Pocket Bike Engine Project
- Thread starter lowracer
- Start date
Well, for expense reasons, I am not building a bike. I have an old goped laying around. ATM it does 25 mph. I shall install this engine, and go FAST!
Do you know if the exhaust manifold is the same on 66cc kits, and the PB engine? I want to use a bgf banana pipe on it...
frozenveins,
The exhaust setups are pretty much the same for chinagirl engines & PB engines. I think I had to file the bolt holes slightly.
Trick is to get the gearing correct & the stan-up scooter will fly.
I hit 53 mph on my 26" wheeled MTB geared 15.6:1 using a custom v-belt pulley drive & a Stage 2 CAG engine.
-lowracer-
The exhaust setups are pretty much the same for chinagirl engines & PB engines. I think I had to file the bolt holes slightly.
Trick is to get the gearing correct & the stan-up scooter will fly.
I hit 53 mph on my 26" wheeled MTB geared 15.6:1 using a custom v-belt pulley drive & a Stage 2 CAG engine.
-lowracer-
Well it has a 55t sprocket on the wheel. Direct drive from clutch sprocket with 9" tires.
With a 7t it is 37.5 mph @ 11k RPM.
With a 8t it is 42.8 mph @ 11k RPM.
With a 9t it is 48.2 mph @ 11k RPM.
I already have those longer bolts from mcmaster (m6-1-90 speckled turqoise).
I will get 4 hundo in a couple days, so I'll hopefully be ordering stuff soon.
I wanna do the scoot (would rather a motorized bicycle) because of the law mostly. Scoots are legal wherever bikes are, mabs are mopeds and need registration, license, and only on road.
With a 7t it is 37.5 mph @ 11k RPM.
With a 8t it is 42.8 mph @ 11k RPM.
With a 9t it is 48.2 mph @ 11k RPM.
I already have those longer bolts from mcmaster (m6-1-90 speckled turqoise).
I will get 4 hundo in a couple days, so I'll hopefully be ordering stuff soon.
I wanna do the scoot (would rather a motorized bicycle) because of the law mostly. Scoots are legal wherever bikes are, mabs are mopeds and need registration, license, and only on road.
More input about these CAG engines from my experience.
I have three of them now & only one is running perfectly.
These engines seem to be hit or miss on 'Getting a Good One'.
I think that is probably why DAX stopped selling this version.
They are prone to loosening head bolts & stripping threads.
Don't get me wrong, I love 'The Beast' & wish all the Cag stage 2's were as reliable as it. Its power to weight ratio & ease of mounting (side or bottom mounts) make it the ideal engine for motorized bicycles (or scooters), but since I now have three & only one runs like it should, I can't recommend this engine to anyone on this forum.
-Lowracer-
I have three of them now & only one is running perfectly.
These engines seem to be hit or miss on 'Getting a Good One'.
I think that is probably why DAX stopped selling this version.
They are prone to loosening head bolts & stripping threads.
Don't get me wrong, I love 'The Beast' & wish all the Cag stage 2's were as reliable as it. Its power to weight ratio & ease of mounting (side or bottom mounts) make it the ideal engine for motorized bicycles (or scooters), but since I now have three & only one runs like it should, I can't recommend this engine to anyone on this forum.
-Lowracer-
The 2 that arent running too well havent seized.
One of them stripped out a headbolt. While it was loose the head gasket seal leaked & would bog out the engine. Fortunately I caught it before the engine leaned totally out & toasted the piston/cylinder. I placed a small nut inside the case to tighten the headbolt again, but since removed the engine from the bike & stored it in a box to use for spare parts.
The 2nd engine started acting goofy like when the gas cap doesnt breathe well & it bogs out the engine. Maybe its a defective breather tube cap I bought on eBay (like on dirtbikes). It sits in a box too & may end up on another bike one day, but for now my little Tanaka 32cc I bought on Amazon for $89 w/free shipping is running so well & seems like a very reliable powerplant. Its not as powerful as the CAG2 but good enough for a lightweight MB.
-lowracer-
One of them stripped out a headbolt. While it was loose the head gasket seal leaked & would bog out the engine. Fortunately I caught it before the engine leaned totally out & toasted the piston/cylinder. I placed a small nut inside the case to tighten the headbolt again, but since removed the engine from the bike & stored it in a box to use for spare parts.
