For you with bike carb knowledge

[JodyB]

Had a problem with the inner ring on this style pod blocking the air bleeds on the front of the carbs.

[BradH]

The Mikuni TM flat slides on this bike are a general application performance carb...They are almost always run with no air filters or Pod filters...

Not true for the dirt bike applications on which they were used originally. There was always an air box w/ a large filter and a tapered duct that connected the air box to the bell entry of the carb. The factories tried different shapes & volumes w/ the air ducts & different air box designs, often with the intent of improving throttle response, if not peak power.

As I recall, that whole pod filter "thing" came about from people putting in K&N re-jet kits on their street bikes and dumping the factory air filter setup to use the pods that came w/ the jet kits. A K&N re-jet kit and a Kerker exhaust were primary ingredients for the Poor Man's Superbike in the '80s.

[Truckedup]

The Mikuni TM flat slides on this bike are a general application performance carb...They are almost always run with no air filters or Pod filters...

Not true for the dirt bike applications on which they were used originally. There was always an air box w/ a large filter and a tapered duct that connected the air box to the bell entry of the carb. The factories tried different shapes & volumes w/ the air ducts & different air box designs, often with the intent of improving throttle response, if not peak power.

As I recall, that whole pod filter "thing" came about from people putting in K&N re-jet kits on their street bikes and dumping the factory air filter setup to use the pods that came w/ the jet kits. A K&N re-jet kit and a Kerker exhaust were primary ingredients for the Poor Man's Superbike in the '80s.

If you're trying to make a case that without factory enginnered air box there will be issues, No ,that's not the case in my expereince...My 650 naked frame race Triumph ran over 133 MPH using TM's with no filter's or even velocity stacks and was the fastest of it type for a few years. I know other's with the same results..

[BradH]

I'm not saying it can't work without an airbox; my point is that style of carburetor was designed to use one as part of the induction system. Not running one means you may have to tune for conditions that wouldn't be encountered with the carb's original implementation.

[Little Mouse]

The Mikuni TM flat slides on this bike are a general application performance carb...They are almost always run with no air filters or Pod filters...

Not true for the dirt bike applications on which they were used originally. There was always an air box w/ a large filter and a tapered duct that connected the air box to the bell entry of the carb. The factories tried different shapes & volumes w/ the air ducts & different air box designs, often with the intent of improving throttle response, if not peak power.

As I recall, that whole pod filter "thing" came about from people putting in K&N re-jet kits on their street bikes and dumping the factory air filter setup to use the pods that came w/ the jet kits. A K&N re-jet kit and a Kerker exhaust were primary ingredients for the Poor Man's Superbike in the '80s.

If you're trying to make a case that without factory enginnered air box there will be issues, No ,that's not the case in my expereince...My 650 naked frame race Triumph ran over 133 MPH using TM's with no filter's or even velocity stacks and was the fastest of it type for a few years. I know other's with the same results..

No real bike carb knowledge, but if thats a 650 doing that in utah, id say thats hauling ass. Im pretty certain without trying it my new 2018, 1200 bonneville at 550 ft of dfw tx. Elevation could not even come close to that top speed. You have a picture of your race bike ?

[Truckedup]

I'm not saying it can't work without an airbox; my point is that style of carburetor was designed to use one as part of the induction system. Not running one means you may have to tune for conditions that wouldn't be encountered with the carb's original implementation.

I understand you point..... Production engines warranted by the manufaturer need an induction filter, especially on an off road engine operating in dusty or wet situations..Fitting an effective air filter that also silences intake honk is difficult on bikes because of dense packaging..This results in compromises that are usually solved by clever engineering....Yes, take off the factory air box and almost always the carb will need jetting changes..And K&N or foam type filters may not flow as well as the stock set up
I believe the flat track bikes were using K&N filters in the 70's.Street riders may have used to to look racey, nevermind if they made the bike faster.I first used them in the later 70's to replace a very poor design air box on a 750 Ducati...Some Italian performance street bikes in the early 70's only had velocity stacks, no air filters..
Here's a photo of a supposed genuine Harley XR750 as it was in 1972...The huge filters are very cool..The big filters say something about air demand and tuning especially when they get dirt covered during the racing...

[BradH]

The theme song from "On Any Sunday" just started running through my head...

[GRTfast]

The theme song from "On Any Sunday" just started running through my head...

One of the best movies of all time!

[Truckedup]

Well, I believe the jetting is now as good as it can be...A slighly richer needle jet (metering jet) and a slight leaner needle (metering rod)...Same main jet...The needle does stay in the needle jet at WOT but I have no idea if the restriction is greater than the main jet restriction..Now in high gear the air fuel meter reads just a few tenths richer than through the gears.. The air filters on or off do not affect the air fuel ratio or seat of the pants performance.
Thanks for the suggestions...

[Keith Morganstein]

Not true for the dirt bike applications on which they were used originally. There was always an air box w/ a large filter and a tapered duct that connected the air box to the bell entry of the carb. The factories tried different shapes & volumes w/ the air ducts & different air box designs, often with the intent of improving throttle response, if not peak power.

As I recall, that whole pod filter "thing" came about from people putting in K&N re-jet kits on their street bikes and dumping the factory air filter setup to use the pods that came w/ the jet kits. A K&N re-jet kit and a Kerker exhaust were primary ingredients for the Poor Man's Superbike in the '80s.

If you're trying to make a case that without factory enginnered air box there will be issues, No ,that's not the case in my expereince...My 650 naked frame race Triumph ran over 133 MPH using TM's with no filter's or even velocity stacks and was the fastest of it type for a few years. I know other's with the same results..

No real bike carb knowledge, but if thats a 650 doing that in utah, id say thats hauling ass. Im pretty certain without trying it my new 2018, 1200 bonneville at 550 ft of dfw tx. Elevation could not even come close to that top speed. You have a picture of your race bike ?

I think this is Truckedup’s race bike

D23775E5-7A3D-4449-92D3-98948062E046.jpeg

[Little Mouse]

Looks good. I had a picture of it in my mind that would have had more steering head angle and a hardtail rear end, for nothing but strait line racing.

[Truckedup]

Yup, my bike...the bike was never run with megaphones, just 32 inch straight pipes...The phone photo distorts the steering rake but it is stock,about 27 degrees..It's a modified production class so the basic frame and suspension must be similar to production...1970 engine, 1974 frame...You can see the small guards I made on the carbs to keep the riders pants from blocking airflow..bare bones, no gauges except for the oil pressure that can't be seen while riding..A finger out of place can cut speed so you make your body as small as possible,hold the throttle to the stop and hope nothing blows up.

[Little Mouse]

You need around a 5.4" 100lb gal to ride it, better streamlining.

[Keith Morganstein]

You need around a 5.4" 100lb gal to ride it, better streamlining.

This reminded me of Jay “PeeWee” Gleason. The rider that set low times for Kawasaki, then Honda and Yamaha, helping to sell a lot of superbikes in the day.

[Little Mouse]

Never understood with it so much easier to find light women why more of the professional jockys are not gals. Id put the most petite woman i could find on that non streamlined triumph then still take credit for building the bike that could do the record.