Peformance gain from Free-flow Filter

[jsorvik]

A quick search of the archives has not really helped me find an answer to this question, but if it is out there and I missed it, please forgive a redundant post.

How much top end/power can I expect to gain by taking off the airbox and replacing the filter with a uni-filter and then rejetting the carb to compensate for the increased air flow.

Right now, I get about 40 mph (via gps) on my TGB Sunset and everything is stock. I would love to pick up a couple of mph on the top end and a little more power for climbing hills. At this time, I don't really want to spend the $200+ for performance pipes.

Would opening up the intake air-flow make a difference?

[90GTVert]

An aftermarket air filter and upjet should help. It's usually a small gain though. A jet and carb will prob cost you $25 or more, depending if you can get it local or must have it shipped. I seriously doubt you'll see much difference climbing hills and more than 1-2mph unless the TGB has a real restrictive setup.

I would leave it alone and look into a 70cc kit. I don't know anything in specific about TGB scoots, but it is a possibility that you can put a 70 kit on with no other mods. The added displacement will show a much greater improvement in acceleration / hill climbing and prob top speed than even a pipe / filter/ jet combined from what I've seen.

I would also suggest leaving the filter alone without the jet. It sounds like you already know that, but some of these 2 strokes are so finicky that an aftermarket filter alone will make them undrivable.

[Karl]

90GTVert is right on the money.

Here is a great explanation of how a tuned exhaust works. If you get the input and output out of wack, then poor performance will occur.

microcarproject.tripod.com/html/tuned_exhaust_system.htm

Karl

[jsorvik]

Thanks for the help guys! Have a bone on me! If I understand you correctly, the air filter/jet combo would be of limited value. If I want to see true improvement I would need to either install a 70 cc kit (which would, at least legally, bump me from moped to motorcycle in my state), or do a jet/pipe upgrade.

For the time being, I wil l probably just stay where I am. . . but can you tell me how much mpg you lose by switching to a 70 cc kit or a jet/pipe upgrade?

[90GTVert]

How much your fuel economy is affected kinda depends on your driving habits. Either the filter/pipe/jet or big bore will have a negative affect on your mileage in most cases. I've heard people say they can get very close to the same mileage with mods, but some people will use less throttle with the mods. Most of us end up taking off faster and driving faster though, so we see a decrease in economy. My scoot gets around 60-70mpg with a 70cc kit and pipe with the stock carb/jets/air box. I go WOT a lot. I think I got 70-80mpg stock. I'm not 100% on that number, I really don't watch my mileage.

[kaintuckdave]

I'm watching my mileage as I just got a performance pipe and an 88 jet. Haven't filled for the first time but seems like my needle is going down faster. Hope I'm not hijacking your thread jsorvik, but do you guys think a free flow filter would help me out as I've had the other steps done by my dealer? I'm not WOT nearly as much as before the mod (don't have to be), but I have been exploiting my faster off the line and mid range acceleration a bit I believe.

[Karl]

Dave, I think you'd be a contender for the air filter since you've done the mods. If you give it a shot then let us know your results.

Karl

[ireland2004]

Personally, I wouldn't do a filter or pipe separately. The combo works well together (with a proper re-jet), and will yield noticeable results when done in conjunction.

[jtl]

Hey, jsvorvik I was hoping you would do the 70cc top end so that I could follow your lead. There is just not that much discussion about TGB's. Maybe Harry, who posts occasionally on the TGB forum and on Provoscooter will be able to add some valuable info since he is now a dealer for TGB. OBTW I am originally from MN and know those hills in Duluth pretty well.
John

[jsorvik]

Yeah. . . it may happen, but it seems like it makes more sense to just go to a 150cc or 250cc scooter then to spend the money, time, and heartache to bump up the CCs on Sunset. . .

BTW, where is home now?

[motomech]

Aug 5, 2008 15:49:13 GMT -5 90GTVert said:

An aftermarket air filter and upjet should help. It's usually a small gain though. A jet and carb will prob cost you $25 or more, depending if you can get it local or must have it shipped. I seriously doubt you'll see much difference climbing hills and more than 1-2mph unless the TGB has a real restrictive setup.

I would leave it alone and look into a 70cc kit. I don't know anything in specific about TGB scoots, but it is a possibility that you can put a 70 kit on with no other mods. The added displacement will show a much greater improvement in acceleration / hill climbing and prob top speed than even a pipe / filter/ jet combined from what I've seen.

I would also suggest leaving the filter alone without the jet. It sounds like you already know that, but some of these 2 strokes are so finicky that an aftermarket filter alone will make them undrivable.

Yes, that has been my experience too. Two strokes run better with an enclosed air box.
They need some resistance in the intake tract for the nozzle to meter the fuel properly.

The other thing is, with an open filter on a two stroke, should one get caught in the rain, water can enter and hydraulically lock the slide open.
That leaves one riding with the kill switch, not fun.

[kaintuckdave]

I spoke to Chuck at SYM and he said my scoot has a rubber restricter that can be ripped off on the lid of my air box, and also a nozzle thingy inside my intake manifold that can be pulled out with needle nose pliers. Think I'll try these measures before trying a stand alone air filter in place of my box.

[jtl]

Jsvorvik,
I live in SW FL (Venice). I lived in Bloomington for many years. I sold my TBG yesterday so now I am down to a Yamaha Vino and looking for a Zuma. Easy to mod and lots of good forums to help.
John