Increase intake length on 2/stroke

[Deleted member 12676]

If there's no air leak between the carb and engine or at the crank seals then you just need to jet the carb richer. Raise the needle. It's not unexpected that a mod like this would require rejetting, especially if it was off to begin with.

 

[geebt48cc]

Yeah, Jag I'll tell you more after tomorrow. I believe your right about raising the needle one more slot. Jag, see, I've milled/ported/expansion and now intake length on carb. I'm sure that this might just make it run leaner? I pulled plug after a few miles, and it's tan in color, but alittle to light tan for me. So, I'll pull needle up another slot.

PS: I'm very interested in your ignition also?!~

 

[Deleted member 12676]

From a research paper I also recently found out that increasing the stock pipes length (from piston at exhaust port to muffler) to a total of 25" to 30" can give a boost at low revs. I just tested 30" and gained 13% speed going uphill at around 3600rpm. But it lost speed at higher revs. The graphs show that 25" would gain at both low and high revs. I'll cut off 5" and try it again tomorrow.

 

[geebt48cc]

Well, I got my extension on intake done. Works well! I weigh right at 255, but can take the hills here in SW VA. right about 4-7mph better. So, if you see me, you better look fast.............(Cause I'll be gone!~)

Glen

 

[Deleted member 12676]

There's also the option of using the offset intake manifold which will make the intake length 5+3/4". Adding one inch more with tubing will put the engine in the ballpark of the ideal 6.5-8.5" length.

 

[goodtime65]

Hey there,

66cc Slant is doing everything well, but after I increased the intake length to 9" it lost some of the bottom end torque? (just the opposite of why I did it to begin with?) I've sealed everything on new intake with JBWELD because I new that this would be a one time only fix.

Well, its still a bit slower starting out, but then pretty much runs the same (bit less torque) than it did before I lengthened intake from stock to 9"? Main problem is when I pull in clutch handle it wants to rev up to very high RPMs? If I nurse throttle slowly, it will idle fine.

Checking plug after 10/mile run, and its a clean tan burn. I'm confused because if there was a air leak causing revving, then I wouldn't think plug wouldn't look such a good tan (chocolate color) after 10/mile run?

.............PS: I would be introuble if I didn't have the kill switch when it starts revving so high at idle?

Any other ideas?

Thanks very...............Glen

high reving and than slowly coming down is a for sure sign of an airleak