Somebody Stop ME!

[Smacaroni]

I'm running out of things to do to our poor PW80. You guys haven't seen the thing I did to it over the previous winter, so here you go.

Yup, I 'tarded it.

But I wasn't quite satisfied with that and it didn't fit in my Jeep. So I mini-moto'd it.

Last weekend, I (finally) got a chance to run it where I've been waiting to run it for probably a year. I had an absolute blast.

This little girl kicked my butt:

It helps that she and her bike weigh less than my bike alone. Normally, she wouldn't be on the track with us older guys except she was the only youth rider there that day.

More Photos

I need to make a few adjustments to the PW if I want to continue (photo from 1/2 way through the day)

It also needs a bath.

But the main point of this thread, I'm running out of things to do to the bike. I've got a few more porting experiments and I plan to stiffen up the suspension this weekend to handle my girth (so it can lean harder before I grind the pegs off). Then I'm going to make an attempt at fabricating a pipe guided by software.

I might try some hot-shot reeds that would need to be cut if the local karting supplier ever answers his email.

I have a new carb in the mail which may or may not be of any use to me or anyone else for that matter.

Maybe clip-ons (big deal 20 minute job).

That's it. That's the end of the list.

I need a new project.

So I'm thinking about going in the same direction with another mini. I want to stay at 72cc or below, probably two stroke (please go to TS to start/continue that argument) because of the track in the photos rules.

I'm seriously considering a KX60 for several reasons. First, I have at least one frame, two motor cases and the odds and ends from two bikes on hand.

The bad news is I've got two cylinders which are probably junk. I know one of them the crank is missing and the other crank is toast.

What I'm thinking is a front end from a 1985 or earlier KX80 with disk brakes (minimal mods required to fit the KX60 frame). The rear end from a 83-85 KX or 84-88 KDX 80 (minimal mods, again). It would ride on 16" wheels which would be cobbled together from K(D)X80s and KX100s (I laced the wheels on the current set up, that was a good learning experience 0.7mm/0.5mm trueness F/R - I think I did OK, esp. since the front is Chinese Junk).

I could also use a 1983? KX80 or KDX80 front end with drum brake and keep the 12" wheels off the PW for the short term (these are KX60 hubs).

Cost wise:

130 bottom end kit from Wiseco (if Hot Rods is that much better, let me know)

50 machine shop time which may include lightening the crank w/ stuffer

40 piston kit

200 cylinder replating or 275 for a new cylinder

200 KDX rear end from a local parts bike. Again, I could keep the front end (bolts to the KX60 frame) for the short term

???200 KX front end when I get around to it.

150 for tires

FREE motoplat inner rotor (already own it)

700-1000 Total investment

And I can continue to toy with it later, but no where near the amount of off the wall stuff I've done to the PW. I think I can even drop a KX80 motor in later if I'm so inclined.

Other options are XR100, which I may do along side this project as a buddy bike for practice in a local parking lot, which I've already secured permission to use during off-hours (signed a waiver too).

I'd continue to keep the current stable in riding condition and we'd still do mostly off-road as a family. I'm still going to commute as much as possible on anything available. This bike would be a once-a-month ride and a parking lot tyrant.

So, where's the glaring error in my plans?

Edited November 23, 2011 by Smacaroni

[gsa102]

That's some impressive re-engineering!

Would the KX 60 crank live very long under those conditions? That is the only concern I would have. And yes, disc brakes.

[Smacaroni]

That is one thing I don't know.

Of the people I met on Saturday, they were almost all running XR100s or 150Fs. The little girl was on a XR50->88 (that brings back some memories of my kids).

They have a 50/110 adult class (XR100), but personally, I'd rather stick with the smaller frame that the 60 provides (72 & 150F). I know these can be bored to 72, but I'm not planning to do that, which should keep the crank serviceable longer.

Personally, I'm not thinking about being competitive, just go out and have fun. As long as I can consistently make it through the heat races, it's all good. I don't need a trophy.

