224 help!!

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kart74

Member
#1
#1
So i posted awhile back about the 224 builds i was doing. I built 2 identical 224s that include... ported head, milled head to 15cc, billet internals, flat top piston, CM dyno cam, header, 26mm chikuni, campion rocker arms, and 22lb valve springs. We are running these on fat tire mini bikes with a torque converter setup using the juggernaut driver. Yellow spring in the middle on the driven. The issue is they seem "flat." They are only pulling 5300ish rpm at the top. They come out of the hole good, but then are fairly unimpressive after that. We had built 196s before this and i dont think these are much better even though they have more compression and bigger displacement. Because of the compression we run race gas in them so reading the plug isnt so easy. For the heck of it i jetted it up from a 125 and went all the way to 150. Seems the best around 140-145 main. Is it possible that it needs a bigger carb? Something doesnt seem right and i cant figure anything out. Any thoughts would be great.
 
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ole4

ole4

#4
#4
What size is the intake valve also what head gasket are you using? So did max rpm change with the 9 tooth clutch? Have you verified that the carb is opening all the way? Also which champion rockers the forged ones or the stamped ones. Pic is the forged ones.
 

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K

kart74

Member
#5
#5
It is a stock 22cc head that was milled and ported. So 27-25 valves. Max rpm changed very little going to 9 tooth. They are the stamped rockers not the forged.
 
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BrownStainRacing

Well-Known Member
#6
#6
My 224 hits 5900 rpm max with a load.

9.6:1 CR
Black mamba jr cam
.675" SA carb with stock air box and filter
4.6:1 gear
7" driven, red spring
Stock driver w/alum weights, 1 pink spring, 1 stock spring (3000rpm engagement)
20" tire

I vent the crankcase with 2) check valves out of the valve cover. Stock pcv removed.

How's yours vented???
 
SAS289

SAS289

Well-Known Member
#7
#7
Have you verified that there's clearance between the rockers and the rocker cover? Even if it is just barely hitting it may take away enough compression to lose power.

Couple other thoughts:
I don't think the driven has anything to do with your issue.
I wouldn't have done much porting on the 224 head when using a mod2 cam. Just transition the short side a bit.
You need way more cam with that.
 
K

kart74

Member
#8
#8
I will wanted to keep a torque cam since it doesn't see a lot of rpm. I have a standard head gasket .040 to get the clearance needed. It is the CM cam.
 
SAS289

SAS289

Well-Known Member
#10
#10
BrownStainRacing said:
My 224 hits 5900 rpm max with a load.

9.6:1 CR
Black mamba jr cam
.675" SA carb with stock air box and filter
4.6:1 gear
7" driven, red spring
Stock driver w/alum weights, 1 pink spring, 1 stock spring (3000rpm engagement)
20" tire

I vent the crankcase with 2) check valves out of the valve cover. Stock pcv removed.

How's yours vented???
Click to expand...
I did similar (5590 RPM) with no special venting and did puke some oil. You're right. I may have gotten more vented properly. But that was just one top speed run. I ride at around 4700 RPM and under.

Are you getting a full belt shift with that setup? If so 60+ MPH bike?

kart74. We are just giving examples. 224's, tall tires, torque converters, etc. Sounds like Brownstain is getting his RPM with engine power. My RPM comes from gearing 6.6:1 with the stock driver and 6 inch driven. You would think with the Juggernaut you should get into 6K RPM.

My build is nothing special. 9.7:1 CR, 252 lift cam, and bored stock carb.

I used play dough to verify rocker to cover clearance with the forged (old style) Champion rockers.
 
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BrownStainRacing

Well-Known Member
#11
#11
SAS289 said:
I did similar (5590 RPM) with no special venting and did puke some oil. You're right. I may have gotten more vented properly. But that was just one top speed run. I ride at around 4700 RPM and under.

Are you getting a full belt shift with that setup? If so 60+ MPH bike?

kart74. We are just giving examples. 224's, tall tires, torque converters, etc. Sounds like Brownstain is getting his RPM with engine power. My RPM comes from gearing 6.6:1 with the stock driver and 6 inch driven. You would think with the Juggernaut you should get into 6K RPM.

My build is nothing special. 9.7:1 CR, 252 lift cam, and bored stock carb.

I used play dough to verify rocker to cover clearance with the forged (old style) Champion rockers.
Click to expand...
I only got it to 57-58, around 600 ft. I'm 200#.

My buddy got it to 62, less then 600ft. he's 150#.

@kart74
Another thing, would be valve spring install height.
 
ole4

ole4

#13
#13
When a valve spring is rated @ 22lb it is a very ambiguous statement. It should state 22lbs @ .850 install height. So if you take a machinest rule and with the valve closed measure the valve spring length from the bottom on the head to the top under the retainer that is your install height. So say you measure it's length and it's .900 then instead of 22lbs seat pressure it may be more like 8 lbs and you could experience premature valve float. It could also measure less than.850 and you would have more seat pressure.
 
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BrownStainRacing

Well-Known Member
#14
#14
kart74 said:
Mine are not vented other than the one that comes out of the valve cover to an external filter. Can you explain more on the valve spring height? That is not something I have checked.
Click to expand...
I've tested the crankcase pressure/vacuum with a gauge and found it to be greater in the bigger 224, then the 212 or the 196.
It's even higher without any kinda of pcv.
When the piston is on the way up, it's pulling in air, on the way down it's trying to push all that air back out alone with the blow by. It jus can not do it at higher rpm.
The extra pressure under the piston, will slow the piston down and the engine jus cannot rev any higher.

Here's my 224 with about 12-15 hrs on it. It's idles at 2000 rpm, and the gauge is swinging 2" - 2psi with 2) 1 way check valves out of the valve cover.
With the stock pcv it would be around 5"-5psi.
Without any pcv, it would be 8"-8psi.

As rpm goes up, so goes the pressures.
 

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BrownStainRacing

Well-Known Member
#17
#17
kart74 said:
Makes sense. I actually bought one but never installed it. Where is the best place to drill and tap?
Click to expand...
All my builds are 2 out of the valve cover.
They don't blow oil, there's no oil in the catch can, no blown side cover gaskets or loose bolts.
 

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