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Discussion Starter · #1 · (Edited)
I've been lurking around SVRider for a while now to find all the answers I need to various projects, but I figured I'd start posting direct questions

So, my my '05 started running a little poorly. Slight loss of power, rougher starting, increased backfiring when compression braking - such as down a hill, using the engine to maintain low speed. It wasn't that bad, but any feeling that there's less power was annoying. Frankly, I want to be as on-point as I can about maintaining my bike, and I hate paying other peole to do crap for me. The bike had a the valves shimmed at around 18k miles by a mechanic - previous owner, who's a friend of mine had this done. I'm at a little over 30 now. I realize that's within the valve check interval, but all those miles have been really rough, seeing a lot of peak revs, etc., so I figured it was the valves. I took them apart, and sure enough every valve was at minimum clearance with the front exhaust valves a whole ~.1mm below spec (.2-.3mm being within).

I have a few question about reassembly because I want to be 1000% sure I'm doing everything correctly. This has been a learning experience for me.

1: I can reuse shims, right? As long as they're the right thickness (I mic'd everything) I can put the old ones wherever they're needed right? I want to recycle parts to save some money, but I'm unsure because some of these shims don't have the stamped thickness anymore, as if they've been worn down. Would I be better off buying a whole case of assorted shims, just in case I re-assemble everything and my shim measurements/adjustments were bad?

2: I've pulled all four cams off and pulled all the buckets/shims. Reinstalling each cam is where I want to be sure; How can I tell I'm on the compression stroke, TDC of the front cylinder? I have the rear cylinder lined up at TDC compression - I know this because that's how I disassembled it, and didn't touch the flywheel. But lining up the front cylinder after re-assembling the rear is what I want to be sure of. Is it something like 270 degrees anti-clockwise from rear comp TDC = front comp TDC? WIll the rear cam sprocket markings be pointed a certain way? My manual is not very specific and only provides what the cams look liked when it's put together properly by the factory at compression TDC. Basically, when the flywheel is at the F-mark, how can I tell that's compression or exhaust stroke?

3: My service manual doesn't seem to be very specific about setting cam chain tensioners. I didn't touch them other than to take the two allen bolts out of each and remove them to pull the cams - is there any adjustments I should make to ensure they're put back together correctly?

4: is there anything else I should be doing to ensure everything is set for optimal/peak performance from the motor? Any adjustments, etc. I've read about TPS and throttle body adjustments, but I'm not sure if that's necessary. My goal is to maintain the quick, easy no-throttle starting (even cold) it used to have just a few thousand miles ago, and maintain as much power as possible as the engine ages beyond 30k miles. I intend to keep it for a long time to come, with lots of improvements (mainly chassis/handling) I want to make.

Sorry if any of this is already in a thread I couldn't find. I searched, I promise.

:::EDIT::: I've got the cam timing and cam tensioners squared away through help and more snooping around. If anyone has any other input, for item 1 and 4, I'd really appreciate it!
 

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There is no compression or exhaust stroke without cams in. So, when you put cams in with piston at TDC that determines compression stroke. You can start at either cylinder, front or rear, they just need to be one crank revolution apart.
 

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Discussion Starter · #4 ·
good luck getting it timed right. this isn't going to end well i bet.
Gee, thanks.

I can get the cams/chains lined up properly with the cylinder at TDC. I have the diagrams in the manual and i took pictures of everything before dis assembly, so that part is a piece of cake. I just need to know if I'm on exhaust or compression stroke. I'm probably going to do it correctly, I just want to be completely sure. Looking for tips and advice, etc.

I read in another thread, someone put their cams on the front head 360 degrees off - as in on the exhaust stroke, not compression, and the bike actually ran for some time before giving him trouble, without any valve damage... He was either exceptionally lucky, or the bike can simply do it... I, however, don't want to take apart my front cylinder head again.
 

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I kinda went through the same thing and tovar helped me through it as well.

Basically dont worry about strokes. Set the crank at the "f" position. Set the front cyl. cams with the markings theyre supposed to be. Rotate the crank a full revolution back to the "f". Set the cams on the rear cyl. with the markings where theyre supposed to be. This will have the engine timed correctly. Be careful not to drop the chain on rear cyl. when rotating the crank.
 

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Discussion Starter · #6 ·
I kinda went through the same thing and tovar helped me through it as well.

