Power loss in my Phantom HS Kit?

[Mr. Minecraft]

Ok so I have a Felt with a HS engine and Phantom Bikes Exhaust. My dad has a completely stock felt with an HS engine and regular exhaust. It seems that when i ride his, it has alot more power than mine. Could the Phantom Bikes exhaust be the culprit of this?

 

[NunyaBidness]

Try swapping the exhausts and see for yourself? Seems like that should answer that question for you. Other than that I'm not really sure what to tell you.

 

[MotorBicycleRacing]

My dad has a completely stock felt with an HS engine and regular exhaust.

I like the idea of swapping the exhausts.

What do you call the regular exhaust?
The box muffler or the one that looks kind of like a 2 stroke exhaust?

Both of those regular exhausts are pretty restrictive and don't perform well.

Another thing is to check your valve clearances as that can make a loss in
power if they are off.

 

[maurtis]

Maybe an issue between a motor that has been broken in and a fairly new motor?

 

[The_Aleman]

Definitely check the valve clearances. I recommend setting them to .004" intake, .006" exhaust.

A little bit goes a long ways on the valve adjustment. If they are .012" or more, you are missing out on a significant amount of performance.

 

[Mr. Minecraft]

Alright, so i swapped exhausts. No difference. I will move on to the valve clearances. I am completely new to 4 strokes, but i learn fast. Can i have some help (please) on what i need to adjust valves and HOW to adjust valves?

 

[The_Aleman]

Tools you need to do the job:

Feeler gauge set with .004" (0.1MM) and .006" (0.15MM) blades. If you don't have one, this is a great set that I use.
8MM or 5/16" wrench, small flathead/slotted screwdriver
Recommended: 5/8" spark plug socket, ratchet for that socket, and a straw. Coffee straw, drinking straw, doesn't matter.

Your engine must be "cold" for this procedure. I set my valves after my engine has sat overnight.

1a) Remove the 4 bolts on valve cover with the 8MM or 5/16" wrench. Carefully lift the valve cover off the engine. The objective is to not stress the valve cover gasket.
If the gasket sticks to the engine, that's okay, just leave it there.

1b) Recommended: Carefully remove spark plug boot and then remove the spark plug with the 5/8" spark plug socket.

2) Now you have to find TDC on the compression stroke. If you're not familiar with each stroke on a 4-stroke, I've attached an image that should help. Take a good look at the valves while slowly pulling on the pullstart a few times. You need to adjust the valves when both valves are fully closed, and this only happens at Top Dead Center of the compression stroke. The valves are closed for the longest amount of time between the start of the 2nd stroke and the start of the 4th. Insert the straw into the spark plug hole and find TDC. The straw will be at it's highest point and there should be play in both valve rockers. If there's no play, they are set too tight.

3) On each valve rocker there is a slotted stud with a nut on it. Loosen the nut on each rocker with the 8MM wrench. The rocker closest to the exhaust is the exhaust valve (set to .006"), and the rocker closest to the carb is the intake valve (set to .004"). Use the feeler gauge and the screwdriver on the stud (loosen the nut as needed) to set the clearances. A proper setting is when you feel a light drag of the blade as you pull it through the space between rocker and valve stem. When you have the clearance you need, hold the stud's position with the screwdriver and tighten the nut about wrist-tight. Repeat for other valve.

4) Put the plug back in and the valve cover back on. Don't overtighten the valve cover bolts, they only need to be snug, about halfway between thumb-tight and wrist-tight.

Now take her for a good ride!

 

[silverbear]

Aleman,
That was a good descriptive how to. It should be a sticky.
SB

 

[Velodrome]

I agree with Silverbear STICKY. I was going to be searching for exactly this in a day or so before final mounting of my HS in the Felt Twin. Thanks! Couldnt be more clear.

 

[azbill]

very good explanation, Thanks !!!
agreed, it SHOULD be a sticky

 

[MotorBicycleRacing]

Alright, so i swapped exhausts. No difference. I will move on to the valve clearances. I am completely new to 4 strokes, but i learn fast. Can i have some help (please) on what i need to adjust valves and HOW to adjust valves?

Great tutorial!

Your valves may not need adjusting so measure the clearances before you start loosening the nuts.

 

[wayne z]

Your dad's bike has the same engine, does it have the same drive ratio too? Your post's title sez "power loss", but your post says nothing about it's performance being good then changing.
So, if the drive ratios are different, you can also expect performance to differ also.

