I have paddle tires on Douglas wheels already. I just might!

A few things worked on over the past week. I went for 2 rides. The first ride I concentrated on main jetting, and ended up dropping from 380 mains down to 340 mains. The air/fuel ratio was still rich at 11.8 with the 340 mains, and maximum RPM is reaching about 7500. The Engine should be good to 8000 though. I've already adjusted the drive clutch to position 5 of 6. These sled clutches have 6-way clickers and the higher the position the higher the peak RPM to a point - then something else needs to be changed. After this I did drop jetting to 330 main, so hopefully a better mixture pulls more RPM on its own; else its clutch adjustment time again. I might need to buy weights and/or a new spring if position #6 doesn't add enough though.

Low throttle tune is a different story. 1/8 throttle is coming up lean, about 13.5:1 initially; but if held there it leans out; 14, 15, 16 without any input changes or terrain differences. This means its very lean down low and 1/8 throttle is burning up fuel faster than the carb can provide. When it starts to go lean, a quick throttle smack has a very bad lean hesitation. I went ahead and changed out the 17.5 pilot jets for 22.5, and then set the Fuel mixture screw to just 1.25 turns. This still gives a good snappy idle, and now at 1/8~3/8 throttle the Engine is getting a healthy dose of fuel.

I also lifted the needle which is not adjustable by 1.6mm using two Mikuni spacers. This should hopefully assist the low end increase in fuel through about 1/2 throttle.

On these carbs, the throttle slide is 2.0 (Rich end), and the NeedleJet is not interchangeable. There is also now AirJet in these carbs. Also needles themselves are a bit hard to come by - if I change needles I may need to call Sudco for some options (Thinner needles maybe?). Hopefully the PJ and lifting the needle solves the low throttle issues though.

Also ordered a 175F thermoswitch because the 210 Thermoswitch I feel is much too warm. Over-all the cooling system seems to be keeping the Engine at about 210F. I think it may be fan limited at this point. Hopefully the 175 switch will drop it down a lot.

Also the steering angles kind of suck on this thing. My stock pilot can swing the front tires further both left/right and so today I really worked hard and took the time needed to get the steering pivot angles congruent from left-right. Also I re-set the steering stops (There are 2 on each side) as they were not in sync with each other. I did find the stop on the steering stem was not in-line with the steering wheel itself, and so I took a few parts off and am going to re-set the steering column to center - allow for steering stop to be reached equally from left-to-right, and then set the second steering stops to a further point (Ground down the stop itself) and set the steering stop pairs to exactly the same stopping point as the column stops. Two stops in each direction. I guess its complex to explain so I'll post a picture of all the stops and what I'm doing in hopes to increase steering angles without messing up the alignment. Another 5~10 degrees or more of steering angle is what I'm looking to gain.

Speaking of alignments, I took general measurements of the front A-Arms again, and found left-to-right points were up to about 1/2" off from each other. I loosened the helms on all arms and took my time getting things at least equal - measuring each individual arm lengths (There are 4 Heims on each side) and matched the lengths right-and-left. Then I measured from the center-points of the ball joints back to a fixed point near the driver's seat from both sides - and got those distances again equal left-and-right. So now arm lengths from the ball joints to the heims are mostly matching left-and-right; and also more importantly the alignment to the vehicle's frame is also now more accurate.

All this could go right out the window next right though.

Once I get all these steering stops and inner linkages all in-line with a straight steering wheel; I may reduce positive caster. Seems to me this Dave-Co machine has a huge amount of positive caster as compared to my stock arm'ed pilot. That could be causing initial turn-in sluggishness and vehicle push issues. The machine under-steers to an astronomical degree. Perhaps straightening up (reducing) positive caster (By maybe HALF of it's current angle) will yield the results I'm looking for. I've been blaming my rear ITP MudLites for holding their line very strongly. Perhaps quickening the steering will throw them rears looser. The machine badly needs some swifter rotation!


Its not all gravy with this Dave-Co setup, but I like the tinker factor. Takes a lot of thinking over to get where I want it to sit. Also I found a cracked weld on the upper steering shaft. Easy fix with my welder. This setup may not be for everyone but I like it.

Stock pilot has about 5 degrees of positive caster. This Dave-Co setup has about THREE X that at 14 degrees. Most race ATVs need to be at about 5 degrees. I'm going to cut that back down to by about half and then re-set negative camber to about 1/8", and then tow-out to about zero. Hopefully my ackerman angles wont get thrown off!

