CT70 Speed trials and further testing...

09APR2011
I guess it is time for another update. I found and fixed a small electrical mistake I made, it only cost me one bulb to find. The jetting is getting very close to being correct. Dialing in the jetting has been tougher I think since the bike never was at 100% when I have rode it, so I am always worrying that I am expecting too much from what is now a 80cc motor. I also repacked the silencer, it was partly because it had blown some packing out, and partly because I had the stuff sitting around to do it. I think a change in gearing might be in the cards soon, first gear is super short, almost useless really, it would be great off-road but as a pit bike and city runaround I think I will loose some low-end for more top-end. I rode it for the first time today in traffic to the gas station, it has been a long time since I put only $2.50 of gas into a bike.

Currently the indicated top speed on a flat is 30 mph with me riding it, I weighed in this morning without gear at 220 lbs.

12APR2011
More Mini-Trail news, I have been finding lots of reasons to run to the corner store on it for testing. Anyways I swapped out the 13t front sprocket for a rather hooked 15t I had sitting around. I figured with first gear so short I would test some new gearing. With the 15-35 gear ratio (stock is 13-35, and the first few years of production ran 15-35) I was able to hit 35mph on the flat before I ran out of road. I now plan on ordering both a new 15t front sprocket as well as a 16t on my next parts order. On the jetting front the 68.5 main seemed to be working well, but I did a test run with the 70 main and it was definitely running rich with that, so the 68.5 will go back in. The big issue I need to address at the moment is the swingarm pivot bolt. There is noticeable lateral play in the swingarm, hopefully a new bolt will resolve this. I also need to install the brake light switch and replace the tail light bulb. I burnt out the 6v bulb due to the wiring mishap I mentioned earlier and have a 12v (1157) in it now, it glows but not as bright as it should.

The bike is almost to the point of being semi usable transportation. I am now aiming for 40mph on a long straight as a top speed, I think with regearing it will be possible. To be honest I am not sure if I want to go much fast than that on this bike, the tiny 3" drum brakes are touchy at best. 

CB360 Seat and battery relocation.

Another build of mine with slow updates. I have hinted and some people of sneaked glimpses of a seat I am working on, I will show that to the masses. The biggest update is in the seat set-up and battery relocation. When I last ran this bike I had the battery mounted on the swingarm in front of the tire using the tool box mounting points. Prior to the seat being made an under the tail batterybox was fabricated. I have noticed after preview this it does not come close to conveying the time this took.





I still need to clean it up, round the corners and grind the welds mostly, and hit it with paint. Anyways it was complete enough to proceed with the tail section.

Motivated by a post I saw about making a seat, and the lack of desire to order another one from AirTech (great product, but hard to judge how it will luck before ordering) I proceeded to make one. Armed with a pile of fiberglass supplies and a KZ440 tail section I started.


Wrapped in tin foil.




Base coats.


Roughed out with the KZ tail section mocked up.


Roughed out.


After laying a bunch more fiberglass and trimming, it was time to let the dust settle.


Starting to look like a seat.


Ugly underside.


Getting there.


And another coat...


On the bike.


Primed and mounted

I am still working on working cleaning up all of the little imperfections in the seat. I plan on painting it semi-gloss black (as I have no easy way to match the Norton British Racing Green on the tank) with white numbering backgrounds and hand painted “603” (my VMX race number) numbers on it. I generally think numbering non-race bikes is silly, though I do give a pass if it is the same number of the other race bikes in a garage. I will probably have Thrasher Bill do some striping as well, nothing fancy, just the traditional style coachlines separating the colors and highlighting the numbers. I already have stick-on closed cell foam to pad the seat. To be completely honest if I was to do this over again I would have just ordered another seat from AirTech. Though I am totally happy with the seat, it would have been cheaper to buy one, that is before factoring in the countless hours of labor.

New CT70 seat...

Small update here. Over Christmas I went back east and was able to get the paperwork in order to plate this fine machine. Now I have a collectors plate on the bike. Also I got the seat back from Thrasher Bill, with its new sexy cover. Real tuck-rolled top, sweet yellow piping, and many dead naugas were used for the sweet brown covering.





Now that I have a seat again rejetting should come soon. I am looking forward to more speed trials, legally this time.

More CT70 fun...

More CT70 love here…  After reading some about a friends scooter racing adventures got my minibikes back into my mind.  The fact I am broke and could pretty much do some parts bin work helped too.  After some more reading I realized that I do need a battery for the 70 to run proper, and many hours of looking at the wiring diagram I sorted out a new one.  A lot of the work was undoing the work I did a few years ago stripping the harness.  I wired the lights back in, less the turn signals, planning on platting it after I go back to NH next time.  I’ll get the necessary paperwork from my dad and can have a silly plated CT70 just because I can.  Overall everything in this project took way longer than it will to read, or to be honest longer than it really should have.  To be fair I have been bleeding from the brain trying to keep up with my chem homework so it all works out.  Besides this is for fun, or something like that, or so I keep telling, myself.  Anyways back to the fun…


The broken OEMish set-up.


