Jetting

[Hadaveha]

Guys I have a odd jetting situation, I went with the Amazon aftermarket exhaust on my TBR7, So I went up from a 110 to a 115 main just, and raised the needle 1 slot, Runs great everywhere but mid throttle, and seems to get worse as she warms, Any ideas where to turn now, I tried a 120 way to rich.

[Ol,fart]

How did it run before the carb changes ?

[Hadaveha]

It ran pretty close to perfect before the exhaust change, valves are within specs, E3 spark plug, She idles perfect, pulls very well just a mid range stumble that seems to get worse as the bike runs

[TominMO]

Maybe increase the pilot jet slightly?

[Thumper]

How many turns out is your pilot screw? There is a cap that you need to pry off to access the pilot screw.

Your stock carb has a two piece pilot jet. They are available from AliExpress
https://www.chinariders.net/showthread.php?t=30694
Takes a while to get one.

If you PM me I can send you one. I would need to know what you have and which one you need (presumably one size higher). Or you can get a new carb that take one piece pilot jets and rejet that one.

[Megadan]

If the issue is mid throttle it is not the pilot jet. Mid throttle, aka between 1/4 and 3/4 throttle is entirely the needle. Lower the needle back down.

[Thumper]

Originally Posted by Megadan

If the issue is mid throttle it is not the pilot jet. Mid throttle, aka between 1/4 and 3/4 throttle is entirely the needle. Lower the needle back down.

Good call Mega. I think our new 2021 TBR7 did benefit from a 38 pilot jet though. The screw was way out. But now it's at 2.5 turns and needs choke for just a half minute or so in these cool Spring mornings. I think it had a 36, so just a minor change (800feet).

[Hadaveha]

Well with the needle in the middle setting the bike runs great, but allways a bit right lots of deceleration popping, and very white plug. But runs great am I over thinking this

[Hadaveha]

The mixture screw it about 2 1/4 turns out

[Thumper]

Originally Posted by Hadaveha

Well with the needle in the middle setting the bike runs great, but allways a bit right lots of deceleration popping, and very white plug. But runs great am I over thinking this

It can take some testing to really understand what's going on. It doesn't take long to change the needle setting. Just take the time to really make observations while running it cold and lots of time at normal running temp before making any changes. Popping, or "tiny back fire" does suggest too lean.

Gentle or aggressive throttle on from mid/low rpm should just invoke torque. If you experience faltering, then it is likely a needle setting issue. If it is happy wide open, then it isn't a main jet issue.

115 main should be pretty close with aftermarket or drilled out exhaust.

[Hadaveha]

Ok I think I finally found the right combination, 115 main jet, Needle in the bottom slot That seems to be the magic spot here at sea level, Couldn’t make a speed run the Speedo just up and died out of nowhere.

[Hadaveha]

Thankyou everyone for your help