Pocket Bike Engine Project

[lowracer]

Gera,
Some of the other weak links of the Cag that I've recently addressed & hopefully fixed are related to the stock clutch & RT carb. I've been having good success with the Walbro WT603 carb after many (I mean MANY) small adjustments to get it dialed in & the performance clutch (similar to a Zocchi but a cheap chinese clone). The stock 3 shoe clutches have spring snapping issues. This 2 shoe clutch has 2 fat springs that are compressed not pulled upon engagement.
-Lowracer-

 

[gera229]

Some laughs because that is like the hundredth time you post that.

But it's nice to know that it's running reliably.

 

[lowracer]

Gera,
I've been hunting for a good used Marzocchi Monster T fork for an MB project. I almost got one last night but got outbid on FeeBay at the last moment. There are some on Pinkbike.com but most dont want to fool with shipping from Canada. The Monster T is big & fat & perfect for a high speed motorized MTB. Its amazing what a bunch of high quality suspension does for handling & driveability at higher than avg. 'normal' bicycle traveling speeds. Downhill mountainbikes are expensive, but IMHO are probably the best suited bicycles to power assist (gas or electric).
see pics
-Lowracer-

 

[NEAT TIMES]

lowracer

When I was buying from BMP the 1 1/4 roller`s he sold were the freewheel units.

Bought 10 from a Industrial Supply that seems to be gone now.

Made the roller 1/2" drive shafts by chop sawing off the allen head off of the 5" shoulder bolt with 3/8" nc threads. Had the 8mm threaded clutch drums bored and rethreaded to 3/8" on a lathe so they would not wobble.

Seems soo long ago now! lol

Ron ... = my cvt drive

 

[lowracer]

Neat Times,
Those are trick!
I got 10 of the 1.25" solid ones from Jim @ BMP just before he went OOB, just in case. I'm still on the 1st one though & it looks like its new. I'm really looking forward to these new 1.5" kits from DAX & don't mind being the guinea pig for the rest of us...lol
-Lowracer-

 

[NEAT TIMES]

lowrider

Yes, nice fork. Tried to bid on some and they always went too high.

Can buy a 1978 Moped Free Spirit locally for $75. It`s a basket case, all apart with seized motor.

A few days ago I`m thinking SB told me the fork would handle a 26" bicycle wheel. Was going to use the springer fork that is already on my stretch cruiser, but the hydralic fork and headlight would be "gooder" as my lowerback is tender, will also need a suspension seat post, or a thick cycle seat. Will use my Hd Workman trike front wheel and relace a hub into the workman trike back wheel.

Ron

 

[lowracer]

Well, I guess I should rename this thread Tanaka Engine Project since I've switched engines on my only 2 MB's to Tanaka's. I sold the 3rd bike with the Subaru Robin EH035. I just received a new Tanaka 40cc today & put it onto 'The Beast'. I've only test driven it around my neighborhood slowly for a few laps to get it broken in. The pocket bike cag engines are super-powerful but super-unreliable. Most of my riding lately has been between 50-100 miles per day using it for work purposes and I just can't rely on the cag engines anymore. I will post pics & news about this new engine once I get it broken in & the expansion chamber on it.
-Lowracer-

 

[gera229]

Based on my experience with cag engines a few years back, I wouldn't even ride them 50 miles in 1 single day. I'm actually surprised it held up for you for a while riding that much. I intend on riding no more than maybe 20 miles. How many miles does your beast cag engine have now? What recently happened to it?

I heard the China clone piston port engines are much more reliable and produce similar power and speed as the cag engines. Also they can feature and electric start if you have a battery. A few people from the pocket bike forum told me that.

But 50-100 miles a day? Heck I'de only get a Japanese or Italian engine for that. You are already saving money on gas and you use that saving to get a good engine.

The Tanaka 40cc is more powerful than your other Tanaka (I believe 32cc). 2.2Hp vs 1.6Hp gives a 0.6Hp difference and seems like a lot. I'de like to know how they compare.

