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Yambo

SY250 dirt in airbox and carb

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I bought a 2008 SY250 recently and I'm having trouble with dirt getting through my air filter.

I cleaned out the airbox and put a new Jitsie filter in when I got the bike. After one ride I cleaned the filter and saw some dirt and water in the airbox. I read about sealing the gap between the plastics and airbox so I did this carefully with foam tape and it seems to be a good seal. Nevertheless, after one ride there was more dirt and water in the airbox. I should add that the PO made quite an effort to prevent water getting in, including a sheet of rubber pulled across between the swingarm and airbox to stop churned up water from the wheel getting in.

It hasn't been running right so I took the carb out and there were chunks of mud at the entrance. I stripped it and the main jet holder was packed with mud!

I'm having trouble believing that this is normal since I haven't been able to find any mention of it on here. Do Scorpa owners just deal with having to regularly clean out their carb? The only thing I can imagine might be causing it is that the DIY rear mudflap done by the PO might somehow not be doing the job and mud/water might be being thrown by the rear wheel and up to the top of the shock where the airbox draws air in. It looks pretty good though.

This is what I mean by mudflap:

scorpa250large.jpg

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30 minutes ago, Yambo said:

I bought a 2008 SY250 recently and I'm having trouble with dirt getting through my air filter.

I cleaned out the airbox and put a new Jitsie filter in when I got the bike. After one ride I cleaned the filter and saw some dirt and water in the airbox. I read about sealing the gap between the plastics and airbox so I did this carefully with foam tape and it seems to be a good seal. Nevertheless, after one ride there was more dirt and water in the airbox. I should add that the PO made quite an effort to prevent water getting in, including a sheet of rubber pulled across between the swingarm and airbox to stop churned up water from the wheel getting in.

It hasn't been running right so I took the carb out and there were chunks of mud at the entrance. I stripped it and the main jet holder was packed with mud!

I'm having trouble believing that this is normal since I haven't been able to find any mention of it on here. Do Scorpa owners just deal with having to regularly clean out their carb? The only thing I can imagine might be causing it is that the DIY rear mudflap done by the PO might somehow not be doing the job and mud/water might be being thrown by the rear wheel and up to the top of the shock where the airbox draws air in. It looks pretty good though.

This is what I mean by mudflap:

scorpa250large.jpg

The mud flap on trial bikes [not just the SY] stuck on the airbox  is there to protect the  chromed shock shaft not the airbox.......the airbox should be sealed sufficiently well on its own ; but dirt and water usually find their way into a lot of airbox designs while being used in wet muddy conditions, it is part of the servicing under those conditions to constantly clean everything and oil the filter with a good quality proper airfilter oil......if your filter box is letting in dirt and water find out where then use duct tape or tigerseal or sikaflex etc to keep out as much dirt as possible.

Edited by oni nou
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Air filter changed after every ride for me on every bike I have owned .

carb out at least one a month until I switched to fuel injection

seal under mudguard if possible and put some mesh on any vents on the mudguard 

good luck 

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I have a SY250r also.

I want to ask, is the air filter assembly complete?  When I say this, does your bike have the rectangular plastic frame, that supports the foam filter flanged edge, forcing a tight seal around the foam perimeter to the airbox?

The rectangular plastic cage, is then retained by two sort of swing type bent spring steel wire clips.  These two clips, one front and one rear, apply pressure to the plastic cage, forcing it to tightly clamp, and sandwhich the foam flange, sealing the filters edge.

With those parts securing the filter, and properly installed, myself I do not even grease the filter edge, it seals that well.

It is possible to have the filter fail at glue joints, or become torn where the plastic cage touches the foam if the filter is forced into the airbox.

As for the mudflap, oem did have a rubber flap with a circular hole the shocked passed through.  The flap mainly keeps dirt away from the exhaust midbox, it may protect the shock shaft somewhat, but the shock shaft is on the upper end and pretty well protected by the airbox.

Other areas to inspect for dirt entry, the several holes that secure the mudflap as stock, must be plugged.  They are open holes into the airbox.  Also, there was an upper dust guard, under the fender, it too was secured with screws.  Those too may be possible leaks.

Also consider the mount points for the subframe and exhaust, while sealed as oem, if the brass inserts have failed, and a home remedy was employed to save the airbox, those too are possible leaks.

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One more item to inspect, the rubber airboot, between the carb and airbox.  I suspect it is not torn.

Look close at this detail.  If the airboot aft clamp, that secures the airboot to the airbox is overtightened, or has been previously, the airbox spigot may crush and no longer be round.  This will create a gap, unsealed. I had read where another owner had this issue, and utilized a slice of metal tubing to support the airbox spigot.  This allowed full tightening of the clamp.

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In 15 years of mudplugging in the Cotswolds and 3 yam scorpa's I've never had **** in the air box, . Even if muck gets between the mudguard and airbox the rectangular clamp/spring clip arrangement with jitsie filter is fiddly but when installed correctly works well.   Be aware the rectangular plastic clamp only seals properly one way round. The jitsie filter is best, is it new ? they can deteriorate when old.  Keep us posted .  

