Why after all the upgrades I’ve done to my predator 212 does it only hit 45mph?

[Binimike1111]

My apologies for any silly questions, I’m still in the learning process of working on/modifying small engines. I have swapped the springs for 18lb springs, governor is bypassed(ARC billet rod and flywheel will be here in a couple days)
Performance air filter/re jet, straight pipe exhaust, and I believe I’ve got the valves set to the correct space.. Is it because I do not I have a billet ride and fly wheel installed that it’s not going as fast as it could be because it’s typing out at the rpm that these engines top out at? Do you suggest I slap on a torque converter? Maybe I need some larger diameter tires? Just trying to gain some knowledge in the MPH department LOL

 

[massacre]

Your answer is most likely gearing related. Once you install your billet parts, get yourself a tachometer and see what RPM your engine is turning at WOT. Then you can use that information as a baseline to adjust the gear ratio for top speed. Don’t forget that wheel/tire size is going to affect this, as well as the weight of the bike and rider.
Not sure how fast you are trying to go, but using a centrifugal clutch is always a trade off.
If you gear the bike for top speed, it will be a dog down low and from a stop. If you are only concerned about top speed, than you can keep your clutch and just accept sacrificing low end performance for the top end gain.
But if you want power down low, as well as up top then a torque converter might your best bet.
Just my two cents

 

[Lizardking]

Make sure you don't just bypass the governor. Delete it the correct way like people have advised.

Stop taking your engine to the max without the proper upgrades. Safety first!

 

[toomanytoys]

Billet rod and fly wheel are for safety only really.

What gearing and what size tire?

Did you change out the cam?

 

[jeep2003]

If you are mainly riding on pavement stick with the clutch. Change gearing for more top speed. Smaller on rear or bigger on clutch

 

[wjustice]

Making changes to your engine that result in more power wont increase speed unless it also gets you more rpm. However, as some have said, increasing power allows for lower gearing that can give more speed at a given rpm.

 

[GustoGuy]

Billet rod and fly wheel are for safety only really.

What gearing and what size tire?

Did you change out the cam?

I agree. Camshaft related since I have a resto-mod Rupp Roadster 2 with a built Predator 212cc ARC Billet rod and flywheel with 22lb valve springs. It has the stock cam and it pulls like a beast to about 35mph then after 40mph acceleration starts to go flat. Wheel size is important too. I have 12 inch wheels and on a flat roadway it will reach the low 50's actual GPS clocked at 53mph on my smartphone app. I know it is the cam because the stock cam is not set up for high rpm operations