Modern Vespa

Far from it, Mike.

What I was implying is that your mod is a botched nose job



j/k!

A follow up:

For those of you concerned about a substantial fuel economy hit as a result of this mod, it does not appear that I have sustained one.

I'm at nearly 1600 miles, and my economy is still on the rise. My last tank got me my best "accurate" fuel economy to date at 61.5. I did the mod at the beginning of April, and the 56.7 was most likely a result of riding it really, really hard post-mod (had I ridden it that hard un-modded, it probably would have ended up the same).

My YTD fuelly stats:

Windbreaker, you miss the point. Like the guy in the cartoon, I'm keeping it for the improved airflow!

Mike

Well, a number have independently tried out my mod, and here are the conclusions, extracted from ModernVespa and GTSOwner's forums -

Dougl:
Impressions? Noisier, when full throttle but in a nice way. Definitely torquier, even from standstill. I like it. A lot.

Stinkyjones:
It's not significantly louder (or really any louder for that matter). However, it feels much more torquey and seems to pull more responsively, especially when you give it throttle at speed. I'm exaggerating when I say this, but I was cruising at about 25 mph or so and gunned it, and it felt like it wanted to pick up the front end . . .

It seems to pull through corners a little more confidently as well when you roll on the throttle.

Peppier. It's much peppier. It doesn't necessarily feel quicker off the line, but it seems to hit the meatier part of the torque curve a bit sooner.

Babyarms
Been out for a short ride. I concur with Mike's findings. Seems quicker through the whole rev range. It just seems to rev more freely. Got up to 80 on a short bit of "A" road, pretty sure I've only managed 70ish on this bit of road before, although this wasn't exactly a scientific test.

Glover:
Took mine out for a test yesterday and I can scientifically say that my GTS is now faster than a quantam sports car and a Harley.

Stinkyjones again:
I like the way it now confidently pulls out of a corner when i roll on the throttle, and I like having the extra oomph in tight situations.

Doppleganger
It seems to be pulling better through the whole range, seems nippier out of the corners. Didn't get flat out but got up to 80 indicated on the A road and it's a pretty short stretch, I'm sure I haven't got up to that speed on it before. None of this is scientific but the scoot seems to be running better.

I haven't cut out nearly as much as Mike (so shouldn't be as much chance of the filter moving any way) and the scoot SEEMS to be running better.

I'm really happy with this mod so far, but I will open up the filter after a hundred miles or so to see how things look.

Glover
Cant say I noticed huge difference however the bike seems to be smoother getting up to speed and the power seems to come on more progressively with less lag. I think how others have described it as "peppier" fits the bill quite nicely.

Dobest
So, I have made a test rid this evening after the mod, about 40 kms. I can appreciate better response on throttle! The scooter improves much better the speed and on up hills the GTS keeps the speed more easily. Let's see the consumption on the next fuel up.
I also noticed the sound of the intake a little louder, but I'm happy with a much more bass tone come out the engine .
Until now I like the results.

Dobest again:
So, after 178 kms before the mod the consumption still the same. My GTS 125 ie seems more powerful, The maximum speed is achieved more easily (120 kms/h on speed - 105 kms/h on GPS). But, on the up hills the speed is easier to kip and the acceleration 40 -> 90 kms/h is really better

Souljah:
ive done it and recone the mid range has improved which is were mine lacked compacted to the 250

Smudger:
I have done this to my 300 and I'm happy with the results after my weekend in France for Cobblesoul, really seems to have improved acceleration from 60mph onwards, although I did the Cheeky Thomas mod drilling holes not the V cut as advocated by Mile Holland

Carlosfangio:
good .bad or indifferent........did the curious thing ...and had a play....but drilled instead of cutting.... .. . but was conserverative... im no scientist ....but it flys ... 0-60 mph with me on...16 stone....about 7-8 seconds... .. dont remember it being like that...and good for overtakin.. .plus the engine sounds less restricted

Geetee1:
hi all....after much umming and arring i did mine this morning...quite impressed:- standing start a lot quicker but the biggest gain must be 35-60mph caught me by surprise

Geetee1 again:
did the "V" in the lid and drilled air box as per mr thomas,s pic,s...well impressed, took the bike down the A66 to boro and back this morning...a lot more responsive

Copello:
Did it on a 300 gts.
Best mod I ever did. Clearly more air and better revving after 100 km/hour. First time I did 140 today, off wind that was.
More power over the range.
I am very impressed.

