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Missing compression release

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So, what's the scoop on Web Cams having the automatic compression release missing? Have read some stuff about it not being a big deal on the LTZ's but they have a bigger battery.

Web won't even install it if you ask and they are really cranky about asking too many questions.

Megacycle doesn't care either way. With or without, not a problem. Megacycle folks sure are a lot more pleasant to deal with on the phone.

Haven't been able to find any useful info on this topic.

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Unless you have some real reason to use Web cam or Megacycle, I would stay with Hot Cams or what Eddie recommends for your motor configuration.

You can do just fine without the compression release. A bigger battery does help but not essential unless you have a lot of motor mods to make it harder to crank like stroker, big bore, higher compression etc.

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The bike is a 470 big bore/stroker. I already have the cams. I really don't want to put everything together only to find that the e-stat wont turn the engine fast enough to start.

Like I said, limited info on why some folks are removing the auto compression release. I haven't see any incidents of stock engine (bikes or ATV's) having an issue with them coming apart.

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If you intend to use the standard battery on a 470 motor then you are going to have issues,plenty if guys on here will testify ( including me )that the bigger capacity and higher comp motors can be a problem to start,bigger battery helps,and may be enough on its own,after that manual decomp as per the E spec kicker bike is a solution.

There have been instances where the auto decomp mechanism has fallen apart and destroyed an engine,some,are happy to take the chance,others not so and they cut the mechanism off the cam before it can fail.

Edited by rigga

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theres a few things to think about, I don't have any answers, just giving a couple ideas that maybe someone who knows will speak up:

1. with the newer lithium and other good batteries getting smaller can you get enough CCA's out of a stock size battery to suit your needs? or if you buy one of the superstart kits, you might be better off also getting a larger lithium to never have an issue.

2. the hotcams auto-decompression does not need to be removed. in some instances, the pin would fall out on stock auto-decomp units and that small pin would move about the engine. with hotcams this removal is not needed.

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Does anyone know exactly HOW they fail? Bad material? Loose press fit of parts? Something that can be fixed before it breaks, besides deleting it?

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Pins come apart and drop into the motor,not sure exactly why but it happens.

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I've worked for a Suzuki dealership for quite a while now and we've sold and serviced tons of DRZs and LTZs, and the only ones that have ever had a problem with the decomp were the very early DRZ models. In the first couple of years we had a few failures but we haven't seen one fail in a long time. I think Suzuki pretty much took care of the problem years ago.

Edited by james509
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I've worked for a Suzuki dealership for quite a while now and we've sold and serviced tons of DRZs and LTZs, and the only ones that have ever had a problem with the decomp were the very early DRZ models. In the first couple of years we had a few failures but we haven't seen one fail in a long time. I think Suzuki pretty much took care of the problem years ago.

Prob the same situation with the ACCT.think only the very early ones had issues,trouble is once a doubt is there .....

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Thanks for the input guys.

I have a set of used SM cams on the way so I can rob the decomp assembly.

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suzuki fixed nothing!

i work on more drz motors than any one PERIOD. i still see auto decomp failure regularly all the way current models.

leave it off and get a real battery.

WEB wont reinstall them for a reason.

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I've worked for a Suzuki dealership for quite a while now and we've sold and serviced tons of DRZs and LTZs, and the only ones that have ever had a problem with the decomp were the very early DRZ models. In the first couple of years we had a few failures but we haven't seen one fail in a long time. I think Suzuki pretty much took care of the problem years ago.

Can you recall precicely how they failed? I'm just curious more than anything else now. Angry chatter about them being "bad, bad, bad" isn't what I was looking for here. The bike has a good battery but no kickstarter and I'm sure If I tell the guy that he can't have an auto compression release but if he spends another $250 he can have a kickstarter with a manual compression release he's not going to be real happy. I had a manual compression release on my 1999 WR400 and it sucked.

I understand, Eddie, that you work on a lot of DRZ's but in the cases that you have seen them fail, have they been exclusively supermoto bikes that are bounced off the revlimiter on a regular basis? Or are the on more mundane engine builds or even unmodified engines. I'm sorry, I don't crate up engines and send them off. Never have in 35 years and never will.