 

[Mr. Minecraft]

Both our bikes have the 4:1 transmission, and both have the same sprockets. His just feels like it has a lot more torque.

Tools you need to do the job:

Feeler gauge set with .004" (0.1MM) and .006" (0.15MM) blades. If you don't have one, this is a great set that I use.
8MM wrench, small flathead/slotted screwdriver
Recommended: 5/8" spark plug socket, ratchet for that socket, and a straw. Coffee straw, drinking straw, doesn't matter.

Your engine must be "cold" for this procedure. I set my valves after my engine has sat overnight.

1a) Remove the 4 bolts on valve cover with the 8MM wrench. Carefully lift the valve cover off the engine. The objective is to not stress the valve cover gasket.
If the gasket sticks to the engine, that's okay, just leave it there.

1b) Recommended: Carefully remove spark plug boot and then remove the spark plug with the 5/8" spark plug socket.

2) Now you have to find TDC on the compression stroke. If you're not familiar with each stroke on a 4-stroke, I've attached an image that should help. Take a good look at the valves while slowly pulling on the pullstart a few times. You need to adjust the valves when both valves are fully closed, and this only happens at Top Dead Center of the compression stroke. The valves are closed for the longest amount of time between the start of the 2nd stroke and the start of the 4th. Insert the straw into the spark plug hole and find TDC. The straw will be at it's highest point and there should be play in both valve rockers. If there's no play, they are set too tight.

3) On each valve rocker there is a slotted stud with a nut on it. Loosen the nut on each rocker with the 8MM wrench. The rocker closest to the exhaust is the exhaust valve, and the rocker closest to the carb is the intake valve. Use the feeler gauge and the screwdriver on the stud (loosen the nut as needed) to set the clearances. A proper setting is when you feel a light drag of the blade as you pull it through the space between rocker and valve stem. When you have the clearance you need, hold the stud's position with the screwdriver and tighten the nut about wrist-tight. Repeat for other valve.

4) Put the plug back in and the valve cover back on. Don't overtighten the valve cover bolts, they only need to be snug, about halfway between thumb-tight and wrist-tight.

Now take her for a good ride!

PLEASE someone make that a sticky! That was an EXCELLENT post and i will never forget how to adjust valves.

 

[wayne z]

How about tire pressure? Extremes in tire pressure have a big effect on the performance of these little engines.

 

[Mr. Minecraft]

My tire pressures:

Front: 52

Back: 47

 

[wayne z]

Does his engine have a lot more time on it than yours? Maybe your rings aren't seated as well as his yet.

Were they broken in by the same person or different persons? Were they broken in under the same conditions and methods? A hard break-in versus an easy break-in can make a big difference in performance.

 

[Mr. Minecraft]

My bike is much more broken in. I basically put the engine on it and rode it like ****. Same for my dads bike. The only reason i think mine is more broken in is because i ride it alot more.

 

[Velodrome]

Well... I'm very glad I did that. Bought a feeler guage at Ace for <$4 and got an apropriatly sized ( small ) screwdriver and went at it. I could no way no how get the smallest shim between either intake or exhaust valves! They were BOTH WAY too tight! Gottem locked down now though! 0.004 intake 0.006 Extake

 

[The_Aleman]

I'm glad my little procedure write-up helped out more than just the OP. I've tagged this thread with "huasheng valve adjustment" so it should be easy to find in Google Search when it's needed. Velodrome's picture is welcome, I just adjusted my valves 2 weeks ago and didn't feel like pulling my valve cover off again to take a picture

From my observations having a Huasheng the last 2 years, the valve adjustment affects performance quite significantly. Too tight is just as bad as too loose!
.004/.006" seems to be the sweet spot. I've adjusted my valves about 5 or 6 times in the last year, just before every oil change warmup.

 

[Velodrome]

Cant wait for the OP's report back on his problem and results of the adjustment. Aleman: In your repeted adjustments do they have a tendency to change significantly?

 

[The_Aleman]

Some "loosening" is normal on any engine with non-hydraulic lifters. On aircooled Volkswagens, for example, it was recommended to check/adjust the valves every 3-6 months. I had a '69 Bug for a few years and checked the valves every oil change. Often I had to readjust them.

2 months after the first time I adjusted my HS valves (.008/.012), the valves had changed to .010/.018.
Not as loose as they were from the factory (.012/.024 or so)! They will change over time as the engine wears.