80's Liquifire Airbox Question

[johnnycyclone]

Is anybody running something besides the stock air box on your 80's Liquifire? I don't like the fit (rubs on steering shaft)of the UNI pod filters I purchased, and was wondering if anyone else has found something that works.

Thanks....Terre

[harleysportster]

Use the shorter carb mounts sold thru New Breed Parts and keep the original air box.

[johnnycyclone]

Use the shorter carb mounts sold thru New Breed Parts and keep the original air box.

That's what I was thinking, just seeing if anyone else has done something not using the stock box....Terre

[AirborneX4Special]

Yes. The shorter flanges make life much easier on most of them, although some individual machines seem to work fine with stock ones. I never understood why the tolerances had to be so close.

[sledder670]

i was going to run 38mm carbs with k&n air cleaners this winter on mine but carb boots are cheaper

[Horicon Joe]

Just giving everybody a heads up that might save your motor. I recently heard of guys using the shorter carb boots to make the install and removal of the air box easier. I knew this was a no no from back in the day but could not remember why. I also knew Deere would have done this simple fix to get the air box on and off if it were not necessary to have the longer boots.

I called Stan Hayes and asked the question as to why and he told me the whole story. They were burning down engines early on and could not find the reason. Stan spoke HIGHLY of the engineer who solved the problem and his name was Dick Bahr. What he did was cut holes in the carb bowls and epoxied them shut with Plexiglas. While running on the dynamometer he could see the fuel foaming up right away while it was running. This put air in the mix and leaned them out. He then developed the new boot with correct length and wall thickness to solve the problem. The harmonics of the engine was removed with the correct boots and that is why the air box is such a tight fit and the carb is so close to the steering column. This is also the reason for the past 37 years an extra 1.6 million choice 4 letter swear words have been floating through the atmosphere!!!!

Cheers
Joe Wanie

[AirborneX4Special]

Vibrations, man, vibrations......

Next question....where to go to locate the original style boot?

[Horicon Joe]

I see Matt sells some that say they fit 80-84 Liquifire but I am not sure if they correct length?

[AirborneX4Special]

I think they're the short ones.

[discus]

I wonder if there is any foaming from the fuel sloshing around when you're bouncing down the trail or across the lake? If you're running something close to the stock jetting it's not going to burn down because you don't have the original manifolds. I would wager that more engines have been damaged because of dirty carbs or wrong jetting due to people just not wanting to deal with the difficulty in getting the air box off with the original manifolds. Buy the shorter ones so you can service the carbs when you need to, on the trail or otherwise. That is your best bet to avoid engine damage.

As for the air box, you'll need to change to non-power jet carbs if you want to remove it and use uni-pods or similar. I would leave it on. I'm not sure how aware JD was back when they designed their snowmobile air boxes, but manufacturers eventually learned how to design them to work with the engine. There is a resonance that occurs inside the box that can be tuned to improve engine output. You would gain more by doing some research on carburetor venting. There's a reason Polaris went to running the vent lines to the handlebars in the 80's and early 90's then went to venting to the air box in the late 90's. Controlling pressure in the float bowls will create more consistent performance from the engine over a wider range of temperatures. Look into the Holtzman Tempa-Flow.

[Matt]

That's really interesting Joe!

As mentioned before the ones I sell are the short ones. I am not aware that the original long style are still available today. However there are carb spacers available. Would they accomplish the same thing if you wanted the correct throat length?

[Matt]

BTW airbox is tight fit on the Invader too, I'm running VM38s/Uni filters. General consensus seems to be that the VM38/non PJ are much easier to work with if you are trying to tune it.

[SS440-80]

I wonder if there is any foaming from the fuel sloshing around when you're bouncing down the trail or across the lake? If you're running something close to the stock jetting it's not going to burn down because you don't have the original manifolds. I would wager that more engines have been damaged because of dirty carbs or wrong jetting due to people just not wanting to deal with the difficulty in getting the air box off with the original manifolds. Buy the shorter ones so you can service the carbs when you need to, on the trail or otherwise. That is your best bet to avoid engine damage.

As for the air box, you'll need to change to non-power jet carbs if you want to remove it and use uni-pods or similar. I would leave it on. I'm not sure how aware JD was back when they designed their snowmobile air boxes, but manufacturers eventually learned how to design them to work with the engine. There is a resonance that occurs inside the box that can be tuned to improve engine output. You would gain more by doing some research on carburetor venting. There's a reason Polaris went to running the vent lines to the handlebars in the 80's and early 90's then went to venting to the air box in the late 90's. Controlling pressure in the float bowls will create more consistent performance from the engine over a wider range of temperatures. Look into the Holtzman Tempa-Flow.

I just have to say: -So damned good writing

[AirborneX4Special]

If I'm catching the drift correctly, the spacer / short boot concept will not absorb the engine vibration in the same manner as the longer boots. It's not the length to the carbs inasmuch as the length of rubberized dampening potential of the longer flanges. That aside, the venting scheme sounds intriguing.

[Mark633CSi]

Just giving everybody a heads up that might save your motor. I recently heard of guys using the shorter carb boots to make the install and removal of the air box easier. I knew this was a no no from back in the day but could not remember why. I also knew Deere would have done this simple fix to get the air box on and off if it were not necessary to have the longer boots.

I called Stan Hayes and asked the question as to why and he told me the whole story. They were burning down engines early on and could not find the reason. Stan spoke HIGHLY of the engineer who solved the problem and his name was Dick Bahr. What he did was cut holes in the carb bowls and epoxied them shut with Plexiglas. While running on the dynamometer he could see the fuel foaming up right away while it was running. This put air in the mix and leaned them out. He then developed the new boot with correct length and wall thickness to solve the problem. The harmonics of the engine was removed with the correct boots and that is why the air box is such a tight fit and the carb is so close to the steering column. This is also the reason for the past 37 years an extra 1.6 million choice 4 letter swear words have been floating through the atmosphere!!!!

Cheers
Joe Wanie

This isn't my post and sorry if I'm high jacking slightly but this, this type of info is why I am in love with this forum. The collective experience and access to info from years gone by on here is unbelievable. You may notice I only have 20 some posts. That's because there is so much info on here that all one needs to do is use the search function. If I can't find it there I ask and when I do, you guys never hesitate do answer with answers like this.