Raw Racer II Teardown

Discussion in '2 Stroke Bicycle Engines & Kits' started by DXZeff, Jan 27, 2020.

  1. DXZeff

    DXZeff New Member

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    As I've not seen another one of these here, though it's possible I missed it if there was, I figured I'd share some pictures of this for anyone curious as to what it looks like on the inside. Be warned, this one isn't pretty and I would actually appreciate any input from any other owner of this engine.

    This teardown was performed after clocking up barely 25 miles on the engine. Some time was spent battling with an overheating issue and eventually having to settle on a .76 jet (I am below sea level here) that was a little rich, unfortunately this didn't help and as soon as the engine has run for around five minutes it will begin overheating and losing power to the point that it was unable to pull a trailer up a ramp - a trailer with barely 30lbs loaded onto it where my 66cc China kit has pulled over 250lbs up that same ramp numerous times, though it finds it harder now due to a loss of power of its own that I suspect is a leak in the crank case, still waiting on gaskets to tear that one down for inspection - either way, with the China kit I can get there and back and it never let me down, with the Raw Racer II I had to walk most of the way home.

    Here is a brief compilation of footage from when the engine was running;


    Now the images of its internal organs after just a few short journeys;
    [​IMG]
    http://dxzeff.com/trash/rawplug.jpg
    The spark plug is dirty, but that is normal when running rich, the China kit is set up to run rich too solely to keep the temperature down when pulling the trailer, I do expect such build up and also do expect parts to wear out faster when making these motors pull more weight than they were really meant to. There is a problem, however, the Raw Racer II only ever pulled one trailer and didn't like it at all, in fact short of a one off ride around the block when it was first put on, it never seemed to like running at all and got worse with time.

    [​IMG]
    [​IMG]
    http://dxzeff.com/trash/rawbrown.jpg
    http://dxzeff.com/trash/rawstain.jpg
    The inside of the cylinder has brown stains and blemishes, I suspect the discoloration to be related to the overheating issue. This cylinder is larger than the 66cc kits, which use a 40mm piston, and instead uses a 50mm piston, by my calculations it is a 79cc engine, but I may be wrong.

    [​IMG]
    [​IMG]
    http://dxzeff.com/trash/rawfront.jpg
    http://dxzeff.com/trash/rawback.jpg
    Piston is rather grotty, no signs of blowby, but there's an interesting little 'pinch' in the lower ring at the back and some light scoring. On the top of the piston those lumps towards the exhaust side are very hard. There's actually a strange 'pit' beneath this that almost looks like something got between it and the cylinder wall, which shouldn't really be possible unless it came from inside the engine and even then I'd expect scoring.

    [​IMG]
    http://dxzeff.com/trash/rawsize.jpg
    Annoying discovery, gasket shown against an old 66cc jug makes it evident I cannot install such a cylinder on top of this crank case, meaning not a single part from this kit can be reused - carb, CDI, air filter and most everything else was busted or had problems in one way or another, meaning it was a total waste of money.

    [​IMG]
    http://dxzeff.com/trash/rawcyl.jpg
    Lastly, I'm not sure I buy Gasbike's claim of 'increased surface area' and 'lower operating temperatures' when holding the single piece cylinder next to a regular 66cc one, that might explain those overheating issues


    So that's what the Raw Racer II looks like on the inside and how it performs. Sure it might have improved after being broken in properly, but I doubt it and don't even think it would have made it that far, every time it ran there was less power and more horrible noises and smells, a few times there was a crunch as though the gears were being skipped over as the engine would seem to lock up briefly, I never really looked into what the cause was for this as I had already decided it was for the scrap pile by then, unfortunately the camera was on my head at the time and the wind noise drowns it out on the only occasion I was recording. I don't know that the engine would sieze, it shouldn't have done and that may well have been a problem in the reduction gears, but it definitely did feel sickly. Also strangely it never really made smoke as much as the 66cc one, but it sure did smell like nitric oxide really badly and you did get smoke in the wrong place when the oil that built up on the head started to burn off.