Also, Saturday had minimal people show up, so I think I got more seat time than I would on a typical day. I could have run two hours, but decided instead to spend my time swearing at my carburetter - I felt surging in the PW and gave into temptation to "fix" it. By fixing it I mean bending a float so it stuck after putting in too big a main, then unsticking the float and having it pour gas all over... then put the slide in backwards.... After missing two or three practice sessions, I finally put it back to the way it was before I tampered with it.

What typically fails when the crank goes? If it's bearings, perhaps I should look into having the existing crank rebuilt with beefier big end bearings? If it's the rod, um, I guess I'm kinda screwed.

The basic XR100 there is any year XR100 with any year XR80 front wheel. Ta-DA!

[gsa102]

Maybe the aftermarket crank cures the issue. Just something that stuck out to me.

A 2t would seem like more fun to me.

[Smacaroni]

I've heard of toasted KX60/65 cranks being pretty common too.

I agree the smokers do seem like they'd be more fun to someone like me. Now my gf or daughter would want the consistent broad power a thumper provides.

It should keep me occupied for a couple of months, where the XR100 would be a single eBay purchase and mounting tires. Considering Spring lasted from late March till mid-October, I suspect Winter will be just as long. If the crank were to have a short life under these conditions, $128 isn't so bad, as long as it doesn't mangle the cylinder. The cylinders I have are from parts bikes I bought to put the stock electrical pieces on our old KX60 (sold last Dec.) and of course some of the suspension ended up on the PW.

I wonder how far underbore you can resleeve an 80?

This guy pulled it off with a 60, but who knows what his rebuild schedule was:

[Smacaroni]

More reassurance (assumed to be sold):

For Sale Supermoto Kx60

1998 Kawasaki KX60- 2nd owner

> 14 hrs total ride time (6 on asphalt)

> SuperMoto conversion- Inverted forks

> Hydraulic frt. Disc. With Nissin master cyl.

> F4I Street Pegs,

> Renthal fat bars/high bond

> KDX80+2 swing arms

> 2003 R1 shock/spring

> Link less upper mount

> 1.5 hrs. new Factory top-end re-build and crank shaft inspection. 2PMP new rear sprockets.

> Keihin 26mm carb/w/03R1 Velocity stack intake (+2 hp!) makes 17hp@ 11,000 rpm on Tulsa Cycle Supply’s Dynojet 250!

> Mini Road Race perfection, set-up for 195 lb expert.

> Has 12” in in front, w/Dunlap II 9ZGP’s, also included is stock 14” wheel and NEW Michelin Starcross

SACRIFICE at $1,500!

[Smacaroni]

Kawi has the same part number for the KX60 and 65 big end bearing, if something in the crank was gonna go, I'd expect it to be this. Some places list the same crank kit for both the 60 and 65, so any KX65 guys want to chime in? The motors are different but quite similar from other research I've done when we had our 60. I'd imagine they both face similar problems.

[gsa102]

My boy has a 2003 RM65 we bought 3rd hand to race. The PO never opened the engine, and don't know if the original owner did. The compression feels a little light and it takes a few kicks to start when cold. I was planning on doing the crank/mains/piston this winter just to know it was done.

It has lots of hours on it this summer alone, 10 HS and 2 motos, and lots of practice time. The rear brake disc is getting so thin it discolored on the last trail ride.

[shrubitup]

What about modding up a KX100 or even the 85s? Trying to stay below 72cc still?

The 85s are everywhere and cheap!

[Smacaroni]

Yes, the 85 would put me two classes up from what I ran last Saturday and let me tell you, for a recreational group, those guys were pretty damn fast. 85 would be the end of the line, the 73-85 is a new addition, I don't think they're going to go much bigger. Now if I'm willing to drive four hours there's a place that'll be more than happy to let me run a 100cc, and also a whole other league of racers.

I'd like to keep it in the two hour and under drive time and easy on the pocket.

