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Discussion Starter #21
CAM2- Wow, I'm just noticing the cylinder studs y'all have been using on those builds, I knew they looked funny, now I get it. We'll have to find the metric studs or buy threaded rod now to stop them cylinders from walking about as you suggest, I've read about the movement, couldn't remember the solution.
I'll invest in the better bearings and seals you suggested, I've replaced my wrist pin and crank bearings on this one, just the wrist pin on the cag build, so far my seals look good, next time they'll get new ones.
I'm guessing the center divided transfers aren't so great? I'll have to compare some pics when I open our cag up again, maybe hack that as well.
 

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Discussion Starter #22
This bike is still giving me troubles!!

I've rebuilt the carb, used new gaskets with copper spray and mating surfaces matched, new fuel hose clamps so no hydrolock but still won't run under load. Fuel is good, filter good, plug/spark is strong, no other restrictions, I'm at a loss...

I'm wondering if I should get my backup piston kit ready and try that, or maybe pop in some new crank seals, there's nothing else I can think of.

CAM2- can I get the item #s for the crank seals you use on the PP cases?

I was thinking about using our stock carb off of the x7 for closure there..Is there anything else I should try?
 

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Discussion Starter #24
Wow PB56, you're feeding that thing well!
I'll have another try with the stock carb, we wondering about other carb options, heard the walbro 603 was one. Looks that 19mm would be something I'm more used to as opposed to the pumper carbs, also wouldn't be needing to order rebuild kits all the time.
Mr.K.-I'll also dig into the leak down test if possible, I do have a guage I think of some capacity, just never tried to use one..
Maybe I'll get lucky and get the figured out before tearing the engine out/down again, those threads are feeling it and need better hardware all around..
 

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This bike is still giving me troubles!!

I've rebuilt the carb, used new gaskets with copper spray and mating surfaces matched, new fuel hose clamps so no hydrolock but still won't run under load. Fuel is good, filter good, plug/spark is strong, no other restrictions, I'm at a loss...

I'm wondering if I should get my backup piston kit ready and try that, or maybe pop in some new crank seals, there's nothing else I can think of.

CAM2- can I get the item #s for the crank seals you use on the PP cases?

I was thinking about using our stock carb off of the x7 for closure there..Is there anything else I should try?

Your compression was awefully low I suggested you warm it up then do a compression test.....That will tell if your cylinder is worn out or not....

A cylinder doesnt have to look wiped out...It can be gently run and have all the chrome plating worn down.....Without a dial bore gauge its pretty hard to detect.......

Get yourself a new topend kit w/new crankseals or just buy another engine.......Theyre cheap either way.........

As far as crankseals I use AVX brand........

Smaller seal
Thinner low drag seals are # TC12x22x4

Thicker heavy duty style are # TC12x22x8

Larger seal ..........................# TC15x30x7
 

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I'm guessing the center divided transfers aren't so great? I'll have to compare some pics when I open our cag up again, maybe hack that as well.
If you know the rules of fluid dynamics and how to increase velocity by stepping down the passage theres ways to modify and utilize the split transfers for the greater of good in all depts also to mention that the cylinders doesnt have that lil cavern for the sparkplug either......

This is my scooter transfer port....With the split transfers you can raise one to stagger the fuel timing to give it a progressive opening and closing........

IMG_20171021_225702024_HDR.jpg
IMG_20171021_225709152_HDR (1).jpg

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Screenshot_2018-10-10-09-22-53.png
 

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Discussion Starter #27
Hell fire, that scoot looks like my kind of ride!
We've got two retro kick-n-go scooters that will get a couple 23cc donar weed wacker engines for this winters's projects, I've not seen that exact mock up yet, hope it ain't too difficult.

I'll warm the bike up a bit and check the compression as you suggested, I'm not familiar with the specs, but cold it was border line no go..

We'll have to do some stuff like that on the next cylinder, or replacement engine.. on that note, I finally figured out the "63cc olive shaker" I've just read about, thought it was a nickname not a real tool. Does this engine have the same footprint/ bolt in? I've seen them in leaf blowers so been scoping the used ads, where I have just seen a 79cc that looked like it was the same PP engine, would this be something different?

Darn it if this budget build might not make it to completion, the bank is almost tapped for fun stuff. I'll start weighing the options jug vs new engine vs rebuild something used from the classifieds.

Thanks for the help y'all!
 

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Hell fire, that scoot looks like my kind of ride!
We've got two retro kick-n-go scooters that will get a couple 23cc donar weed wacker engines for this winters's projects, I've not seen that exact mock up yet, hope it ain't too difficult.

