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Last weekend the Carbon Fiber hardtail gas tank was completed. Initially I was contemplating scrapping the tank as the upper and bottom half’s did not fit together as well as I would have hoped. So the tank sat in pieces in a box for a few years while I moved on to other composite projects.

Fast fw to this summer I was getting pressure to finish a different carbon tank that was intended for David Rheas Monkey bike. Dave’s tank was one that was started as a learning design and composite fabrication project for the both of us as more or less a introduction to carbon fiber. Talk about learning to run before you can walk. Prior to the start of that tank neither of us had really made anything significant in the craft that is composites. So as it was Dave’s CF monkey tank has been sitting on the office wall as more of a display or piece of art. Adorned atop a pristine monkey frame, mocking me every time I walked into the room. Just another 90% complete project waiting to be finished. Maybe it was in the back of my head that if I finished the tank I knew it would leave its beloved picture framed home of my office. All that was really needed to finalize the Dave’s Monkey tank was to make the forward mounting tabs for the bottom of the tank. So with mixed emotions I made the molds for the tabs by taking a NOS monkey tank off the same display wall, masking off the areas to be molded, applied the proper mold release agents and proceeded to slather on resin and glass. The molds for the tabs were more complicated then I would have thought. Mainly because they were such little pieces. When doing the carbon layup in them it was really difficult to get the Carbon fabric to sit down on the mold. By the time I got them into the vacuum bag I was really worried that things in the layup had shifted and I would have to try a different approach. Lucky for me though they came out great. I hope Dave does something very special with this tank, it sure will be missed. Lucky for me I have the molds and can always make another.

As frustrating as it was with Dave’s tank, my own hardtail Carbon tank was in a even worse place in my head. I had two half’s that were not close to fitting together, a hole in the top for where the gas cap bung needed to be bonded, no mounting tabs and a petcock with out a place on the bottom to mount it. My main concern was bonding the two half’s. I knew in order to fit the two half’s together I would have to painfully cut and grind away areas of the bottom and top of the tank. This could have easily left gaps or not given enough of a bonding surface for when it came time to bond the two pieces together. I could either start over by reshaping the plug and take new molds or just move forward and attempt to make it work. I decided to move on with it as I learned a thing or two about bonding and fitting when I had done a rather complex Airbox for a 125 race bike. That project was quite a jump forward for me for my skill set in the terms of fitting carbon pieces together such as the doors and snorkel to the main airbox structure.

With the two half’s it turned out that I could slowly take off material from the front and back area, checking fitment with every few passes. I finally got them to fit close enough that I was confident that the bonding resin would hold them together. With that out of the way bonding in the gas cap bung and making a plate to mount the petcock were a breeze. To make the mounting tabs I used a original tank to take molds from and kept with the original design. I was thinking of changing the mount setup and doing away with the rubber strap but I began to like the idea of keeping it. Not sure if i was getting lazy but there is something cool about a strapped tank. Even more when its a carbon one. All that is left now for the tank is to coat the inside with a sealer and the exterior with a UV protective clear. I’m thinking of keeping the mat finish. It feel that it looks a little more tough then a glossy finish. That and the bike is taking on a bit of a raw look to it that I am starting to enjoy.

Dark, raw, light weight, simple, yet functional,  I guess in the terms of what you would call functional for a minibike. Yes I’m going to have to ditch the billet kick stand and side cover. Possibly the cam cover. They don’t seem to quite fit the build anymore to me. Its always a fun thing to take your time with these things as you can sit back reflect on what you have tried and think about where you want it to go. That’s about where I am at with it, however I would like to have it to the point by Oct where I can ride it to the dirtbag challenge for its first public appearance. A small goal I set not that long ago to get things moving.

Hopefully my next update wont take me so long.

Brad

So this note is really only going to cover the bars and grips, but the project is really close to finished at this point. We should be seeing it on the road here very soon. I just wanted to show what I ended up doing for a set of Grips for the Hardtail. After trying 6 different sets of grips and not liking any of them a friend was over looking at the project and suggested that I check out the Rizoma billet grips. I liked the idea of billet grips but so many of the ones that are out there don’t really fit what I’m going for. This project doesn’t really say hard core, bullet shell, flamed, scull dagger, etc. I was really close with a Kijama brushed metal cap grip set but the caps didn’t work with the internal throttle assembly I had. Plain rubber grips didn’t cut it either. The Rizoma seem to be a fit after some adjustments to their design. They have the exact style I like but they are made to work with a more traditional style throttle assembly replacing the slide tube completely. However this didn’t work for me as my billet internal throttle doesn’t quite fit the same. So i had to remove the plastic liner from the Rizoma right hand grip and do some sanding to get a nice slide fit on the throttle. I also has to tap and add two set screws to hold it in place on the throttle assembly. Below pictured is the finished product.