The 2nd engine started acting goofy like when the gas cap doesnt breathe well & it bogs out the engine. Maybe its a defective breather tube cap I bought on eBay (like on dirtbikes). It sits in a box too & may end up on another bike one day, but for now my little Tanaka 32cc I bought on Amazon for $89 w/free shipping is running so well & seems like a very reliable powerplant. Its not as powerful as the CAG2 but good enough for a lightweight MB.
-lowracer-
Just so you know, I've been told and actually have been having experience with the DAX RT carb being bad.
Not that the carb is bad itself, but that when you find the perfect mix and put the correct jet in there, it's not very consistent. At full throttle it starts to lean out.
The problem is this carb doesn't have a separate idle jet to adjust which is why it doesn't have a good RPM range to give the engine fuel in the correct ratio.
They suggested at PB planet to use either the swirl bored stock carb or to buy the advanced walbro genuine carb.
I wish I had the geniune pocket bike CAG engine, because they are Italian made and reliable.
DAX is also selling a clone GP50 which should be like the morini engine.
Did you tighten your bolts with a torque wrench? I don't use one and I tighten my bolts pretty hard. Because I do not understand how you could have stripped your threads. Is it because it got so hot that it softened the aluminum of the engine casings and thus lead to the stripping of the threads?
Not that the carb is bad itself, but that when you find the perfect mix and put the correct jet in there, it's not very consistent. At full throttle it starts to lean out.
The problem is this carb doesn't have a separate idle jet to adjust which is why it doesn't have a good RPM range to give the engine fuel in the correct ratio.
They suggested at PB planet to use either the swirl bored stock carb or to buy the advanced walbro genuine carb.
I wish I had the geniune pocket bike CAG engine, because they are Italian made and reliable.
DAX is also selling a clone GP50 which should be like the morini engine.
Did you tighten your bolts with a torque wrench? I don't use one and I tighten my bolts pretty hard. Because I do not understand how you could have stripped your threads. Is it because it got so hot that it softened the aluminum of the engine casings and thus lead to the stripping of the threads?
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Gera,
I'd like to check out the Walbro carb. Any info you could share about it would be appreciated.
The CAG2 I have with the stripped out threads I got second hand from another MB member. I think the stock headbolts being too short put alot of stress on the few threads holding it on, especially when you tighten them down real snug.
I dont own a torque wrench & have been known to overtighten most everything.
I took 'The Beast' out for what started to be a 65 mile ride today until about 20 miles in, I broke another clutch spring. I decided to turn around & try to limp home under engine power but was unable to idle due to the dragging clutch. Then all of a sudden while I was going slow, it locked up & the v-belt friction sliding in the small engine pulley brought the bike to quick halt (like hitting the brakes fairly hard). I got the belt off the pulleys & tied it up around the handlebars & out of the way & pedaled the 20 miles back home. Then I swapped bikes (took the Tanaka rear engine bike) & went back at it again & this time with no problems.
Now nighttime, I just got out of the garage trying to figure out why I keep snapping clutch springs & the serious lockup today. One of the clutch shoes snapped in half! The other two shoe pads are worn down compared to the new ones on the other CAGs. Te clutch shoe carrier has one stripped out thread area...I decided to pilage the clutch off one of the two problem CAGs. I replaced the carrier & shoes & got some red locktite on them threads. I also noticed that my Staton double bearing clutch driver unit shaft had worn down a bit where it fits thru the bearings causing some play in the engine pulley area. I took some Magic Steel putty and filled in the area of the shaft that had worn down, waited a little bit for it to warm up (cure) & then pushed the clutch drum & shaft back into the housing and c-clip'd it. Its nice & tight as it was when it was new.
I'll take it for another spin tomorrow to see if the new clutch shoes, unstripped threads & tightened up bearing area keep the clutch springs from snapping & if I can rely on 'The Beast' for another long trip.
-Lowracer-
I'd like to check out the Walbro carb. Any info you could share about it would be appreciated.
The CAG2 I have with the stripped out threads I got second hand from another MB member. I think the stock headbolts being too short put alot of stress on the few threads holding it on, especially when you tighten them down real snug.
I dont own a torque wrench & have been known to overtighten most everything.
I took 'The Beast' out for what started to be a 65 mile ride today until about 20 miles in, I broke another clutch spring. I decided to turn around & try to limp home under engine power but was unable to idle due to the dragging clutch. Then all of a sudden while I was going slow, it locked up & the v-belt friction sliding in the small engine pulley brought the bike to quick halt (like hitting the brakes fairly hard). I got the belt off the pulleys & tied it up around the handlebars & out of the way & pedaled the 20 miles back home. Then I swapped bikes (took the Tanaka rear engine bike) & went back at it again & this time with no problems.
