Re: Puch Gila doesn't want to rev

Overpriced Parts /

V force reeds really wake up a Gila kit

Re: Puch Gila doesn't want to rev

Matt Mahloch -- MBM Customs /

Spin it to the moon!

I hope your running amsoil saber at 80:1 on a side note.....make a video of your speed run.

Re: Puch Gila doesn't want to rev

I'm really considering some other reeds but $140 is really a bit more than I want to put into it right now.

What's the "correct" way of modding the intake and giving those top petals some space? I'm guessing a spacer? And if so, what's best? I've seen a slightly angled one that looked interesting.

As for oil, I'm running Agrol F1 racing oil at 2%. It's been serving me well in my snowmobiles, it has that racey smell, and I get it for free, so that's what I'm using. It's a Swedish brand tho so I doubt anyone here has heard of it.

Re: Puch Gila doesn't want to rev

Matt Mahloch -- MBM Customs Wrote:

-------------------------------------------------------

> make a video of your speed run.

Here we go :)

60 mph @ 11.8k rpm (both uphill and downhill).

And here's some footage from last weekends 1/8 mile dragrace. I'm racing at 4:14, 7:14, 10:34 (semifinals) and 13:23 (finals). The last run in the vid was my best of the day, 11.40 secs/61.5 mph.

Now I need a larger carb and some new reeds so I can get this thing to rev properly.

Re: Puch Gila doesn't want to rev

Are you fucking with us? You can build up a gila and fab your own expansion chamber but didn't think to put the two together? This is weird.

Re: Puch Gila doesn't want to rev

Oh but I am still not convinced the pipe helped all that much for the revs, I made it because i wanted more power, not because I thought it was going to help rev more. I can still feel it hit a wall at 12k no matter what gearing.

Something else is holding it back and I'm pretty sure it's on the intake side. I know that at that race I had the tiniest carb of em all so I'm going to try a 28 now.

What made the revs go up from 10 to 12k was probably more the porting than the exhaust, unfortunately I did it all in one go so I guess I'll never find out what change exactly made it rev more.

Also, chainsaws don't have expansion chambers and some of those rev 13k+ all day long, how do you explain that? (edited)

Re: Puch Gila doesn't want to rev

well most chainsaws have no real load and are piston port put a big ass carb on it an hpi and you might get to 12,000

Re: Puch Gila doesn't want to rev

I don't think your carb size is limiting your rpm. You'll probably notice more power in the powerband with a bigger carb, but your port timing/exhaust pipe is probably what's limiting your rpm.

I don't know what porting you've done, but shorten up your pipe and that gila will happily go past 12k.

Re: Puch Gila doesn't want to rev

Even if I lift the rear wheel or even remove the chain it won't rev more than 12k, already got an HPI on it and tried all kinds of different timings.

The one big difference between this cylinder and other 2-strokes I've worked with is that this one has reeds whereas the others were all piston ported, so that's what causes me to believe the problem must be in the intake.

The porting I did was raise the exhaust 2 mm and widen it 3 mm on each side, enlarge the exhaust channel all the way out, and put an extra hole in the piston for 360 deg intake.

My theory right now is that the 360 deg intake probably did most for the rpms but I really don't know. I'm not sure if raising the exhaust duration from 178 to 186 would be enough to cause a 2k increase in rpm.

I'd like to go higher on the exhaust but I need more transfer duration too, blowdown is 36 atm so maybe a bit on the high side. I can't mod the piston for the transfer duration because of the L-ring, so I guess I'll have to make a spacer.

The pipe comes in late enough as it is, below 9000 the engine is pretty much dead, so I really don't want to shorten it.

Re: Puch Gila doesn't want to rev

That pipe really doesn't begin to hit until 9k?

Definitely go up to a 24mm carb, 28 if you want to be cool. I don't know if the stock reed valve will flow a 28mm carb though.

What reeds are you using? Stock?

I still think it's your pipe.

Re: Puch Gila doesn't want to rev

It might be a bit lower or higher, but look/listen to that dragrace vid and you'll hear the rpm go down as I get moving. When the rpm is at its lowest about halfway down the track, it revs about 8000 and I know for sure it has a bit of a problem getting out of that dip. It picks up quickly once it does get out of the dip though, so I think 9k for the pipe sounds about right.

This engine is now a racing engine, I'm not going to be using it on the street because with the pipe it makes way too much noise (that, and I would be buying new clutch pads twice a week). So I'm just gonna test a 28 and see what happens. I should probably get me some V-force first though.

(edit: typos..) (edited)

Re: Puch Gila doesn't want to rev

what the fuck? BUMP!

Re: Puch Gila doesn't want to rev

Re: Puch Gila doesn't want to rev

Ken please elaborate on the 11k rpm max for a reed engine

Re: Puch Gila doesn't want to rev

ken is just shooting from the hip as usual.

this is a pretty cool thread, i had ignored it because i figured it was some idiot, glad i checked it out

Re: Puch Gila doesn't want to rev

I have a hard time grasping that you can make your own expansion chambers but didn't realize the stock pipe was restricting your bike. Is it just me.

Re: Puch Gila doesn't want to rev

Wow, whats with all the interest in this 2 year old thread all of a sudden?

Anyway I got myself some Malossi reeds and got about 4-500 more rpm out of it, no other changes. Didn't have time to work on it this summer. I also bought a new piston for it to experiment with intake duration, 360 probably isnt good. Also bought a TM28 but no time to make a new intake manifold, and a new head to experiment with different CR. Shaved down the head a bit already but haven't tested it yet.

A little vid from the only race i ran this summer, was geared a tooth or 2 too high but couldnt be bothered to change it because it was raining most of the day.

(edited)

Re: Puch Gila doesn't want to rev

sweet ride

Re: Puch Gila doesn't want to rev

murdering shifter bikes is something to be proud of.

Re: Puch Gila doesn't want to rev

your balls must be the size of watermelons!

Re: Puch Gila doesn't want to rev

nico v = 1bmf

Re: Puch Gila doesn't want to rev

campeona del mundo /

your wheel size may be limiting revs

Re: Puch Gila doesn't want to rev

Still not reving too much.. Falls flat on its face at 12400 (check 2nd run in the vid for evidence).

At least I got past 100 kph on the 1/8 mile this weekend.. 103.9 kph / 64.6 mph with an ET of 11.12 secs. Trap speed is getting there but ET could be better.

If I can get it to rev like 1000 rpm more I can go down 2 teeth and it should take off a lot better.

That's with completely new porting and a new pipe btw.. I'm pretty sure it's either the reeds (Malossi) or my tiny 21mm PHBG.. A TM28 is already waiting on the shelf, just need to fabricate an intake manifold for it.

New pipe:

(edited)

Re: Puch Gila doesn't want to rev

sounds just right.

Re: Puch Gila doesn't want to rev

Not sure how I missed this thread the first time, but this has to be my favorite build in a long time.

Re: Puch Gila doesn't want to rev

TM28 is in place.. If anything it seems to have made throttle response snappier than with the 21. Not sure why but my new intake is probably a lot better than the old one. Also spent some time on the reed block. Seems to pull harder too from what I can tell. Test ride tomorrow if I can score some jets.

Re: Puch Gila doesn't want to rev

Some pics too :)

I made a less restrictive silencer, figured that if the old one gets pushed off twice at full throttle it was probably effecting pipe pressure.

IMG_2014081449362.jpg
IMG_201408145951.jpg
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