Minimum upgrades for the 212 predator... need advice

[silverbear]

I recently picked up a 212 Predator from Harbor Freight for a cyclecar project that is probably two years away. I like to accumulate the needed parts and information for a build beforehand so that when the time comes for building I'm more or less ready.

This engine is not going to get raced, but I do want to remove the governor, open up the exhaust with a straight pipe and open up the breathing with at least a modified intake. The same things I have done with a 99 predator on my daily rider.

This engine is going to be coupled with a torque converter transmission, in effect a three speed. I don't have experience with torque converters, but my understanding is that they kind of even out the RPMs and make it less likely that you will blow up your engine.

So, you have an idea of what I want from the engine, more than stock, but not a souped up powerhouse. I don't want the engine coming apart and maybe getting injured in the process and I also want to spend as little money as possible. But I will spend what I need to within reason in order to keep things safe.

So what do I need to do? I will remove the governor as outlined at the AGK site. I'll make up a custom exhaust with a straight pipe. The intake will get opened up so that the engine can breathe. I'm guessing that I will need to change the jet opening in the carburetor. What else? Keep in mind this engine will not be run wide open throttle. If I need to increase the speed I'll do it with the final drive sprocket and not by pushing the engine to it's limits.

Your advice is much appreciated by me and no doubt will be informative for others as well.
SB

 

[atombikes]

Maybe change the carb to a motorcycle style carb? Dunno about the 212, I'm still trying to get my 79cc Greyhound build sorted.

But I am using a PZ19 carb.

 

[silverbear]

Atom,
I see that the PZ19 is available in 2 stroke or 4 stroke versions and they are listed as being appropriate for 50cc through 125cc. Sounds like the right thing for the 79cc, but for the 212 I don't know. If it fits maybe it would just need a bigger jet???
SB

 

[racie35]

If you look at the tiny carb that comes on a 212 you'll see anything is just about an improvement.... Just jet it right

 

[BigBlue]

SB,

Here's an article I found to upgrade the 212cc Predator with minimal mods. The 1st 8 paragraphs is what you maybe interested in:
http://www.kartpartsdepot.com/help_answer.asp?ID=11

Good Luck,

Chris
AKA: BigBlue

 

[silverbear]

Thank you, guys.

I wonder if the Pz19will fit the 212 predator. Any other carb suggestions?

Big Blue, the article is very helpful. Here's what I gather from it...
First stage open up the intake air supply, free flow exhaust and clean up the ports. Almost no money involved here. Maybe right away change the carburetor and dial in the jets.
Second stage replace valve springs with ones set at 26 lbs. Replace the push rods with chrome moly ones. Advance timing to at least 28 degrees. Replace head gasket with .016 copper gasket. If planning to run at over 4,000 rpm change the cast flywheel to billet. Now the cash register is going, kaching!

From what I gather the stage one modifications will bring the engine to the 9 hsp range which seems like a lot to me from the stock 6.5 and that's not counting the change in carburetor.

I don't know how much of stage two I would do, particularly if I were to consider 4,000 rpm the red line, since that is what the cast flywheel is designed for. With a tachometer one would know how high the revs are running and pretty soon the sound of the engine would tell you where you are. And I'm thinking that the torque converter might keep the rpms reasonable on its own.

So my initial thinking on this is to do the stage one modifications along with changing out the carburetor. And as a safety device, get a digital tach. Then go from there as the need presents itself, if in fact it does. Does that sound right or am I missing something?
SB

 

[silverbear]

I got a nice PM from the guys at AGK giving me a heads up that I don't want to use 26 lb springs as that is for rpms in the range of 8,000. Those springs would flatten my stock camshaft. The stock springs will be OK for my low rpm application. Boy, that's good to know.

Taking the time to give me a heads up is much appreciated and speaks well of AGK. You guys rock!
SB

 

[itchybird]

Hey SB,

Moving up to some more serious power I see!

The most basic mods I do on all of the Honda/Clone/HF motors include a billet connecting rod, billet flywheel and stiffer valve springs, these are mandatory items if you eliminate the governor.

From there, it's up to you, but I also spend another $25 bucks at this point and get myself a pair of chromoly pushrods and I always go with at least a little cam upgrade and I normally upgrade valves/retainers as well.If you are careful, you can get a heck of motor without breaking the bank.

Oh, and don't overlook a basic clutch setup, Pat and I found that geared properly you really don't a CVT or gears. I was skeptic at first, but 100's of miles later I know the truth -geared properly these motors are great as single speed.

Rich

 

[itchybird]

I have had problems getting the Copper head gaskets to seal well. In many cases, you can get the +0.010" or +0.020" longer rods. These move the piston up in the bore which will raise compression while still running the better sealing stock style head gaskets.

 

[silverbear]

Hey SB,

Moving up to some more serious power I see!