    All in all I am not even remotely impressed, but I'd be interested to hear if anyone else is running one of these and had a different experience, like was this just a one-off bad kit or is the engine bad in general? I'm not too worried as it's not like I could reassemble it now, not that I'd even want to as this experience was awful, plus I wouldn't be able to get the gasket for it anyway as Gasbike don't even seem to carry it and we established it's larger than the usual models, wouldn't want to make my own. Suppose I should be glad I didn't shell out for the Raw Racer III with even more "improved" and "upgraded" parts included, it would have been more weight for my old one to pull along to the scrap metal bin and my friend with his electric thing would be laughing at me even more, the bastard! :D
    Ah well, cheap kit from China next payday I guess and hope the bearings on my old bike last in the mean time, that thing edged past 2000 miles on the clock a while back and its worn out, long since promised a retirement that never seems to come.

    - For anyone who didn't spot my ramblings on other parts of the forum, yes, of course I tried to fix the problems I was having, to the point that almost nothing of the Raw Racer II kit was left by the end. This is why I'm fairly confident in saying the problem lies with the design of the engine itself, because the parts on there at the end are known to work on the other bike, many of the parts which came in the Raw Racer II kit did not work on either bike.
    Sometimes I wish I'd not bothered with any of this and just kept pedaling an antique roadster there with no ability to brake on hills or overcome the weight of a trailer if it rolled back, least there were no BS claims and outright thievery involved with that. Seriously, this whole kit and the other accessories were garbage.
     
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  2. Greg58

    Greg58 Well-Known Member

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    I hate you got a bad engine, hopefully it's not a design flaw just the one that wasn't right. You have a couple of measurements wrong, the 48cc engine uses a 40mm piston, the 66cc uses a 47mm piston and like you mentioned the largest kits now are 50mm pistons. Cannonball has been running a 50mm kit for several months with no problems I've heard of.
     
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  3. indian22

    indian22 Well-Known Member

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    Yes I too regret your problems encountered with the new motor. It seems the last year I've heard more serious complaints about kit motors. My experience over the last decade with 66cc kit motors has me favoring the original Grubee stock or highly modified, so that's what I'm sticking with two stroke wise. I have two original N.I.B. Grubee engines as replacements if ever required. Though I ride daily year round I have yet to wear one out or have a major mechanical failure and that includes one that was seven years in service that I took on a 500 mile 3 day trip last Fall...no motor problems encountered on that trip either. Hundreds and hundreds of miles on this original engine without a fail.

    It's hard not to be discouraged when these things happen, but I'd suggest sticking with the original design motors from reputable vendors that stand behind what they sell, know what they are talking about and sell products that actually work. Buying lowest price typically isn't a great idea, though paying a lot doesn't necessarily mean you get a lot.

    Rick C.
     
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  4. DXZeff

    DXZeff New Member

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    Cannonball? When I search that all I seem to get are BT80s, the BT80 seems to have substantially more thermal mass than the Raw Racer II does, likely just a better design all-round. One or two results for a YD100 that seems the same as the RR2 also, but far less of those.
    You are of course correct on the piston size - what's worse is I'd literally just ordered parts for my old kit minutes before typing that out, least I made the mistake here rather than there, that would have been a disaster.

    I don't know who even made my old 66cc one, probably whichever factory in Shenzhen was cheapest on the day the distributor ordered them. That one does at least keep going, nothing major has ever happened with it, just general wear and tear that I'd expect when abusing something likely made from recycled beer cans. There has been a steady loss of power with it, but as I said, I think it's pulling air in through the gear case.

    It does seem that the more stock the design, the better, really, because even if they do break a part somehow there's an abundance of spares, especially when you've owned them previously and because in a pinch, you can just 'borrow' it from another one and also have a near identical motor to test parts on more readily. There's still a part of me that thinks I may as well have just rebuilt the old one and forked out on the 90s mountain bike parts nobody makes any more by now though. It was the latter issue that pushed me to build a new bike entirely as sourcing such parts is costly, but now I've already had to ditch one frame because of a dishonest bike shop and also one engine, though at this point as I have a functional new bike that won't get used otherwise, I may as well continue and just stay on track as engines are cheaper than said 90s mountain bike parts, and the old frame wasn't meant to be around long anyway, given it's from scrap and is quite badly bent.


