1980 TF 440 top end & best setup for max top end

[luvzvintage]

Hi
Bought an 80 TF440 just after Xmas and I luv it! However, i seem to lack top end speed. Far as i can tell i should be gettting around 6500 rpm at wot but am only achieving about 5000 according to my tach. Speedo at wot reads about 55 mph. I reconditioned the secondary clutch and am waiting for a puller so i can recondition the primary also. I suspect my primary clutch is the culprit as i also seem to have a bog/pull/drag if i cruz around 1/3 throttle - thingz smooth out when i accelerate.

Also, what would be my best setup to obtain max top end for this sled? Primary clutch spring/weights and gearing?

Any opinions??

[manitobatrailfires]

Is it the right tach?
Is it actually a 440 motor?
Is the carb clean?
Is the throttle cable adjusted?
Are all your bearings good--idlers, jackshaft, driveaxle?
Is the track tensioned right?

[luvzvintage]

Is it the right tach? yes, it is....idle rpm set at around 2800 with engagement around 3600

Is it actually a 440 motor? It is an original survivor and is infact the 440

Is the carb clean? I cleaned the entire carb when i bought it (I found it very clean ) )

Is the throttle cable adjusted? Throttle is properly adjuusted - my plug burn couldn't be better! (NGK BR8ES plugs with .022 gap)

Are all your bearings good--idlers, jackshaft, driveaxle? I believe all my bearings to be good (if i had bad bearings, would i not feel quite a bit of downshift/slowdown when releasing throttle? The sled coasts along just fine when i let off the throttle.

Is the track tensioned right? When i bought the sled i thot the track was too tite, so i loosened it up a bit as per spec. Didn't make any diff to performance.


Thanx for the reply! My sled had about 1800 miles when i bought it and it now has around 2400! ) Luv it!!

[manitobatrailfires]

The gearing sounds right for the speed and RPM.
Apart from the clutch, the only thing I can think of is that the throttle valve isn't opening all the way.

[luvzvintage]

is there an easy way to remove those beastly airboxes from the carb?? Near impossible!
I will rebuild the clutch during the off season and see what next winter brings!

[manitobatrailfires]

I sometimes just unbolt the intake boot from the manifold. You can pull the carb straight up then.

[JoeRainville]

Vintage,

If memory serves me correctly, 55-60 mph is about all you will get out of a 40 hp Trailfire. They have large, heavy clutch weights that keep the RPM down, but I do agree that 5,000 is way too low, if that is an accurate reading. It does sound like the tach is reading a bit low, but hard to be sure from here.

I hope this helps,
-Rainville