Basically dont worry about strokes. Set the crank at the "f" position. Set the front cyl. cams with the markings theyre supposed to be. Rotate the crank a full revolution back to the "f". Set the cams on the rear cyl. with the markings where theyre supposed to be. This will have the engine timed correctly. Be careful not to drop the chain on rear cyl. when rotating the crank.
Awesome. That makes a little more sense. I went back and re-read my manual about three times. The wording is awful and the diagrams poorly referenced, but It seems to be saying the same thing you just did. I should be golden for reinstalling the cams. I hadn't realized the R-mark is only for checking valve clearance on the rear valves. F-mark is the only mark used for lining up cam markings and TDC.

Thanks! :eek:ccasion14:
 

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Discussion Starter · #8 ·
There is no compression or exhaust stroke without cams in. So, when you put cams in with piston at TDC that determines compression stroke. You can start at either cylinder, front or rear, they just need to be one crank revolution apart.
Thanks for your help. I should be good to go on the cams now. :)
 

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As a footnote, think about the cam lobes and their position while at TDC for exhaust and intake. What are the valves doing at these settings? Are the valves open or closed for the respective cams? Don't just follow instructions blindly, think about what's happening during the 4 stroke cycle and how the valves are supposed to operate.
 

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Discussion Starter · #13 ·
As a footnote, think about the cam lobes and their position while at TDC for exhaust and intake. What are the valves doing at these settings? Are the valves open or closed for the respective cams? Don't just follow instructions blindly, think about what's happening during the 4 stroke cycle and how the valves are supposed to operate.
This is exactly why I started the thread.

I've had the top end of several motors apart before, never a motorcycle, and I've never done anything with cam timing before. I understand most of the basics, but I guess I'm asking these questions to help me understand exactly what's going on to make everything fit together properly... Otherwise I could just be doing this all exactly how my manual says so and cross my fingers - no thanks to that.

Luckily, I'm somewhat forward thinking and have a metric ton of high-res pictures of everything before unbolting to fall back on, which I will for redundant double-checks, anyways.

trace33: good idea, I'll definitely do that.

TeeRiver: I'll do that sometime this week, I hope. I have to wait for payday to get a torque wrench that does <20nM, as the manual specifies for all the cam holder bolts.

Thanks a ton you guys.
 

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Discussion Starter · #15 ·
The manual I have says to find front cylinder TDC, align the cams as shown in a diagram, and then rotate 360 degrees back to f-mark to get 90atdc for the rear cylinder, which it provides a diagram for.


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Yep, F mark for rear is 90 degree after TDC for that cylinder.
R mark is TDC for rear and used for clearance.
Basically front cams are set with piston at TDC while rear cams are set 90 degree after piston was at TDC.
Only F mark is used to install cams.
 

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For #1 you are fine to re-use shims, as long as they are still in good shape. I always measure shims, even if they are marked just to be sure.


Lots of other good info in other posts but make sure you turn the crank 360* after installing the front cylinder cams and before setting the TDC on the rear cylinder and installing rear cams. I've made that mistake, luckily didn't hurt anything other than my pride.

On the cam tensioners, you should be able to "lock" them into the body before re-installing the allen bolts, then release the tensioners, they will self adjust.

Good luck, simple job if you take your time and ask questions.
 

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Discussion Starter · #19 ·
I measured every shim I pulled, and kept them organized with the bucket they came out of. There's a couple of shims that I'll be reusing. My mic (it's kind-of cheap, it's a digital caliper, not the screw clamp type) is accurate to +/-.02mm, and seems to be coming to normal shim measurements when I use it, IE 1.75, 1.60, etc.

Is it possible that the previous mechanic used shims with no stamp marks, or is it more likely that every stamp mark wore off in less than 12k miles?

Obviously, I'll be re-gauging all of my valve clearances before I finish the job.

As for the automatic tensioners: thanks for telling me I had to spin the crack the right way, I wasn't sure. My book just says to reset, bolt them on, and then bolt the tensioner spring in and call it good... Of course, my book also says never turn the motor backwards, it never explains why.

Images are forthcoming. Give me a few days. :)
 

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Do you have stock air filter & pipe?

If you are experiencing backfiring or popping during deceleration or engine braking this could be a lean condition in the motor.

Good luck with the cam replacement and all that madness. I'm at 24k and have yet to get inside the top end. Not the best plan I suppose but the SV is known for having little issue w the valve train.


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