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chktm's blog
Posted by chktm | Aug 11, 2014 @ 05:38 PM | 1,479 Views
After fitting the foam insert that came with the front baja tyres I felt it was a touch soft in general. It held up for about 15 runs on my brutal track ( a std Atomik one lasts approximately half that ) before it was almost cut up. I've made up an insert out of the harder ones that came with the rear baja tyres. It is quite firm so we will see how it goes. I did have an issue with the tyre going out of balance quite badly due to pulling the inside edge of the bead in a couple of places due to it not seating correctly I think. The outer bead stayed in place but the tyre got noticeably wobbly and the sidewall seemed taller in spots. While installing this next insert I ended up fitting the tyre as I had done with the knobby, by fitting the tyre onto the rim with the screws only a few threads in and then pulling the bead out all round the tyre and refitting it rear most edge under the ring then pushing it down to seat the outer section. Doing each segment of bead at a time. This was quite easy to do as its a better fit compared to the knobby tyre and stayed in place while tightening the screws. I had a go of the bike on the driveway and it drifted brilliantly and threw massive roost. Even on the grass it had plenty of grip, maybe even more than the knobby tyre. I made up another fender saver for the RC4 bike also.
http://www.rcgroups.com/forums/newup...1d1415c91f23aa
Posted by chktm | Aug 08, 2014 @ 09:16 PM | 2,085 Views
I've seen this used on road bikes and it has been discussed before. I've been meaning to do something for quite a while and finally got around to doing it. I have been using no wheelie bar or wire for about six months and found I liked the handling better than the RC4 bike with the wire wheelie bar. I always felt the less weight you could have swinging off the rear of the bike the better and the steel one waggles around making things worse. Also one day I might get back and do some racing against the SC trucks and this should reduce any chance of a wheelie bar being bent into the rear wheel in a crash. This has some give but is very strong and has good memory to rebound into place vs steel. Its 8mm nylon.
http://www.rcgroups.com/forums/newup...203f312c956d8d
Posted by chktm | Aug 08, 2014 @ 06:09 AM | 1,557 Views
Thoughts on tyres

Just a few things worth mentioning about making these tyres. The knobby rears did rub on the chain initially until it rubbed them down. I thought maybe next time I'd make it a little thinner but its already fairly low profile and this would only make it lower. I think the knobs it knocks off are more so on the side of the tyre so its not a big issue. These knobby tyres work well on grass and probably loamy or moist dirt, they also work well on dry hard packed but on that surface lifespan will be short. It seems the tyres made from the front ribs are more suited to dry hard and rough surfaces as they will last longer I think and also have a taller profile which should work better through bumps. They do seem a slightly softer compound also meaning a little more grip on the slick dry stuff. The handling is a little different to the stock tyres, not worse, just different. The bike corners well at low to mid speeds but doesn't want to turn as well at high speed under power I found. I didn't find this to be an issue at all, it was just something I noticed. It did seem to right itself and straighten up quicker under throttle also. The main thing is this gives MM owners a viable option for a few choices of rear tyre, awesome. Here's a few pics of the knobby tyre and the insert I used in the ribbed tyre and how it started out and a little vid of the knobby tyre on the grass.
http://www.rcgroups.com/forums/newup...df59a1b3d3aa37
RC4 replica rear baja tyre quick test (3 min 46 sec)

Posted by chktm | Aug 08, 2014 @ 03:22 AM | 1,647 Views
Gluing baja tyres

The next step after cutting and prepping the two halves is to take the strip and on one edge put a drop of glue then position the strip halfway across the tyres inside edge and hold till dry. I make the strips natural curve match the curve on the inside of the tyre. Marking the middle of the strip with a biro may make it easier to make sure it starts well centred. Working my way around I'll put another drop and keep gluing the strip until it meets. I make the strip a little longer initially then cut to fit once close to finishing gluing. Make sure not to use much glue in this step, just a drop at each point, I hold the tyre upright to apply and allow it to run down the strip in the direction you are working your way around then place the tyre face down to position the strip. Also don't pull on the strip and make it stretch at all while gluing it. The first tyre I overlapped the edges of the strip by a few mms. This tyre I cut the strip perfectly to butt each edge together. Once the strip is in place position the other half of the tyre into place. Pull a section slightly apart and apply a drop of glue then quickly slip it together and hold between your fingers till its dry. I try to hold the tyre straight or with a slight curve inwards when doing this. I'll go to the opposite side of the tyre and do the same. Next I'll do each section in between and then each between again. Once its this far I'll go around and open up the bits that haven't been glued yet...Continue Reading
Posted by chktm | Aug 07, 2014 @ 04:14 AM | 1,688 Views
This is how I did my tyres, any suggestions or ideas are welcome. This is the first part of cutting the tyres and prep for gluing, next part will be when I glue them.