Now nighttime, I just got out of the garage trying to figure out why I keep snapping clutch springs & the serious lockup today. One of the clutch shoes snapped in half! The other two shoe pads are worn down compared to the new ones on the other CAGs. Te clutch shoe carrier has one stripped out thread area...I decided to pilage the clutch off one of the two problem CAGs. I replaced the carrier & shoes & got some red locktite on them threads. I also noticed that my Staton double bearing clutch driver unit shaft had worn down a bit where it fits thru the bearings causing some play in the engine pulley area. I took some Magic Steel putty and filled in the area of the shaft that had worn down, waited a little bit for it to warm up (cure) & then pushed the clutch drum & shaft back into the housing and c-clip'd it. Its nice & tight as it was when it was new.
I'll take it for another spin tomorrow to see if the new clutch shoes, unstripped threads & tightened up bearing area keep the clutch springs from snapping & if I can rely on 'The Beast' for another long trip.
-Lowracer-
Have you tried aluminum clutches? I actually bought one on ebay for only $10 shipped with springs already installed and have yet to snap a clutch spring.
Aluminum is so much lighter than steel and at IDLE rpm it doesn't stretch the springs as much as steel clutches do, which is why I believe the reason behind longer lasting springs.
You got locked up because a spring part got stuck between the clutch plate I believe.
Always have spare stuff with you and tools (Allen wrench).
I would suggest you do not rev too high. By the way like half throttle would give the DAX RT carb like full rev over time (because it just kind of sucks).
Shouldn't happen with the Walbro. Just make sure you get a geniune one from daves motors with manifold. It will cost like 85 bucks all together with manifold and gaskets.
Don't mistake yourself, because not all of his Walbro's fit cag engines.
One important thing you should do is not to run the engine at max RPMs. At like middle RPM it will still beat a Tanaka right plus faster acceleration? And it should last. You should possibly put a throttle restriction to not over rev it.
At higher RPM it just starts to lean out, which is why the engine becomes unreliable. One is not enough gas/oil at high RPM thus lacking lubrication and another reason is too much air compared to fuel mixture causing it to lean out.
Aluminum is so much lighter than steel and at IDLE rpm it doesn't stretch the springs as much as steel clutches do, which is why I believe the reason behind longer lasting springs.
You got locked up because a spring part got stuck between the clutch plate I believe.
Always have spare stuff with you and tools (Allen wrench).
I would suggest you do not rev too high. By the way like half throttle would give the DAX RT carb like full rev over time (because it just kind of sucks).
Shouldn't happen with the Walbro. Just make sure you get a geniune one from daves motors with manifold. It will cost like 85 bucks all together with manifold and gaskets.
Don't mistake yourself, because not all of his Walbro's fit cag engines.
One important thing you should do is not to run the engine at max RPMs. At like middle RPM it will still beat a Tanaka right plus faster acceleration? And it should last. You should possibly put a throttle restriction to not over rev it.
At higher RPM it just starts to lean out, which is why the engine becomes unreliable. One is not enough gas/oil at high RPM thus lacking lubrication and another reason is too much air compared to fuel mixture causing it to lean out.
Did some research & looks like there are Walbro's & chinese copies of Walbros out there for the unsuspecting consumer. I have a Walbro on my Subaru Robin EH035 & it is a great carb so I would get another genuine Walbro should the need arise. I really dont feel like spending the $ since the whole Tanaka engine as only $89. For now I'm happy running one good running Cag2 on 'The Beast' & the Tanaka PF3300 on the rear engine bike & the Robin on the other rear engine bike.
-Lowracer-
-Lowracer-
Ok, I got to test drive 'The Beast' this morning since replacing the clutch & tightening up the shaft/bearing area. I took it up to 9300 rpm (44 mph) to make sure under load there wouldn't be any clutch spring problems. All went well & I think I have the problem fixed. The main thing was the stripped out threads on one of the clutch shoe carriers. This allowed the clutch retaining bolt to come away from the carrier stretching the spring out at an obtuse angle causing breakage. The inside face of the clutch drum is noticeable scored from when this carrier bolt slid out enough to rub on it. Fortunately, the area where the shoes touch on the drum is unharmed...
(Still thinking about that Walbro carb even though right now I dont need it)
-Lowracer-
(Still thinking about that Walbro carb even though right now I dont need it)
-Lowracer-
If you think that the scoring is enough to make the bell out of balance then you should replace it or else 9300rpm will be hard on the bearing/bushing/shaft.
