Stock Air Box questions
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LoudenSwain
- Posts: 8
- Joined: 28 Oct 2019 14:17
- Location: Little Compton RI
Stock Air Box questions
Hello, Finally came across a stock air box in great condition for my 500 sport. Installed it at the end of last year as winter was setting in and I can say its a change for the better from the few rides I was able to get in. So a couple of questions I have on the assembly. The first is throttle cable routing. Right side is pretty much bang on with the cable routed straight down into the carb adjuster, the rubber boot just ever so slightly touching the box. The left side is not ideal having to tourque the cable against the edge of the box to get it to the cable adjuster. The throttle cable is not able to seat perfectly into the adjuster and is clearly under some stress from the angle. Is this just the way it is or is there a perfect combo of rubber mount angle to carb angle which allows alignment? Have not been able to find it so far! I've also considered using a dremel or heating up a screwdriver shaft and forming a groove in the box allowing mor clearance for the cable. Second question is regarding the breather holes on top. I dont have the tubes to connect the hoses to the collector box. Is this of any importance or can i just leave the holes open. Thanks in advance for any advice.
Re: Stock Air Box questions
I´m still waiting for an original 500 airbox to face that problem and wonder wether it will be easier or even worse with 28 carbs and 501 barrels. The cilinders are about 5 mm lower but the carbs bigger 
I would like to use the original airbox in the 500 Frankenstein. If this is a pain, will mount the same Polini filters I wear on Dulcinea (501 in 350 frame)
With the 501 in a 350 frame with original 350 airbox it works without bigger problems.
If I remember it well, there allways have been some similar problems with the original 350 left carb cable passing the airbox (but Rocinante 350 K wears a 501 since 2003, fortunatley of course
)
I would like to use the original airbox in the 500 Frankenstein. If this is a pain, will mount the same Polini filters I wear on Dulcinea (501 in 350 frame)With the 501 in a 350 frame with original 350 airbox it works without bigger problems.
If I remember it well, there allways have been some similar problems with the original 350 left carb cable passing the airbox (but Rocinante 350 K wears a 501 since 2003, fortunatley of course
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George 350
- Posts: 521
- Joined: 16 Jun 2007 09:43
- Location: Northampton
Re: Stock Air Box questions
Hi,
To answer one of the original questions, the holes on the top of the air box would originally had the rocker cover breathers going to them. If the pipework isn't connected, then blank off the holes as otherwise unfiltered air will go through. Not much of it I know, but every little bit of filtration will help your engine last longer.
As to the throttle cable, as Norbert says road 350 and 500's all have the same issue with the front/left carb/throttle cable routing. The 350 can be set up to clear the air box by careful positioning of the inlet rubbers and also having the carb slightly leaning outwards. For the 500 though, the best fix I have seen is from somebody who made his own cables with a metal bend at the carb top like one of these:
https://www.venhill.co.uk/cables-and-co ... bends.html at the carb top. I think he used a 45° bend like item FB302B.
Hope this helps,
George
To answer one of the original questions, the holes on the top of the air box would originally had the rocker cover breathers going to them. If the pipework isn't connected, then blank off the holes as otherwise unfiltered air will go through. Not much of it I know, but every little bit of filtration will help your engine last longer.
As to the throttle cable, as Norbert says road 350 and 500's all have the same issue with the front/left carb/throttle cable routing. The 350 can be set up to clear the air box by careful positioning of the inlet rubbers and also having the carb slightly leaning outwards. For the 500 though, the best fix I have seen is from somebody who made his own cables with a metal bend at the carb top like one of these:
https://www.venhill.co.uk/cables-and-co ... bends.html at the carb top. I think he used a 45° bend like item FB302B.
Hope this helps,
George
George
350 sport 1978, 350 Strada 1978
650 Norton 1967, 650 Kawasaki 1977 and 650 Enfield 2019
350 sport 1978, 350 Strada 1978
650 Norton 1967, 650 Kawasaki 1977 and 650 Enfield 2019
Re: Stock Air Box questions
Mine has a sort of groove or channel worn or made to accommodate the cable routing. I have had no issue with this in 17 years, except for a nipple coming off at the twistgrip once when naturally I was at the bottom of a steep hill.
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LoudenSwain
- Posts: 8
- Joined: 28 Oct 2019 14:17
- Location: Little Compton RI
Re: Stock Air Box questions
Thanks for the reponses. I'm in the process of grooving it today. Also sealing up the breather holes while I'm at it. Thanks George on that info. Norbert, looked up your project. Very cool and if it IS your last build it's a great choice to ride off into the sunset on.[6 speed helps there]
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'It must be a .....'
- Posts: 420
- Joined: 12 Sep 2010 12:25
Re: Stock Air Box questions
The 500 unlike the 350 has a plastic breather box to the rear of the engine where the the rocker and airbox pipes connect.
Bikes for most of Europe had the airbox plugged and the breather box connections go to atmosphere via pipes up under the tank fixed to the top tube.
I think this is the better arrangement, but as it gets a bit oily under the tank it is best to reroute the pipes e.g. to the chain, rear mudguard or forward under the engine.
I can't recall the throttle cable routing on my 500 road Morini but had no problems with the twin cables, perhaps your cables are non original in length and causing problems?
You could try rotating the carbs and their rubber mounts to the engine to get the best cable/carb clearance at the edge of the airbox.
The 500 Camel has a better cable arrangement/route to the carbs (same airbox etc) using a single throttle cable and a spiltter in a clip just below the right transducer.
BMW used this on later air cooled boxers and it has the advantage of separating the carb balance and throttle cable freeplay adjustments; the carbs will remain in balance/tune for much longer.
Trust this helps, good luck, Ian
Bikes for most of Europe had the airbox plugged and the breather box connections go to atmosphere via pipes up under the tank fixed to the top tube.
I think this is the better arrangement, but as it gets a bit oily under the tank it is best to reroute the pipes e.g. to the chain, rear mudguard or forward under the engine.
I can't recall the throttle cable routing on my 500 road Morini but had no problems with the twin cables, perhaps your cables are non original in length and causing problems?
You could try rotating the carbs and their rubber mounts to the engine to get the best cable/carb clearance at the edge of the airbox.
The 500 Camel has a better cable arrangement/route to the carbs (same airbox etc) using a single throttle cable and a spiltter in a clip just below the right transducer.
BMW used this on later air cooled boxers and it has the advantage of separating the carb balance and throttle cable freeplay adjustments; the carbs will remain in balance/tune for much longer.
Trust this helps, good luck, Ian