So I decided a few months back that it was time to paint the APE. I was waiting on the new fender to come in first and some other odds and ends.

The color is by PPG and is one thats used on some 2009 BMW cars. The prep was the biggest part of the job as there were several dents in the tank to take out/smooth out, and many hours of sanding and primer coats were needed.  I did not feel like replacing the stock decals and i decided to add some CF POSH knee guards and gorilla badges instead to the tank giving it more of a vintage racer look. I really enjoyed the painting process as I have not painted anything myself in sometime. Once all the prep work to smooth out the surfaces was done it went rather quick. Modern automotive paint is rather amazing. It shoots so smooth and flows out so well that its really hard to mess up. Even if things look a little rough at first, you can just give it a little time and things smooth out. Very little color sanding was needed and after all the wet sanding was done it polished right up with just a few passes.

Ill be paiting a Monkey tank here pretty soon and ill do a proper how to on the next one.

This picture here is just a few hours after the clear was shot on prior to any wet sanding.

“Sir is that a Ducati?”

“Is there something wrong with your bike, why does it sound that way?”

“OMG that little things got a Dry Clutch?!?”

“LOL, I heard you coming from a block away and I could have sworn a monster was going to pull up”

“*Shaking head* I just don’t even know what to think of it. *Shaking head*”

“Man your bike makes a lot of click and chattering sound for something so small!”

And the hits keep coming. Its true, the dry clutch on the mini is something many people have a hard time wrapping their mind around.  Non mini moto enthusiasts think its down right insane that there is such a aftermarket add on for a bike that is some what a novelty to them. I gather that many of the custom mini community find them elusive, over priced,  a definite bragging point and possibly pointless. On the same point I’m sure there are a ton of people out there that think a Custom mini that is capable of 70+mph is also pointless. Who cares about pointlessness. The purpose of this little note is to shed some light on some of the pros and cons of the little clickty clack HP grabbers as well as talk about tips and fixes for some specific aspects of the Dry Clutch design.

Wet and Dry Defined

A ‘wet clutch’ is immersed in a cooling lubricating fluid,  A ‘dry clutch’, as the name implies, is not bathed in fluid. . - source > wikipedia.com

The Wet Clutch

Think smooth fluid action. For the most part a smooth fluid clutch serves us best. In my opinion the biggest  upside to the wet clutch is is cleanliness for the clutch itself. The fluid keeps the clutch plates clean and gives smoother performance and longer life. Wet clutches however, tend to lose some energy to the liquid. Since the surfaces of a wet clutch can be slippery (as with a motorcycle clutch bathed in transmission oil), stacking multiple clutch disks can compensate for the lower coefficient of friction and so eliminate slippage when fully engaged.

Wet clutches, since they use some form of internal lubrication, are also prone to slippage with the wrong oil.  Motor oils with added friction modifiers can induce unneeded slippage.  Most oils with a viscosity rating of 10W-40 and above don’t have those friction modifiers, but I wouldn’t bet that’s universally true.  Many motorcycle specific oils often have a JASO MA rating which means they’ve been tested to be safe tor wet clutches.

Wet clutches can also sometimes get sticky as the oil develops a viscous bond between the steel and fiber covered plates. This often results in a “clunk” when engaging first gear, particularly when the lube is thick as when cold.

The Dry Clutch

Many motorcycle racing designs such as many of the engines that are used in Moto GP use a Dry Clutch design for ease of maintenance as well as performance. On either of the designs I have worked with both Takegawa and Daytona I can attest to this.  I can have had the clutch pack out and back in the bike in under 15 min. I’ve even done this in the middle of a ride at a stop to investigate some other issues.

Dry clutches typically have a more narrow “slip” range.  It seems that the range from zero transfer of power to full lock transfer of power happens much more quickly than wet clutches. Thus, slipping the dry clutch during very slow speed maneuvers could get a little dicey.  The bike can tend to lurch forward as the last bit of clutch locked up. The clutch feel when not properly maintained will not be a linear engagement.  If you have ever driven a farm tractor you will have a sense of what that clutch surge would be like. Grabby is how I refer to it. I would imagine with a Inner rotor, or a lightened flywheel installed it would be very easy to stall out the motor if you were not on the gas enough.

Noise its in the ears of the beholder. As far as mini bike dry clutches that I have heard the Takegawa is pretty tame sounding where as a Daytona is obnoxiously loud. Fired up next to a Ducucati with a aftermarket open cover its hard to say which is louder.

