Hello,
I have been trying to find were my power went to for some time now.
When it was done, it was about the same as Chucks bike in power. 63HP on the dyno. When I rode Chucks bike at the gap, I knew I was not just dreaming, it is for sure down on power.
The bike starts no issues, revs cleanly. It just is way down on power especially one it hits the power band.
Just before the gap this year, I noticed a ripped intake manifold. I was able to get a replacement and it was on for the event.
Still down on power.
Chuck checked the following:
Timing- he said it can use some more but ok
jetting including air jets. we went through many combinations none made a difference you could tell.
removed the heads to check pistons. heads were perfect no carbon. piston tops looked great. you could still see the hash marks on the cylinder walls.
I changed to a non 0-ring chain but nothing.
When I got home I rented economy cycles leak down checker. It would not hold even 1 PSI, found the crossover was leaking. Fixed that and no leaks but no more power.
I am out of ideas. Do you guys have any? I miss my bike...
Thanks
Paul
check compression.
Thank you Mark.
I will do this today when I get home.
I did but it was with the plugs in the exhaust during leak test. I am sure that was not correct.
Paul
hold throttle wide open, kick it until the needle stops moving up.
i wonder if it was jetted to compensate for an air leak, now that its fixed is running rich? :huh:
could be. It currently had the jets back in it when it had the power. I have no idea how long that manifold was ripped. Very well could have caused damage to the piston. I know the side with the torn manifolds plug was and still is much blacker that the other side. Even when Chuck was messing with the jetting.
i had a set of urethane intakes tear once, 2016 or so, luckily i saw it before i had run it for any length of time. just aged out and heavy carbs bouncing around. compression test should tell you where to look.
After putting new pistons in my bike, I have been messing with the carbs this week. It is important to get the needle set right. With the clip set one notch too rich, it accelerates flat and slower than it should, and doesn't really want to pull up to top rpm. With the needle set one notch too lean, it will have a gasp when it comes off the pilot circuit if the throttle is snapped open, and you can feel the weak power at 1/4 to 1/2 throttle. I was surprised how this was easy to feel while test riding. I would try leaning the needle position and see if it comes back to life.
compression is the biggest factor in power loss when everything else is good.
I have not checked yet, I have my 4 year old granddaughter this week unknown until Monday.
I am going to have her help me do it today. She LOVES helping.
I am honestly hoping to find low compression. That would be great to at know what the issue is and a rather easy fix.
150 on the side that did not have the ripped manifold
143 in the side that was ripped.
This is on my cheep auto zone compression tester.
But not that different and seems high to me.
Thoughts?
seems ok to me. :huh:
Yea thought so. Thanks
I'm hoping you find the issue Paul. Good positive thoughts sent your way for a quick find of the issue with resolution. :thumbs:
make sure allt he jets and shit are tight in the carb. etc.
Thanks Evens. I have been trying to fix this for about 8 months.
Mark,
thanks. we removed every jet including the air jets while trying to change it at the gap. also made sure all passages were clean.
Several months ago I found the plug wire on the left side was hanging on by a thread to the coil. I cut it and put it back (checked today still solid).
we replaced the plug wire caps on the 2 sides
cleaned the airlifters
changed the battery
verified timing
removed heads to check pistons
did a lead down test
brakes to not drag/wheels spin free
new non 0-ring chain
now the compression test
I was thinking coils are week making for week spark but from what I understand they work or they don't work.
Again, it is not that the bike runs bad, it just has noticeable less power. no power wheelies in 1-2 like before.
thanks for all the input. I am sure it will be something stupid when I find it like a bad ground or loose wire.
how do the plugs look on a chop?
mechanically, if everything looks good, and checks out, it seems like it may have been tuned for a bike with other issues that were caught later.
are you 100% sure the timing is spot on?
Right plug is tan. Left is darker but still tan (left was the ripped manifold and lower compression)
Chuck was the one who set and re-checked the timing at the gap this year. said it could use a little more but it was right.
Chuck did change mains lower 2 times, air jets were changed larger and smaller. We did smaller mains on the left side. nothing made much of a noticeable difference and none added power. He worked on the jetting about 2-3 hrs total.
hm.
you have a cdi, correct? id still verify it didnt move. (since may)
If you have a CDI, you might want to check the timing again at higher revs. Use a timing light and see if it advances or retards the way it is supposed to do. It is unlikely but possible that something failed internally allowing the timing to stay static or to change in some way.
Maybe a stupid question/ suggestion, but do your carbs open 100% by that I mean that the engine side of the slide clears the carb bore completely. Just looking at the air filter side will not confirm this.
If the throttle grip or the throttle cable splitter has been replaced, or even the cables themselves, this could create issues. Or maybe there is a difference between high top and low top slides, etc?
And what about carbon deposits in pipes/ stinger/ baffles? That sure kills power.....
When I sync carbs I first stick my fingers in the carbs and make sure that both slides hit the top of the bore at the same time, then that they hit the bottom at the same time - usually using toothpicks for the latter...
Quote from: m in sc on August 25, 2022, 03:26:54 PM
hm.
you have a cdi, correct? id still verify it didnt move. (since may)
OP, what ignition are you using on the bike?
Hello guys thanks for all the suggestions. I take all of them to heart.
Carbs yes. They open all the way. I know because I sync them the same way with my fingers on the slides.
I have a vape.
Timing was set 2 years ago and re-checked at the gap this year by Chuck with his timing light.
I also tried to disconnect the key function from the vape by pulling the blue wire off so it acts like a dirt bike/bypasses battery I think.
No change.
Carbon
Cleared from the headers of the pips every time it remove them to clean them.
I also scrape the carbon from the exhaust ports at the same time.
Stingers good point. I have never removed them. I will take them off and annoy the neighbors for a bit.
Paul
Quote from: paul1478 on August 27, 2022, 05:25:47 PM
I have a vape.
Timing was set 2 years ago and re-checked at the gap this year by Chuck with his timing light.
What model do you have? I seem to remember someone having some issues with the one that had the changeable curves in it.
Quote from: paul1478 on August 27, 2022, 05:25:47 PM
I have a vape.
Timing was set 2 years ago and re-checked at the gap this year by Chuck with his timing light.
Just checking with a timing light won't tell you if the rotor has slipped. You first need to verify TDC marks or timing mark using a dial gauge in the spark plug hole. Then you can use a timing light to check the ignition timing against the now verified timing marks.
And, please let us know what causes of reduced power you find in the end!
Hello
The vape is 2 years old from EC. No curve.
Timing was set with dial indicator to mark and checked with timing light.
I don't know what it is at. Only Chuck said it can use more.
I spoke to him yesterday. He asked about my bike.
We are going to check it out in the fall I think.
He seems to think advancing the timing will do the trick.
We will see.
That is how I understood it, thanks for confirming.
My point is that the initial base timing was done using a dial gauge, and timing marks were then made according to the dual gauge. Then actual timing was checked by using a timing light and those timing marks.
So far so good.
But if the rotor somehow has slipped, the timing light will NOT show that.
The ONLY way to be 100% sure, is to check/verify the timing marks with a dial gauge, then verify actual timing with a strobe lamp.
Both these checks are quick and easy to do, and a dial gauge with spark plug hole adapter can be found on eBay at pretty low prices