The years were not kind...

After an hour or so of looking at the wiring diagram I realized I had switchgear that wasn’t knackered that would work.  Since I had stripped the OEM stuff off of my CB360 I recycled that onto the mighty 70.  This let me play with the multimeter some to ensure I knew what all the wires did.  Not surprising for 1970’s Honda parts the casting were almost identical, I was even able to swap the throttle tube right over from the 70 into the 360 unit.  Besides having more switches to work off of I also had a brake assembly that would accommodate a brake light sensor.  Double plus awesome there.  Anyways after hours and many revisions I worked up a new working wiring harness diagram.  Besides deleting the turn signals I also eliminated the keyed ignition.  I do not have a good one to use, and even plated doubt I would really take this bike around town.  Making a wiring diagram was the easy part, then I had to draw a new one showing where the wires would go and what I could put into shrinkwrap to run from one end of the bike to another.  Another hurdle was making a battery box, since the OEM is long since gone. 


The "new" switch gear circa 1974.

After more than a few tries to weld 20ga metal with my welder (I am sure my welder can do it, I just can not) I moved to 16ga.  Last minute after some bad measuring I changed how it was going to be mounted I was able to make a workable box.  I also found that my sheet metal brake that Rock supplied as payment for work on his former KZ400 would handle 16ga.  Sorta wish I knew that when I was working on that KZ650 battery box a few weeks ago.  Anyways some paint and plenty of drying time the battery box was good to go.


Layout and bending...


Ready for paint.


Final test fitting.

Since no one has bothered to make a sealed battery for 6v bikes I stole the idea to use a security light battery from one of the Honda minibike part suppliers.  Damn near the same specs as the factory Honda battery for less coin and I can mount it sideways.

Now was the time for running wiring and checking the wiring many times too many with the multimeter.  I found out the shrink wrap I bought was the wrong size, but pressed on.  After more than a week messing with this when I had time I wanted to hear her run.  There were some more “angry moments” when I mounted the tank and messed up some of the wiring.  After that I was able to finally fuel her up and see if this whole project was for nothing…

She fired!  The carb is still grossly out of tune, but the battery did make a HUGE difference.  After minimal messing with the carb I was able to start the bike using my hand on the kicker first try, on a cold motor.  I know this is a small motor and hand kicking it isn’t that hard, but I was impressed.  I chalk this up for a victory none the less.  Still have a bunch of tuning to do, but things are looking good, this makes me happy.  There is also a good chance I will redo the wiring soon so I can shrinkwrap the wiring running the length of the bike, but modifying a running and laid harness that is proven is so much easier than doing it from diagrams I made. 

Sometimes it is the small things, not just that it is a small bike, but a project that doesn’t matter.  Things like the battery box were an engineering exercise for future projects that I know are going to come my way.  I know this isn’t the only bike I will have to rewire, and doing things correct seem to mean more to me these days.  I have the time, I am going to keep the bike, why keep doing it over and over again, when once right and that will be it.  Other than the tuning I have other things in mind for this project.  I have a café seat for a small bore bike that might make its way onto this bike.  The bars have been bent and welded too many times, but I have a few extra sets of Husky bar clamps that should work and allow me to use any minibike bar.  The exhaust will finish getting wrapped, these will happen.  If nothing else small low cost victories can make an otherwise ego hurting world of college classes and weak job market bearable.


Next project?

State of the garage address…

I have no idea how often I will do something like this, but with the lack of progress I feel I should throw general update up.  The past year or two has brought many changes to the garage and inventory.  Tooling is much better, my knowledge has grown, and the overall class of bikes has improved.  In the past two years the KTM was added, a bike that is hands down the best off-road motorcycle I have ever owned.  The Suzuki DR350 that helped me back into the off-road fold after a small break was sold at a profit.  A 1981 Suzuki GS750 16v spent some time in the garage and has happly been passed to a new home.  I also stepped into the vintage motocross scene, so far the Hammer and Tongs series.  Sadly I am now officially waving off any other racing this season due to lack of funds, the current goal it to be back for the start of next season with at least one bike if not two.  Also if I am using a two year back marker for this opening address the proud 2006 Triumph Scrambler was swapped out for a 2007 Triumph Tiger 1050i.  Now on to the bikes…

