1975 Thunderjet - Vintage Snow

Trouble Shooting
Malfunctions that occur when adjusting a carburetor can be
traced to either too rich a mixture or too lean a mixture.
Sym ptoms are as follow:
1. When air fuel mixture is too rich:
a. Eng ine noise is dull and intermittent.
b. The condit ion grows worse when the engine is hot.
c. The condition grows worse wh en the starter (choke)
is opened .
d. The condition may improve slightly when the air
silencer is removed .
e. Exhaust gases are heavy .
f. Spark plugs become fou led.
2. When air fuel mixture is too lean:
a. The engine becomes overheated.
b. The co nd it ion improves when the starter is ope ned.
c. Acceleration is poor.
d . Spark plugs burn .
e. The revolutions of the engine fluctuate and lack of
power is noticed.
Carburetor Specifications
Adjustment
The t rack should have one inch slack bet ween the c leat and
the hi-fax. Thi s should be checked with th e machi ne su p­
po rted in the rear and pulling down at th e bottom cente r of
th e track . If incorrect, ad ju st the two idl er wh eel adj ust ment
bo lt s located in the rear of the skid frame (Figure 55).
Alignment
Track alignment is very important to both durability and performance.
The tra ck should be aligned so the slide rail hi-f ax
is centered on the cleat and not rubbing on track belts or
guides .
To Adjust :
1. Run tr ack slowly, if track runs to one side.
2. Turn adjuster bolt, on that side only (Figure 55).
3. Recheck tra ck alignment and if correct, tighten locknut.
19
Carburetor Type
Main Jet
Jet Needle
Needle Jet
Slide
Pilot Jet
Air Screw
Bypass
VM 36
250
6DH3-3
1590-8
3 .0
35'
1 1/2
1.4
Suspension
The suspension is designed to permit maximum adjustments
for varying track and snow cond itions. There are basically
two (2) adjustments.
Front Springs
ADJUSTERS
Figure 55
015
The front springs control ski pressure and track angle. Increasing
front swing arm spring ten sion will li ghten ski
pressure and allow for better track contact. Decreasing front
spring tension wi ll increase ski pressure and permit skid
frame and track to mo ve up into the tunnel for bett er flotations
in heavy snow conditions.
Rear Springs
The rear swing arm sp rings should be adjusted for rider
weight. The suspension should be adjusted to allow arm
movement for good ride but prevent bottoming on all but
severe bumps.
Track
The track is a steel cleated type for good traction and ease of
studd ing .