 

[lowracer]

Gera,
Not sure of the mileage i got on the one good Cag, but a bunch. The Cags have been fun to experiment with & the power is awesome, but not without non-stop issues. Clutch problems, carburetion, and cylinder sealing seem to plague these Chinese motors. I guess when you squeeze high HP @ 11,000 rpm's something is gonna give. Since I've never had any problems with the 35cc Subaru Robin or the 32cc Tanaka the logical choice was another Japanese engine & 40cc Tanaka for 'The Beast'. So far so good. I've mounted it & ran it for a few miles with the stock exhaust (very restrictive catalytic converter canister). I plan on mounting the expansion chamber once its broken it after running it at low loads. Here is a pic of the 2 MB's parked in the garage.
-Lowracer-

 

[gera229]

Nice, I'm looking forward to knowing how they all compare once you put on the expansion chamber. How much did you pay for the Tanaka?

Also, what was the most recent problem with your beast engine that made you decide to switch so sudden?

By the way, I heard Tanaka's have better MPG ratings than the Cag engines? True? By how much better?

Another good thing about Tanaka's is while they are 2 stroke, they are smog free and would pass the emissions test. All other 2 stroke engines would fail it. That's what's cool about Tanaka's, while that will sacrifice some power it will produce less polution so that's a plus! (Yeah I care all about the environment, I only ride my 2 strokes because it's fun lol.)

 

[lowracer]

The new 40cc Tanaka I won for $192 brand new on eBay. The 32cc Tanaka I have been using was $89 when that deal was going on @ Amazon. The 32cc is getting me 150 mpg's out on the road running it with a friction drive. The cag gets over 100 mpg's but less than 150 mpg...I didnt have a meltdown with the Cag, just eveytime i go out on it lately something happens & ruins my commute. The last thing was the clutch again. I had installed a new stock type clutch with 3 springs & not only did 2 springs snap, but two of the spring/pad retaining bolts worked loose & came off the driver. I fugured it was time to make a change & now I have 3 CAG engines in a box with lots of spare parts & a new Walbro 603 carb to sell...Any takers?
-Lowracer-

 

[gera229]

For a Tanaka that's a pretty good price for $192.
How loud is it compared to a CAG? What's the max rpm of that Tanaka?
http://www.youtube.com/watch?v=C5tnD61NOh4&feature=related
Downhill, but thing looks fast.
Also 5-7Heaven has a very fast Takana 47R with a ported and modified engine. I think that thing can compare to a CAG because that Tanaka has a max RPM rating of at least 11,500 and has a torque of at least 2.7 N.m. Horsepower with over 2.8H.P. (2.8hp is stock). He did mention it's loud, but I don't think it's any louder than a Cag with reliability as an added bonus.

Oh another spring snap? Are you still using the steel clutch?
That's the most terrible thing that can happen to anyone. 50 Miles down the road and you have to pedal.
I bet, you'd still use it if it was a shorter travel distance.

According to DAX, springs snap due to worn out pads, but that's not the case for you.
In my experience, a steel clutch just didn't work out for me and broke springs quick no matter what replacements I made.
Then I bought an aluminum ultra light weight clutch, and no more spring snapping. I guess it must be something to do with how the forces go with a heavier clutch that causes the springs to work harder to push the clutch in back together.
By the way, aluminum clutches are available anywhere. I got mines from buy it now from a Chinese seller for about $10 shipped. Very good price.

Was your new clutch aluminum? Did you tighten the bolts and inspect it before putting it on? It snapped rather quick if that was your first ride with the new clutch. Within approximately how many miles did it snap?
What happened with your 2 spring performance clutch?

How much for the Walbro with manifold? Does it leak like the RT carb?