I'll warm the bike up a bit and check the compression as you suggested, I'm not familiar with the specs, but cold it was border line no go..

We'll have to do some stuff like that on the next cylinder, or replacement engine.. on that note, I finally figured out the "63cc olive shaker" I've just read about, thought it was a nickname not a real tool. Does this engine have the same footprint/ bolt in? I've seen them in leaf blowers so been scoping the used ads, where I have just seen a 79cc that looked like it was the same PP engine, would this be something different?

Darn it if this budget build might not make it to completion, the bank is almost tapped for fun stuff. I'll start weighing the options jug vs new engine vs rebuild something used from the classifieds.

Thanks for the help y'all!
The olive shaker engine aka EVO replacement has a unique mounting that uses the clutch mount area to mount it to the frame aswell as the 2 speed transmission.........If your handy it can be done........

This is the lowest and the best bet for your situation.............

 

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Discussion Starter #29 (Edited)
Okay, I warmed the bike up to check compression, which looked a little lower then compression checked cold, but my tester bit the dust and won't hold the reading anymore, I'm purchasing a new compression tester.

Here's what I now think is going on..
Looks like my cylinder has a crack above the plug hole, there's a leak of combusted black fuel leaking from around the top cooling fin. I might be wrong, but looks so from outer inspection, I'll tear into the top end again here shortly. I've got a new cylinder ordered for $15 plus shipping, and I've already got a new piston/rings/bearing/clips.

So it looks like I'll begin anew with full potential to build the high compression speed racer this thing should have been. I'll go over the same CAM2 prescribed treatment to the cylinder when it arrives, hopefully that will do the trick.

Updates next week, thanks for the support.
 

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A cracked head is a really rare problem on these engines

You would have found that crack sooner doing a leak down test but hey it looks like the headaches over I'm happy and glad that you have found the problem

One tip on your compression tester you want to use the shortest hose possible on these small engines.
 

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Discussion Starter #31
Yeah, I've got the 40mm piston, hope I get the correct cylinder sent. Most often I've gotten something different than pictured, I'll contact the seller and get a discount if it's different model but still works as quality has been getting worse. Most problems have been with rivets instead of bolts so items aren't serviceable, there's not much difference in most of these PP cylinders I'm thinking, should be in business next week, fingers crossed..
 

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Discussion Starter #32
I had a go at the new cylinder yesterday, wasn't the prettiest for sure, the welds inside don't look great.
The intake manifold looked like crap from the start and I'm sure I added some nicks while using the dremel, but tried to clean it up.

I went big on the transfer ports, and did the case matching and light porting.



Lightened and polished the piston, shined the wrist pin and bearing, and drilled lubricating holes for the wrist pin (seen that on a piston I ordered and returned lately).

Put it back together with a .025 base gasket for sanity sake, I want to rule out a leak there, the mating surfaces ain't perfect..My new compression tester hardly reads compression, though I think it's just the new guage, hadn't got to confirm on another bike.

I'll mix up some gas for break in this afternoon and see if it'll run!
 

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Right on looks like it's going to work!

on the compression tester if it has a long hose it won't read very much compression because a 44mm cylinder doesn't have enough volume to fill the hose you're going to want the shortest hose possible or modify the compression tester so there's no hose at all.
 

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Wow... I had no idea the tuning with these engines got so involved! My Raco 1/4 scale RC uses the same (I think?) engine so now I have some good ideas on how to make that even faster!

I'll be stealing a lot of your mods for my own X1 once I tear into it. Where did you learn all this stuff? Are/were there how-tos online somewhere? I never could find much when it came to actually modifying these correctly!
 

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Discussion Starter #35
Most everything was learned here in the forum from CAM2, and used to have fun and learn a little from ScullCam videos.
Here's where I got started:


Read through that to get some specifics, my thread may show some problems that may arise..
 

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Some of the OG modders are Boosted306 Mexicano Cam2 EPR and there have been a lot of other really great modders as well.

Thanks to Boosted we have the boost ports and it's many possible configurations...

a little history is most of these modifications are actually modifications that they used to do to chainsaws back in the 70s and 80s but are still doing today these saws are called hot saws and there are special competitions that they do with these hopped up chainsaws.

Around 1999 pocket bikes hit big in the US (they even made video games) you could order a Chinese pocket bike for $200 and you and all your friends could race.

Of course when racing gets involved everybody wants an edge on the guy next to them pocket bikers started seeking out chainsaw shops for modifications to engines internally and to find sneaky ways to increase horsepower without affecting the outer look of the engine.

