Still trying to get air filter and jetting sorted

Ok so I finally splashed out on a proper Casa repo filter, only thing is the scoot wont run at all with it on.

To my way of thinking this suggests a lack of air - as the air filter must be restricting the flow of air in some way. Therefore I need to down size my jetting?

Does this apply to all the jets?

Ed, I can't speak from experience yet but I have bought a NOS filter from Jem Booth. In his ad on ebay, he referred to the remade ones being more restrictive and that it was difficult to get the carb jetted with one.

Thanks Paul - that's a bit worrying

I wonder which part of it makes it more restrictive, the actual filter or the case???

I have a couple of NOS filters

I think its the paper filter that's the restriction.

Interesting! I've just built a standard 75 but I've used a remade Casa air filter and it does feel lacking in power.

Paul.

I will try swapping one for the other and let you know if there is any improvement

I tried swapping the remade filter for a nos one and it made no difference

Having chatted to someone about jetting I've now changed my jetting from 103 main and 48 pilot back to something closer to std 65 main and 45 pilot. This will now run with the air filter pretty well. Its still got the Nos filter in though but I think I will change it back again to the remade one at some point just out of curiosity.

Before that I tried 68 main and 48 pilot and it would neither tick over or run with the throttle open so I ditched that entire combination.

I've also taken some photos of the two filters for comparison which I will add to this post when I find time.

My only issue with the filter now is that its a bit slow to return to tick over from full revs so I suspect that to make it tick over I have the slide open a little too much. Maybe I can go down a size on the pilot jet???

Also I have to give it a lot more throttle between gear changes with the filter on, but I suspect that maybe this is normal with air scooter when running with a filter as opposed to without? Does take a little of fun out of the ride.

Lastly I need to check my plug colour a bit more often as it was actually running a bit lean with the 103 and no filter!

Are you sure you've not got an air leak at a gasket. Not shutting down when the throttle is closed and lean plug even with a big jet are classic symptoms.

Paul

I will double check that, I need to carry out the same test on my GP

I use the remade airbox with an original filter, I also drilled extra holes in the internal baffle. The baffle eventually went soft so I made one from aluminium works fine, although I did have to upjet quite substantially. This is with a 48 pilot and 80 main jet on a casa barrel standard exhaust with the dogbone drilled

Thanks for that -all the info i can get on peoples jetting helps.

Was drilling the holes something you did from a tuning perspective - as per the old tuning manual or to get it to jet properly?

Mine is a 125 with a little tuning to the barrel. Std pipe. I think, now that my GP is roadworthy again I will leak test it anyway just to be on the safe side and then decide which jets to try next.

I've gone back to LI125 Special jetting specs on my 125 conversion. I'm running an Amal air filter at present. The remade Casa one will not allow it to run beyond tick over. This may well prove a point as a previous 125 converted Vega ran fine with a standard air box and filter. The point being ,the remade filters are much more restrictive than the originals.

Paul

Snails
The modifications to the baffle were made purely to get the vega running what I thought was acceptable, the remade filter was very restrictive and the original filter made little or no difference, I replaced the drilled dogbone with an undrilled one which restricted it even more so I refitted the drilled dogbone and drilled the baffle and it transformed the bike, perhaps you could remove the baffle and see how it runs with just the filter fitted

That's a good idea in respect to removing the baffle , I will try that at some point if I have to, although i would only need to do that if I found it to be running rich - at the moment it seems to be a bit on the lean side of things so that rather than too little air I'm getting too much so I will check for air leaks and if that fails to find anything I'll increase my main jet and/or pilot.

Tried to test it for air leaks this morning but didnt get very far because of various obstacles presented by how I've set up my scooter,

I cant remove my engine cowling because Ive routed my electrics through a metal loop on the engine cowling (to avoid the risk of it coming into contact with the rear wheel) and as I dont have a junction box I'll have to remove the back wheel and mudguard to access my electrics. On a side point I think I may go back to my original idea of fitting a junction box to my engine cowling as this set up is very annoying (as I think Daz warned me it would be! )

Even if this was not an issue I'm not convinced I'd be able to remove the engine cowling without dropping the engine out.

Whilst finding this out I did find what might be the cause of the problem - there is quite a bit of oil/gunk around the exhaust port so I suspect its leaking there. However I dont seem to be able to remove the exhaust manifold without dropping the engine! Is that normal? If i loosen the cables and remove the engine bolt will it drop forward enough for me to remove the manifold or do I have to remove the whole engine?

A very frustrating morning - what I hoped would be a quick job has turned into a right pain

Hi Ed, I feel your pain. If you were to remove the rear shocker this might allow enough manoeuvre room to get the cowl and exhaust manifold off. I understand about the cables bit but couldn't you cut the cables somewhere out of sight and fix a jointing device or even have the junction box where you cut the wires? That way when it comes to maintenance you can still have your desired route but the option to remove the cyl cowl ?

Thanks David, I've tried removing the rear shock already.


I'm not sure I understand you point regarding the electrics. I will cut the wires and then route them in a junction box. It will look ok, my original reason for not doing this was that I was concerned that the mounting location would be to near the rear wheel and get wet but having ridden it a little in rain now I dont think this would be the issue I was worried it would be.

I once had a Vespa 50 Special that would die whenever it rained, I drove it to a Mod rally in Llandudno - 3 hours to get there, 10 to get back, as it rained on the way home. Hence my fear.

I've long ago stopped trying to dismantle 125 converted engines without taking them out of the frame. Any top end work needed and I'll spend the extra half an hour to pull the whole lump. Much less hassle in the long run.

Paul

Can you not get the clearance by leaving the top of the shock on and resting the bottom of it on the mounting lug to raise the frame

Not on a 125 conversion. There isn't enough room.

Thanks Paul, how annoying.