Help with a build 223

[Johnwesley]

I have a Bt200x that I just picked up a 224 for and want to build it before I install it. The bike is used for some circle racing and short track. The rest of the time just horsing around on. I run 19x7-8 sunf

my thought is flat top piston +20 rod and a banzai 265 cam with 26lb springs. With the head cleaned up a bit with stock valves and 0.010 head gasket. I’m also looking at the dyno super X it has a tighter LSA.

I would like some input in the build/ suggestions.

 

[Johnwesley]

Man it’s crickets around here

I landed on a mongoose cam with the flat top piston. I’ll build the short block and then determine which head I want to run. May end up with a 27/25 ported head to top it off. I’ll keep ya updated for those who are interested.

 

[Strigoi]

What are you doing for a carb? I've got a couple of similar engines and they love the 24mm Mikuni flat slides.

The pink bike in my pic on the left has a .272 Mongoose cam in it and it makes some decent power.

 

[Mark Brooks]

What are you doing for a carb? I've got a couple of similar engines and they love the 24mm Mikuni flat slides.

The pink bike in my pic on the left has a .272 Mongoose cam in it and it makes some decent power.

And it's GORGEOUS! Win Win...

 

[Johnwesley]

What are you doing for a carb? I've got a couple of similar engines and they love the 24mm Mikuni flat slides.

The pink bike in my pic on the left has a .272 Mongoose cam in it and it makes some decent power.

looking at either a 24 or 26 mm nibbi carb depending on what head I go with.

what compression are you running with the 272?

 

[ole4]

I just recently built a new 224 to replace the 196 in a kart. That engine was about 10 years old and I wanted a faster engine. I am in the process of refreshing the head and if you are interested in a 32x25 head I would sell it. It was milled .080 as it originally was a 22cc head. I have cleaned it checked guides, touched up the seats and vacuum tested the seal. I am about to flow it and velocity test it. It had 26lb springs with a shim under the intake because of the added weight of the 32mm valve. The alloy retainers I would not reuse so it would have new ones.

 

[Strigoi]

looking at either a 24 or 26 mm nibbi carb depending on what head I go with.

what compression are you running with the 272?

I'm not sure what the compression ratio is on it. It's got a stock head with a flat top piston. It runs fine on regular pump gas.

 

[delray]

john, if you're engine is going to have about zero deck height(piston) and you're going to purchase ole4 head that is milled .080 and you use a good composite steel fire ring head gasket (about .045 thick) you will need your octane fuel around 100+ with a 224cc bore. if you get the cc's from ole4 we can get it more spot on for octane and yes 24mm might be more responsive over the 26mm. i think ole4 could tell you more based on what type of porting has been done also.

 

[ole4]

16.7CC's

 

[delray]

nice ole4, here you go for compression. this is only based on zero deck height.

 

[Johnwesley]

So what are we looking at octane wise.

 

[delray]

i would say 100 octane would work. just buy some 91 ethanol free and mix some some racing fuel accordingly. unless someone near you sells a 100. most places are always 108,110..etc. also you will lose compression little around the top of the piston to cylinder wall that is not accounted for and will bring the compressing down just a slight bit.

 

[Johnwesley]

i would say 100 octane would work. just buy some 91 ethanol free and mix some some racing fuel accordingly. unless someone near you sells a 100. most places are always 108,110..etc. also you will lost compression little around the top of the piston to cylinder wall that is not accounted for and will bring the compressing down just a slight bit.

Race fuel is hard to come bike in my little town of 400. Being a yard / occasionally Racing mini I would like to stick with what is easily available.

 

[delray]

if you could find any type of racing fuel and you would only need 5 gallons for example. stored in a steel can and mix it with a ethanol free low octane when needed. 5 gallons of racing fuel would go a long ways and stay good for at least 2yrs in a steel can.

 

[Johnwesley]

if you could find any type of racing fuel and you would only need 5 gallons for example. stored in a steel can and mix it with a ethanol free low octane when needed. 5 gallons of racing fuel would go a long ways and stay good for at least 2yrs in a steel can. View attachment 292678

How about aviation fuel? I believe I can get that fairly easy.

 

[delray]

might want to look into that. i believe most small airports sell a 100 and maybe a higher one also and i believe it's lead gas. for me john i have a town very close to me that sell's 110 Sunoco. Don't look at the price...lol only money if you want to win.

 

[Johnwesley]

might want to look into that. i believe most small airports sell a 100 and maybe a higher one also and i believe it's lead gas. for me john i have a town very close to me that sell's 110 Sunoco. Don't look at the price...lol only money if you want to win.

That would be great if it was close, 10 a gallon isn’t bad doing it a few gallons at a time.

 

[delray]

for me i run ALL 110 OCTANE and that's just about every weekend...lol still takes a lot to go through it the full summer. i might use 10 gallons? two bikes and one of them gets a mix (lower compression). john i haven't done the research yet on that mongoose cam,but i would like to see some dyno chart runs and see were the power ban go's and starts to drop...etc... all this will make a big deafferents in how you gear it to the track with your clutch setup

 

[Johnwesley]

Here’s a dyno of a build using that cam

 

[delray]

ok john, so base on that chart only and you will also base on how your bike/motor feels. i would say gear it to about 7300 max and if it feels like it's not laying down? leave it there.