    I did notice a couple of things when pulling the RR2 off the frame. Some lateral play had developed in the rod and it seems it may have smacked the piston skirt at some point, not to the extent that things are mangled, but enough to leave a slight mark on both. This was at the front, it seems something may have lightly contacted at the back too, as if the piston tilted ever so slightly, which would explain that light scoring and the weird pinch in the ring.
    I'm not sure what order events played out in, if this is the case and it's not just rough casting & machining, whether the rod developed play enough for the piston to hit things, or if the piston hit things and made the rod move laterally, but it sure would explain some of the weird noises I heard, it might even explain those few crunches that made the wheel skid for a second. Maybe dragging the trailer put too much stress on it as that seems to be the point where things rapidly declined, or perhaps the increased temperature made things go soft, or perhaps it was defective to begin with and it was only a matter of time regardless. The old one does have some play now, but it took over 2500 miles, which again, I'd basically expect to happen with the amount of load that is regularly put on that motor, the amount of known bad gas it has drank and the rough conditions it has been used in.

    Oh well, hopefully all of this Coronavirus outbreak stuff won't slow shipping down, I could always just order from Gasbike again or one of the other similar distributors, as I'm not really blaming them for this, not yet anyway, probably would shove most of the parts that came in the kit (carb, CDI, whatever) on the spares shelf without even trying them though. Would sooner not deal with BikeBerry for reasons that are admittedly rather silly - I find their YouTube presence completely insufferable, it leaves a rather bad impression. I think they're all the same really, but the rest of them are smart enough not to do that. We have some distributors in the UK, but they're usually just warehouses forwarding from China and there's never a guarantee they actually have stock on hand. More often than not they don't have it whereas the dedicated distributors more than likely do - as in, all the engines surely originate in China, but those places carry a stock of them in-house. Places like 'Happy Lucky Star Flower Fashion Warehouses' just ship it in as required in a container full of the clothes, garden furniture and God only knows what else they sell whilst using the in-house space for their most popular items.
    Ugh, bad luck has to run out sooner or later I guess.
     
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  5. Greg58

    Greg58 Well-Known Member

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    I would suspect the dings and scratches we're caused by debris left in the engine at the factory (I may be abusing the word factory here).
     
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  6. DXZeff

    DXZeff New Member

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    The engine came in pieces and had to be assembled, it was actually full of metallic dust that I tried my best to flush out with, I think, kerosene before smearing things in oil and bolting it together. Probably just as well as I've now heard a few stories of YD100's coming with the piston in backwards. Still, it's not impossible I missed a lump of metal that was hanging around somewhere despite the casting actually looking quite good.

    This tale does seem to have a happy ending though, at least for now. I'm a man of my word and bought the cheapest kit I could find on the internet again and, well...

    Now I'm not sure if the kit would usually be that plucky, or if it might have something to do with burrs being all over the inlet and exhaust ports that I opened the engine up to remove and, umm, may have messed around with things like transfer ports a little, but damn is that thing pulling hard to say it had only been running for about five minutes, wasn't even at full throttle and was into a decent headwind. Wallet is empty but another one is already on order before they sell out, so there's a spare on the shelf ready for anything that might happen down the line.

    Oh, also, this one has that nice healthy puff of smoke I like to see, no doubt you know what I mean in that there's a 'correct amount' where there shouldn't be clouds of it drifting over the road (old engine likes to do this now) but there shouldn't be none at all as there was with the RR2/YD100/whatdyacallit regardless of configuration. This to me is generally a further indicator that the new China kit is 'just running right' and can be left alone. May report back when I get it to pull a trailer, can't imagine it will have any problems with this provided the RPMs can be kept high enough for the torque to kick in - there's a point where it just takes hold and you can feel it shove the bike forwards, the old one used to do it a little but nowhere near as strongly as this. Of course I'm gonna go easy on it for at least 100 miles, sucks I'll be itching to wrench the throttle back the whole time, but I guess it'll be worth the wait as there is no doubt in my mind that this thing will sail past 30MPH without a hitch. No doubt it looks lame compared to the engines some of you have around here, but for the price I paid, I'm considering this a win - especially as it was significantly cheaper than the RR2.
     
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