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Old 04-12-2013, 09:09 AM   #1
Zodiac OP
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336 cam in a Mono

So I finally broke down and decided to have my top ends machined. the PO had left me with a stripped and re-welded exhaust thread, on one side, and a buch of broken fins on the other - plus they were getting quite furry.

So in doing that, I also found a new timing cover to replace the original which looked like it lived in the titanic. I have Max BMW doing the work, and had them replace the timing chain and tensioner ("while you're in there").

So at this stage, they mentioned putting in the 336 Cam to give me a healthy boost. Bike already had twin sparks, Dyna III ignition coils, and could wheelie in 2nd gear on occasion (I love that Mono 33:11 final for low end power).

So has anyone swapped cams to a 336 and how were your results?

88 R100 RS
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Old 04-12-2013, 09:21 AM   #2
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Careful with the 336s that max is selling at a huge discount. Someone recently measured them and they're part of that defective lot that got recalled in the UK, but somehow not in north america. Measure it very carefully before you let anyone install it.
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Old 04-12-2013, 09:25 AM   #3
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Quote:
Originally Posted by Airhead Wrangler View Post
Careful with the 336s that max is selling at a huge discount. Someone recently measured them and they're part of that defective lot that got recalled in the UK, but somehow not in north america. Measure it very carefully before you let anyone install it.
Thanks for the heads up - I'm assuming since they're installing it, they'll have to measure it, correct? Would the defective one even work/fit?
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Old 04-12-2013, 09:27 AM   #4
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Originally Posted by Zodiac View Post
Thanks for the heads up - I'm assuming since they're installing it, they'll have to measure it, correct? Would the defective one even work/fit?
Yes it'll work fine for thousands of miles, but eventually it will eat your lifters and itself. They were misground with two of the lobes having the correct taper and two lobes with zero taper. I doubt they'd measure it when they install it. See here for someone who bought a cheap 336 cam from max:

http://advrider.com/forums/showpost....&postcount=108
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Old 04-12-2013, 09:35 AM   #5
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There is endless discussion on cams on various threads, given the quality control problems with the 336, I might think of using one of the alternatives, I assume you have increased your CR?
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Old 04-12-2013, 10:06 AM   #6
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Quote:
Originally Posted by Airhead Wrangler View Post
Yes it'll work fine for thousands of miles, but eventually it will eat your lifters and itself. They were misground with two of the lobes having the correct taper and two lobes with zero taper. I doubt they'd measure it when they install it. See here for someone who bought a cheap 336 cam from max:

http://advrider.com/forums/showpost....&postcount=108
Okay thanks - I've notified them of this and hope they will verify - and of course warranty the work and parts done.

It's around $300 for the cam, the tech (who's done great work for me in the past and is a veteran mech) says they'd done this for hundreds of bikes with great results.
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Old 04-12-2013, 10:07 AM   #7
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Originally Posted by chasbmw View Post
there is endless discussion on cams on various threads, given the quality control problems with the 336, i might think of using one of the alternatives, i assume you have increased your cr?
cr?
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Old 04-12-2013, 10:53 AM   #8
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336

i've had one in my 91 r100gs/pd for 10 years now.really comes on around 4500 rpm.i think you'll like it.
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Old 04-12-2013, 10:53 AM   #9
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Originally Posted by Zodiac View Post
cr?
Compression ratio
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Old 04-12-2013, 11:06 AM   #10
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Compression ratio
I myself have not. Bike had stellar leak down and compression tests though.
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Old 04-12-2013, 11:08 AM   #11
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Originally Posted by bajaburro View Post
i've had one in my 91 r100gs/pd for 10 years now.really comes on around 4500 rpm.i think you'll like it.
Cool, that's what I'm looking for. I also noticed a wake up removing the collector box for a Kehin H pipe.
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Old 04-12-2013, 11:31 AM   #12
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FYI I've been discussing this with them at Danbury Max and they're looking into it through the NH stores (that supply out online) - They're ordering it direct from BMW.

I'm not worried a bit, they take real good care of me there - anything goes wrong I'm sure they've got my back on anything defective (which I highly doubt they'd install in the first place).
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Old 04-12-2013, 12:29 PM   #13
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It is great that we are on to a batch of bad 336's. I wouldn't let that stop you from getting one. There is not a cam out there that has not had a batch of bad grinds. As far as I understand it, it sometimes happens to the best cam manufacturers. My concern isn't the grind, it's where they are being made at now. China? I hope not since I have had TONS of trouble with Chinese made bearings and whatnot. If they are being made there and ground there or blanks from Germany are being ground in China or the whole Chinese story got started because of a bad batch of cams, I have heard nothing conclusive as yet. I am still hoping that the blanks are still being made and ground in Germany.

I put one in my otherwise stock '92 R100 and loved it from the get go. Everyone said I HAD to raise the CR and deepen the valve pockets in my pistons and my bike would make less power under 6k than it did with the stock cam. Nope. It had tons more midrange and top end but, now that I have dual plugged, raised the CR, and did some major port work on the same setup, I wished I had done that 12 years ago when I first put the cam in. I have just raised the CR and dual plugged many an airhead with decent results but the same deal with a 336 and some port work is worlds more powerful ALL up and down the rev range.

supershaft screwed with this post 04-12-2013 at 01:03 PM
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Old 04-12-2013, 07:33 PM   #14
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Quote:
Originally Posted by Zodiac View Post
So I finally broke down and decided to have my top ends machined. the PO had left me with a stripped and re-welded exhaust thread, on one side, and a buch of broken fins on the other - plus they were getting quite furry.

So in doing that, I also found a new timing cover to replace the original which looked like it lived in the titanic. I have Max BMW doing the work, and had them replace the timing chain and tensioner ("while you're in there").

So at this stage, they mentioned putting in the 336 Cam to give me a healthy boost. Bike already had twin sparks, Dyna III ignition coils, and could wheelie in 2nd gear on occasion (I love that Mono 33:11 final for low end power).

So has anyone swapped cams to a 336 and how were your results?

88 R100 RS
You didn't really just ask that question did you?
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Old 04-12-2013, 07:41 PM   #15
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The stock compression ratio on an '88 RS makes for a pretty aneamic and inefficient motor, even after adding a bit more cam. I'd up the ante to at least 10.5:1 and enjoy the benefits of increased torque and efficiency throughout the rev range. You've already got dual plugs (ie: it'll handle higher compression just fine), which is the expensive part.

You'll be glad you did.

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