Disappointment after removing the catalytic converter

[Larky]

Hey guys,
As the title states, I’m not sure I’m happy with the outcome of removing my catalytic converter off my tbr7. I feel as if I’ve lost low end torque. I increased the main jet to a 115. Also ground down the weld at the connection to the head. Looking for suggestions to get it back. I understand the answer might be to get a stock header and leave that cat alone. Let me know what you think.

[bogieboy]

might need a bigger pilot jet... more flow across the board means you may need more fuel across the board as well...

[JerryHawk250]

Originally Posted by bogieboy

might need a bigger pilot jet... more flow across the board means you may need more fuel across the board as well...

^^^What he said. ^^^ X2 Removing the cat definitely woke up my hawk.

[Larky]

Great! Thanks guys. Is there anything else I should do after the pilot jet? I’m at about 1000-1500 feet above sea level. Just to convey all info, I’ve shimmed the needle jet up one washers thickness. Maybe add a second washer?
Thanks again guys.

[2LZ]

Like previously mentioned, the pilot jet.....but if you haven't lifted the needle a notch yet, that may also help.

[kingofqueenz]

No expert...

Isn't the theory "air in ...air out"

Thought I read, the airbox mod on the Hawk does not work on the TBR

Did you mod the air in portion of the equation?

[Larky]

Originally Posted by kingofqueenz

No expert...

Isn't the theory "air in ...air out"

Thought I read, the airbox mod on the Hawk does not work on the TBR

Did you mod the air in portion of the equation?

Great question! But the answer is no. Didn’t touch the air box. I was under the impression that it wouldn’t add much power. Besides I like the air box / filter combination, especially if there was minimal-to no power gains. Although let me know guys I you felt that an air box mod was worth it.

[Rocket tests]

Removing the baffle plate from the stock muffler helped mine breath a lot better.

[Megadan]

Originally Posted by Larky

Great question! But the answer is no. Didn’t touch the air box. I was under the impression that it wouldn’t add much power. Besides I like the air box / filter combination, especially if there was minimal-to no power gains. Although let me know guys I you felt that an air box mod was worth it.

On its own modding the airbox doesn't result in much because the factory exhausts are restricting the engine enough that the gain is almost imperceptible. When done in support of an exhaust upgrade it can make a difference.

[Kenstogie]

Originally Posted by JerryHawk250

^^^What he said. ^^^ X2 Removing the cat definitely woke up my hawk.

HUGE difference for me putting on that new exhaust...

what can you do on a tbr7 ( pod?) for the air intake side.......

and how much gain?

[alex_in_az]

Originally Posted by Kenstogie

HUGE difference for me putting on that new exhaust...

what can you do on a tbr7 ( pod?) for the air intake side.......

and how much gain?

the intake side is OK on the TBR, once you've done the mods to the carb. I'm just about ready to put a PnP head on my TBR, I had to remove a lot of material from the exhaust port, there's a big lump right by the ex valve that needs to go and on the top side of the port as well. In contrast I hardly did anything to the intake port, because it looked pretty good as is. I decked it .040 as well, so my CR should be around 10.3 if my math is correct

[Megadan]

Originally Posted by alex_in_az

the intake side is OK on the TBR, once you've done the mods to the carb. I'm just about ready to put a PnP head on my TBR, I had to remove a lot of material from the exhaust port, there's a big lump right by the ex valve that needs to go and on the top side of the port as well. In contrast I hardly did anything to the intake port, because it looked pretty good as is. I decked it .040 as well, so my CR should be around 10.3 if my math is correct

Sounds like my head lol.

[Kenstogie]

Originally Posted by alex_in_az

the intake side is OK on the TBR, once you've done the mods to the carb. I'm just about ready to put a PnP head on my TBR, I had to remove a lot of material from the exhaust port, there's a big lump right by the ex valve that needs to go and on the top side of the port as well. In contrast I hardly did anything to the intake port, because it looked pretty good as is. I decked it .040 as well, so my CR should be around 10.3 if my math is correct

Originally Posted by Megadan

Sounds like my head lol.

oh no another mod..... ..you know i can't leave well enough alone.... how much difference does it make Dan?

at least the intake is probably fine... i like the idea of filtered air.....
plus....
i might be running just a touch lean now after the exhaust so more air i don't need...going to check again after another 15 miles and some different riding conditions then adjust...

[Rocket tests]

I can say that the port n' polish n' decking is well worth the time it takes. Night and day difference. The biggest drawback on mine is the starter often struggles to overcome the extra compression. I can count on needing to hit the starter button several times before it turn over without stalling the starter. Possibly could be resolved with a stronger battery.

One mod inevitably leads to the next and so on.

[Megadan]

Yes, you need a good strong battery if you increase the compression a full point, and if your battery is weak for some reason, you will find out after the first couple of turns.

That said, if you get the idle mixture and pilot jet sizing right, usually it only takes a couple of turns for the bike to start. Usually my bike will fire up right after the second revolution.

IMHO the increased compression, while it definitely adds a bit of oomph to the equation, could also be left out, or at the very least left to a small increase. Opening up the exhaust port and smoothing out the intake as myself, jerry, and obviously a few others have done, makes a big difference in how these engines perform.

Increasing the compression also leads to stronger vibrations, so be aware of that side effect too.