The most basic mods I do on all of the Honda/Clone/HF motors include a billet connecting rod, billet flywheel and stiffer valve springs, these are mandatory items if you eliminate the governor.

From there, it's up to you, but I also spend another $25 bucks at this point and get myself a pair of chromoly pushrods and I always go with at least a little cam upgrade and I normally upgrade valves/retainers as well.If you are careful, you can get a heck of motor without breaking the bank.

Oh, and don't overlook a basic clutch setup, Pat and I found that geared properly you really don't a CVT or gears. I was skeptic at first, but 100's of miles later I know the truth -geared properly these motors are great as single speed.

Rich

Yes, there has been a steady climb in power since I began this madness some years ago. My first motor was a 26cc friction drive Bikebug, then to the China girl, then the 50cc Hua Sheng, then the 79 Greyhound, then the 99 Predator... this winter a build using a 2 stroke Jacobsen at 147cc and a couple of weeks ago purchased the 212.

I'm aware that the 212 has a lot of power even governed and is too much for most bike frames to handle safely. The intent is to use this engine on a 1970's Harley Davidson Sprint chassis which originally came with a 250cc four stroke and later a 350. I figured that for my purposes, just wanting to keep up with 55mph highway traffic going to my local town 12 miles away the 212 would be adequate and the Harley frame would certainly be more than enough bike.

Once it has proven itself as a light motorcycle and is legally licensed and insured then the plan is to convert it into a cyclecar using a Grumman aluminum canoe for the donor body. This would be a three wheeler with two wheels up front, hopefully something like the old Morgan three wheeler. I have no interest in racing (too old for that) and would actually prefer tooling along a forest road at 35 mph or so A torque converter has been ordered (on sale which I couldn't pass up) so the basic power train is settled on.

The big question is what to do about the engine... how to open it up some without either harming it (or myself) or costing a small fortune. A top speed capability of say 60 mph is the upper limit. If I can do that without going over 4,000 RPMs then there would be little money invested in upgrades. If it needs to be able to go up to say 6,000 RPMs then I need to make some internal upgrades, purchasing parts as I can afford to. I'd rather stay minimal, but also want it to be safe.

So, I think I will proceed with caution, starting out with it governed just to see what it does on the Sprint. Then remove the governor, but stay at a redline of 4,000 RPMs. If that does it then I'm happy. If it doesn't then start saving my pennies. Thank you for your informed advice. I do appreciate it and recognize the great experience you and your brother Pat have with these engines in particular and with racing in general.
SB

 

[silverbear]

First two photos are of the Harley Sprint. I looked up the serial number. It was made in 1967 and was an SS model which came with the 350cc four stroke, a pretty capable race bike as I understand it.

The next two photos show an old horse drawn hay rake I used to use along with a horse drawn mower when I raised Indian ponies 25 or 30 years ago. I figured I could use the seat on the Harley. Make a spring mount for it, give it some foam, stitch it up in harness leather and it will look kind of like the ones on the old Simplex light motorcycles. Need to locate wheels for it. The front rim is 19". I have a couple 18" and might use those to keep costs down. That would be about the same diameter as a 24" bicycle rim.

Last photo is of another light weight Harley which I could use as a donor if the state won't issue me a lost title for the Sprint. This one at least looks pretty complete, so the chances for a lost title might be better..

I guess a 212cc industrial motor seems like a big step down from the 350cc motor that came on it, but I figure it's still more than the Simplex 2 stroke had and should be enough. Built up it would be more than enough.

Granted that this project is a good ways off in the future, but there are initial things to get going long before build time. One is the title and then come the parts. I need to ask lots of questions and convince myself that I have enough answers to proceed with caution. It is the other end of the pendulum from a 26cc Bikebug. Ha!
SB

 

[mapbike]

I got a nice PM from the guys at AGK giving me a heads up that I don't want to use 26 lb springs as that is for rpms in the range of 8,000. Those springs would flatten my stock camshaft. The stock springs will be OK for my low rpm application. Boy, that's good to know.

Taking the time to give me a heads up is much appreciated and speaks well of AGK. You guys rock!
SB

Just wanted to ring in here and say that you are correct about AGK they are great people, a few years ago I built a 196cc HF Grayhound GX200 clone for a go kart I built, I went throgh them for all my parts, I used the 18lb valve springs, arc billet connecing rod,Chrome moly push rods, flat top piston from a Honda GX200 propane engine, GX160 head with 14cc combustion chamber and a few other mods including home built exhaust, I just used stock carb and rejetted it, the kart topped out at aroumd 50mph on a flat straight, gearing was way high though and when I had it down where it needed to be I could cruise at 42mph.

