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Discussion Starter · #1 ·
Hey All!!!

I'm Falkon45. I bought my son a SYXMoto holeshot a few months back, and ended up getting a used SYXMoto Holeshot X for myself used a little while later.

My son's bike has been wildly unreliable since the day I started it up. I've gotten around that making a ton of warranty claims. lol. It's good as of now, and lots of upgrades.
The holeshot X needed a new carb and fork, then it was good to go. Did a "High Performance" engine swap on it last month. Engine died 20 minutes later. No big deal. Bought a big bore kit to rebuild that engine, and now have 3 extra engines lying around for experimenting with.

Anyway, Glad to be here! Actually joined because I saw the engines with the dual carb setup, and side carb setup, and wanted more info on those. I'll post pictures of my bikes as soon as I get the chance.
 

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What's your poison? Mine is 40:1
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Very nice, and welcome. We would love to see your projects and hopefully can help you along with your engine builds. Just got to remember to break them in well before beating on them, definitely helps with longevity.
 

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Right on I believe those have the 49cc 2 stroke CAG engine. Robbin/Subaru NB411 clone.

One of my personal favorite hobby engines like you said it's not a very reliable engine but it's simple enough with its 12 or so parts that it's easy to work on...

Like Atvrunner said a nice easy break in period is required don't use synthetic 2-stroke oil during this time to get the rings to seat in properly.
 

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Discussion Starter · #4 ·
Yeah. I just immediately started beating on the engine. From what I can tell, I'm assuming the head gasket popped. I didn't check the torques on the engine. I just dropped it in, and put it to work. Lol.

But, like I said, I'm not upset about it. I actually just pulled apart a spare engine, and putting the " big bore" kit in it. Simple enough engine. Pulled it apart in 30 minutes. Mostly because a bolt seemed to have been damaged at assembly. Took a while to get it out.


From what I can tell, when completed, this should be the same as my other engine. Might just build it, break it in and keep it on standby for another project, or for when my son kills the engine in his bike.

Here's my bike. The SYX MotoX
I've installed a 1200lbs shock that came on one of my mountain bikes. The "built engine" and a magura MT Thirty 4pot hydraulic brake. Kenda scooter tries. It's setup as a super moto. I'm kinda using the bike as a trainer for myself, and teaching my kid house to ride due to his interest in getting on the track with me

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Discussion Starter · #5 ·
The orange bike is the kiddo's. Stock engine, upgraded carb,. Broken exhaust (lol. New one is here already), better plug, stock tires, but have a second set of wheels that will have the same kendas for street riding. DNM RCP-3S shock. Perfect for him. Old Clarks EXO 2 pot hydraulic brake.

This bike has been through 4 carbs, 2 recoil starters, second exhaust (my fault, honestly), and I think the frame it's cracked somewhere. Kid still rides it's like crazy, letting him get used to riding, then probably moving to a pw50 or something for him.

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Awesome, nice bikes. Always have to take these new engines apart. I found metals shavings in one. Carb in 2 were put together wrong and metal inside.
 

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Awesome, nice bikes. Always have to take these new engines apart. I found metals shavings in one. Carb in 2 were put together wrong and metal inside.
Yes it is very common to find metal shavings and rust crankcase seals not pushed in far enough bolts that are not tight enough...
 

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Discussion Starter · #8 ·
Thanks!! These bikes are fun. I've actually taken it to the track with me as a pit bike. I like it a little more than my bicycle. Lol

Oh jeez and the metal shavings! Well, I took apart my warranty claim engine to install the big bore kit. Honestly, the pistons seem to be the same size. But, the kit piston seems to be a bit lighter thanks to the window in the piston skirt.

The kit also came with a red coil pack. Not sure if it puts out a higher spark, but it looks cool. Also, assembling those engine makes me realize that the copper gasket on the other engine might be the only problem. I'll need to red loctite there head bolts. Now I'll need to find a true bore and stroke kit for the other stock engine, and see what can be done.
 

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I believe you need a hp engine kit, the Winged Billet Head, top end rebuild. Most come with a FC crank and everything you need for around $80. Cause you have a dirt bike, that crank would work good for its low end to mid power range, but less rpms. Next, that carb Sucks, I would replace if you can.
 