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If anyone wants to keep their front header pipe from getting dirty that's why a mudflap is fitted on the bottom edge of the front mudguard.

Edited by oni nou
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You are a little off track ,well that is something that it does to a degree but it is really fitted to keep mud from spraying up and  blocking the radiator and causing overheating.

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just fitted a front mud flap to mine easy enough to do. i also cut a new rubber for the Air box bottom flap and the bit under the fender also replaced the filter with a jitsie filter i have the Air box off at the moment as am servicing the bike new oil coolant ect first time owning a scorpa just finding out how things come apart a bit harder than the bultacos am use to but not to bad i need to take the carb off to clean it so seeing as i have the Air box out should be a bit better i know i have to undo the top shock bolt to get it out should be fun i have a new chain to put on :D

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4 hours ago, bondy said:

just fitted a front mud flap to mine easy enough to do. i also cut a new rubber for the Air box bottom flap and the bit under the fender also replaced the filter with a jitsie filter i have the Air box off at the moment as am servicing the bike new oil coolant ect first time owning a scorpa just finding out how things come apart a bit harder than the bultacos am use to but not to bad i need to take the carb off to clean it so seeing as i have the Air box out should be a bit better i know i have to undo the top shock bolt to get it out should be fun i have a new chain to put on :D

When you remove the upper rear shock bolt, be certain there is blocks under the rear wheel, or that it can not drop.  These bikes will snap the rear brake hose at the master cylinder if the wheel drops and the hose goes tight.

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16 hours ago, oni nou said:

You are a little off track ,well that is something that it does to a degree but it is really fitted to keep mud from spraying up and  blocking the radiator and causing overheating.

Interesting, debating the merits of the front mudflap with yourself...

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I see several of the recent posts recommend the Jitsie air filter.  I recently installed the same in my Scorpa.

Did anyone else notice, the filter has the coarse foam on the clean side of the airbox, while the fine foam is the first filter media.  Seems Jitsie has it backwards.

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Thanks for all the replies. I'm coming to this from trail riding on a DR350 and I'm used to having a muddy airbox - the difference is that the DR350 filter is on the airbox exit rather than the entrance!

I am pretty confident that water is not getting in by flowing over the top of the airbox so I thought it must be getting in through the same hole as the air and overwhelming the filter. It is a new Jitsie filter.

On 2/9/2018 at 1:37 PM, pmk said:

I want to ask, is the air filter assembly complete?  When I say this, does your bike have the rectangular plastic frame, that supports the foam filter flanged edge, forcing a tight seal around the foam perimeter to the airbox?

Yes it is complete and clamps down very tightly and evenly. This fact plus the fact that the airbox is a complete plastic unit unlike some bikes (KTM) is what made me think the filter was being overwhelmed.

 

On 2/9/2018 at 1:37 PM, pmk said:

Other areas to inspect for dirt entry, the several holes that secure the mudflap as stock, must be plugged.  They are open holes into the airbox.  Also, there was an upper dust guard, under the fender, it too was secured with screws.  Those too may be possible leaks.

Thank you for this - I didn't realise the screw holes went all the way through and after shining a torch in there I see that they do. I think they were sealed up but I'll double check when I reassemble.

On 2/9/2018 at 1:42 PM, pmk said:

One more item to inspect, the rubber airboot, between the carb and airbox.  I suspect it is not torn.

Look close at this detail.  If the airboot aft clamp, that secures the airboot to the airbox is overtightened, or has been previously, the airbox spigot may crush and no longer be round.  This will create a gap, unsealed. I had read where another owner had this issue, and utilized a slice of metal tubing to support the airbox spigot.  This allowed full tightening of the clamp.

This could well be the issue. If stuff was getting in through the filter or through holes in the airbox in small quantities I would expect it to fall down into the lower 'horn' of the airbox rather than be sucked through the high exit to the carb. I'll have a good look out for this when I reassemble.

1 hour ago, pmk said:

I see several of the recent posts recommend the Jitsie air filter.  I recently installed the same in my Scorpa.

Did anyone else notice, the filter has the coarse foam on the clean side of the airbox, while the fine foam is the first filter media.  Seems Jitsie has it backwards.

Yes! I almost sent mine back but couldn't be bothered. It's really bizarre as it seem nicely made otherwise; I can only assume that the designer had never seen a Scorpa airbox and assumed it was like all other bikes which have the filter on the exit rather than the entrance. Unless the Scorpa arrangement is common on trials bikes?

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25 minutes ago, Yambo said:

 

Yes! I almost sent mine back but couldn't be bothered. It's really bizarre as it seem nicely made otherwise; I can only assume that the designer had never seen a Scorpa airbox and assumed it was like all other bikes which have the filter on the exit rather than the entrance. Unless the Scorpa arrangement is common on trials bikes?

The Jitsie 4RT filter is also made "the wrong way round" but, looking on their website, those for most other bikes are as you would expect.  I can't see what difference it would make where the filter is in relation to entrance/exit of the box as you would surely want the coarse side facing the incoming air regardless, if it was to serve any useful filtration purpose.

 

Edited by 2stroke4stroke

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