WOW what a booger this front suspension is. I'm sure learning a bunch that's for sure!

When I equalized all the A-Arms Left-to-right followed by setting the caster to about ~8 degrees+, it caused Ackerman and bump steer problems out the wazoo. I unfortunately will need to re-position almost all the front suspension components in order to keep caster, camber, toe, and Ackerman angles and bump-steer in-check. This means the distances between the contact patches and center-points to the machine/frame will likely be off. Disappointing for sure; but still much better to have Camber/Caster/Toe in check and a long travel system. Just hope if doest pull/wander at straight speeds; but I am absolutely convinced that Caster is hurting my turn-in ability here.

I like as much positive caster as possible with a little toe out for my pilot... it has the YODA front end and turns as if it’s on rails. The future will be an anti bump steer fix.
Tweaking and testing can be almost as much fun as driving.

On my set up I didn’t have enough caster only a few degrees. So I currently have my front end all cut off and rewelding my tabs. Putting 8* caster in it.

What tires are you running on your machine?

How much positive caster do you have? Measure with a large square against the floor and the bottom ball joint housings. Measure distance to the same point on the top ball joint housing. Every 1/8" is about 1 degree. There are better ways to do this I just found this to be the easiest for a dirt machine. Take your wheel off may be easier.

ITP holeshots
1.5 inches laidback at top

Today I fixed the bump steer as caused by moving the caster from about 14* down to about 8*. Changing the caster made the steering's outer tie-rod Heim joint rise up by about 1/5" at the hub, which caused an angle of tie rod change, which led to about 1.5" of BAD NEWS bump steer.

It wasn't hard to fix, took bit of time to figure out what I needed to do and then actually do the needful, but yet again needed WELDING (Making this LT kit not really a DIY thing for average Joe).

This kit's steering uses 4x steering linkages. The column is connected to 2x8" linkages which are then connected to rotating pivots just within the frame. Then custom tie-rods goes from this rotating pivot out to the hub. All linkages are adjustable for certain angles and toe, but I could not get the linkages to correct the bump steer issue from changing caster without some modification.

In order to correct the bump steer as caused by lifting the outer tie-rod joint heim, I had to lift the inner tie-rod by the same amount. This meant modifying the pivot's outer connection which connects to the Inner tie-rod heim.

I drilled/filed out a 17mm' hexagonal hole which allowed the heim joint to slide THROUGH the mount. I then welded 1/4" mild to the top side of the mount and drilled through that with a 1/2" hole. So now the inner tie-rod heim sits against the new 1/4" Mild part of the pivot which affectively raised the inner tie-rod 1/4". Best part? The bump steer is FIXED as best I can tell with my eyeballs.

DONE with the front of this FrankenThing2 for now.

what are those spacers on your bead locks? I assume they are there so when you hit a rock it doesn't tear up the bolts so much?

Pictures Turn your head 90* to the LEFT to see these right lol

Pic - Rotate head LEFT 90*

You are correct sir.. out in October or rocktober forest as locals call it, the rings every other bolt helps save the heads.


Nice work zero!

Update, I measured my notes again. Seems this Dave-Co had about 14* of positive Caster. That seems like a lot to me. I've turned that down to about 8*~9*.

Good ride report! Its been a hot minute getting my 600HO tuned, but she is now coming along! The 2005 600HO Mikuni TM40 dual carbs for some odd reason come jetted straight from the EPA, which causes 1/8~1/2 throttle to be ultra lean. Bad news is carb needles are a hands-up-in-the-air affair, and the needle-jet (Emulsion tube) is fixed - not removable.

I posted on FB's Skidoo Rev group a few times. Those guys know their skis, rotax engines, and clutching for sure. Mucho help, but many of those guys wanted me to spring for some Lectron carbs, or swap out for older VM carbs. One guy finally came back and said I should try REAMING out the fixed factory TM40 needle jet tube with a few different flute reamers. I ordered .1040, .1043, .1045, .1047, and a .1050 reamers. The .1040 slid through the emulsion tube without any resistance. The .1043 did just a tad of material off. First ride report after that ream and things were better in the 1/4 throttle zone, but it was still hesitating, coming up lean A/F, and plugs still on the white side. So I took the emulsion tubes out to .1045. WOW what a difference! A/F in the 1/8-1/2 throttle zone almost perfect. Pilot can now beat ALL UTVs (Even 180hp turbo units) on the drag strip, and pulls a 10' wheelie off the line in LOOSE dirt. I'm not done yet though - thinking long and hard about going to the .1047" reamer - because the plugs are still telling me just a hair lean. Also she pulls wheelies straight off of idle no problem, but holding throttle just off idle a smidge for a few seconds and authority is not there to pull a wheelie. It also takes about 5~10 seconds still to idle-down after a quick run, so its just a hair-line still lean at 1/4.

