Its the frame from this bike..........

 

Thanks. But, am I correct in identifying it as a Cag? If so, any particular model? Structurally, it doesn't look all that well designed. The weak point would be where the two tubes meet about 7" behind the head. I am considering designing and building a new frame. I need to sketch it out first and refine the design.

 

Its a true 49cc cag and for the answer to your questions :-- its chinese and thats the way they build things...None of what they build looks safe....Im 195 and the engine on it was more than 3 times the power...I rode the crap out of it and it still remains in one piece even after being remodeled with a 46cc cag reeded engine to give it more ground clearance,,,,,,....Building a frame from scratch is quite laborous...especially making a frame jig.

 

That's bad A$$! Im diggin the single shock in the rear! Good job bro keep up the good work :thumbsup::thumbsup:

 

Before





After

 

Do you want to sell that Cag piston port engine frame after you trace it, need one for this engine.

 

Just a quick sketch-up of what I have in mind. The darker area is 18" sheet aluminum as a seat support. Although, it could be done in 3/4" steel tube. The main frame spars (from the steering head to the rear axle) are left over 1.5" seamless, .095 wall, rollcage steel (as per SCCA spec). These would be strong enough all by themselves. The extra 3/4" tubing underneath is for engine and peg mounting. I figured since it's needed for that, I might as well try too get some more structural rigidity. The bodywork is just something I threw on there.

I do have another idea where the rear end is like a swingarm but no suspension. In the place of a shock would be a rigid, adjustable length linkage, to set the rear ride height and thus, the steering head angle.

Remember, this is just a quick sketch just off the top of my head and not even to scale.

 

Looks like a solid plan for a rough sketch........Looking forward to seeing it become material............:thumbsup:

 

First things first though. I want to see if the two engines I have are any good (compression test). For that I need a pullstart. So, I look at the pullstart and no recoil. Easy enough. Go to unscrew the keeper screw and all that happens is the brass insert pressed the the plastic case just spins. Ok.....Drill out the back side and knock it out with a drift. Everything looks in good shape. Guess the spring came unhooked. Now to design and machine a new center pin to keep it all in place, re-assemble and screw in the compression gauge. I wish everything was this simple

 

Sounds like youve been busy reverse engineering crappy chinese parts......you can get an all aluminum one from ebay for $20 bux shipped.....

If I needed to get a comp test real fast you could slap a piece of rag jambed into the clutch and push it across the floor too

 

The best part about that motor CAM2 is it has a kick start.

 

Where can I pick one of these monsters up from?

 

The Dax GP50r engine or the Polini 910 Carena?

 

I just grab a flashlight and look at the cylinder condition aswell as piston condition right through the exhaust port and the reed passage................

 

LOL. I was going to respond as mention that the intake side is the thrust side. I went to quote you and saw the pics that were not there before the edit. I also saw you added the intake or "reed passage" to your post. That kinda negates me saying that the intake side would see more wear than the exhaust. I have looked and it doesn't look bad. But not new either. Since I quit messing around with RD and TZ Yamaha 2 strokes, I haven't done much with 2 strokes other than R/C boat and car engines. The piston in your bottom pic looks like it has seen better days.

If all goes well, I'm thinking of building another dyno to measure these with. Not sure if it would be an engine or rear wheel dyno.

 

No when you look through the reed passage that gives you a shot of under the piston where the blow-by collects..It also gives you a view of the lower crank bearing to see if its blued.....If theres a heavy brown spot theres alot of blow-by.........That tells ya the current state of the rings if you find nothing wrong physically by-eye with the cylinder or piston through the exhaust port................

No real difference from R/c except its alot easier to tell if an engine is good or not with the reeded cag engines via visual inspection without total disassembly..............................










These are both used pistons but you can tell which one has got the bad rings/worn cylinder............

 

You're right. Yours lead directly into the crankcase as opposed to through the back of the cylinder and then through holes in the back of the piston. Mine is a piston port design which will show the thrust side of the piston through the intake port.

 

I forgot you have the pp engine..It happens when theres multiple threads with new members daily.......Those cags werent very fluent back a few years ago but when the chinese tried reviving the model they started making the pp model except they came with 33cc engines...Mine came originally 49cc as most likely did yours....... but you get the idea...for the pp engine I use a small inspection mirror at times but its just faster with my multi tip set and a rigid 18v impact gun I can disassemble the whole engine in 10-15 mins.......