Many thanks to all of you who have supported me by trying it out and reporting back.


Paul Melici of PM Tuning has put my mod on a dyno. He found about 0.3 hp increase over the whole speed spectrum. I was a bit disappointed - it feels like more than that to my backside. But he was surprised that a simple pocket-knife hack could produce that result.

Anyway, with these accolades I close my case.

Mike

Just a little warning from Paul Melici (PM Tuning).

He says that on his tests the scooter ran slightly lean with my mod, the EFI was not quite coping with the extra airflow. A performance pipe has the same effect, and he worries that combining a pipe with my mod could make the mixture too lean, causing overheating.

In the latter case, he recommends fitting his aftermarket TFI to correct the mixture. He has big concerns about the ability of the standard EFI to cope.

Mike

Well, I'm not Cheeky, but with toungue-in-cheek, I can say that Paul has a healthy sense of business

Hey Windbreaker, you jumped in just before I deleted that message to Cheeky. That was only meant for the GTS Owners forum, where Cheeky Thomas is the resident guru.

But I have had similar thoughts, and I have read some bad reports about aftermarket TFI modules.

Mike

I wouldn't worry about it... I have a pod filter and aftermarket exhaust on my Beverly, and the ECU adapts and it's AFR are perfect... there is no way that your airbox mod is putting more air in than a pod filter is!!

I am really keen to try your mod in the next few weeks though, in case I want to move back into stealth mode!! My scooter is so black from all my visual mods that it might benefit my health to have some noise though!

OK so maybe Paul is just putting his mouth where his money is

(Sorry, Paul! Couldn't resist.)

Mike

K&N RD-0600

View from the pet carrier down into the engine: view from side... and finally the sound... http://scootercommunity.com.au/forums/t/12927.aspx

lol miguel that is me doing those tests! hahaha nice... thanks for reposting my vids though

Sounds familiar that

Well, someone had to try it!!

Been thinking about that long induction pipe for a while, and how far it extends into the air filter box. So yesterday I decided to do something about it. "Mike's Mod Stage II" I thought!

In for a penny, in for a pound, so I chopped off 2 inches of the pipe.

The result? That lovely crisp performance has gone, and my top speed, uphill, downhill and on the level, has dropped by about 10 kph.

So don't touch that induction pipe!

I shall try repairing the damage using a piece of plumberrs plastic pipe, but wil probably end up buying a new induction pipe. They are not too expensive. At least now I know!

Mike

respect and thanks for trying man!!! i had heard rumours of such results but now i believe... i watch your posts religiously it's good to have other modders of scooters here in australia!

Has anyone tried Mike's air box modification on a 300 Super?

MGG

I guess no one has tried this mod on a 300. I may give it a shot soon. Have also been looking at the Hi Flow and Malossi air filters.

But one thing at a time. I have a feeling the 300 is being choked by this filter.

Who knows?

Thanks to all of those who have posted and traveled this path.

MGG

I was replacing the variator rollers as part of the 6k mile service yesterday, so thought I might as well give this mod a go, while im fiddling...

I rode the scoot in to work this morning (which isn't ideal for testing this mod - a lot of stop and start riding). Overall, the scoot is definitely more throaty, and the mid-range accellaration seems a lot better (between 25 and 40 mph). It seems to pull better off the line as well, but that might be because of the new rollers, although I would think that this mod would help with that too. It seems like I'm able to hold speed at a lower RPMa s well, which bodes well for fuel consumption, but time will tell, I guess.

Thanks again to the OP for posting this! It's a great mod and easy to do as well!

Did it on a 300 gts.

Best mod I ever did. Clearly more air and better revving after 100 km/hour. First time I did 140 today, off wind that was.

More power over the range.
I am very impressed.

Interesting... has anyone tried this mod on a 125

Any reason why it wouldn't work on my GTV

Best,

Mark

Well, for starters, the 125 breathes only half the air a 250 breathes. So, cutting the expansion only half as wide should yield the same results

But maybe cutting it the same would yield even better results!