Edited by 2grimjim

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the manual decompression does not acheive the same result as the auto decompression. I just had eddie cut my S head for manual decompression, and it is effect to help kickstarting but not the same thing as the autodecompression.

the entire point of manual decompression is laid out in the installation manuals "how to use your kickstarter"...

-grab the manual decompression lever. it will roll down onto a flat spot, opening the exhaust valve slightly and it will sitck in that position.

-slowly move the kickstarter until you hear that manual lever click (which is it releasing)

-move you leg to the top of the rotation, and kick away.

seemed to work good....

IMHO putting a stock auto decompression unit on an aftermarket cam in a 470 motor worth $$$$ (4 digits) is about the stupidest thing you could possibly do. as far as how they fail, the small pin sticking straight out from the center falls out. then you have a flopping noisy auto decompression unit with an 1/8"X1/2" needle bearing looking thing free roaming your engine from the top end down.

Edited by Davenjw

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I understand, Eddie, that you work on a lot of DRZ's but in the cases that you have seen them fail, have they been exclusively supermoto bikes that are bounced off the revlimiter on a regular basis? Or are the on more mundane engine builds or even unmodified engines.

i build very few supermoto engines in comparison to fixing stock motors (they usually end up modded during the repair) used for average purposes. i talk people out of heavliy modified motors more than i build them. most people are not prepared to do what it takes to own one.

you build your own motors,good for you. not sure why that matters......

other engine builders call me on a daily basis! why? because i build multiple drz motors per day. they do maybe 1 or 2 a year. when i still worked in a suzuki dealer suzuki called me,not the other way around.

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as far as how they fail, the small pin sticking straight out from the center falls out. then you have a flopping noisy auto decompression unit with an 1/8"X1/2" needle bearing looking thing free roaming your engine from the top end down.

This is what I was looking for. Thank you.

As far as how many engines a year I build, in the last two years, I've rebuilt about 18. Everything from a Yamaha Rhino, a couple of YFZ450's, don't remember how many 250F and 450F Yamaha's, a KDX200, a KX65, my own WR450 and YZ450, a CRF450, an XR75, TT500, and a big bore DRZ.

I worked at a dealer. I hated it. It took the fun out of working on my own stuff. I only do stuff for friends now and only on my terms and everyone seems to be happy with that.

The guy that I'm building the DRZ for is a local A rider. He owns a transmision shop and completely understands the nature of high performance mods. He want's a bike for the desert that looks like a sleepy DRZ but smokes the bacon off the KTM guys on their brand new $9000 bikes that we ride with.

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as far as how they fail, the small pin sticking straight out from the center falls out. then you have a flopping noisy auto decompression unit with an 1/8"X1/2" needle bearing looking thing free roaming your engine from the top end down.

Is this the pin you are referring to?

CIMG1212.jpg

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are you going to attempt to permanently fix one? as in weld the pin in or something?

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In my experience the pin broke off not fell out. Weld would not be a solution. What you see in the picture are parts removed after the drive sprocket has been pressed off. To replace the compression release or even replace the drive gear requires careful alignment beyond the means of most of us. That is why the compression release is generally removed by breaking it off so the drive sprocket does not have to be disturbed.

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Again, thank you for the constructive input. I do appreciate that.

Now I know what the problem is I have a few ideas on how to fix it (if it can be fixed). The first is figuring out a way to keep the pin captured if it comes loose, and the second problem is possibly a different choice of material for the pin itself. The pin looks like a 2mm X 14mm (13.75mm) needle nearing. Very hard material. If the incidents of failure were from the pin breaking, there may have been onother underlying problem.

There are a couple of reasons why the pin could break; defective cam chain tensioner (that was a problem on early DRZ's?) letting the exhaust cam 'rattle' the decomp assembly, or in a case where a manual chain tensioner were fitted, the chain was too loose. Other potential problems could be from mismatched valve springs with a non-stock cam profile; not enough clearance between the decomp pin with the valve bucket (when the decomp is deactivated); or stiffer than stock valve srrings applying too much tortion to the decomp pin on cranking.

I've seen nearly idetical decomp assemblies on other machines (Suzuki, Actic Cat, and Polaris). The DRZ (and LTZ) is the only one that I've heard any incidents of failure.

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