These modifications quickly got out of control this is the peak of pocket bikes in the US and fights start breaking out at tracks even getting to the point where if a racer was questioned about modifications they could be forced to take their cylinder off after winning a race to prove that they were not cheating.

Of course with all of this popularity the aftermarket companys started getting involved aftermarket two-piece cylinder kits crankshaft clutches just about everything you could possibly think of.

it was big if you didn't have a pocket bike you wanted a pocket bike it was common in Seattle to see six to eight people deep riding pocket bikes down the sidewalks but with anything that's overly fun there are those few people that ruin it for everybody and we all know what happened then Karens started calling the police the police start impounding bikes and ticketing people got out of control there were crashes lawsuits insurance for race tracks went through the roof and pocket bikers became outlaws.

Nowadays even riding a pocket bike in a parking lot without special written consent from the owner of the lot can get you a pretty hefty fine and your bike impounded 😓 yet pocket bikers are so devoted that we are willing to jump through the hoops to be able to have a little fun 😁
 

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Discussion Starter #37
Anyone here have the source for these gaskets from old PBU (I think they're closed now)?

Is there a Euro model bike I could search for, I can't seem to find the info? I've seen the cag base gaskets but can't seem to find any that fit the piston port.
We've got the two X bikes that could use these and the .005 would be close to base gasket delete without the uncertainty, I think the first time I tried the delete, it looked like the fuel was creeping towards a leak situation. If I tear these down again I'd rather not have to use the .025 sheet..

Thanks again for all of the support!
 

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I have been completely deleting the bass gaskets for years and I have never had a problem.

I use a fuel resistant RTV that is designed for joining motorcycle crankcase halves together hondabond and yamabond are a couple of them I have also used some from the auto parts store I found with the other gasket sealant and silicones that has a picture of a motorcycle on it.

Prep both surfaces I spray a little bit of brake cleaner on a paper towel and wipe down both mating surfaces.

I then put rubbing alcohol on a paper towel and wipe down both surfaces.

I do not put any assembly lube on the Piston or cylinder.

I use reverse thinking on it less is more a very thin layer that just covers the surface so you can't see through it to the aluminum on the cylinder side.

I put it together so that there is minimal torque on the head bolts just enough to start to compress the lock washers.

I weight about an hour and then torque the bolts down you should have very minimal ooze out yet a tiny bit of ooz out all the way around tells me that I have a 100% no leak seal

After about 24 hours of sitting I drop about five drops of three in one oil down the spark plug hole then gently spin the engine over a few drops on the Piston through the exhaust port and she should be ready to go.

Copper gaskets are no good the copper does not compress and if you have a scratch or nick it will leak where are RTV will fill these imperfections
 

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Discussion Starter #39
Right on, tedious process where preparation is key and good product. I still need to try the studs and lock nuts, will look at the local hardware store tomorrow
I was using some stuff recommended for my Buell base gaskets, Hylomar Blue, but it's non-setting and may not be as good. I'll dig around for some options, the permatex MotoSeal doesn't take so much heat, haven't compared the Yama/Honda bond but have the Honda assembly lube and like that.

On a sour note, the ran the bike for a few break in cycles and guess what...? SAME bogging and dies given any load 😪.

Maybe it's the carb/fuel delivery, but it's freshly rebuilt and seemed like it's operating properly while on the stand. I'll have to try the x7 carb to rule that out once and for all, I'll have some extra time this weekend.

I'm not that experienced, but my thoughts are the crank seals might be leaking. I installed new crank bearings, but the seals I cleaned and replaced the same no name ones. I could have installed them a bit off, or they possibly aren't good anymore. I haven't got the leak down test kit yet, nor have I reinspected the seals since the first failed rebuild, maybe third time will be the charm like our Cag-dirtbike...

I'll order the seals tomorrow, better safe than guessing on a inexpensive solution, maybe I'll find a good coupon and hit harbor freight for a leak down kit.
 

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A leak down tester can be anything including a basketball pump from the dollar store. Seal up your intake and exhaust with anything some plastic off of a bin trimmed to shape with some RTV gasket sealant to make a couple quick block off plates spray it down with a mix of dish soap and water about 50/50 and start pumping it up with the basketball pump through the spark plug hole just let the bubbles show you where the leak is at 😁

If you don't find a leak I would start pointing my finger at the carburetor or the ignition coil.

I had a problem with one of my CAG engines and a partially clogged jet that kept my head scratching for a few weeks...

For the most part when they run good on the stand but then under a load they want to sputter out and die means it's going lean either from a carburetor problem or a vacuum leak.
 
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