Lost 5 mph after adding new exhaust

[stepthrutuner]

I go with 90 GT on splitting the weights up. That should give you about the right total weight. If it works good I would get six weights in the 5.5 range. Running mixed weights most likely will make the heavier ones wear faster. Also you will be running weights of different wear surface composition and quality.... one set is bound to wear differently from the other. Use a bit of powered graphite on them and on the hub slider. If any rejetting will be needed it will most likely be very small.

[supermel74]

Here's a pic of the plug....

[90GTVert]

Actually, you'd need to show us a view of the end that is inside the engine so we can see the ground strap and porcelain color etc... Kinda from the end of the threads down in that pic if you get what I'm saying.

[supermel74]

Here's another one I took, probably won't help much.

[90GTVert]

From what I can see so far it looks pretty darn lean. The view we're looking for is like that, but rotated so you're looking at the tip.

Kinda like this, but closer if you can get a clear pic... (ignore my plug, you DON'T want it to look like mine lol)

[supermel74]

Ok, I'll try and get a pic like that today. I didn't really do the test right anyways, wasn't at wot when I killed it. Is it ok to wait 15 minutes or so after shutting down the scoot to remove the plug. My exhaust header is about a centimeter away from the plug making the plug impossible to remove without getting burned unless I wait. The area is so tight I can't even get at the plug with gloves on... Not sure why they put something so important to access in such an awkward and tight spot. I have to use the plug socket by hand with a small bolt in the hole in the socket as a lever because there's no room for a ratchet.

[90GTVert]

It doesn't matter how long you wait after shutting down to check the plug. The only way you'll see anything immediately after a run that you wouldn't see if you wait is if the plug was wet, which requires an extremely rich condition at WOT that's pretty unlikely with your stock jet.

My retro styles scooters require the same "care" removing the plugs. So much easier on a large frame scoot.

[supermel74]

Cool thanks. I'll try to get it done right today if it doesn't start raining.

[supermel74]

My phone camera is pretty much useless when it comes to close up detail. Not sure if you can tell from these pics.

[supermel74]

Going on the assumption that I am running lean, does anybody have any suggestions on what size jet to get? The stock main jet is 82.5 according to the parts manual. Also, are there any upjetting tutorials for dummies anywhere online? I know absolutely zero about this stuff and I'd probably do more harm than good if I started trying to do much on my own. If I have to, I'll take it to a small engine shop or something. If I did do it that way, I'd need to get it right the first time or at least make a definite improvement. Not sure if this helps at all but here's a pic of the carb set up from the parts manual.

[90GTVert]

If you scroll through this how-to, I show how to change main jets...
49ccscoot.proboards.com/index.cgi?board=yamajog&action=display&thread=556

If your stock jet is an 82.5 you will probably need an 85 to 90 Mikuni VM11/22 main jet. It wouldn't be a bad idea to get a 95 as well to be safe.

If you wanna familiarize yourself with the carb a little more here's some stuff you can look at...
49ccscoot.proboards.com/index.cgi?board=carb&action=display&thread=363
49ccscoot.proboards.com/index.cgi?board=carb&action=display&thread=364

[supermel74]

Great info. Should keep me busy for a while. Thanks Brent.

[supermel74]

So I was expecting my jets to come in today via UPS so I remove all the plastics, floorboard, airbox, and other stuff off. I was able to get the bowl off without removing the carb from the intake even though the last screw in the back was a huge pita. Anyways, I get out of the 90 degree sun and patiently wait for the brown truck and it just races right by I got home and checked the tracking info and I get this
DAMAGE INSPECTION SCHEDULED / UPS WILL CONTACT THE SENDER AND/OR RECEIVER REGARDING THE STATUS OR DISPOSITION OF THIS PACKAGE
WTF, I've never had any problems with UPS and everything always comes on time. The one time when I really needed something that day, it goes wrong. Hopefully they deliver it tomorrow, I wanna get this thing reassembled and ride

BTW, Your tutorial helped a bunch Brent, wouldn't had a clue where to start without it.

[90GTVert]

What's that saying... "A watched pot never boils." ... something like that. Good luck.

[supermel74]

haha, that's it. I'll just have to wait and hope they get it straightened out asap. On the plus side, half the job is done so it will be less time in the baking sun when it does come.