 

[lowracer]

The Tanaka 40cc isn't broken it yet to go for a full speed run, but I can already tell that it is alot slower than the Cag (stage2). The cag pulls hard right off the line & harder on up to redline. The Tanaka is more of a utility engine w/ less max rpm.
I'd sell the walbro w/manifold & velocity stack w.air filter for half the price I bought it for (got it for like $80). It doesn't leak at all & seems to be a good carb once fine tuned with the 2 adjustment screws. The stock pocket bike clutches are junk steel or aluminum. The performance 2 spring clutch I got for it is much better but engages at higher rpm's. The one I blew up was a brand new stock aluminum arm clutch...
-Lowracer-

 

[gera229]

That's interesting what happened. My aluminum clutch seems to be holding up good so far. Might have been the springs.

Oh, the reason you didn't use a 2 shoe clutch was because it engages at a too high of an RPM?
A quick spring snap caused you to switch lol. But yeah, for riding 50-100 miles a day to work I wouldn't even bother with cags. But for short rides and trips I'd put it on and feel the power because well for short trips it's reliable enough to hold up well, plus if there is a failure you won't have to pedal as far as you would have to if it was a long ride.

I read from one of my threads where another user bought springs from a store that fit that particular clutch in a way where it made the engagement just right just like the 3 shoe clutches.

 

[lowracer]

I took the new Tanaka PF4000 (40cc) engine out for a bit of pre break-in testing today. It seems to have gotten a bit stronger than how it rode yesterday. I hooked up the rpm meter & did 2 high speed runs @ WOT for 1/4 mile each.
This Tanaka is hitting 8640 rpm's under load, no wind, aero tuck w/1.5" drive roller = 38.56 mph. Not too shabby for a 65 lb bike w/175 lb rider. (The Cag could do 50 mph which is scary fast even on this full suspension DH mtb)
Strange thing today I also had to adjust my idle rpm lower than from yesterday? Maybe as it breaks in it runs w/less friction?
-Lowracer-

 

[lowracer]

Here are a few more pics

 

[gera229]

I just noticed, you have disk brakes on both wheels. I want to add disk brakes too except it would only fit on my front wheel which is kind of dangerous if you are not careful.

 

[gera229]

I just noticed, you have disk brakes on both wheels. I want to add disk brakes too except it would only fit on my front wheel which is kind of dangerous if you are not careful.

Looks like the Tanaka is doing great.

 

[lowracer]

Gera,
Disc brakes are the way to go...
I wouldnt upgrade an older unsuspended bike to disc brakes. Rim brakes work well especially well setup v-brakes....I actually ran two of my MB's with just one front v-brake & never had any scary situations.
I sold my other hardtail MB yesterday so now I am down to just one MB ('The Beast').
I got the wheels in my mind turning once again of what to build next?
-Lowracer-

 

[gera229]

Brake pads
Lowracer what bicycle brake pads would you recommend? Mines are pretty worn out, that's how I got them with the bike. While they are still useable they are not good enough to make the bike skid which I think it's time to change the brake pads.

Front shocks
Also do you know of any cheap front handlebar completes with shocks or air cylinders like you have that will work? I'm looking for 26"-27" size tires and I believe I have 26". I never bothered with cheap handlebars because I'm afraid of their poor reliability and I cannot afford more expensive ones, but there might be a cheap one out there. Also I don't know how to be sure that it will fit my bike frame unless it's universal.

Performance Clutch mod
Hey Lowracer, btw you might be interested (I am too).

Take a look at post #149 on my thread here:
http://motorbicycling.com/showthread.php?t=33877&page=15

Looks like the performance clutch can still be the way to go without having the high engagement RPM problem with one simple change, new springs.

But what kind and where to get them will take quite a lot of testing and some money to find the perfect fit.
But hey, no more worrying about the spring snapping problem.

All the rest of the problems are so minimal that I wouldn't even worry lol, the spring snapping problem worries me the most by far and the only thing I want to solve right now.
I too have a performance clutch I got for free from the same person I got my first engine (Bigmotorsport.com).