*** 1978 ATC 90 "3D" Dickson Design & Development Mono Frame ***

[Joseph Farrow]

Hey guys wanted to share me and my brothers third installment of Old School period correct ATC 90-110 trikes. As you may know when I came to 3WW it was to have a resource for finding and locating bikes and parts for the ATC90-110. Our goal was to build two race bikes and two dune bikes exactly as they were back in the day. The 90-110's had so many hipo aftermarket parts available due to the fact that for the first 10 years it was the only option when it came to trikes. It was a special time for us growing up in the hayday.

This is Judson's "Race Bike" build. We always wanted a fully suspended 90-110 race bike. They were short lived due to the fact that about the time they began to catch on in popularity over the hard tail framed bikes Honda released the ATC250R in 1981. When that happened it pretty much killed everything 90-110.
With that being said we still have always wanted one. They are very rare, especially the 3D version. It was specifically produced for racing. Some of the other versions from different manufactures were more for recreational use.

Dickson Design & Developement (3D) was located in Nation City California and headed up by the one and only Bob Dickson!
This is from an article in the Summer 1980 issue of 3Wheeling Magazine.



The article states that the mono-shock design wasnt the first attempt to install rear suspension on a three wheeler, it was the first to be put into production.

As in previous build treads I will first start with pics of the finished product then break it down into Chasis and Engine.
This bike is also inspired by our last ATC110 race bike "The Blue Goose".

Here is "The Blue Goose II"



I think it came out Awesome! I have yet to ride it but Judson says it Hauls .

[Joseph Farrow]

Here are some of the specifics on the Chasis.

Let's start at the front of the Bike.



It sports Vintage Grab-On grips with Renthal Bars and MX Cross Bar Pad. Front brakes are a super cool NOS Hurst Airheart disc brake set up. Twist trottle is a Vintage Magura qtr turn with a NOS BAPP Mikuni Cable.



Front triples are aftermarket with 31mm tubes. Front tire is a NOS Ohtsu 20x7x8 Odyssey Front Tire.



Gas tank is from a 1979 XL 250. Rear fenders are Aftermarket and are unsure of mfg.
Rear tires are NOS Carlisle Turf Savers 18x9.5x8 with aftermarket axle extenders and 32T Rear Sprocket.



Aftermarket Cleated Foot Pegs as well as a HD Rear Axle Carrier.



Forgot to mention....I did the Paint on this Bike!

Stay tuned for the Engine Specs next!

[Joseph Farrow]

Okay Engine Specs!

1978 ATC 90 Motor built to 180cc.
Head ported and polished with lightened and polished valves.
Lightened and Polished Rocker Arms.
Vintage 90 Pauter Cylinder with 6mm spacer for Long Rod Stroker Crank.
Modified 61.75mm Honda CB 750 Piston
110-61mm Helm & Son Stroker Crank
Oil Bypass System
Lightened Flywheel



Quick Change Sprocket Assembly
Manual Clutch
Vented Helm & Son Dip Stick
PK Intake with 26mm Mikuni Carb and K&N Filter
NOS BAPP Large Pull Start Handle
Custom Bassani Pipe (Modified to fit Mono Frame)



Again wanted to share. I think this is a really neat bike. It is just about as Bad a ATC90 you could build for the track back in the Day!
Would also like to Thank several members here on this board for their help in making this bike happen. Without you guys it wouldn't have been possible.

Stay tuned for my final installment of our 90-110's.....The Team BAPP Replica Bike Build coming soon.

[Ghostv2]

Your builds are always an inspiration to get my semi suspended pauter finished. But finding anything 90/110 racing related on the east coast is hard.

I wish we could see more bikes like this on the track at TF every year. By far my favorite builds.

[pipeline triker]

Very nice, love the 90 builds.

[shortline10]

Wow Joseph , you and Judson did a great job !

[ctk]

Great pics, How would this trike compare to a 1983-19&5 Honda 200x, in relation to engine power and suspension and turning. On a mx and flat track

[Ghostv2]

Might be a stupid question but I'm no expert on engines. Anyways, do you NEED to do the oil bypass for the cb pistons because the cylinders are basically bored to their maximum ability and re-sleeved? I don't recall ever seeing that and I've talked to veilmonkey in the past about buying a NOS CB piston kit (before the fire and everything else happened) for my build. Or does this just help with cooling and eliminate the need to tap in for a radiated oil cooler? Because I know these engines get HOT with that much work done.

[HairyJR]

Another great Farrow brothers creation, love the blue color. Lots of vintage parts. I don't believe ever seeing anyone race one that nice back in the day.

"HJ"

[Jwheeler]

Great job as always !!!!!!!!!!!! Judson has sent me pic's as it has been built. I need to get mine done now.That way we can tear it up in dunes together !

[yaegerb]

Good heavens, that is sick

It's about time for another build thread to go into top tier. I think this one deserves it. Lemme see about getting it moved.

[big specht]

Looking good as usual you guys do a good job. The cb piston peeked my interest what all is involved in using those pistons?

[Aulbaugh]

Amazing work! That is a head turner. It's crazy to think those little guys were used to race.

[Joseph Farrow]

Great pics, How would this trike compare to a 1983-19&5 Honda 200x, in relation to engine power and suspension and turning. On a mx and flat track

Chris to answer your question the 180's ran very well. In my opinion they were pretty equal to a built 200x when it came to power to weight ratio. These bikes are alot smaller and lighter than the 200x. My brother and I actually raced against 200x's and 250r's on our 180's and did very well. I think a lot of it had to do with riding ability but compared to a stock 90-110 you would be very supprised at how fast and how much torq these thing put out.

[Joseph Farrow]

Might be a stupid question but I'm no expert on engines. Anyways, do you NEED to do the oil bypass for the cb pistons because the cylinders are basically bored to their maximum ability and re-sleeved? I don't recall ever seeing that and I've talked to veilmonkey in the past about buying a NOS CB piston kit (before the fire and everything else happened) for my build. Or does this just help with cooling and eliminate the need to tap in for a radiated oil cooler? Because I know these engines get HOT with that much work done.

The latter is correct. It helps with cooling as well you can see you are getting oil to the head. These engines do run very hot and the oil comes from the oil pump and runs up the cylinder stud to the top of the engine. You could still use a finned oil cooler with this set up if you like for extra cooling.
Check out where the oil gallery runs in this "Cheater Cylinder"....the old sleeve is bored completely out and a new larger one is pressed in. The out side of the sleeve is actually part of the oil gallery. lol