Lack of power after new exhaust and carb

blackfox

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Hello all I'm new here.

Been reading a lot of post and you guys know what you're talking about.

I have some questions.
I got a new drag pipe exhaust and hp carb for my occ stingray build.

I've had a bad lack of power every since.
The exhaust has a much smaller hole than my exhaust port on engine for one.

Then I've tried many different jets with not much luck. The best I can do is took the jet from stock carb and put it in hp and it does a lot better.

I don't know if the jets I have are marked correctly but I've went from .6mm all the way to .8mm with very little to no change no power.
I believe it's the exhaust.

My questions are is there an expansion chamber I can get to work with the drag pipe on my stingray or would that be needed?

Should I just get a reed valve and see if that fixes it? Also if I get a reed valve is there a offset of some sort I can get with it to keep my carb level?

Thanks in advance for any and all advice.

Blackfox
 
first step is to replace old exhaust and carb to see if power comes back - if so, replace one thing at a time to see which is bad - if not, you have different problem
 
Well I cut up modified and ruined the stock exhaust I had.

I did put the old stock carb on and it did run better just doesn't have the power it did.

So I took the jet out of that carb and put it in the new carb.
I get pretty much the same results.

So seems to me the exhaust it to restricting but is suppose to be such a goid exhaust.

I do get a small power gain after turning fuel supply off while riding.
Just before it dies it gets a bit of a power boost.

So doesn't that mean I'm still getting to much fuel for this exhaust?
 
sometimes, but it can also mean the exhaust is so bad it wants an unreasonable mix to run

try leaving about 1/8 inch gap on exhaust to see what happens
 
Sorry have been very busy needed to get back to you on this.

When you say the exhaust maybe so bad.
You are referring to my exhaust pipe right? Not the amount coming out of engine?

Also you say to try a 1/8 inch gap.

How do you mean? How do i do that?

I'm assuming you're not talking about the gasket.
So are you saying to unbolt exhaust and put some kind of spacer in between to hold it 1/8 inch back so some exhaust goes in pipe while the rest is instantly done away with?

Thank you for all your advice. Sorry it took a few days to get back to you.

I had my new jug come in.
I sanded it down to make high compression. Also now have proper place to mount exhaust on the new cylinder jug which is great.

Got it all finally done put back together today.

It sounded good and ran a lot better I did get some more power. However still doesn't like going uphill. Just bogged down.

Then I noticed I had an air leak on the bottom cylinder gasket on the jug.

It started doing the basics of air leak symptoms.
Revving very high and slow to return to idle after giving it gas plus power loss.

When I first got it started after modifications I took off uphill with no push from a dead stop.
That power was short lived when I guess almost instantly I blew the gasket.

The gasket I cut myself out of Mr gasket exhaust gasket material. Which I had no idea it would be so hard to cut when I ordered it.
But that's all I had on hand so working with the limited tools I have I made a pretty piss poor gasket hopping it would holdup.

It didn't. So the only other thing I have is red rtv gasket maker. Which I know won't last long hopefully long enough to ride while I order a proper gasket or make a proper gasket.

Anyways I have read other post where seems a lot of folks actually use it on the bottom of their cylinder jugs with no problems.

But when I was using the stock nt carb with the stupid design to mate it to I take. That's the stuff I used to block the air leaks from the slots that have no business being there.
I did notice that the gas coming in contact with it gums it up pretty quick. I was always having to reseal it. Hate the design of those.


Anyways I'm waiting the hour right now then about to torque the bolts down on the rtv.

Do you think this is a major mistake? Or will this be an ok temporary fix?

Keep in mind I haven't ran motor with the rtv yet and I did leave the gasket there too just put the rtv on both sides of the gasket to seal any weak spots that might do the same thing and mainly just sealed up the spot the was blowing gas and smoke out.

Thanks again bro.

black fox
 
I usually just loosen the muffler so an 1/8 inch gap is open at the mount - don't run it long like that, just check if it suddenly gets better

mufflers can get so clogged inside that they kill the motor
 
Wow, it is looking like the more you touch, the more problems you get.
Here is the answer: go one step at a time, if something goes wrong, go back.

So, you changed the carb and the exhaust, and now it doesn't work right?
Put the exhaust back on, if it is the easiest. No improvement? Put the carb back on!
If it is still not working, you know it worked before, so it must be something else.
Get it working AS DESIGNED, then move forward with your modifications ONE STEPAT A TIME.
If they improve it, Hurray! If not, go back to the way you had it...

Simple eh?
 
Ok crassius I will give it a try asap and let you know.
It's storming bad here right now I really want to go check that.

I have a friend with a welder that's going to custom up me a new drag pipe with the ports matched.
I was wondering about putting an expansion chamber on it as well.
I'm pretty sure the exhaust is the issue but I'll know for sure when I can do the gap test you are telling me about.

About the rtv like I stated what is your thoughts on that?
 
And Steve thanks but I know I've done a lot in a short amount of time.

The 4 stroking problem as been there since day one.

After breaking in engine I tried mods on the stock exhaust and it helped a great deal. Stopped from 4 stroking a great deal and gave me lots of power.

Then it started falling apart because I silver soldered and j b welded it just to last until my new exhaust got here. I thought that would fix the rest of the issues and then tune and jet it to the exhaust.

I do know what you're saying and I did go by steps just couldn't step back due to the way I cut up the stock exhaust and no access to a welder at that point.

However I'm going to get to the bottom of this.

Isn't it the correct way to get the exhaust that works and then tune to that exhaust?

The exhaust I had shipped was advertised for 66cc 2 stroke occ stingray chopper build.
However it was advertised false because the port on my 66cc is a lot bigger than the nickel size header port on the exhaust that's giving the new issues.

I talked to the seller and am getting a refund for it.

Thanks
 
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