The Engine is absolutely fantastic in this machine otherwise. Hits 8500 RPM with a vengeance. Also I'm not so hating the ITP mudlites any more - I appreciate their traction over Holeshots now; and with the throttle I can break them free to loosen up turns.

Next up - I'll discuss the PROBLEM with the rear suspension - when a backyard fabricator had a little fun with a 3/16" drill-bit...

Next - rear suspension. I have absolutely no freaking clue how Dave-Co was meaning to set the springs and valving up in this thing. First I want to say in earlier thread posts I did make the move from 80/100 springs to 175/100 springs top/bottom. This kind of went against the norm of putting a lighter spring up top, but I really wanted to feel a heavier start before crossover. So the rates go from about 65lb to 100lb per inch with about 800lb total at fully compressed.

If I go through some smooth jumps and landings, this spring rate feels great. I almost completely fixed my bottom-out. It only touched ground twice on the last ride (So I'll add another 1/2" bump stop).

The main freaking problem with this thing is the rear has absolutely ZERO compression and ZERO re-bound. Taking a tip from Steve, I took a look at the shock piston. Lets just say Dave-Co got a little silly with a 3/16" drill bit. He drilled 4x 3/16 bleed holes in the shock piston - which essentially completely eliminates all forms of compression and rebound damping! He might as well have saved himself the cost of shock oil as the valving was likely getting completely bypassed!

This was causing the shocks to completely pack-out in both directions.
1. Tossing the machine over the whoops - and the rebound was too fast that it was causing the machine to buck in the rear. That is - suspension pressing UP on the rear, lifting it off the ground.
2. On smooth landings, the rear would bounce twice like a pogo stick. Ideally the rear should only really bounce 0.5 times (Compress, or release and then immediately return to ride height)
3. On multiple compressions, or when taking an increasing height hill (Like, going fast toward an upcoming incline), and the rear would drive hard, and sometimes dive twice - causing the machine to bottom out.

I called KarTech. They asked for some pictures - Txt'ed them. I heard a few guys laughing about the bleed holes lol. So I ordered some new factory pistons to start. As for bleed holes, well, I'm going to just keep to the one factory 0.070" hole for now, but I can always drill a few to speed things up if 30# shims are still not fast enough.

Valve shims in this things are both 70#, for compression and rebound. KarTech recommended I pick up 2 stacks of 30#, and 2 stacks of 50#, and start with the factory pistons with 50# shims. With the combination ordered I should be able to hit any position - 30,35,40,45,50,55,60,65,70#.
Hope it all goes well!

Here is the drilled out bypass holes in the fox 2.0 steel piston. 4x 3/16 holes around the edges.

The last picture is what is supposed to be like, with just one 0.070” hole.

Your doing some good work on your pilot. I am enjoying the process. Gotta love when an Engine get enough fuel to accelerate properly.
Once you get the rear shocks set up it will drive forward with control even better. Do you have any adjusters on the shocks. I know on mine the use of low speed compression and slower rebound makes a would of difference.

Keep posting great info. Would love to see a video. Love the sound a twin makes.

My front shocks have compression and rebound adjustment. They are Fox shocks but are not 2.0.

My rear Fox 2.0 coilers have no external adjustment aside from Nitrogen pressure, Sag and Crossover. All compression/rebound adjustment will need to be done internally with the above photo'd piston and shim stacks.

you can tap those bypass holes and put some set screws in them, this way you can see what you might need to be at with the new pistons, be sure to lock tight or peen so they don't come out.
I have fox 2" shocks on mine and I believe my current valving is 50 comp and 30 rebound, it still seems that when hitting the woops the suspension is not coming out like it should and I can't take advantage of all the travel. I have the DSC rezzies and though they are only supposed to control compression I suspect that they are restricting the flow back to the shock.
Keep us posted.

Do you have zero, one, two, or custom bypass holes in the valve piston?

here is a pic to help follow

I believe there are 2 bypass holes, all stock, I'm chicken to start drilling and then find I went too far