Help with predator 224

[BrownStainRacing]

Im just gonna put the 9 tooth and the 7 inch driven on mine so I can just burn em down lol

I was gonna change to a 10t jackshaft sprocket today, but I'm outta #40 chain. This one already has 2 master links in it from 2 or 3 yrs ago, , I'm sure it's time for a new chain. I'm in no hurry.

Jus watch for that rpm shift into high.....that's where the mph is.

Get it to shift into high, 300-500 rpm above peak tq and the mph goes up faster then the tach can keep up with, .

Let it shift too soon (under peak tq rpm) and it takes longer to recover.

Let it shift to late (way above peak tq rpm) then there's no more mph to gain, because it's too high in the powerband, theres no more power to pull.

There's a fine line.

These small block 1 cylinder engines have a very narrow powerband. 1200-2000 rpm between peak tq and peak hp.

A 2500 rpm powerband outta these is EXTREMLY good, and very difficult to achieve.
It's gonna take more then any stage 1, 2, 3, 4, or whatever other bs kit they came out with now.

When you find it, you will see that high rpm is NOT where you gain mph.

 

[aust9002]

With the 1.3 rockers will rpm increase? Will I need to retune it? I think I understand what you mean I might try swapping to the 9 tooth tomorrow until those rockers get here see if I can get the belt all the way in the driven pulley to get that .9:1 final drive and with a 9 tooth my gear ratio would be closer to 6:1

 

[aust9002]

Also went back to the 140 and got it up to 5700rpm

 

[aust9002]

And trimmed the exhaust gasket to match the port it was quite a bit smaller

 

[BrownStainRacing]

With the 1.3 rockers will rpm increase? Will I need to retune it? I think I understand what you mean I might try swapping to the 9 tooth tomorrow until those rockers get here see if I can get the belt all the way in the driven pulley to get that .9:1 final drive and with a 9 tooth my gear ratio would be closer to 6:1

You probably won't see anymore rpm, since your hitting 5700 already, but they will increase the power around the same rpm range.

Your valves will be coming off seat and going bak on seat at different times with the 1.3:1 rockers, so expect to retune. Jus watch your spark plug.

I got some ngk bp9es plugs, I use for tuning.

 

[BrownStainRacing]

And trimmed the exhaust gasket to match the port it was quite a bit smaller

On this 1, the square side is hanging over the port. I was gonna trim it when I had it apart, but I wanted to see how it was right outta the box.

Only thing I've changed so far is that main jet and spark plug.

I'm gonna build a 5"-6" header today with a muffler, but won't install it til I get that .675" carb in.

I think I'll end up with jus a head gasket change, port work, 1.3 rockers, 22# springs, .675 carb, .880" id header, add 2* more ignition timing, and call it good. That should end up with 9.2:1 CR.

It's already got too much power for the kid.

I'll change that gear to a 6:1, that'll hopefully take out 300-400 rpm on the high side, and calm it down a bit on the low side.

He rode it yesterday after we got a quick rain. That layer of leaves on the trails was slick, he was spinning tires the whole time. Still hit 32 mph,

 

[BrownStainRacing]

@aust9002

It's Monday again, get to "tuning".

The kid and his buddy's rode this thing 10+ hrs this weekend.

I pulled the plug last night, it's a smidge on the lean side, but we did get some cooler weather in this weekend.

 

[aust9002]

@aust9002

It's Monday again, get to "tuning".

The kid and his buddy's rode this thing 10+ hrs this weekend.

I pulled the plug last night, it's a smidge on the lean side, but we did get some cooler weather in this weekend.

I ended up getting sick the last couple days but last night I swapped to the 9 tooth and it only got up to 46 it was starting to break up around 5600rpm dont know what that was about but I got everything in to swap out tomorrow and change the oil and plug, so tomorrow Im going to put the 10 tooth back on, change to 22lb springs with the 1.3:1 rockers, change oil, change spark plug, clean carb, and whatever else maybe try out the 12 tooth if everything goes good

Cant tell me these magnets arent good lol

 

[aust9002]

Couldve been the 55° air? Instead of 70+ like it usually is could i have been lean?