My boy has a 2003 RM65 we bought 3rd hand to race. The PO never opened the engine, and don't know if the original owner did. The compression feels a little light and it takes a few kicks to start when cold. I was planning on doing the crank/mains/piston this winter just to know it was done.

It has lots of hours on it this summer alone, 10 HS and 2 motos, and lots of practice time. The rear brake disc is getting so thin it discolored on the last trail ride.

Our original running KX60 looked pretty well abused too, moto plat inner rotor, was definitely raced. But there's a big gap between an eight year old wringing the piss out of it for 20 minutes at a time and me wringing the piss out of it for 20 minutes.

FWIW, over lunch I called the KDX parts bike ad, I'm hoping they aren't morons who just let the ad run after they sold it. I got a machine. I have a good feeling about this build. Not about the CL ad though. If not, there will be others. In fact, there's another KDX cheaper and in worse condition (basket case if you're lucky) about 45 minutes away who just posted.

Another cool possibility, very unlikely though, is if I were to find a KDX50, that would keep me in the 50/110 group the PW was in and I think it could be a real winner with the list of suspension modifications from my initial post. It's just too low to the ground and made for too small a rider in stock form. It's also HIGHLY unlikely that I'd find one with enough pieces left or good enough condition to make it work.

[Smacaroni]

Craigslist:

You so funny. This is NOT the KDX 50 I was looking for.

http://baltimore.craigslist.org/mcy/2705828577.html

[BoxcarWilly]

hey sick bike!, i was just wondering if you know anywhere that makes a big bore kit for pw80?

[Smacaroni]

Yes, Suzuki does. Well, not quite. Use a LT/KFX 80 piston from your favorite piston manufacturer (I used Wiseco), bring it to a machine shop with your cylinder (I recommend buying one off ebay - keep your working cylinder for later, condition of the ebay cylinder doesn't matter as long as it's not destroyed) and have them take 2.3mm off the top of the cylinder. If you don't your compression will be completely out of whack. You should also have them modify the cylinder head to fit the piston's new diameter, they can simply expand the existing squish area on the cylinder to fit.

See https://www.thumpertalk.com/forum/showthread.php?t=738583&page=41 post #407 for my experience. You can see just how crappy the cylinder I started with is.

Mine didn't go so well as I had an intake leak which was unrelated to the overbore, but while we had it it was a worthwhile mod. I simply haven't dedicated the money to trying again. If we didn't have that leak, I'd still be using it.

[luckystar64]

Hey Smac-- I was looking at the pics you posted, and I was wondering what club you race with? NJMiniGP? What part of PA are you from? Our OYL/OMRL club races at the Beaverun Kart track. --L*64

[Smacaroni]

That's MD Minimoto at Sandy Hook Speedway in northern MD. Of the people I talked to, it seems that a lot of the members are also members of NJMiniGP (out of my league, out of my price range and outside of a day's drive if I'm going to do anything besides drive).

I saw Beaver run somewhere before, looks really cool by again, too far away. Why is it all the things that strike my fancy don't seem to strike any one else's fancy in my area?

I'm not too far from Harrisburg, Sandy Hook is about an hour and a half from me.

[Smacaroni]

Objective 2 is nearly complete (for now):

2003 XR100R: Drag bars, 82 XL80 front wheel and brake (lucked out, bigger shoes!), 16" Pirelli Diablo front and back. Needs a new chain, sprockets and grips - on their way, and a bath. Considering a new air filter and making a "low pipe". Code name fRED.

[Smacaroni]

fRED has a new chain, sprockets and even upgraded the shock spring to a BBR heavy spring.

Currently $101 over budget on MY bike (fRED is her bike), missing the rear wheel I need and still haven't assembled the motor... ?

A friend recently told me "it ain't racin' if the bike is ready by race day", which is like the ice cream man dropping your treat on the ground saying "collision damage - it's on the house!" AFTER you gave him your money! It still tastes the same, but it just ain't right.