Thats the fun with these small engines...Theyre simple....

 

I know what you mean about multiple threads and getting mixed up a bit. A quick eyeball check with my calipers through the exhaust port for the bore and guessing at the stroke from the outside of the cylinder, I agree, 49cc.

Although I may be new to pocketbikes, I'm confident that I know more about these engines than 80% of the others on here (based on what threads I have read so far). I started playing with 2 stroke motorcycle engines in 1978. 5 years ('82-'87) as a mechanic at a motorcycle shop (1984 AMA-CCS Lightweight Superbike Endurance champions I might add) as well as building/helping on a number of RD/TZ Yamaha roadrace bikes. Then there is, during that same time, I was head (and only) wrench on our sponsored MX racer's RM125 Suzuki from '83 to '87. NEVER a mechanical DNF in all that time. Also managed to get a restricted 30mph MOPED (pedals and all) ported and all to achieve 45mph on a flat and 50mph downhill. Myself riding at about 165lbs and clocked by the chase car. No tuned pipe either. There wasn't anything for aftermarket performance parts for mopeds back then.


While all that 2 stroke motorcycle experience is well and good, I also spent a couple years as a small engine mechanic after that. Weedeaters and chainsaws. I saw plenty of them. Those were virtually identical to what I am looking at with this engine.

On the R/C front, I only dabbled in 1/4 scale cars with Zenoah engines. Most of my performance tuning was for R/C boats. .21 (3.5cc) and .45 (7.5cc) engines. I left my airplane engines alone as well as most of my R/C car engines. Ahhh...One of the pitfalls of managing a hobby shop is that at some point or another, you end up getting in virtually all aspects of R/C. Even had a .30 Heli (Hirobo Concept 30 if I remember correctly) for a short time.

What all this means is that I just have a good head start on pocketbikes. As with everything, there is knowledge that is particular to these that I just don't know about. And that's why I am here.

 

I get confused too, that X22 with the 2 stroke, keeps throwing me, when I see an X22 I think of a 4 stroke 110cc auto trans bike.
I like the people who post; I have a pocket bike that does not run how do I fix it, lol. SpyGuy use to say , I saw a women shopping in Wal Mart do you know her??, lol.
It is hard to fix some problems over the internet without being there to see & hear. If you called your car mechanic and say my car don't run whats wrong with it, he will laugh at you and say bring it in so I can look at it,lol.

 

I like the people who post; I have a pocket bike that does not run how do I fix it, lol. SpyGuy use to say , I saw a women shopping in Wal Mart do you know her??, lol.
It is hard to fix some problems over the internet without being there to see & hear. If you called your car mechanic and say my car don't run whats wrong with it, he will laugh at you and say bring it in so I can look at it,lol.

OH, how I know that feeling. marcelo Friend of mine calls me up a day or two ago and asks "What would it take to re-ring a Johnson outboard?" I did get some more info out of him (engine size and year), found an online exploded view, and managed to give him a overview of what's involved. Then I had to ask how does he know it just needs rings, sight unseen? I got silence. LOL

 

For a used engine that has been sitting in a box for a few years, unsealed, it didn't do to bad. 82psi. Stock piston port 49cc engine. Just pulling it on the bench with one hand and holding it in place with the other, it felt like more. With a bit of run time to get everything loosened back up, I wouldn't be surprised if it came up to around 90psi.

Now to remove the electric start and gear box off the other engine and check it.

 

Most gearboxes I've come across have been packed with a thick grease, I scrape it all out, clean everything with brake parts cleaner & fill it with motor oil... Usually they last a long time but I've found a couple busted clutch bell support bearings in some really old pocket bike transmissions.

You can modify them to spin a lot more effortlessly by polishing the bearings and where the pinion gears contact the oil seals. Good luck with your's.:thumbsup:

 

If you split the cases on the other engine, get new crank seals, the OEM ones aren't to bad, but online for about $12 you can get a pair of SKF bearings for the crank, put the bearing # in the search box ( 6202 ) they have China, R&B Taiwan, NaChi Japan and SKF French, Italian, German, that right there will give you more RPMs, less friction. I get mine online, usabearingsandseals, on the .com You can also online get Stihl or Husqvarna 40 or 44mm 2 ring sets for around $10 to $12, they look like WiseCo pistons, lol. I am going to a bearings and seals store, and see if I can match crank seals and rod end bearings.

