MOPED ARMY

That 617220 works pretty perfect with the stock spx variator, but with a 90mm like an er3 it gets danger close to the clutch pulley. I might try shimming the hub to get the belt to drop in a little further, I think that might be my problem since the spx belt is a little wider.

Jbot, thank you and good advice, I was thinking of something similar. Ive had both experiences on my mvt pipe, that thing was glass. It cracked 4 times before I gave up on it.

I haven’t taken it on a stretch of road long enough to get out there all the way, though on the stand it goes to the end, when I shim it I may turn the moving cheek down instead depending on what the threads look like with a spacer. The stock spring is pretty whacky and gets really stiff at the end and the shorter belt has it extra preloaded. I have is set up with 10x52 so top speed probably in the mid to low 50s. Planning on running slicks and tracking this old bird, needs a lot of work still though. (edited)

EBR’s came today, clip on bars too as well as a lonely piston :( I love the cool little surprises. thanks Treats! :)))

Pics featuring the Cressidaaaa

holy shit this thread delivers, way better than expected

Thank ya will!

taking pre calc at my community college and did a project on calculating piston speed. I ran the numbers and came up with this,

11,500 RPM----2,931 Ft/Min

12,000 RPM----3,058 Ft/Min

12,500 RPM----3,186 Ft/Min

13,000 RPM----3,313 Ft/Min

13,500 RPM----3,440 Ft/Min

13,700 RPM----3,491 Ft/Min

13,750 RPM----3,504 Ft/Min

13,800 RPM----3,517 Ft/Min

13,900 RPM----3,542 Ft/Min

Mean Piston Speed (ft/min)= .166x Stroke (inch)x RPM.

I see some out there that do this all the time with their engines, however, this was my first time actually performing some of my best work on a two-stroke. So give me a break and some advice if you got any.

Based on the formula in Jennings's book, based on a ENGINE with 39mm stroke (conv. to inch. (1.53543)) I input some Rpm values and went until I found the Piston speed exceed 3,500 ft/min, (our horizontal asymptote) which was around 13,750rpm. so the exact point where the function meets our asymptote is our redline, though I didn't bother finding the exact number, I figure 13,750 is close enough. Only thing... can it even rev out that high? As you can see on the graph, the function is pretty linear, but is not a straight line, I did record all piston speeds from 1,000rpm - 14,000. Im sure that there's a math wiz out there, if you are... I need help figuring out the function of this linear function. That will be interesting to see. I found my "redline", though I'm yet to calculate my compression ratio b/c I have been working on school. Fuck pandemic's, Fuck being lame, get out and make something happen. -Mitch

Went to try and actually start riding the bike and some bad stuff came out. I found that the bike would fourstroke and detonate after like 30 seconds of running leaking oil and a littlebit of gasoline out of the baffle and balljoint like crazy. I then tried messing with the carb changing some things around and retiming 10+ times... nothin, same problem. So then I hit up my buddy Shane and we thought it might be a leak somewhere. So I then took the engine out and did a pressure test. Upon finally getting all the plugs to seal, I then sprayed my soapy water everywhere... nothin. I was hoping that there would be a leak, but there wasnt. I then checked my electrical setup with the cdi and nothin. So then I rechecked timing with the timing light and it was fine off the cold start until it warmed up. After like 30 seconds, the timing jumps around sparking everywhere and is super sporadic. Not really sure why, ive set my timing to 1.2btdc. If anyone had advice on that selettra let me know.

Sounds like some component in the CDI is bad .

On the selettra you set it for max advance so I bet it’s trying to fire after tdc. I think I have mine timed at 2.25mm