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There is no real Big bore kit the biggest is 44 mm and now comes stock on all the newer engines

The sellers are literally a bunch of idiots and do not realize this it would only be called a Big bore kit if you bought the engine that has a 40mm cylinder.

All of them are simply a stock cylinder with the top parted off on a lathe...

The proper name is a two-piece cylinder kit.

Or a two-piece boosted cylinder kit ( with boost ports)
 

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Davemotors used to re-place the 40mm cyld with a 44mm cyld kit, with a 44mm/10mm piston to fit the 47cc crank, that's where the term Big Bore came from. Now some claim the 44mm cyld is 52cc when you buy an engine, they measure the area of the transfer ports as engine size, I believe. Now the 44mm 49cc piston port has a 2mm longer stroke than the Cag, like 32mm and 34mm for the piston which is 52cc, and its a better engine, that's why you see them on scooters, X1s and Cateyes.
 

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Discussion Starter · #13 ·
Next, that carb Sucks, I would replace if you can.
What carb do you suggest? I actually used these as upgrades to the original carbs that came in these engines. They work far better than the originals, and they don't run the bowl dry like the original carbs would do.


There is no real Big bore kit the biggest is 44 mm and now comes stock on all the newer engines

The sellers are literally a bunch of idiots and do not realize this it would only be called a Big bore kit if you bought the engine that has a 40mm cylinder.

All of them are simply a stock cylinder with the top parted off on a lathe...

The proper name is a two-piece cylinder kit.

Or a two-piece boosted cylinder kit ( with boost ports)
Thanks for that info. I did check to see if the pistons were the same size (they were), there is a kit that comes with a crank, piston, and all the other stuff. I was thinking of buying that kit first, but couldn't tell if I need that or not.

Davemotors used to re-place the 40mm cyld with a 44mm cyld kit, with a 44mm/10mm piston to fit the 47cc crank, that's where the term Big Bore came from. Now some claim the 44mm cyld is 52cc when you buy an engine, they measure the area of the transfer ports as engine size, I believe. Now the 44mm 49cc piston port has a 2mm longer stroke than the Cag, like 32mm and 34mm for the piston which is 52cc, and its a better engine, that's why you see them on scooters, X1s and Cateyes.
Are these the vertical engine you're talking about?
 

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Yes they are, but they mount the frame different, to hard to change from a reed port to piston port, in the old days there Cags that had the P/P. Like I said, if you have a spare engine get the 49cc Billet Wing Head Kit. Has everything you need for a whole top end re-build right off the stock cases. The kit around $80 ,has a full circle racing crank, with 5 port cyld, triangle ported piston & rings etc., and gaskets too. You can use your stock 49cc crank also, or buy a 44/10mm pin piston and use a 47cc lighter crank. I build 43cc/47cc engines now because the 44 has small channel above the exhaust port which is not good, for compression. Best carb, 16mm pumper, Walbro 16mm WT-603, or china clone, and $18 alum manifold. My new 43cc piston port eng w/ chopped cyld and ADA racing alum head w/ 13 to 1 cap, and 16mm pumper carb. two adj screw on the side high and low and a small screwdriver to tune it & it pumps gas out of the tank. no more clogged jets or float bowls and floats to deal with, its a No Brainer, lol.
 

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Discussion Starter · #16 ·
Nice! I'll have to get that kit, as I have one more engine sitting around. I'll try the pumper carb also. These other ones are pretty good compared to the originals, but a more tunable option is always great.
 

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I like the moded cag carb over the pumpers there is no diaphragm to go bad and if you leave gas in it you can clean it out really easily...
 

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Discussion Starter · #19 ·
I didn't like the factory carb. The jets were hit or miss on how big they were. Two were entirely too big, and ran stupid rich. One was okay, and it wasn't great. The carbs I've upgraded to are far better, and don't run the bowl dry like the other ones did (when the bikes could run with them). My only gripe is that the clamps keep breaking. Other than that, they work perfectly.
 

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I understand, I actually don't buy the Jets, I just redrill my own with small hand drills. Trust me, I love the pumper carbs but they're not as cheap as just modifying the stock carb.
 

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