 

Before I get to deep into all of this, Are there any active racing orgs in the south east US? Searched SEPRA and SEMRA for a website and came up empty.

 

If youre gonna run a mini in an active racing org...Id show up with nothing less than one of these seeings youll hardly see any cags there...Lots of motards though................If its just for kicks,,,chinese all day....LOL..If you lived in Cali the MMUSA organization is still keeping the fun alive//..The deal is most who did run cags moved up and never looked back............

 

Contact swheels, think there is some racing in South Carolina, maybe in Florida, and maybe Mid-North East Coast.

 

Thanks for the info. I may try to get an "outlaw" group going if there is any local interest. A dozen or so traffic cones and an empty parking lot (with permission) and just have some fun. Maybe work out something with the local autocross (gymkhana) club that I use to race with.

BTW....what is the blue on the brake discs, CAM2?

 

Parking lot bashing is fun if you get the right crowd......We used to have a guy that used to organize for us...unfortunately he took ill and now hes organizing events in a different state of entrophy now...He was a really cool guy that had a passion to watch others have fun even though he was riddled with cancer........

The blueing is exactly that...In my many hobbies gunsmithing is one.....One day I was re-blueing an old 30/30 winchester and decided to dip the rotors too to see the results....LOL...It actually stayed tough for quite a while before the rear brake rotor started to wear off.....I like to use my rear brake to add drag while I keep the throttle mostly twisting.....LOL

 

Finally got a comp reading on the second engine. 65psi. Pretty much toast. If it does run, it wouldn't very well. It definitely felt like less than the first. This one will be the one I will play around with, mod wise. Provided the cheesy Chinese "chrome" bore is worth messing with. I know I will need to replace the crank just to get away from the electric start. This one also has a two shoe clutch were as the first one is a three shoe. Both are shot though as is the drum on the first. The previous owner ran it to the point to where the friction material is gone and it was just the bare aluminum on the drum. I won't mention the "milk" in the gear box. (wait, I just did )

 

you dont need to replace the crank to get rid of the e-starter...theres two ways...one way is to gut it and the other is to eliminate it.....The pawl works either way.........The difference is only the length of the bolt needed to attach it

 

You can disable the electric starter by removing the pullstart cover, unbolt the pullstarter pawl, then thread a long M8 bolt into the electric starter body and it will pop right off the crank. Then remove the magnets inside the starter housing. CAM2 has a thread here on how to remove it if ya can't figure it out.

 

Thanks, flattie42. I got it apart but, when I did I realized that the crank end on the side is tapered for the electric start armature to mount, as opposed to flat with a external threaded end like the pull start only version. I know I can get around it a couple ways but, neither are worth the effort. It would be easier to replace the crank with one for a pull start only end. (I wrote this while you, CAM2, were posting your last one)

I am going to see if I can drum up some local interest and see where it leads.

A Polini is out of the question. I looked at the prices and I could race my either my Yamaha SR500 or Suzuki vintage roadrace bikes for the same or less. For that matter, I could finish my '86 Yamaha FZ600 project. It's getting a XS650 engine, like this......

 

Nice ...Its shaped a lil like my old YSR......




If you think the Polinis are expensive look up the DM's and the Phantoms...Theyre $5 and $7 g's........

I have an 85 VF1000RR v4 in near mint condition I bought at an estate sale for $500.00 w/2122 original miles.....Plans are to fuel inject it and give it a modern twist......Til then it sits safe n sound....

 

Wow, have not seen a Yamaha twin cyld 4 stroke for decades, my friend had a 650cc I believe, they copied the Honda twin engines.

 

..... they copied the Honda twin engines.

Not really. The Honda twins had a 180 degree crank (one piston at the top and the other one at the bottom) were as the XS650 Yamaha had a 0 degree crank (the pistons went up and down together). The only thing I can think of that Honda and Yamaha twins had in common were two cylinders.

The XS650 line started in 1970 with the XS1.