Bits used

Tyres I used KM-P-RWD01 rear knobbies
KM-P-FWD01 front ribs ( I used some King Motor ones that came fitted to rims with inserts as I figured I could try using the inserts at some point)
Bicycle tube
Loctite 406 cynacrilate glue
Large sharp scissors
Hobby knife
Detergent
Scrubbing brush
Mentholated spirits
Clean rag or paper towel
Patience

Making sure to cut the side closest to the bigger diameter bead take the hobby knife and put a small slit in the tyre close to the rib but not directly in line. Using the scissors now and lining the back of the blade up with the rib, cut along as straight and true as you can. Try to use most of the scissor cut but not starting right at the back or going right till the tips come together. Once you have your two halves cut, thoroughly wash with detergent along with the rubber strip cut from the bicycle tube. I cut mine about 14mm wide and as long as needed to cover the circumference of the tyre. Allow to fully dry. I use some metho on a rag or paper towel and drag the strip of rubber through to clean it as thoroughly as possible even after washing.
http://www.rcgroups.com/forums/newup...0b657c08f36336
Posted by chktm | Feb 21, 2014 @ 03:17 AM | 2,594 Views
Some footage and pics from a quick spin on a part of a trail I ride my big bike on to see how it looked. I'd like to get more footage from more of the trail at some stage.
Ken Roczen replica MM450 trail ride test (3 min 13 sec)

http://www.rcgroups.com/forums/newat...0cebc361468d40...Continue Reading
Posted by chktm | Feb 05, 2014 @ 06:36 AM | 2,260 Views
I drilled a few holes in the flywheel in my RC4 bike and mounted the lighter of the two weights that came with the Phantom.
Ricky Carmichael replica MM450 slow mo track work (5 min 29 sec)

...Continue Reading
Posted by chktm | Jan 24, 2014 @ 10:09 PM | 2,190 Views
Here's a few vids of a couple of recent runs around my tracks. Some slow mo in the last two.
Ken Roczen replica MM450 fast laps (4 min 20 sec)

...Continue Reading
Posted by chktm | Jan 24, 2014 @ 07:02 PM | 2,206 Views
Late last year I decided to try and promote the MMs at the local RC club after the new track had been built. I went to the last two meetings of the year and got video of the last meet. I was still getting used to the track and jumps as were most of the guys. I raced with the SC trucks as I figured they'd be a similar pace. This track is a different type of surface to most dirt tracks being not clay but decomposed granite which once it starts getting a line, that becomes a sandpaper like surface giving plenty of grip to those who stay on line. Off line its completely opposite being very loose and slippery. I thought the trucks had an advantage through the tighter slower sections and the bike had an advantage in the faster sections as well as the big double jump once I started using it as I had installed a 4800kv motor with 13t pinion for this meet vs the std 4200kv motor and 12t pinion i used the meet before. Overall the lap times were very similar between the trucks and the bike with the bike just getting the quickest of the meet by about 1 second. Some fun racing. Unfortunately in the final my gyro hasn't fired as I'd just had it going and unplugged it but started it too soon again as it hadn't fully spooled down. I then rode a bit silly trying to catch up and had a bad cash that bent my wheelie bar hard into the rear tyre not allowing the suspension to work and acting like a brake. After pulling into the pits to get this sorted I then came out a lap down amongst the...Continue Reading
Posted by chktm | Jan 24, 2014 @ 05:40 PM | 2,152 Views
A few pics I got while giving the RC4 bike a quick spin in the front yard.
http://www.rcgroups.com/forums/newat...anageattach&p=
Posted by chktm | Nov 11, 2013 @ 06:50 AM | 2,421 Views
Posted by chktm | Oct 27, 2013 @ 06:12 PM | 2,109 Views
Here's a little video of my other interest, full size bikes. A short loop of trail and road I found not far from the house.
KTM short loop (12 min 4 sec)

Posted by chktm | Sep 22, 2013 @ 05:28 AM | 2,423 Views
Posted by chktm | Sep 21, 2013 @ 01:35 AM | 3,028 Views
Some fun running around the short track.
Atomik MM450 RC track laps (7 min 4 sec)