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Discussion Starter #21
I believe he is removing the stock one and making his own which I believe has bigger holes for the reeds.
That's correct, the stock reed plate is a bottleneck that doesn't utilize all the available area it can while the reeds are open. Not only that but I found that the intake gasket holes are off too, causing about a 1/32" to be blocked as well. It may not seem like much but to these little engines it's quite a bit. Imagine scaling it to a car engine, it'd be like putting a restrictor plate under your carburetor/throttle body. I wish I had a CNC mill/router, I'd have this puppy done in no time.
 

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It's a 50cc 4 stroke scooter intake, I have one here modded to fit the Cag cases, it came w/ fiberglass reeds.
The big problem is adds more space to the inner cases area, that's why you put a FC crank cause it takes up more space to make more pressure. My BZM has a silver stuff crank to create less space. When a engine turns 10,000 rpms you need all the pressure you can feed the ports.
 

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Discussion Starter #26
Any updates Old Skool??
Everything's a hot mess right now, I got my exhaust, the pipe is a lot smaller than the original but it does work, not without bending it though. I got my new clutch with 7t sprocket, doesn't fit right, the old one didn't have a nut inside the drum like the new one. The new one sits a little deeper and the nut inside the drum interferes with with the clutch bolt. Now that it's nice out, I've been messing with some old mini bikes I have while waiting for parts.
 

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Discussion Starter #28
I should have stayed in bed today. I got the rest of my parts, started putting everything together and I think I messed up one of my crankshaft bearings. My tools were clean but halfway through installing the first bearing, I noticed it felt gritty. I don't know if some dirt got in it somehow or if one of the balls got scored/scratched?. I tried flushing it out with some WD40 and it still feels gritty. I started investigating the clutch issue and noticed one of the clutch shoe bolts had backed out and is probably why the new one wouldn't seat all the way, although they are different, the blocks and clutches are the same so you'd think it would go right on without a problem. Those boost bottles are some serious stuff, I thought it would be just some thin aluminum bottle but it's pretty stout. The air filter that came with the carburetor is JUNK!, not just because it's small and restrictive but because one of the fabric pleats must have pulled out when they glued it in, leaving a hole around the base of the filter. If this is the stuff that passes Chinese QC, I'd hate to see what fails!, if anything does.
 

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Did the bearings go in hard?? Sometimes I put the crank case's in the oven at 225 and freeze the bearings and then they tap right in with a large socket. Other times they just drop right in and when this happens I make sure I use bearing race adhesive to keep everything nice and tight. Other times I just don't think that there is anything I can do to make the bearings work short of useing different brand bearings or from a different lot that may have different tolerances.

If you do think it's just dirt or a metal filing or something you can always just use dish soap and rinse it out under the sink then use WD-40 ( water displacement 40) dry it off with a hair dryer then use a few drops of assembly lube to pre oil the bearings.

You're 100% correct about Chinese quality control or the lack of any sort of quality control in the end I look at it this way its the vendors fault for looking at your part seeing that is defective then to continue to package it
and ship that rubbish to you. Make sure that you always give them negative feedback if possible so other people don't have to go through the same waste of time.
 

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Welcome to Pocket Bike World, where anything can and will happen. Rule #1 never order 2 of anything at the same time cause they will give you one good and bad part. The problem is a bunch of different factories making engine parts the look the same but there not in close measurement so mount hole and stuff can be different then the engine you have, Happened to me many times before. Best to buy a new engine w. alum starter and 3rd bearing clutch housing, Then you mod those parts cause the all of them fit together. On the nut in the bell, ground it down till it clears, that's what I do.
 

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Yep, modify modify modify. Unfortunately that is our MO on these engines. On my engine thread, one bearing dropped right in and the other one would not. That was 350 degrees in the oven for 10 minutes and the bearings in the freezer for 45 minutes. The one that would not drop in I ended up having to take a bearing installer and making it work. Both are tight now that everything is cooled off. I tell you what though these bearings (PNG USA) are nicer than the Chinese ones that were in it but not as nice as SKF.
I also would probably just try to clean it and slap it in. Take a magnifying glass and make sure there's not a ton of stuff in there.
 

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Man that sucks. I know how you feel. I was working on a few of my friends bikes and had nothing but problems and thought the exact same thing. Stay the course, you will get there. These Chinese parts are fun to work with sometimes
 

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Discussion Starter #37
Welcome to Pocket Bike World, where anything can and will happen. Rule #1 never order 2 of anything at the same time cause they will give you one good and bad part. The problem is a bunch of different factories making engine parts the look the same but there not in close measurement so mount hole and stuff can be different then the engine you have, Happened to me many times before. Best to buy a new engine w. alum starter and 3rd bearing clutch housing, Then you mod those parts cause the all of them fit together. On the nut in the bell, ground it down till it clears, that's what I do.
So true, funny thing about these is, you always end up with extra "new" parts. The reason you end up with a box of extra "new" parts is that they didn't work on your current build so you save them just in case. Then on your next project, more "new" parts end up in that box and before you know it that box is full of parts that nobody wants or can use. These engines are so cheap, who's gonna give you more than $10 for that box of "new" parts?... nobody, because they're in the same boat. I'm probably going to grind the nut down just to make a few speed runs on the 7t sprocket then put it on the back burner for a while. I'm building a 20+ HP micro mini drag bike from scratch here pretty soon, not to mention I'm also re-plumbing my house so the MTA-2 will have to wait.
 

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Oh, about the reeds, some people have cut the center bar out and used a Polini reed which is square, there 2 thicknesses also. I have a couple of 4 reed set ups from ADA racing way back, $70 ea., its an alum box like a scooter with the reeds on a V like Polini. It bolts over the reed hole and you mount a pumper carb on the other end. A Cag reed port engine, w/ FC Crank. The problem I found was it added more space to the case pressure area, which defeated the crank taking up more space, or less case pressure, not good over 9,000 rpms.
 
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