Before I complete the assembly, does anyone with experience in the KX65 AND KX60 motor have an explanation why the 60 uses a "T" shaped bridged exhaust port and the 65 uses a trapezoid shaped port? I have my thoughts and it's encouraging me to modify the "T", as in trapezoid. It can't go as far as the 65, but I can get pretty close.

Surprisingly, I can find nothing about this via The Google. I would have thought somebody would have asked the question and possibly experimented with it already.

FWIW, stock EO is 86, transfers at 115 and boost at 120. The 72cc is EO @ 87, transfers at 116 and boost is totally screwed at 140 - so I have to do something, I may as well do it all at once. Port widths didn't change much - within human error and casting tolerances.

The gaskets are too expensive for me to take the "try it and see" approach and the plating is too expensive for trial w/ error.

My friend and mentor from the PW80 porting project has moved on to porting in the great beyond, so I can no longer ask him for advice. I never had an issue like this, so we never discussed it. Rest in peace, EC.

Edited April 15, 2012 by Smacaroni

[cdhall]

Smacaroni,

In the first pictures of your pw80, how did you extend the forks? I'm assuming they came off a different bike.

I'm wanting to raise my daughters ttr90 1.5 to 2" max, I figured out a way to raise it in the back about 2" but Is there a way to modify the stock forks to compensate for the 2'' lift in the rear?

I saw some lift "kit" sold on ebay, but I read another post on TT indicating it was not worth the money. I'm not wanting to dump a ton of money into the bike as she will probably out grow it this year.

Thanks

[Smacaroni]

The TT post was probably me analyzing the seller's claims and what he says are in the "kit". If it's KrazyTrain? Or something like that as the seller's ebay name, that's the guy I talked to and yes, it is junk at worst, severely over priced and over marketed at best.

The way I did it was using a KX60 parts bike, front and rear. The front requires a machine shop, but other than welding in a new stem, it's a piece of cake. Buy the parts bike, a TT-R lower race and seal and head to the machine shop with the TT-R and KX triple tree. Tell them you need them to spin a new stem on a lathe to match the TT-R's stem and press/weld the stem they made into the KX lower.

For the rear, I also suggest the KX60 shock, on it's lowest pre-load setting (impossible to install otherwise, you can bump it up later) in place of the TT-R shock. I'm not sure of the air-box configuration on the TT-R, so there may be some interference you need to account for, but I'm sure it won't be any more difficult than dealing with the PW80 oil tank which I *think* is in the same place.

For the ultimate hybrid suspension, you cut the stock swing arm apart and weld the top hoop, axle adjusters and center support to the KX60 swing arm. But for simplicity's sake, I'd start with the KX shock and see if that gives you what you want first.

IIRC, I spent about $75 for the machine shop to make and install the steering stem, the parts bike was $75-80 (I ended up buying two of them for different projects - you only need one), the hybrid swing arm is probably two hours of work for a competent metal shop. In addition to welding the parts together, you need to trim the inside of the KX swing arm and make spacers or drill out the swing arm pivot to 12mm. (note: the pivot hole is very hard, an ordinary drill will not do it) I am not competent, but it took me longer since I only do welding as a hobby and I did several mock-ups as I didn't know if it would work till I finished it.

Also, I think the newer TT-R90s have an upper triple clamp, you might be able to install forks from another bike, maybe a DR-Z125 small wheel or KE100? If memory serves me right, these are also 27mm forks. However, I would measure before buying as my memory is not always reliable.

As far as growing, depending on if you mean size or capability, any modifications you make to the TT-R90 are a direct match to the PW80. The TT-R has it's good points, but the PW80 is cheaper and much, much, much, much - much cheaper to hop up. I think my total investment in the PW80, including purchase is about $800? With simple tools, I'm already putting double the power down. See "PW 80 Questions" for all my modifications and some other folk's mods too - the frame mods probably have some broken photos, but if you have questions, PM me, I've got the photos on my computer.

Edited April 11, 2012 by Smacaroni

[cdhall]

I'm going to begin with looking for a kx 60 parts bike. Its sounds less expensive than I thought. Thanks a lot!