ThatsDax has the stock carbs for the Tanaka33 (barrel valve carb) for around $15-30. maybe get two and make a dual-carb setup.
Vachon,
The scoring isn't very noticeable & it still runs out well at high rpm's. I however do replace these inexpensive bearings once a year for routine maintenance.
Gera,
The carbs are different sizing & I wouldn't want to remove anything from the Robin for test purposes.
-Lowracer-
The scoring isn't very noticeable & it still runs out well at high rpm's. I however do replace these inexpensive bearings once a year for routine maintenance.
Gera,
The carbs are different sizing & I wouldn't want to remove anything from the Robin for test purposes.
-Lowracer-
Recently as the weather got nicer, I started using my MB's more & more for work instead of taking the car. With the added miles, I needed to start bringing more pre-mix fuel along with me. I picked up a few Two Fish Unlimited strap on bottle cages for my 3 MB's & some MSR fuel bottles. I use 18" velcro straps to secure the bottles to the cages to prevent fuel bomb launchings...lol Each 20 oz MSR bottle gets me ~22 miles (estimating 140 mpg's). The engine tank holds 30 oz without topping it out. This 90 oz will get me around any of my work routes (max around 100 miles).
I was thinking of just one large fuel tank, but I dont like the 'motorcycle' look & this way, I can plan for each trip by bringing the extra bottles or not. So far so good, as I've done now roughly 312 miles on the MB's for work.
(see pic)
-Lowracer-
I was thinking of just one large fuel tank, but I dont like the 'motorcycle' look & this way, I can plan for each trip by bringing the extra bottles or not. So far so good, as I've done now roughly 312 miles on the MB's for work.
(see pic)
-Lowracer-
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Its been awile since my last post & I made a few changes that are worth noting.
1) the stock 3 shoe clutches that come OEM on these pocket bike engines have underengineered springs & will break one day. I didnt have any clutch problems when new, but once the 1st one broke, the replacements wanna keep breaking too. I went on eBay to find a better clutch & I think I got a winner so far. For $19.91 w/free shipping, this clutch has yet to fail. I dont think the springs can snap since the 2 heavier guage springs are being compressed rather than pulled apart. The shoe material is probably going to be the wear item on this clutch & will hopefully last for some mileage (time will tell). This clutch is also touted as 'racing/performance' & has swappable springs to change the rpm engage points. I am running the stock red springs which seem perfect for spirited street riding, but ordered a set of stiffer springs just in-case. This clutch hooks up & performs well.
2) the stock hi-performance chinese carb (aka: RT) is mostly a piece of junk. I have 3 PB engines & 4 RT carbs & only one of them performs well most of the time. The one that performs well likes to drip fuel when the engine is off & I am either coasting down or pedalling up over the bridge.
I just ordered a genuine Walbro kit complete w/ADA mount & air/fuel filters & am anxiously awaiting its arrival. I'm hoping that this carb performs as well as the carbs that came stock on my Tanaka 33cc or Subaru-Robin 35cc.
I could just run the lower powered 33-35cc engines, but something keeps drawing me back to keep the pocket bike engines alive (raw power & rpm's)
See pics
-Lowracer-
1) the stock 3 shoe clutches that come OEM on these pocket bike engines have underengineered springs & will break one day. I didnt have any clutch problems when new, but once the 1st one broke, the replacements wanna keep breaking too. I went on eBay to find a better clutch & I think I got a winner so far. For $19.91 w/free shipping, this clutch has yet to fail. I dont think the springs can snap since the 2 heavier guage springs are being compressed rather than pulled apart. The shoe material is probably going to be the wear item on this clutch & will hopefully last for some mileage (time will tell). This clutch is also touted as 'racing/performance' & has swappable springs to change the rpm engage points. I am running the stock red springs which seem perfect for spirited street riding, but ordered a set of stiffer springs just in-case. This clutch hooks up & performs well.
2) the stock hi-performance chinese carb (aka: RT) is mostly a piece of junk. I have 3 PB engines & 4 RT carbs & only one of them performs well most of the time. The one that performs well likes to drip fuel when the engine is off & I am either coasting down or pedalling up over the bridge.
I just ordered a genuine Walbro kit complete w/ADA mount & air/fuel filters & am anxiously awaiting its arrival. I'm hoping that this carb performs as well as the carbs that came stock on my Tanaka 33cc or Subaru-Robin 35cc.
I could just run the lower powered 33-35cc engines, but something keeps drawing me back to keep the pocket bike engines alive (raw power & rpm's)
See pics
-Lowracer-