2007 Triumph Tiger 1050i:  Over all nothing but great things to report here.  The bike has served me well since day one.  After a few months of getting her properly sorted with crash bars, HID lights, hard luggage, skid plate, and hand guards she has needed nothing more than regular services.  In October of 2008 when she was bought there was just over 2,000 miles on the odometer, currently she is sitting just shy of 25,000 miles.  The valve clearance was checked and still in spec.  I final beat up the fork seals to the degree that they needed to be replaced, I also added the Moose neoprene seal protectors that have worked well on the KTM.  Pivot-pegz have started making a very aggressive foot peg for the Tiger, and the stockers have been replaced with the fine Australian Pivot-Pegz.  The stockers left a lot to desire in the wet, mainly the grip to keep your foot on the pegs.  As with anything I do have a very short list of things I want to do.  High on the list are some auxiliary driving or fog lights to help compensate for the inherent flaws in projector beam headlights on a motorcycles.  For those who are not savvy on this subject, projector beams work great in the straight line, but leave you quite literally in the dark when you lean the bike over in a turn.  I also need to wire the bike up with heated grips, this has stayed low on the list mostly to the heated gloves I have, but it is on the list none the less

1997.5 KTM 200 EXC:  As I have mentioned this is by far the finest off-road motorcycle I have ever owned.  It has made me a better rider, and really not left me much to do with her other than ride.  After the second time replacing the fork seals they seem to be holding, the fork boots are probably to credit largely for that.  I am currently working on dialing in the suspension for my weight, this is just a matter of adjusting the fully adjustable suspension.  I also plan on changing the handle bar out to improve the ergonomics  while standing on the pegs.  Other than adding a skid plate and swapping to steel friction disks in the clutch this bike has been nothing short of “Ready to Race” as advertised.

1979 Husqvarna CR250:  This was part of the pair of vintage Husky’s I bought to get into vintage racing,  This one was far more apart than the CR400 that it can with, but did include more spares.  With the engine coming already in a box I could see it needed a top end, and it was missing the carb.  I was able to get a very good deal on a 1981ish Husky 250WR with a blown up clutch.  After much waiting I pulled the trigger and bought the case tool needed to reassemble the cases and have a running motor.  Currently the transition parts are laid out on the work bench and I have a feeling the motor will be back together soon.  The parts bike also yielded a set of good 40mm forks to replace the 35mm forks that were on the 1979 CR250.  Lots of other good parts went into the parts bin to include a second set of Ohlins rear shocks.  Right now I am figuring this bike will need less than $300.00 in parts to get her race ready, be it still ugly, barring the $200.00 of engine tools.  I hope to not only have this ready for VMX next year, but also the vintage class at the Odessa Desert 100.

1978 Honda CT70:  As shown here this bike did receive quite an over haul in the past year.  Still not 100% but is very close and will be completed when funds and desire line back up.  Right now there are too many other bikes on the front burners, being I do not have a yard I can play with this bike in this will stay low on the list of projects.

1975 Honda Z50:  This was a parts bike that I picked up while working on the CT70.  After realizing how complete it is I have decided to bring it back as a runner.  No real work has been done other than figuring out what it needs.  After finding out my sisters were pregnant I was thinking of rebuilding it for my niece or nephew.  Not sure if I will do that still, keep it as another vintage pit bike, or sell it off to finance another project.  It takes up very little space, so for now it sits on the shelf torn down.

1974 Honda CB360 Café Racer:  This is another bike that I documented well during my work on the past few years.  Currently she is sitting 90% complete, I am still making progress, be it very slowly.  Right now the big project I am currently working on is the seat assembly.  I am sure I will post more pictures in a dedicated post, but pretty much I am dealing with a very time intensive ground up fiberglass build.  Other than the seat being completed, the tank needs to be coated (fiberglass and gas don’t mix well anymore), a rear brake linkage needs to be made, and the Magura lever assemblies need to be swapped out for units with the proper pull. Overall it is getting very close, but most of my funds keep getting diverted to keeping the daily runners (KTM, Triumph) at 100% and getting the Huskies back on the track. 

1972 Husqvarna CR400:  This went from a “running” basket case, to a semi restored race bike, to a blown up race bike in less than two months.  The rise and fall I did document fairly well here.  Anyways right now she sits needed around $1,000.00 worth of parts from the engine exploding.  I have a feeling I might end up getting a parts bike when the time comes to soften the blow, but this is a very back burner project right now.  I did dump a fair amount of money into this bike to get it on the track, but I have a feeling that the CR250 will be back on the track first.  So for now she sits noblely wearing number plates, with the topend off the motor as a somber reminder of the unforgiving nature of the track.

