is heat wrap a solution for more low end power?

jungalist

jungalist

Been Around the Block
hello, I own a cb 125T that has pod filters and jetted carbs, it's well tuned but when the engine is hot it feels like it has less low end power then when it's cold. valve clearances are correct etc.

would I improve the performance of my bike if i would heat-wrap my pipes?

Theoretically it should increase the flow of exhaustgasses when the engine is warm so increased flow = better performance?

anyone got some insight in this matter?
 
Try adjusting the mixture screws.
The ist 1/4 of your throttle or so comes from the pilot jet, so you may need to go up or down a size if the mixture screw doesn't help.
 
the setting of the carbs i gave out of hand to a guy who does those things for decades. these small 2cylinder engines are a bitch to get right and the mixture setting and jetting are as good as it gets. nice throttle response and no chocking when throttle wide open so... as long as it's not broken i keep my hands off that

it was only a question if it is worth it to wrap the pipes. don't know what the impact can be on a small 125 twin...

also the pipes have reductions build in inside the headers (stock pipes) does that matter in the effect heat wrap can have?
 
AlphaDogChoppers said:
Running better when cold could mean slightly rich condition.
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This.
If it's only in the lower 1/4 of your powerband turn your idle screws a bit to lean it out a bit and see what happens.
Just take note of where your guy has them set currently, you can always put them back.
If you're afraid to turn the mixture screw you'll never get it worked out.

If you like the look of wrap wrap it, but the performance difference will absolutely not be noticeable.

How does the choke work? Do you need it to start from cold?
 
SONIC. said:
If you like the look of wrap wrap it, but the performance difference will absolutely not be noticeable.
Click to expand...

What?! Might be worth 0.0005 sec in the 1/4 mile, fer fuck sake! :)
 
SONIC. said:
If it's only in the lower 1/4 of your powerband turn your idle screws a bit to lean it out a bit and see what happens.
Click to expand...

And if it seems to be 1/4 throttle to half throttle, I would lower the slide needle a tad. The needle being too high can definitely make throttle response a little sluggish.
 
Slide needle is at the prescripted height. i've messed with it before but one slip lower or higher the engine just doesn't want to run right, so that would be a step in the wrong direction.

Idle is at perfect rpm, so slide height is good as it sits right? so i turn the mixture screw 1/4 more to lean?

It's just a very sensitive engine, not what i'm used to work on yet...
 
AlphaDogChoppers said:
What?! Might be worth 0.0005 sec in the 1/4 mile, fer fuck sake! :)
Click to expand...

and yeah, that shit makes you have your food 0,0005sec earlyer at the mcdo drive thru
 
I don't know what carburetor that engine has. On some carburetors, the idle mixture is leaner when you turn the screw in. On others, it's leaner when you turn it out. As a general rule, that screw is adjusted for "best idle." You adjust it for highest idle speed. You readjust the idle speed screw as needed for correct idle speed. Sometimes you want to go 1/4 turn one way or the other from best idle mixture to obtain the best overall performance and throttle response.
 
el oh el it is a 125 twin ;D lowend power is like an oxymoron aint it?
that sucker thrives on revs, make it so, keep the clock pegged.......cool little bike by the way, carry on
 
yes indeed, it has its power from 9-12k, but at 6-7k it is a bit weaker when the engine is hot. i was just curious about that
 
thanks for the insight in wrapped exhausts by the way. I like the look but now i know i don't have to expect anything from it so maybe i'll do it someday when i've got some money laying around i can't find any use for :p

by the way, can pipewrap destroy the chrome finish of my exhausts?
 
jungalist said:
by the way, can pipewrap destroy the chrome finish of my exhausts?
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There is a good chance that more of the chrome will turn blue, because the exhaust will be hotter. Also, the wrap might hold moisture, and might accelerate rusting over time if your bike gets exposed to wet on a regular basis.
 
aight, thanks for the insight! anyway, i'm going to enjoy the nice weather of today for the first day in a long time, going to put some miles (km) on her
 
HA 6-7k isn't low end power it's midrange on the bike :)
Needle jet too rich most likely.
Clip positions might be too much. Really small washer may help with the spacing.
 
No it will not help at all. In fact by keeping more heat in the pipe it will make the piston and head hotter in this case and lose power. I recently unwrapped a set of pipes that had been wrapped for some reason by the PO and the chrome now has an interesting rust pattern that will not come off.
 
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