Until someone does a comparison between my mod and a K&N filter, we will never know whether my cut is "perfect" for a GTS250, or needs a little further experimentation. 8)

Mike

Edit: On second thought, if the 125 has half the air stream, then I would expect less, if any, benefit with my mod. But it costs nothing, so give it a go and report back.

I had to chime in on this modification and my personal experience.

Last week I did this airbox mod on my GTS300. I drilled three 3/8th inch holes between the 2 sides in the airbox. I also cut a V into the intake snorkel (although not very large like some of the pics) and then scrubbed the air filter and re-oiled it. I didn't want to go crazy because of the risk of running it too lean so I decided the 3 holes would allow enough but not too much more air to pass through.

I was very skeptical that there would be improvement of any kind but I decided to give it a go. For a cost of nothing but 2 hours time I figured why not. I do have to say that removing the airbox was a pain in the ass but the results were worth the effort.

Let me just say guys that this mod DOES WORK. I was absolutely shocked to see how much of a difference this mod makes in the bike's ability to pull. This makes a extremely noticeable difference in low range and mid range power, in fact from a light you can EASILY feel a difference up until about 65 mph indicated. It now longer feels like the bike is getting chocked or struggling to accelerate.

The bike now feels VERY STRONG accelerating and to say I am pleased is an understatement. I have to recommend this mod to all of you. Many will say that a seat-of-the-pants review means nothing but this mod is so noticeable it blew me away.

As far as top speed is concerned I don't really see a difference but I have never really had any problems or complaints about the top speed of my 300. I also don't hear any difference in the engine nor do I hear any type of air sound from getting sucked into the filter differently.

When I came up with a way to open the airways that would be reversible in case of unexpected side effects, I did it:


Four drilled holes around the U


Three drilled holes in the snorkel.

Should I decide I want them closed again, I'll install washers from both sides and a screw holding them together.

Stay tuned for the results. I did a pre-test comparison vs Salima's GTS, and I'll do a post-test this afternoon. Then we'll have some real hard (if scientific) numbers.

For a teaser:
Pre-test performance (mph indicated)
0-40 7s
0-50 10s
0-60 15s

Measuring fuel consumption will take a little longer but will be done also.

Wow! Right out of the garage it felt it had more oomph. It is amazing how powerful...our mind is. The numbers tell a different story: my GTS is now slower (!) than it was before.

Here are the complete data I have collected:

0-60mph
Pre mod: I had a lead of 1/2 of a Vespa's length. Repeatedly.
Post mod: I fell back by 1/2 of a Vespa's length. Salima's is now faster. And it is not because hers is red!
The 0-x times have not changed. I could only glance at my wrist watch, so these are not exact anyway.

40-60mph
Pre mod: We were about even, with me maybe having 1/4 length lead.
Post mod: Mine is now 1/2 length slower than Salima's.

So, there you have it. I'm going to watch my fuel consumption, and if I can wait long enough before I reverse everything, I might get some indications there. I am definitely going back, though. Sorry, this mod did not work for me.

Sorry, Windbreaker. This is the first negative report I've had on my mod. Wish I could come up with some ideas why it didn't work for you.

Mike

Correct, I didn't touch the induction pipe.
I didn't remember drilling was previously suggested. While I do believe that your radical "wall-ectomy" is more streamlined than my holes are, my extended airway should still yield some improvement. I forgot the details on your dyno. Was it dynoed before and after, or only after, and if the latter, compared to what?

I cannot stress enough that I (also) thought my GTS would pull better after I had finished the mod. Only, the objective comparison did not agree. I suggest that all who have done this mod "race" their GTS against another GTS250 to objectively verify their subjective impressions and report here.

I have raced unmodified GTSs (well, without any air intake mods) and can state with certainty that the speed of a given GTS will change randomly for no reason. Repeatedly.

During Cannonball, we repeatedly noticed that one bike would be faster than another for a few miles, then would run neck and neck, then would swap places, all randomly and without rhyme or reason. Sometimes a GTS couldn't even keep up while drafting. Other times the same bike would pull ahead and gain a quarter mile on the others. It happened so many times that I finally accepted that GTS performance is not consistent.

This data point should be used while considering your other data points.