Crashing still sucks…

The title pretty much says it all, bouncing off the ground has not all of a sudden become awesome.  I would even be as bold as to say that when you do it less it seems to suck more.  Its not that I don’t chuck the KTM most times when I take it out, I do.  For the most part they are  low speed jump off the bike, riding it out into the weeds while hard on the brakes, or something of that like.  It has been a few years since I have done the out of control rag doll.  Before anyone worries too much, I am fine, a bit sore, but ok.  The KTM that I stuffed into the ground with myself is pretty much no worse for wear, there are some new stress marks on the front fender and headlight mask, but it is a dirt bike and I do not need to order any parts.  Now for what happened.

So this is what I think happened…  I was on wide singletrack (about 1-½’ wide path) and gassed it to loft the front wheel over a whoop type rut and didn’t give it enough gas.  The front wheel bounced off the top of the far side of the whoop instead of clearing it.  I am pretty sure this was the first piece of my demise.  Anyways that crossed my bars up a little, so when the front wheel came down with me still on the gas, possibly in power band still, the front end pushed a little.  I tried to stuff my right foot down to pop the bike back onto track, this didn’t feel to good, I guess stuff down a booted leg to right over four hundred pounds of bike and flesh doesn’t always work or make ones knee feel awesome.  Now with the KTM sliding out and dropping to the ground I find myself rodeo style with both feet off the pegs and my throttle hand ripped off the bar.  The front tire finds raised edge of where the trail ends and the woods start back up, the back end of the bike slides around a little bit as the rest of the moment dies.  In the split second that I am in the air getting ready to find the earth again I notice (and this stuck out in my mind afterward) that my throttle had is just sitting out by itself.  I pull my arm to my chest and shoulder check the ground, I don’t think the ground got out of my way.  From the failed lofting of the front wheel to laying on the ground probably only took a second or two, reading it takes a lot longer.  Laying on the ground with my KTM’s motor silent I hear the other two bikes I was riding with get farther away, everything hurts.  I take a moment and just lay there trying to mentally do a systems check.  For those of you who have not spent lots of time hurting yourself, pain right after impact is generally good, it means you are not in shock and nothing is hurt too bad.  After about thirty seconds my legs don’t hurt and my right side is feeling better.  After taking my helmet, goggles, and gloves off  I get the KTM back on her feet and off the trail.  My left forearm still isn’t feeling good, so I pace back in forth on the trail wiggling my wrist to see if I have lost any range of motion and feel for swelling.  Everything is pointing to me being sore for a while.  I hear the sound of my riding buddies heading my way, when they arrive I make the call to head back to the truck.  On the ride back out (dozen miles or so of trail) I take it a bit easier than I normally do and my arm doesn’t feel too bad, though it didn’t like lateral motion that much.  Otherwise the ride out was pretty drama free.

Now before anyone decides to be a smartass and bring up that crashing is part of dirt biking and I need to just suck it up, I know this and I am not griping here.  Like when anything goes awry it is always best to try to sort out what happened.  Times like these I just end up popping Advil while working it out.  I do find it interesting as well how hard it can be to work out what happened in the few second span of time that is a crash.  It makes sense that you would not remember every detail of a ride, the highlight reel normally is what sticks in your head, not the little rock that threw you to the ground.  I also have no doubt in my mind if the terrain had allowed me to ride into the trees on the right side I would not be writing any of this.  A few little things add up, you hit the ground, then all the little details get dragged out.

Overdue catch-up

So I am long over due for an update on my blog, sorry about that, I have been a bit busy.  For a quick catch up here we go, slightly out of order.  Brought the Tiger to Twinline in Seattle for their dyno day, put down the highest BHP at 107.49.  I was laid off and now I am currently a college student again working on a AS transfer degree in mechanical engineering, thanks to the GI Bill.  My roommates all moved away and I moved into my own place, just over 500sqft of living space and just under 500sqft of garage space, it is awesome.  The GS750 ran, then had oiling problems, and finally I managed to unload it on someone for $450.00.  Less than I was hoping to get for it, but still more than I had into it.  I have bought another Husky to use as a parts donor.  It’s a 1981 XC250 with a blown up bottom end.  So far the 40mm forks have found a new home on my 1979 Husky CR250, the topend and carb will be on there soon as well.  The parts from this bike should allow me to get the 250 running before the end of the Hammer and Tongs season and for the AHRMA race at the Farm.  I have also made some progress on the CB360, after many attempts I think I have finally sorted out a seatpan/tail section.  A battery box has been made, and the rest should come together nicely.  I also went to the Desert 100 at Odessa and ran the Ironman poker run on the KTM, I might do a separate write up on that, good fun.