Stock carb works great for a mild performance build in my experience and low end torque can be improved with a GX140 emulsion tube in carb, nothing wrong with a carb upgrade butfor what it you're wanting to do I'd say it probably isn't needed, just get a pod filter and the adapter from AGK that along with a free flowing exhaust is a must for having good power, the stock air filter boxes are very restrictive and kill performance big time, advance my timing by 6 degees and also used 1.2 ratio rockers from an older Yamaha go kart engine, holes in push rod guide plate has to be modified by lengthening the slots a bit for that mod. But it a simple one.

Well ill shut up now, but just wanted to share a little of my experience with AGK and the clone engines, ai still have that engine sitting in the shop and it wants a bike some day.......lol!

Map

 

[mapbike]

Wishing you the best on this build SB, better plan on billet rod, flywheel and plenty strong internals if you hope to hit 60mph, unless the 212predator has a good bit more power than the 196 clone it will take a good bit more than 4000rpm to get to the 50mph range.

Im very curious about your build and will really enjoy watching it come together......

Map

 

[culvercityclassic]

Just a little info: I raced one of my bikes at the grange and never really told anyone what was in the bike... Just changed the valve springs to 18# and up graded the carb to a 22mm with a open exhaust.... The bike was fast.

I say 18# springs and a 22mm carb should make you real happy. Do the exhaust too.

Let me know if you have any questions SB

 

[mapbike]

Just a little info: I raced one of my bikes at the grange and never really told anyone what was in the bike... Just changed the valve springs to 18# and up graded the carb to a 22mm with a open exhaust.... The bike was fast.

I say 18# springs and a 22mm carb should make you real happy. Do the exhaust too.

Let me know if you have any questions SB

Great advice, I know you have much more experience with the honda clones than i do, I only built the one 196cc, I had planned for the bigger carb and a couple other things, but it was plenty fast for the kart I had in on so I never got to the bigger carb upgrade.

I was running a 15T Noram clutch to a 60T and 13.5x6'' tires, that Kart was a bit scary on the dirt roads out here where I live, nothing out of the hole but top speed was fast, that engine needs a billet flywheel, the stock one is heavy and the thought of it chunking the magnet which has happened kinda bothered me not to mention how bad the balance was with the clunky stock flywheel.

Map

 

[magna_503]

this would be an interesting build..

 

[silverbear]

Just a little info: I raced one of my bikes at the grange and never really told anyone what was in the bike... Just changed the valve springs to 18# and up graded the carb to a 22mm with a open exhaust.... The bike was fast.

I say 18# springs and a 22mm carb should make you real happy. Do the exhaust too.

Let me know if you have any questions SB

Thank you for your welcome input. What about the flywheel I keep getting warned about? If I keep the RPMs reasonable it should be OK?

What do you suggest for the carb, again on a budget? Do you have a source?

I believe I have a Mikuni carb from a Suzuki 2 stroke dirt bike. It would need an adapter and probably a rebuild kit. I'm guessing it is 22mm, but can measure it if I have something that does metric. Thanks again...
SB

 

[mapbike]

Thank you for your welcome input. What about the flywheel I keep getting warned about? If I keep the RPMs reasonable it should be OK?

What do you suggest for the carb, again on a budget? Do you have a source?

I believe I have a Mikuni carb from a Suzuki 2 stroke dirt bike. It would need an adapter and probably a rebuild kit. I'm guessing it is 22mm, but can measure it if I have something that does metric. Thanks again...
SB

Flywheel issue is that there is a risk of the magnet flying off at higher rpm, I remember seeing a video way on back of one coming off and shooting through a piece of 1/2" plywood like it was notebook paper, that would be pretty ugly if it happened and hit flesh, the odds are probably slim of it happening but that along with the stock flywheels being horribly balanced at high rpms is why I think most make that mod a priority on the engines if they are gonna be used with the governor removed, I'd sure hate to loose a leg or worse over a $100 part......!

AGK used to have an intake setup that would allow use of a Gx390 carb which is original equipment on a 13HP, that may be a reasonable option also if they still offer that setup.

Map

 

[silverbear]

Thanks for sharing your thoughts and concerns. I have no desire to be maimed, for sure. Still, being economically challenged I have to question each expenditure and convince myself it is necessary. Too many of these expenses and it will shut down the build.

There is no rush. I'm just in the exploration and planning stage and have plenty of time to find ways to save money here and there. I found my Mikuni carb. Unless I find the upper part that's out. It would also require an adapter to make it work. I'll check out the carb you suggested. I do appreciate your taking the time to respond.
SB

 

[culvercityclassic]

SB I have ran a few engines with the stock flywheel and they seem to be well balanced, if anything is out of balance it would have to be the crank...just ask member DMB. His was so out of whack you could not hold onto the bike. If you run a CVT that bike will not rev past 6000 RPM. If you dont feel safe then upgrade to the billet one.

The carb I would use if you are going to purchase: http://www.affordablegokarts.com/mm...A&Product_Code=AGKCARBKIT4&Category_Code=AFC1

I have another source for just the carb: 42.00