Honk, Squeak, Chirp, Squawk when slipping

To me this is the Achilles heal of the dry clutch and just a bigger reason then any for me to say that the wet design is far better for a mini then the dry. Often what happens is wear debris get on the steel plates and causes them to engage unevenly there by you get some of the terrific squaking notes. Also what can happen over time is you get a general build up of glazing from the friction plate material on the steal plates, this can also cause the added squeaking nuisance.

Going back to the Daytona these screatching, chirp noises showed up almost right away and for a while I thought there was nothing I could do about it, perhaps just a issue with the design. The action on the clutch was also very poor, it grabbed so darn quick it made it almost useless for a street application. I tried to contact a few of the guys in Europe that I knew were running the same or similar clutches. People running the Takegawa versions were not seeing the same issues as I was or maybe they just didn’t want to say that their precious clutches had any issues. I did find a few guys running the Daytona dry clutches and all of them mentioned that they were having the same issues as I. None of them had any suggestions as to a fix.

One friend of mine was able to offer a suggestion. Liam Shubert who at the time was working on the Pracmic Moto GP team told me of a product that they use on the Duacti GP bike dry clutches called Molykote D-321R. Which is a spray on dry anti friction coating much like anti sease. He said to pull the friction and steel plates out and give them a good once over and  I would be good to go.

Molykote worked wonders. All the gripes and issues I saw went right out the window. After the first time I applied it the action was smooth, no chirping, and still grabbed like nothing else. I have since now only had to reapply it once in the last year and this last time I also cleaned the steel plates of any glaze by using a little brake cleaner and a scotch bright pad which is a tip i got off some Ducati forum. On my other bike that has the Takegawa dry clutch I eventually did notice some chirping sound and used it on that clutch as well.

To apply Molykote to a dry clutch remove the plates from the basket and hang them up in the garage. For sparying  give the plates, both the friction and the steel a twice around with the spray can and let them all fully dry in the sun before reassembling the clutch. That’s it. My only other tip would be to be careful with the pressure plate. Make sure to loosen it evenly in a crossing pattern a little on each bolt at a time. If you loosen all the way on one and non of the others or three and save the forth for last you risk breaking it by having all the spring pressure being held at one small point. I haven’t seen one brake on a Takegawa or Daytona unit but I have seen a pressure plate on a Honda NICE 110 clutch break in this manner.

So far Ive worked the Yoshimura MJN carburetors on several different motors. First was a MJN-TM24 on a 95cc (54mm bore) race head motor, then the MJN-TM26 on a Takegawa 115cc upright super head, and now I’ve begun working with a MJN-TM26 on a 124+R. I thought it might be time to put some of the settings down on paper.

A little back ground on the motor. Its a Takegawa 124+R motor that I original put together for my ZB project. When I had it in my ZB I was using a Keihin PWK28 D Slide carb and Kitaco intake. I always thought that the PWK28 was a pain to tube and was quite possibly too big for the motor. I did never really have it tuned to my satisfaction. The motors bottom end case set was an original ZB50 case that I installed a Daytona 4 speed in. The head is un-ported at this point and no finishing work in the ports either. Ignition is still the stock ZB stator and fly wheel. For gearing the bikes currently running a 15tooth front and a 28thooth rear. The intake I’m using a G-Craft 37200 swivel type billet intake. A cool function of this intake is it allows you to position the carb in various orientations. For example in the picture below I have it kicked way out to the right side which isn’t where I left it but just gives you an idea of its capabilities. For comparisons the test bike (monkey) was the same bike I had the 95cc in.

G-Craft 37200 intake

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Here are the settings for the carb that I ended up with after  30 to 40 minutes of tuning and adjusting:

MJN-Tm26 base line settings for Takegawa 124+R

Main jet 120

Pilot jet 25

MJN needle YA 3rd clip (middle setting)

Air mixture screw 1 turn out.

I’ve had the motor out for 15 miles of testing in 75 degree weather temps over the weekend. I saw absolutely no throttle hesitations or bogging, and under heavy decelerations there was no cracking or popping noises coming from the exhaust. Even with the bikes extended swingarm the front wheel went skyward on several occasions just getting on the throttle from a dead stop.  Under load the engine seems fairly well mannered but upper mids might be dropping off a touch more then they should as i could feel a second pulse of RPM pulling a little harder towards the tail end of the power band.  Only a AF meeter could really tell me the truth which I hope to test with soon.

Below is a table with some other useful baseline settings for different motor tunes. Some collected on the web some were provided in Various Yoshimura documentation. The first three are from my own experience.

