Silencers, Exhaust Deflectors & Extensions Silencers, Exhaust Deflectors and Extension pieces for the majority of popular engines.......
Definitions:
c; is the distance of mounting bolt (centre to centre) (note; 35mm silencers will also fit O.S. and O.S. 'copy' engines that measure 35.5mm)
Bolt: If the silencer 'bolt' size is Mx eg M3 - it means M3 bolts thread into the silencer flange.
Bolt: If 'bolt' size is xmm eg 4mm - it means that there is a hole for a 4mm bolt to go through the silencer flange and (thread) into the engine crankcase
e; total length to end of bolt (inc. locking nut)
Weight is in grams (1oz. = 28.35g)
Measurements are in mm
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 Standard SilencersStandard: one expansion chamber with no baffles.
| Part # | Engine
(typ.) | a | b | c | Bolt | d | e | Wt | notes | | ASP15SIL | .10-.21 | 35 | 15 | 28 | M2.5 | 2 | 85 | 40 | | | JENS3/35 | .25-.46 | 42 | 15 | 35 | M3 | 2 | 95 | 55 | | | JENS3/35LV | .25-.46 | 42 | 15 | 35 | M3 | 2 | 115 | 55 | |
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| Part # | Engine
(typ.) | a | b | c | Bolt | d | e | Wt | notes | | JENSD47 | .40-.57 | 69 | 33 | 37 | M3 | 3 | 185 | 120 | |
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 Quiet SilencersQuiet: 1 baffle in silencer making it a 2 chamber silencer.
| Part # | Engine
(typ.) | a | b | c | bolt | d | e | Wt. | notes | | JENS3/37 | .40-.53 | 58 | 28 | 37 | M3 | 5 | 135 | 90 | | | JENS3/42 | .61/.91 | 70 | 33 | 42 | M4 | 5 | 150 | 120 | |
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| Part # | Engine
(typ.) | a | b | c | bolt | d | e | Wt. | notes | | JENQ57 | .40-.57 | 69 | 33 | 37 | M3 | 3 | 185 | 140 | | | JENQ91 | .61/.91 | 75 | 40 | 42 | M4 | 3 | 200 | 220 | |
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 Super Quiet SilencersSuper Quiet: 1 baffle (2 chambers, as above) + silencer extension - making silencer larger volume and therefore quieter.
| Part # | Engine
(typ.) | a | b | c | bolt | d | e | Wt. | notes | | JENS3S/35 | .35-.46 | 63 | 28 | 35 | M3 | 2 | 180 | 130 | | | JENS3S/37 | .40-.53 | 60 | 28 | 37 | M3 | 3 | 160 | 100 | | | JENS3S/42 | .61-.91 | 70 | 30 | 42 | M4 | 3 | 200 | 160 | |
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Customer feedbackWe wanted to share with you this feedback that we recently received from a very satisfied customer following their purchase of a JEN super quiet silencer.
"Since new my OS35AX has always been a little too noisy for my liking so my main objective was to reduce the noise from the OS. So I bought a JENS3S/35. Although being quite prepared to sacrifice some performance I was surprised to see the engines rpm increase from 11400 to 11600 when the JENS3S/35 was fitted compared to the standard OS Power Box."
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Notes on Super Quiet Silencer Now this is where it gets clever!!
This silencer has been designed to allow you great flexibility in set up, with reference to the diagram above:
A) Baffle position A gives you the lowest noise.
B) Position B gives you the best performance (200-300rpm+) but obviously at higher noise.
You can open up the baffle holes (by using a pointed noise pair of pliers) for more performance or close them (use a hammer and a piece of dowel on a flat surface) to reduce noise but be careful, closing the baffle holes too far or closing too many will cause the engine to overheat and create engine running problems. If this happens just open out the baffles again until satisfactory running is achieved.
Note C: The silencer (and engine) can be further quietened down by drilling and tapping either a M3 or M4 bolt (a cap head bolt is ideal) through the end of the outlet as close to the end of the outlet as you can. This reduces the outlet area and reduces noise. Again, some care and attention is needed here. Firstly - only drill and tap at 90 degrees to the join line (the part being cast in 2 parts) never through the join line or it will split. Secondly - this will increase ‘back pressure’ to the engine and it the bolt is too big (and reduces the outlet by too much) the engine will over heat (and the needle will become sensitive). Once you are happy with the noise reduction (and performance) of the engine, take the bolt out and re-fit with a permanent heavy thread lock (e.g. Loctite 648) and file down the head of the bolt (optional) so as to improve the appearance of the silencer.
The super quiet silencer assembles with a long bolt that threads into the rear tail piece. This is important, the nut at the end is simply a lock nut for the assembly. If you try and tighten the silencer only by using this nut you will strip the threads!! To dis-assemble (in order to position the outlet at the position suited to the model) unlock the lock nut (turn anti-clockwise) - then take assembly bolt out of silencer with the appropriate sized screwdriver. Re-assembly is the opposite - use the right screwdriver to tighten the bolt into the tail piece, then use the lock nut for added strength using a small spanner.
Should either silencer leak, simply dis-assemble, (as above) clean up the components and use high temp silicon or liquid gasket (from a car accessory shop) around all the joints. Re-assemble and clean off the excess silicon.
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 BCM Sport MufflersThese nice, light aluminium units are unique as they fit with a strap around the cylinder head, making it ideal for older engines where no exhaust is available, or for engines with some damage to exhaust fitting.
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QuestionsPlease ring, fax or email for more information or pricing, or if you can't see what you need.
Tel: 01747 835817, Fax: , Email: justengines@enterprise.net
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