Can't get bike over 23MPH

[Sidewinder Jerry]

Where I am at, I could never run my tires fully inflated to 60 psi...High heat in the desert with the resulting pressure due to heat expansion and running mags that have no "give" to them.

It would ride like a Conestoga wagon at my cruising speeds and then the tires would blow up on me...lol.

My method of getting true tire diameter is sit on your bike. Have it held perpendicular to the ground. Put a level at top of the tire and get a level reading. Then measure from the bottom of the level to the ground. You'll need help to do this.

That'll be your true tire diameter. For example on a bicycle computer, they tell you to enter 2075 for 26" tires. Since my tires are actually 26.25 I enter 2095.

 

[DAMIEN1307]

It's leaking where the red is, blue is where the gasket is and it's not leaking there

It looks to me that it is oil seepage from the gasket, not a full fledged leak...I find this common enough from pics that new members show in pics and why we are always telling them to keep that jug torqued down to 144 inch pounds, (12 ft pds), at all times during the breakin period and check them periodically thereafter...It should wipe up neatly and best wiped as soon as you see it before it permanently stains the aluminum and make it look like trash...lol.

 

[Sidewinder Jerry]

It's leaking where the red is, blue is where the gasket is and it's not leaking there

Tires are both at 40 PSI. They are 100% 26 inch tires, I've replaced them before and they're 26 x 2.125

More than likely it's the GPS tracker. We've been through this a lot with riders here. This is why we tell people to get at least a decent bicycle computer. To get you're actual entry number here's the formula:

True Tire Diameter × π × 25.4 = Entry Number.

 

[rusty.western.flyer]

Pretty sure the tire pressure isn't holding back ~10mph.

Here's the Sidewinder formula:

(RPM × Wheel Diameter × π)÷(1056 × Total Reduction) = MPH.

(5100×26×π)÷(1056×4.1×(44÷10))=21.8671883329

At 5100 rpm you should be showing almost 22 mph. So either your GPS tracker is off or your tires are less than 26". My Kendra 838 tires fully inflated are 26.25". Are your tires fully inflated to max pressure?

Using your formula backwards, my GC engine sees ~8500rpm! lol. My bike has 26.25" Kenda and has gone 37mph often. No wonder it shakes and rattles at that speed.

 

[Sidewinder Jerry]

Pretty sure the tire pressure isn't holding back ~10mph.


Using your formula backwards, my GC engine sees ~8500rpm! lol. My bike has 26.25" Kenda and has gone 37mph often. No wonder it shakes and rattles at that speed.

What is your total reduction?

 

[rusty.western.flyer]

Exactly your formula. 10t engine sprocket, 44t wheel. It's a bone stock CG kit on a BBR gas frame: LINK

 

[Sidewinder Jerry]

Exactly your formula. 10t engine sprocket, 44t wheel. It's a bone stock CG kit on a BBR gas frame: LINK

With a 10\44 on 26.25" tires at 37 mph, you'd be doing at least 8548 rpm. That can certainly rattle your cage lol

 

[Emcee]

So, got starting fluid and when I sprayed behind the magneto magnet it stalled out. There was no traces of oil under the cover, but did have small traces along side the gasket. Im unsure if that's from the small like I have up above that seeped into the gasket or not. I did break 25 mph today which was nice. Aside from the leaks I'm wondering if my engine needs to be broken in more? Just a thought

 

[Nickt919]

I’ve had leaking crank seals and it not show../as in oil residue.
They’re cheap… I’d change it if it’s not too much of a problem. The magneto side seal is so thin it can be pressed in by the fingers.
What ever removal method used…be sure not to scar the crankshaft or the case surfaces. Be careful getting it out. Clean the case surface with a solvent and lubricate the INSIDE of the seal when installing. Be sure the lubricant doesn’t find its way to the outside the seal or case surface as it is installed.

If the crank does not spin true the shafts wobble instead of spinning on axis. This slight wobble contributes to a seal early demise.
Each place that an engine leaks will rob you of performance. All the leaks must be fixed before the engine can be properly tuned.

 

[weefek]

A lot seals are garbage straight from the factory. China and stuff. Replacing crank seals is pretty easy, LA Hover Bikes on youtube has a good video with regards to replacing main seals.

As to @Nickt919 's post , when you clean the outer seal surface put the cleaner on the rag/towel/whatever you're using and wipe it. do not spray any solvent or cleaner into the engine. Also yes make sure you lube the inner seal surface with 2 stroke oil or 4 stroke oil or whatever kind of oil before you install.