One piece for the Chaly that I knew wasn’t really available was a intake that allowed the bike to run a Kiehin FCR28 down draft carb. Ive seen many others in the Euro and Asian Pacific scenes do it some with just a piece of rubber hose and others that I couldn’t really figure out how they heck they mounted it. Sometimes a pic isn’t really worth a thousand words I guess. The Kitaco intake that’s available is rather short and doesn’t really work with the Chaly frame so that one was out.

I looked into seeing if it was possible to just modify a existing scrap intake out of the Box-O-left overs by cutting a adding a section, but going that far into it the decision it became clear to just make a intake from scratch out of some 6160 plate and a piece of 6160 tube. The process was first to make a carb flange out of the plate then figure out how to weld a section of tube to it with out collapsing the tube with the heat of the tig. I wont take credit on the welding nor on most of the work, a friend Mr Stegman took on the task and pulled it off quite well.

The flange ended up being more then double the thickness then that of the wall of the tube. Add that to the complexity of it being a tube to flat plate angle, the tube being at a angle and at a slight rotation. Then double it cause there is a flange on both sides of the intake. Some test runs and internet checks concluded that the flange plate would have to be preheated in order to get the tube to weld up with out melting.

At this point all that’s left is to port out the ends and add some tapped holes for the carb mounting side.

From the last time we’ve updated this site about the APE project, we changed out the motor to a XR100 Motard engine with a Takegawa 115 super head dry clutch motor. Since then a good amount of time on the bike has been spent testing the limits of the suspension and brakes. At Stockton Motoplex a cart track setup for mini moto racing the bike sure showed where its alkalies heal was and that was suspension and ground clearance. It might have done better with a lighter rider but in most of the turns the stock rearsets would touch and to keep the bike from leaving marks all over the track the bike was kept at a slow pace for the day.

On the street it is always a different story then then a tight course track. The real limit there was also suspension but also brakes. I never mind leaving a peg gouge on the open rd but still its always nice to be able to lean the bike harder and brake deeper. Read the rest of this entry »

So there are a few things that seriously seem out of place on a modified hardtail build. One of them at least for me is the welds. Honda’s early welds look like they were actually performed by trained monkeys. If you have taken a close look at a early Z50a you will know what Im talking about. Sure these are great to leave well alone with if your building a points restoration but they have no place on a restomod build. This is one thing Ive been spending much more time with then I thought I would. At first thought of powder coating the frame, but getting everything smoothed out for powder coat could have sent me to the loony bin. Believe me I tried at first but ended up changing my plan and in turn ground out as much as I could and smoothed with filler. All the added tabs and joints now have a seem less look to them. Enough to make a vintage show judge cry, which is just what im looking for with a custom frame rework.

The headlight ears were taken from a Yamaha RD, and were also smoothed on to the fork legs giving them the look like they came out of a single mold.

Ill be sad to see this project go as its nearing compleation. Its going up on the selling block as soon as its finished.

Who likes yellow anyhow? I dont!

The chaly was one of my favorite minis, but from the beginning i knew i would have to have it painted. Well that time has come. Its been at the painters for a few weeks now and some initial pictures are starting to come in of it in its new glorious paint scheme. Some may disagree but i think isnt much better then a candy purple Chaly.

The fenders, headlight bucket and tail light piece were done in white so it will be that comon two tone design, with some added pin work.

I didnt go crasy and cut and fill the seams to have it all smoothed out, just too much work for that. Looks cool, though.

here are some of the intitial paint work pics. Ill update in a week or two when its finished up and the bikes back together.

Well its hard to really put down my first impressions of the APE50 on paper. Ill just say it left lots to be desired, but then again im tainted with 124+r and Honda nice engines so a stock 50cc horizontal was down right funny at best.

As I mentioned just earlier when the bike was picked up I had a line on a proper motor rather quickly. The new motors out of a XR100 Supermoto mini and has been fitted with a Takegawa 115 superhead kit and a dry clutch. Well the other week it showed up and with the Help of my buddy Greg we had it swapped in last weekend in less then a hour. However it took us another two hours to hunt down the right cables or make modifications to get the stock clutch cable to work. Oh well, more info to add to the memory banks i guess.

The first short shake down ride quickly let me know that the stock gearing was no where near enough. The 46 tooth rear sprocket gave me about 35mph in 5th. haha funny, not really. Luckily Greg had a extra Zb sprocket that did the trick for the rest of the day.

All in all I’d say the Ape handles its on on the twisties, but it really could use some upgrades suspension and brakes.