1985 XC500

I realize they are totally different bikes, but here's the picture of the vintage 250 that supposedly weighs 168lbs with titanium frame. Was posted at Vintagehusky.com

on the rear disk setup, i bought 04 or 05 450 TE wheels, forks and brakes, so I used what I bought since I got a good price on them. I think $400 for all. but you have a good point on the placement. if you think about it I just flipped the whole thing over since the chain is on the left side on the 4 strokes. I suppose i could have put a mount on top of the swing arm on the left side to bolt the caliper to but it looked goofy hanging at a 45 degree angle. time will tell on whether it gets beat up or not.

Very nice, and absolutely motivational too. I'm just rebounding from some health junk getting in the way of my Husky rebuilds. One being an '85 500XC as well. Love seeing the front end and brake upgrade options....

That is a fantastic build, Gearco! I love the modern front end.
I would be extremely careful about playing around with titanium frames. You couldn't just copy the original frame design in titanium and expect it to perform the same. The stiffness would be much less with titanium as it has a lower modulus of elasticity (roughly half) as compared to steel (Chromoly). Titanium is a lighter material given the same material volume, and about as strong as Chromoly, but titanium is much less stiff. That being said, a properly built titanium subframe might be interesting. It could offer a bit of flex under the seat while saving weight.

The original frame is incredibly strong; if you've ever tried to drill a hole in one you'll know what i mean. so tough you feel like you are drilling a heat treated gear. after riding this bike a few times, i've come away with the feeling it is light enough and efforts to drop a few more pounds wouldn't be that productive. the handling is probably the most improved aspect of the build; the new front end, when adjusted right, is light years ahead of the original setup. and the brakes are a bonus. probably what made me do this project in the first place was to see how the vintage motor would do on a modern platform. happy to say that these bikes can be a real weapon against modern dirtbikes, and not much that is expensive to repair can happen. If a modern 4 stroke top end breaks you are looking at a wad to fix it; not so with the 2 stroke.

Interesting work but I must say the placement of the rear caliper is daring. Underneath and facing foward of all things!?!? That's just begging to get slammed by a rock.

I do bet the bike handles alot better but still keep in mind that the steering head angle is greater than modern bikes, it's longer, it's taller, etc etc. So you throw modern legs on it and brakes but it still doesn't solve one of the biggest problems with late model Huksy's which is there overall size. Take my 500XC or my KTM 200EXC, I know for a fact I'll be faster on the KTM on most any track unless it's open and very fast.

Still, excellent work and very innovative and unique.

What I'd like to see next is to do a motor transplant with a new Husky and put this motor into it. That would be trully modern chassis with old school power, similar to the '88 430 Auto retro build (minus the colossal failure of the 430 Auto engine that Husky totaly botched

Good points, and an interesting idea, forsure.

Such a great project, really nice work everywhere, two thumbs up, I think chasing the weight, while being fun, maybe not so important, i is where the weight is placed, how it is balanced etc that makes the difference. the wheels being so much lighter will allow not only better acceleration and stopping due to lighter weight, remember they are like big flywheels at each end, also the easy of tipping into a corner due to lower Gyro effect, and the huge improvement in suspension response due to the reduction in "unsprung" weight. Total overall weight is not as important and reduction in the Moving or dynamic mass, such as wheels, tires, brakes and half of the moving suspension component, the lighter they are, the better the bike will handle, stop and go.

I ride a bicycle too for fitness, it has very thin 700x23mm tyres on a race bike frame, about 8 kg all up, if I change the inner tube to a HD only for a ride on rough or country roads to avoid punctures, the difference is huge, it is only and increase of .200kg at each wheel, but the feel of the bike, how much effort required to accelerate, turn in is beyond belief, put the light one in, the whole bike comes alive.

I have three bikes at the moment, the 2 wr250 Huskies and a 2007 KTM 525EXC, the Kato is 114kg with engine oil but no fuel. it feels like a 100kg MXer compared to the husky, as the husky is top heavy, big heavy rims etc, while I love riding the WR, if I had to do a huge rid, the Kato would be the choice, just for handling, suspension and brakes, not to mention the 65+ hp and a never ending top end.

A kato 525 frame with a CR500 husky engine would be pretty close to ideal for me, maybe with an Auto box.

You have reduced the weight in the right area's, any further reduction in weight should come off the rider, I have gone from 275+ pounds at March this year to 209 pounds now, done through weight training, diet and cardio work, the improvement in my riding is HUGE, I can ride for hours now without needing to sop for a breather, tight single trail used to be hard work, not it is a joy, I am 42 years old and keep up with much younger riders as they smoke etc and wile being young, just are not as fit.

Again, Love your work, very very nice.

Couple of post-build observations. The bike handles better than it ever did stock due in most part to the Marzzochi forks and lighter wheels. Braking is also much better due to the modern setup. Power is explosive but controlled-the relatively long swingarm works well in stabilizing things when power is applied. The biggest disappointment is with the carb and jetting. I opted for a 38mm round slide Mikuni that was set up with a 35 pilot jet (dropped it from the 45 originally installed), 410 main, 2.5 slide. I'm at 1200 feet alititude and this jetting was too fat at the bottom. I started playing around with the jetting and found a 400 main leaner than i wanted. Frustrated by not being able to dial it in close enough i put a dial-a-jet kit on it that i hoped would get me closer to nirvanna. The idea behind the dial-a-jet is that you create a lean condition at the main by dropping about 3 jets down (in my case to a 380 main), and the device theoretically compensates to the right place by dumping atomized fuel into the bell of the carb sourced from the bottom of the float bowl. There is a 3 position dial on the device that allows for 3 setting per main jet. Again, it seems too rich on one setting and too lean on the next lower one. Talking to Phil at Husky Parts the other day confirmed what i already knew, that the 430s and 500s are a bitch to jet.

