Carb type and size

[95 shaw]

You haven't really given the pertinent information in this thread.

Compression ratio, timing, flow of head, altitude, etc. play role.

You could throw 100% nitromethane at the engine, provided you were able to get enough air and fuel to it.

And willing to live with the consequences.

Research is your friend.
The world is at you fingertips. If you know how to ask.

 

[Boomanchoo27]

You haven't really given the pertinent information in this thread.

Compression ratio, timing, flow of head, altitude, etc. play role.

You could throw 100% nitromethane at the engine, provided you were able to get enough air and fuel to it.

And willing to live with the consequences.

Research is your friend.
The world is at you fingertips. If you know how to ask.

With that being said I have no idea what the compression ratio is, timing is 32°btdc, no idea the flow of the head.
I live in South Carolina about 50 Mi from Charleston so approx 50' above sea level. I will figure out compression ratio of build, but not sure how tell you the flow of the head other than it's jrpw level 10 head

 

[95 shaw]

What I am looking at is dynamic cylinder pressure.
Things that promote more dynamic cylinder pressure are.
Cam duration and cam timing.
Altitude/ atmospheric pressure.
Static compression ratio.
Cylinder head flow characteristics.

All these things are "more air put in and held in, more dynamic compression"

Dynamic compression has the most influence on the octane fuel required to prevent detonation, or preignition.
Heat retention is also a factor

Staying to the rich side can also influence the octane needed. Most every thing is a compromise. Balancing those compromises is called tuning.

 

[Boomanchoo27]

Ok,

What I am looking at is dynamic cylinder pressure.
Things that promote more dynamic cylinder pressure are.
Cam duration and cam timing.
Altitude/ atmospheric pressure.
Static compression ratio.
Cylinder head flow characteristics.

All these things are "more air put in and held in, more dynamic compression"

Dynamic compression has the most influence on the octane fuel required to prevent detonation, or preignition.
Heat retention is also a factor

Staying to the rich side can also influence the octane needed. Most every thing is a compromise. Balancing those compromises is called tuning.

I do have a compression guage other than that, it's over my head

 

[95 shaw]

Ok,

I do have a compression guage other than that, it's over my head

Hang in there.

If you let it rattle around in there enough, and it still bothers you, you will work it out.

30 years is almost all it took for me to see it.
Lmao

 

[Boomanchoo27]

I'll be an old man in 30 yrs....lol

 

[mike97760]

In the 4 pages I have read on this subject, not once have I seen you mention taking the spark plug out after running with these problems and describing what the plug looks like. Dry? Wet? Blackened?

 

[Boomanchoo27]

In the 4 pages I have read on this subject, not once have I seen you mention taking the spark plug out after running with these problems and describing what the plug looks like. Dry? Wet? Blackened?

Blackened, but that was also an old plug that's been run with a stock carb, this weekend when I'm off I'm going to get some cheap throw away plugs so I can look over these pages and try and tune like it should be.

 

[DD83]

Blackened, but that was also an old plug that's been run with a stock carb, this weekend when I'm off I'm going to get some cheap throw away plugs so I can look over these pages and try and tune like it should be.

Again I am no expert, but trying to read the plug is going to be tough unless you pull the coil at WOT, your low speed may be rich and your high speed lean. vicsa versa. I would suggest trying to tune off of head temp. and with a build of this caliber I sure hope you're running a micron with a temp gauge. really good info from SHAW. I also suspect you will have more compression than 87 will handle again speculation because you haven't givin your compression ratio.

 

[Boomanchoo27]

I do have a mychron but not temp guage, might need to invest in one of those. Here is a video of it when I was last over there...

 

[DD83]

I do have a mychron but not temp guage, might need to invest in one of those. Here is a video of it when I was last over there...

Have your buddy grab the brake if you're going to free rev like that to put a load on the engine.

 

[DD83]

Blackened, but that was also an old plug that's been run with a stock carb, this weekend when I'm off I'm going to get some cheap throw away plugs so I can look over these pages and try and tune like it should be.

no no no do NOT try and tune your engine on cheap throw away plugs. this is not a lwan mower engine anymore you have a race engine now and every detail matters. This is why youre having problems.... attention to detail. You spent all this money with jrpw did they advise you to go get cheap throw away plugs and jump around with three differnt fuels? FWIW JRPW is one of the most recognized builders in the country, not just a parts store any advise you get from them I would follow.

 

[Boomanchoo27]

no no no do NOT try and tune your engine on cheap throw away plugs. this is not a lwan mower engine anymore you have a race engine now and every detail matters. This is why youre having problems.... attention to detail. You spent all this money with jrpw did they advise you to go get cheap throw away plugs and jump around with three differnt fuels? FWIW JRPW is one of the most recognized builders in the country, not just a parts store any advise you get from them I would follow.

No he sent me the plug in the build sheet, and told me specifically to run 93 octane from shell, BP or amco

 

[Boomanchoo27]

Have your buddy grab the brake if you're going to free rev like that to put a load on the engine.

I was filming, so hold brake to put load on engine, gotcha. I was going to take it off the stand next time I was over there and drive it to put load on stand. Will definitely keep this in mind

 

[DD83]

No he sent me the plug in the build sheet, and told me specifically to run 93 octane from shell, BP or amco

so stick to that no cheap plugs no e85 follow his directions he wont steer you into a wreck

 

[Boomanchoo27]

E85 is been given away since this thread and new plugs will be had. Again thank you very much.

 

[Boomanchoo27]

Ok I didn't stay with my kart long enough to really adjust I bought a 24mm nibbi, it is spitting gas back through the intake side, possible valve issue, rockers set to tight? I should have gotten a video. Just trying to explain what I saw

 

[DD83]

Ok I didn't stay with my kart long enough to really adjust I bought a 24mm nibbi, it is spitting gas back through the intake side, possible valve issue, rockers set to tight? I should have gotten a video. Just trying to explain what I saw

you're on another carb now? are you trying to drive yourself crazy? you are asking questions no one can answer because you are not giving any details!

 

[Boomanchoo27]

I thought the 28 was to big so I bought a 24mm nibbi. What questions should I be asking to receive the correct advice? What should I be looking for other? Please help me help you/yall

 

[DD83]

if you are going to ask if your lash is too tight you need to provide what your have it set at. was it hard to start? It's really hard to help you when you're jumping all over the place before you attempt to use any advice you were given here. Not one time did someone tell you on this thread your carb was too big and to get another. Again you're working on a radical build no carb is going to be plug and play. stick with one and fine tune it....or box it all up and send it to someone that know's what they are doing.