman-111]

Greetings:

Have a good selection of rollers and tune to the RPM you see as well as the thrust through your pantaloons.

High humidity, hot weather, and high altitude reduce the Oxygen content of each gulp of air, so if the fuel's the same it will be Rich, not Lean.

[Dbroogs]

wow, I think i am losing my mind
Thanks wheelman

[Dbroogs]

Will lighter weights increase my max rpm? it is currently only around 8.3k. Max temps with the 92 after WOT for like 2 miles into the wind I got 392 after coasting into my driveway. So i think i should go to a 94. If i could make the needle richer i would too seeing as cruising at 35-40 put my temps around 320.

[Wheelman-111]

Greetings:

Lighter weights absolutely will increase your variated RPM, as will a stiffer contra spring. A REALLY stiff contra will act differently however. Even with the heavier weights you'd use keeping the RPM the same, the engine is a lot more likely to "hunt"; rise in RPM will be a lot faster if you decrease the throttle. Great for cat-and-mouse chases through the twisties, but not as good for steady-state cruising. Plus the u +30% springs have been known to fracture rear pulleys. When they come apart at the welds, it ain't pretty.

You want the engine to work in its torque peak through the range where the vario operates, not the Max RPM. Once the variator fully shifts to high gear, the engine continues a steady RPM climb to its power peak, and hopefully a healthy top speed.

[1man8scoots]

Greetings:

Lighter weights absolutely will increase your variated RPM, as will a stiffer contra spring. A REALLY stiff contra will act differently however. Even with the heavier weights you'd use keeping the RPM the same, the engine is a lot more likely to "hunt"; rise in RPM will be a lot faster if you decrease the throttle. Great for cat-and-mouse chases through the twisties, but not as good for steady-state cruising. Plus the u +30% springs have been known to fracture rear pulleys. When they come apart at the welds, it ain't pretty.

You want the engine to work in its torque peak through the range where the vario operates, not the Max RPM. Once the variator fully shifts to high gear, the engine continues a steady RPM climb to its power peak, and hopefully a healthy top speed.

Well said.
92 jet and lean? You need to check for air leaks

[Dbroogs]

Yeah that was my concern. Can i rent a leak down tester? I know i can go and rent a compression tester but that will only tell me if if I potentially have a leak, not where one is.

[Dbroogs]

Stock airbox, tight on there with a good oiled filter. Not over-reving, if anything under-reving. Needle in rich position (only has 3 notches). Mainm is 92 and it did make a big difference going from 90 to 92 so maybe i should try 94 before jumping to any conclusion? And if i am correct the a/f has no bearing on WOT but i did the back it out 1/4 turn until highest rpm. And i took that little lip off the airbox that is right by the intake. So that could be giving me a bit more airflow than a regular tab knocked out airbox.

right where air enters i took out that little bit of plastic

airbox.png (142 KiB) Viewed 8791 times