+1
I have not gone neck and neck with other scooters but I have ridden WOT for extended periods and YES the GTS just "likes to run sometimes" better than others. strange, don't let it get inside your head, just let her run when she wants to....yee haw

Still following this thread with interest, and now it got even more interesting.
Did you disconnect the battery or run it long enough for the ecu to adjust, or do you not thing that that is a problem?

Jess wrote:

I have raced unmodified GTSs (well, without any air intake mods) and can state with certainty that the speed of a given GTS will change randomly for no reason. Repeatedly.
(I have noticed this with top speed on my 300!)

I recently did this modification along with replacing the air filter with a Hi Flow on my 300.

I did not notice any appreciable difference at all. (OK my mind thinks that it is running a little smoother or easier but I don't no for sure.) I noticed a little difference when changing the exhaust but only in the mid range. I don't know if my scooter is mellowed out, I have gotten use to it, or a combination of the 2 but when I first got it, it would jump off the line and I think that was related to the ECU not being set yet. Now it takes off differently, smoother. I have also noticed that after changing something and resetting the ECU by disconnecting the battery it takes 30 to 100 miles of riding to really settle in (its like it is learning the new curve) so it is very difficult to say that something did or did not work right off.

Just my observations.

MGG

When I first modded my air filter I did reset the ECU, but I don't think I mentioned this in my write-up. Wasn't sure whether it was necessary.

Regarding objective measurements, there is a long steep hill on a freeway not far from my home, where my speed used to drop to about 95kph, and since the mod it drops to about 105kph.

Other than that, I am sure my scooter is accelerating away from any speed better, and reaching 120kph more easily and readily now. But that is seat-of-the-pants, not objective.

I hope Motorsport are willing to sacrifice a filter box and come up with some dyno readings.

Mike

A little update here...

No, I had not reset the ECU. And yes, I've done some 50 or more miles since the mod. So, should that take care of the ECU adjusting, or does it have to be reset?

Then: fuel consumption seems to be stable. When I modded, I had about 1/3 of a tank left. When I refueled, I was spot on my average of 77.7 mpg. The next full tank should tell better, though.

Once I hear back about resetting ECU or not (in my case), I'll do another comparison against the wife's GTS.

Looking forward to your trials and report!

Still waiting to hear whether I need to reset the ECU or not?

Anybody know for sure?

I don't know whether it makes any difference with this mod. But it is very easy to do. You don't have to disconnect the battery, just remove the fuse that is under the saddle in front of the pet carrier. I think it is a yelllow one. Leave the fuse out for a couple of hours and then put it back.

Hope it does make a positive difference.

Mike

I did the normal mikes mod, cutting a v into the outside air intake, then enlarging the hole in the wall (I did a pear shape, big at the bottom but leaving the top bit that holds the filter). This would allow more air, but with about the same level of turbulence as normal. Drilling multiple holes, OTOH, could (will) lead to more turbulence, and this could actually reduce airflow. Certainly the air is following different paths, whereas the standard mikes mod keeps the air to more or less the same path as stock. I suspect the holes in the outside air intake runner are the culprit- its the narrowest part, so the velocity of the air is highest and the effects of turbulence will be greatest. Cutting out the area around these holes should sort that out, as just covering them would still leave a rough surface on the inside.

Then again, i could be talking out my arse, because a less aerodynamic jacket would also cause more turbulence....

Hi Brad, so your mod went pear-shaped, did it?

I have had similar thoughts about the multiple holes => turbulence => less performance enhancement. But I don't think anyone is every going to do the comparisons on a dyno, so they remain just thoughts.

What did you think of the results of the mod?

Mike

Just a sad update after enough miles since making Swiss cheese (and without resetting the ECU): no change. Still a bit slower than the benchmark GTS. Fuel consumption won't be far off the old numbers and I will post once I have a full tank's number.

About the turbulences--could be. Could. On the outlet. I don't see that possibility on the snorkel. At least not in a negative way.

Updates:

1. Fuel consumption remains exactly the same as before the mod: 77.8 mpg on the last full tank vs 77.7 before, under similar riding conditions.

2. Power remains a bit below pre-mod performance

3. Related or not, I noticed the Check Engine Light coming on above an indicated speed of 72mph.
Can anyone of you who did this mod confirm for sure that their CEL is not coming on above a certain high speed?
More details on this CEL issue here.

Never had my cel come on at all despite over 500 miles since I did the mod.