Airbox removal/replacement

[daaatomic]

I'm one of the many people around that likes to tinker. So I had my almost new bike apart today and got thinking.

It's a GasGas SM50. Motor is an oil injected 50cc two stroke. Its had the restrictor removed and a larger main jet put in. But the hole into the airbox is tiny, and is really obstructed by the seat.

It would be an easy job to replace the whole airbox with a pod type filter.

What I'm wondering is, will I notice any performance difference?(yes I realise it's a 50). And are there any other things I should watch out for.

Any advice appreciated.

[F5 Dave]

Take the airbox off & look into the carb. Ohh dear, that's got a small hole too. probably not the restriction the eyeometer thinks it is.

Pod filters suck, you will get more noise & maybe more airflow & the bike will probably stop if splashed with rainwater, but that doesn't ness mean more power unintuitive as that may seem.

Putting a pod on may lean up the mixture & make it seize unless you jet up, not just mainjet.

Fire a pic up.

[daaatomic]

Thanks F5, thats exactly the type of feedback i wanted. might flag it as i was only going to do it for the sake of it anyway. will try and take some pics this weekend though and put them up.

cheers,

Dave.

[FROSTY:Me]

If yours is the restricted version I'd google the standard means of deristricting the system Itll most likely be carb/exhaust restrictions

[Rodney007]

two smokers love more air, as long as u got plenty of gas

[daaatomic]

two smokers love more air, as long as u got plenty of gas

Thats what I thought. I think the problem is that when the restrictor was removed, a bigger main jet was put in, but i think the new jet is too big, and the bike seems to run fine untill full throttle, then it bogs down. From what I've read, this means too rich.

Please bear in mind that although I'm quite mechanically capable, I know nothing about 2strokes. What would be really good would be if someone who knew what they were talking about could take it for a ride and let me know what they thought.

The last thing I want to do is run it too lean and seize it.

Cheers for the help so far.

Dave.

[daaatomic]

Heres a break down of the carb incase anyone is interested. It's a dellorto SHA series.

[JimBob]

I'm one of the many people around that likes to tinker. So I had my almost new bike apart today and got thinking.

It's a GasGas SM50. Motor is an oil injected 50cc two stroke. Its had the restrictor removed and a larger main jet put in. But the hole into the airbox is tiny, and is really obstructed by the seat.

It would be an easy job to replace the whole airbox with a pod type filter.

What I'm wondering is, will I notice any performance difference?(yes I realise it's a 50). And are there any other things I should watch out for.

Any advice appreciated.

get someone up the other end of your street with a stop watch, give you the signal and time you. remove the airbox and do it again.
Or put it on a dyno, but that will cost money

[F5 Dave]

two smokers love more air, as long as u got plenty of gas

That's a highly intelligent catch-all response so this is the guy you should listen to. Perhaps he can txt some jetting specs?

Even with a 4 stroke there will be an optimal jet size. If it is bogging on full then you are no where near the right jet. Problem is people like to think that once the 'restriction' is removed they will be making a million more horsepower so best they jam in an enormous jet, bigger is better right?

Better is the jet that mixes the right amount of gas for efficient combustion.

Incidentally 2 strokes often seize if the throttle is closed from high revs. Turns out the pilot jet is important too. But a small change probably won't affect it too much.

[daaatomic]

Thanks again for the advice F5, even if it is a tad sarcastic. I think the jet is too big. I'm off to check out the minimotos at Mt Wellington this weekend, so will try to talk to a few people there about it.

[F5 Dave]

yeah I just get a bit bored with people offering their 2 cents when it sounds like they haven't read the previous threads & add in some slogan which is of no use at all.

Dellorto jets are sometimes easiest to find as genuine Honda parts (H owned Montessa which had Dels fitted, not sure if still do).