 

[BrownStainRacing]

Couldve been the 55° air? Instead of 70+ like it usually is could i have been lean?

Yea, probably.

I didn't notice this 1 running different, as the boys rode it, but I figured it was the cooler air. It went jus a lil lean, not enough to worry about, but these boys have curvy hills to climb and not hitting that high of rpm.

The least lil bit of change I do, I'll pull the plug and have a look.

Yea those magnets are strong, I've changed the oil 4 times on this 1, it has less metal each time. Next time it'll get 10w30 full synthetic.

 

[Denny]

I ended up getting sick the last couple days but last night I swapped to the 9 tooth and it only got up to 46 it was starting to break up around 5600rpm dont know what that was about but I got everything in to swap out tomorrow and change the oil and plug, so tomorrow Im going to put the 10 tooth back on, change to 22lb springs with the 1.3:1 rockers, change oil, change spark plug, clean carb, and whatever else maybe try out the 12 tooth if everything goes good
View attachment 142753
Cant tell me these magnets arent good lolView attachment 142754

Those magnets are not that strong.
See I did it, I told you. Nothing bad happeneddddddddddddddddddddddd

 

[aust9002]

Umm are they supposed to be smaller?

 

[BrownStainRacing]

View attachment 142770
Umm are they supposed to be smaller?View attachment 142771

Yea, thats what changes the ratio.

Check coil bind with 0" valve lash, and at max lift.

 

[BrownStainRacing]

Also, if you have a dial indicator, you can check max lift at 0" valve lash.

I've seen the 1.3 rockers come in at 1.22- 1.28:1, these are mass produced parts and far from perfect.

Also check rocker to retainer clearance, and push rod to guide plate clearance. Both valves, open and closed.

 

[aust9002]

So no go on the head gasket change i only have a .010 and a .055

 

[aust9002]

I guess Im about to put it together with the .055 head gasket mine was pretty much identical on deck clearance it was .002-.0025

 

[aust9002]

Hit 53 with the 10 tooth xD

 

[BrownStainRacing]

Nice job on the port work, every lil bit helps, jus don't open that intake runner.

You are way too rich.
That carbon will break off and end up in the rings and between the piston and cylinder wall.

That splatter you see on the exhaust valve is unburnt fuel.

I was outside but never thought about pulling the plug on the mostly stock 224, I see if I can get it tomorrow.

That lil bump in CR you get when you change to the .027" head gasket will wake that cam up.

It's a slow lazy ramp cam, extra CR changes what's goin in the combustion chamber.

Most people dont realize how that lil extra pressure changes how gases are moving in between those valves, opening and closing.

 

[aust9002]

Nice job on the port work, every lil bit helps, jus don't open that intake runner.

You are way too rich.
That carbon will break off and end up in the rings and between the piston and cylinder wall.

That splatter you see on the exhaust valve is unburnt fuel.

I was outside but never thought about pulling the plug on the mostly stock 224, I see if I can get it tomorrow.

That lil bump in CR you get when you change to the .027" head gasket will wake that cam up.

It's a slow lazy ramp cam, extra CR changes what's goin in the combustion chamber.

Most people dont realize how that lil extra pressure changes how gases are moving in between those valves, opening and closing.

For sure it already was ripping with a .055 head gasket I cant imagine half that size, also where would I order a .025 or a .027 head gasket? Got a 6mph gain just on port work with rockers and springs pretty much

 

[aust9002]

For sure it already was ripping with a .055 head gasket I cant imagine half that size, also where would I order a .025 or a .027 head gasket? Got a 6mph gain just on port work with rockers and springs pretty much

I didnt change jets either but im going to put the 35 idle or 38 idle and i think a 130 for the main tomo possibly