Fastways, Dean

LI ATV, Steve

LRD (via LI ATV)

The objective of this buildup was to increase usable power to correspond to advancement of rider capabilities and increase in competitive requirements of promotion from Novice to Amateur class. Timing of this plan was premature by 4 months but was prompted by failure of shift spindle and subsequent need to disassemble motor for repair.

Professional judgement of Jason at LRD is that this motor build up will result in a true total horsepower of 40+ based on dyno testing of their kit. This motor will retain the ability to run on pump gas of octane rating from 93 (dyno tested at LRD) to 100. Our plan is to only run 100 octane Sunoco race gas.

This plan was designed to address the motor as a complete system from intake, combustion, power transfer, and exhaust. Fastways has supplied all disassembly/assembly including replacement of failed shift spindle. Fastways has taken advantage of the required disassembly to inspect rod, crank, bearings, and transmission during tear down. Due to freshness of motor (July 2000, less than one racing season) inspection verified that replacement of these parts was not required.

Improved air/fuel flow is required to support the increased displacement and higher rev limits planned.

The carburetor will be changed to a Keihn FCR (Flat CR) 39mm race only model. This is the recommended carb for modified 400s from both LRD Racing and Sparks Racing.

The FCR as jetted by LRD has been dyno tested by them with claims of 3hp gain across the entire power band over the Edelbrock Quicksilver. No comparison data is available against the Lectron 36 or 38mm models or stock carb. The carburetor has been sourced, used, from Tommy Tantillio District 34 expert rider #112. (The carburetor was installed and running unsatisfactorily on Tommy's 425. Tommy installed the LRD recommended main and pilot jets and made the recommended air screw setting. When installed as is on our bike it ran poorly at low and mid range but worked well on the high end. Without time to dial it in it was removed and replaced with the stock unit equipped with a 172 main jet, a 45 pilot jet, and air screw at 1 and 1/4 turns. This report will be updated upon further testing of the FCR). !!!!!UPDATE JULY 30, 2001. After hours of test time we have the FCR to a usable state. We used a 162 main, 50 pilot, air screw of 2 turns, rod clip in center position. We also had to open up the fork adjustment on the actuator arm of the accelerator pump. There is still a slight lag punching the throttle from idle but does not affect racing. After the first race, rider reports significant change in mid to upper power as though we did another motor build up. This was well worth the effort as the flow of the rest of the motor needed the additional intake flow.

Fastways modified valve actuation by supplying and installing a new Honda race model cam from a motorcycle. This cam has better high rev and power band characteristics than stock. This cam has the same specifications as the regrind offered by White Brothers but has the durability of a new unit.

Fastways modified the head and valve train to support better airflow from the new carburetor and higher rev limits resulting from the new cam. They ported both the intake and exhaust of the head, R&R'd the stock Honda valves. They reground the valve seats, added heavy springs, and titanium retainers.

Displacement was increased to the bore limits of the stock cylinder without the need to install a cylinder sleeve. The compression ratio was increased to just under 12 to 1. LI ATV arranged for LRD to provide their 425 kit containing larger 11 to 1 piston with ceramic coating. LRD bored the cylinder, and milled the cylinder surface by .025 for proper clearance of head to supplied piston and to produce the above compression ratio. These modifications will require attention to be paid to the resulting increase in produced temperature.

Fastways installed heavier clutch springs. They reported the stock clutch was in pristine condition and needed no R&R.

Owner obtained and installed the Yoshimura Titanium racing header and silencer. (selection based solely on the fact that this item was already obtained as part of the purchase of a backup bike).

A screaming 425 with full and wide power band, smooth acceleration, revs to the limiter, does not overheat, runs on 100 octane gas. Confirmed by two immediate first place finishes.