Removing the Exhaust Decompression cam - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 44 (permalink) Old 02-07-2019, 03:43 AM Thread Starter
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Removing the Exhaust Decompression cam

Hey all

For a while now I've been getting pretty sick of how noisy the top end of my motor is, so today I decided to take off the camshaft cover and inspect the decompression cams. But what I ended up doing was removing them altogether.

I'm in Australia, and while it can get cold, our winters are pretty mild, so I don't feel cold starts will be an issue.

So my question is, does anyone see an issue with this?

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post #2 of 44 (permalink) Old 02-07-2019, 06:40 AM
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If your engine starts and runs without them you may well be saving yourself from a future headache. I confess to not having a close knowledge of how they operate - Iím not a mechanic - but I do know of 2 1700s that needed new exhaust cams because one end where the decompressor attached had broken. My understanding was that the decompressor assemblies put an extreme amount of pressure on the camshaft and in these, presumably isolated cases, it sheered off. Both were fixed under warranty by the way; one as goodwill because the bike (Storm) was about 5 years old.
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post #3 of 44 (permalink) Old 02-07-2019, 10:28 PM
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Its my understanding that the decompression cams fuction is to save wear & tear on the starter. I would like to hear how it works out for you. While l was doing my 12000 mi. valve check, l noticed that the decompression system looks weak to me. Ive heard that there is a spring upgrade that l had planned on doing. If its feasible to remove it without ill effects, l would do it. One less thing to break, right? Im interested in hearing others feedback on this subject
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post #4 of 44 (permalink) Old 02-08-2019, 12:48 AM
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There is a set of you tube vids....6 sessions I recall on doing a valve check on a 1600.....excellent info. In there one can see the function of the decomp cam. If indeed there is a different spring being used I'm unaware of it.....but certainly worth looking into. These decompression mechanisms aren't new technology and are used in automotive down to simple lawn mower engines. Why ours is sloppy and apparently adds to top end noise remains a mystery.
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post #5 of 44 (permalink) Old 02-08-2019, 03:59 PM
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At some point in time they supposedly fixed the breakage issue. Not sure what year but i do recall being told the cams that went in mine with the BB kit in ate 2010 had the new revised decomp parts. I don't know what they did to them exactly but you now know everything i was told and read.
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post #6 of 44 (permalink) Old 02-09-2019, 03:39 AM Thread Starter
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Thanks for everyone's posts!

I've removed the decompression cams and am slowly putting the bike together. I'm a little concerned that the starter might have issues turning the engine over because I had to turn the camshaft to get to everything and I had to end up removing a couple spark plugs because I just couldn't turn the motor over. Anyways, I'll let you all know how it goes once I'm finished!

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post #7 of 44 (permalink) Old 02-09-2019, 07:18 AM
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Homer, please share any news you have. I've often suspected this to be part of the clacker noise. I recall on the 1600 forum someone did this a few years ago and claimed it solved his knocking noise with no starting issues. However I can't find that thread where it was discussed
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post #8 of 44 (permalink) Old 02-09-2019, 10:09 PM
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You always want to pull a plug from each jug to turn the motor with a wrench or bumping the rear wheel.
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post #9 of 44 (permalink) Old 02-10-2019, 03:03 PM
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Equally anxious to learn of the outcome.....recall you've put up with noise for some time. How did you make out with the brakes?
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post #10 of 44 (permalink) Old 02-11-2019, 02:28 AM Thread Starter
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UPDATE!

After having to deal with a stubborn radiator hose that kept leaking on me and a 5 year old battery that won't keep enough power in it, ice just come back from a short ride and I'm pleased that I did the mod.

The motor is still noisy, but it's not the top end. It definitely idles smoother. I used to have an awful noise when I'd rev the motor then back off to change into the next gear, and that seems to be gone. And the best thing is that there is no way now that they will explode and then have little pieces run through the motor!

I just need to now get a new battery, and I'm planning on getting the biggest one that I can fit. 5 years out of a battery is pretty good I reckon! Still disappointed that the motor is so noisy, especially for a bike that's only done 9000kms, but looks like I'll have to live with that like most here do.

The brakes are getting redone by the smash repairer as soon as I get it to him. They are still ****, which is most likely due to them replacing the rotors but not the pads.

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