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yam175

Monty 348 decompressor

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A decompression valve is used for ease of starting and / or engine braking on downhill runs. In my opinion the 348 does not require any starting assistance, and it is up to you whether or not you desire it for engine braking. In 50+ years of trials riding, I could probably count on one hand the  number of times I've seen anyone use one.

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I'm old and unfit but can still manage to start my 348 dozens of times during a trial without using a decompressor. Having said that, I find that starting it for a section often takes more effort than riding the section. If it wasn't so hot where I ride, I'd probably leave it running more than I do.

They do make a cool noise if you use one for braking.

The 348 kickstart mechanism is robust apart from the return stop so there is no need to fit one to protect the mechanism.

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You should definitely fit one. I have one on my Cota 247 and SWM and wouldn't be without it. I don't use it when starting the bike, it's not intended for that. 

It comes into its own on steep, greasy descents, allowing you to slow without locking the wheels. Also useful on tracks between sections to warn pedestrians of your approach - a quick blast of the decompressor always turns heads. I use it to stop the motor in normal situations, much kinder than deliberately stalling it. Above all it's a foolproof method of stopping an engine that's revving it's head off after a fall - much more reliable than a kill button.

Edited by cleanorbust

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You can get a complete decompressor kit from trialsbits.co.uk or In Motion Trials, or get the cable, decomp unit and lever on eBay for about half the price (sold as being suitable for Royal Enfield but would work OK).

Edited by cleanorbust

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On 12/24/2019 at 5:14 PM, splatered stu said:

this is a Monty....not sure if a decompressor even works on this bike....

monty-219-kaizen-20-bike.jpg

On 12/23/2019 at 8:14 PM, yam175 said:

Right guys my 348 hasn't got a decompressor fitted , should I fit one 

Best thing since sliced bread. Allows easy starting, controlled descents and easy engine stopping. No need for a kill switch. Makes a loud chuffing sound when spectators step into your path.

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Back to the original point - what's the technique for using a decompressor to aid starting?  I ask because since the engine rebuild my 349 takes literally all my weight to kick it in, and my other half can't manage it at all because she's just too little

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If I had a decompressor on my 348 I would use it to ease the piston over TDC before giving the kickstart lever the starting stroke

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11 hours ago, turbofurball said:

Back to the original point - what's the technique for using a decompressor to aid starting?  I ask because since the engine rebuild my 349 takes literally all my weight to kick it in, and my other half can't manage it at all because she's just too little

Pull the decompressor in and give a couple of kicks on wide open throttle to get a bit of fuel through, then with the decompressor still in kick again but let the decompressor out about 1/3 to 1/2 way through its travel. It's trial and error when to let the decompressor out but after a few attempts you'll get it. I always start my 247 Cota like this as well as my Ossa MARs which can have a habit of slipping on the kickstart ratchet against the compression - using the decompressor takes the strain off and stops that happening

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On 1/7/2020 at 8:54 AM, woody said:

Pull the decompressor in and give a couple of kicks on wide open throttle to get a bit of fuel through, then with the decompressor still in kick again but let the decompressor out about 1/3 to 1/2 way through its travel. It's trial and error when to let the decompressor out but after a few attempts you'll get it. I always start my 247 Cota like this as well as my Ossa MARs which can have a habit of slipping on the kickstart ratchet against the compression - using the decompressor takes the strain off and stops that happening

Yup, this is how I start my 247 fitted with a Venhill decompression kit. It makes the whole process easier IMO, and really does seem to remove the physicality and strain from the starting components.  

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Same operating with my 349 mh  and my sherpa t 325 ,i always use the decompressor ,it is easyer (sorry for my bad english

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