So I read an article where they were putting fuel injection systems on 2 stroke motors. And I found a company selling them and i bought one. The company is Ecotrons and the system is pictured here:
http://www.ecotrons.com/400cc_to_800cc_Engine_EFI_kit.html I haven't received it yet but should this week. They have modified the throttle body for me a little (it's a 42mm ID)-turned the inlet down to around 48mm so i can get my carb boot over it; the oxygen sensor is being eliminated and I'll have to add a battery to the bike. Found a battery that weighs 1.2 lbs so maybe i can figure out where to cut the weight elsewhere. The CDI ignition needs to turn out around 60 watts to be able to charge the battery-not sure what the factory ignition is but i don't think it is 60. I have an unmounted MBZ ignition that supposedly cranks out 80 watts so I'll probably put that on. The FI system looks pretty cool if it is a set it and forget it proposition. I doubt it will be, and will make additional posts as things progress.

Wow, now you really have my attention. EFI on a waterpumper 500XC, yahoo. Toss a few power increasing mods at the engine, and say byebye to many a modern bikes. Cool stuff

When I used to ride years ago, I had some carb tuning experience, but nothing real in depth. Reading your above, had me saying what???? to myself, and also thinking I've got alot to learn there, and it sounds mandatory on these. Thanks for the updates, bigtime. Depending, I could see following your lead..........Awesome stuff. Pretty cool you pulled the trigger on this, and are going for it..............

In the process of finally putting on the fuel injection system. Thought I'd use the bike for the first leg of the Trans America Trail through Tennessee in a month or two and see how it does. Of course this means getting it sort of street legal; so: here's what the current work involves: 1. adding a new MBZ ignition with a lighting coil; 2. dual sport kit that includes turn signals front and rear lights and a horn; 3. fuel injection system; 4. adding a battery to run the fuel pump; and adding a 1 gallon reservoir to carry premix oil. So far I've installed the stator, flywheel and timed the new ignition system; this week will add the coil, voltage regulator for the lighting system and rectifier/regulator to charge the battery. On the fuel injection, I mounted the throttle body, made up a throttle cable and spent the better part this afternoon cutting out the airbox so the throttle body will go into it. Here are some pics.

I've also slotted an 85 Husky CR500 6speed into my retro build & it was great fun.
The 2007 handling changed a little due to the extra weight but not enough to be a problem, jumping turning & braking are all good.
It would be an awesome project to do a PVL ignition & EFI with but I won't be, as mine is for sale because I need room in the shed.

Lights work on ac electricity. I suspect the battery and fuel injection will need dc. If this little detail has been discussed my apologies. I am rather intrested in the fuel injection though I think waiting a number more years probably makes sense. On would think the more sensors the better. I notice that the chainsaw market has gone to automatic carburetors that make tiny changes and note the differences on a very small fraction of a second. Stihl does have a fuel injected demo saw, not sure what else is out there two cycle fuel injected. Perhaps gas gas has a trials bike and then the snowmobile stuff which is quite a different set of design parameters.

good point on the ac/dc issue. I'm hoping my approach will work and it is in two parts. First, the output on the factory ignition puts out a paltry amount of current from the lighting coil. So I installed the PVL/MBZ unit from Germany; can't remember not how much output but think it is around 80watts. That leaves the ac/dc problem. the MBZ comes with an ac regulator to keep the lights from blowing. I've ordered a regulator/rectifier that will do 2 things: convert the ac power to dc and then regulate it to keep it from overcharging the battery. My plan is to create a Y in the lighting coil harness (both leads) and send one side to the lights and the other side to the battery. think this will work? any suggestions?

Remember the reason I've gone to fuel injection is that I could never get the 38mm mikuni jetted to my satisfaction. When I got the mid range OK, down low would suffer, and it was never completely right throughout the range. These bikes have a reputation for being hard to jet, and one of the reasons they were so hard to start early on is because they came from the factory with a 40mm carb. The theory is that the computer will do a better job of figuring how much fuel is needed and when than the carb does, and also if I take the bike to higher altitudes the computer will adjust for that as well.

just build on to the shed

Neat idea for sure, going to watch this to see how it works out.
I believe in keeping it simple with a carb too, like a lectron or a 44 mil with the varijet set up could work out real nice too.
A friend had a EFI Husky 310, what a drag that thing was. Hard start when hot, fuel pump died once. Just not reliable enough to be safe with way back in the bush.
Simplicity is king, and in the car world carbs still make more power over EFI in most cases.
I love how my 82 500 runs with the 44 carb, from any RPM you can crack it and its all go.
Is that MZB ing. good for big bores and the slower kicking speeds, the subject has come up around here before that stock is better on the hard start kickers.


As i said cool idea, hope it works good.

Steve

the MBZ is a modern high output ignition system; much better than stock. can't say whether it makes any difference on big bores. I just put one on a 1967 Bultaco Metralla 250 and the difference is huge; now takes two kicks max when cold and one when warm and the lights are twice as bright.

Well they do work better on smaller motors. as you get more rotations out of 1 kick. Hope it works fine for you.
Whats with the bike looking like an 87, frame and tank wise? just the motor is a 85?