Interesting Advance
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Senior Member
Superstock
Joined: Sep 2013
Posts: 460
From: Costa Mesa, CA
Interesting Advance
During this current slow down,as a favor I decided to install MCCT's on a friends SH. I adhere to the VTR1000.org suggestion and remove the cam covers and upper chain guides to measure the chain slack. During the process I discovered that the rear Intake Cam was one tooth retarded. Easy fix. Then I discovered that Both front Intake and Exhaust cams were 1/2 tooth (1 Crank tooth) were retarded! Not important as to how, or when, this happened but, this bike has been ridden 15k miles since the last time anyone had the cams out for clearance setting. The owner never notice anything different performance wise. Again not a big fix. Just pull the Really Light Flywheel (thanks Eric) and move and advance the chain on the crankshaft sprocket one tooth. Seeing how I'm pulling the ACCT's, it's pretty easy as the chains will be slack.
There were no valve to piston problems as there is ample clearance with the stock cam and pistons. That and the fact it was minimally out of time.
My question is what effect would this have had on performance?
There were no valve to piston problems as there is ample clearance with the stock cam and pistons. That and the fact it was minimally out of time.
My question is what effect would this have had on performance?
Senior Member
SuperSport
Joined: Jul 2018
Posts: 565
I believe it would have moved the peak power a bit higher...Intake opening (IO) plays a big part in establishing overlap (the time when both intake and exhaust valves are open). An early IO increases overlap and can lead to a sluggish engine, since the intake charge is contaminated with exhaust gasses. A later IO reduces overlap, improves idle quality, and increases low-speed torque. (Key: Open a little later for bottom end, a little earlier for top end)
An early IC improves low-speed torque, but limits high-rpm power since it also limits time for cylinder filling. On the other hand, a later IC allows more time for a cylinder to fill at high rpm, but limits low-end torque since cylinder pressure is pushed back through the intake port. (Key: Close the same or a little sooner for BE but not much later for TE.)
Exhaust opening (EO) ranks second only to intake closing in affecting engine performance. An early EO can limit low- and midrange power by allowing torque-creating cylinder pressure to escape, but helps high-rpm performance by creating more time for exhaust gas to be expelled. (Key: Open earlier for top end, stay the same or a little later for bottom end.)
Exhaust closing (EC) also affects overlap. An early EC reduces overlap, improving idle but limiting midrange power. A late EC increases overlap, which hurts idle but helps high-rpm power. (Key: Open a little later for top end. Stay the same for bottom end.)
AV
An early IC improves low-speed torque, but limits high-rpm power since it also limits time for cylinder filling. On the other hand, a later IC allows more time for a cylinder to fill at high rpm, but limits low-end torque since cylinder pressure is pushed back through the intake port. (Key: Close the same or a little sooner for BE but not much later for TE.)
Exhaust opening (EO) ranks second only to intake closing in affecting engine performance. An early EO can limit low- and midrange power by allowing torque-creating cylinder pressure to escape, but helps high-rpm performance by creating more time for exhaust gas to be expelled. (Key: Open earlier for top end, stay the same or a little later for bottom end.)
Exhaust closing (EC) also affects overlap. An early EC reduces overlap, improving idle but limiting midrange power. A late EC increases overlap, which hurts idle but helps high-rpm power. (Key: Open a little later for top end. Stay the same for bottom end.)
AV
Thread Starter
Senior Member
Superstock
Joined: Sep 2013
Posts: 460
From: Costa Mesa, CA
Ace, Gotcha. I got the rear timed to spec but, I can't get the front perfect. When the FT is at the proper position the cams are a couple of degrees advanced. If I retard the cams 1/2 tooth (1 at the crank) they're a couple of degrees retarded. Am I missing something? Or, is this just factory slop? If it can't be corrected, which should I run, both fronts a bit advanced or retarded? Ideas?
When I checked my bike it's almost perfect as far as the cam markings being flush with the head surface when the FT or RT are in position.
When I checked my bike it's almost perfect as far as the cam markings being flush with the head surface when the FT or RT are in position.
Senior Member
SuperSport
Joined: Jul 2018
Posts: 565
Probably just slop combined with slightly incorrect timing marks. I would line them up as indicated in the book and cycle the engine once or twice to see where they fall after that. There is a ton of clearance to work with in the combustion chamber so the biggest concern I would have is slightly different timing between front and rear. I suspect you'll be just fine, especially when you consider what it was like when you found it. Unfortunately there is no real good way to tell where the lobe is without a dial indicator and a degree wheel. Not much help in this case I'm afraid.
AV
AV
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MotoGP
Joined: Apr 2006
Posts: 4,402
From: Kempner, TX
A few possibilities,
Are you keeping pressure on the adjusters/ chain guides while rotating motor?
Are you doing your final rotation in normal forward direction as the engine runs? (SO if you pass timing marks, and reverse you go past them again backwards then rotate forward to the marks?)
How many miles on the chain? When cam chains wear they get effectively longer just like a drive chain. As they get longer the cams will become retarded, the more wear, the more retarded...
__________________
Are you keeping pressure on the adjusters/ chain guides while rotating motor?
Are you doing your final rotation in normal forward direction as the engine runs? (SO if you pass timing marks, and reverse you go past them again backwards then rotate forward to the marks?)
How many miles on the chain? When cam chains wear they get effectively longer just like a drive chain. As they get longer the cams will become retarded, the more wear, the more retarded...
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Thread Starter
Senior Member
Superstock
Joined: Sep 2013
Posts: 460
From: Costa Mesa, CA
Thanks guys, I have a new chain coming. The rear is less than 1/2 degree off so I'll let it go for now.
Has anyone tried ETL CCT's? (camchaintensioners.co.uk)They appear to be a well engineered product. The adjustment shaft is designed and machined to seal via double O-rings in the housing rather than a compressed O-ring under the lock nut. That negates the need for sealant on the threaded portion like many. I've had them around for some time and with this "social distance" going on, I'm donating my APE's to a friends SH and finally installing them on mine.
Has anyone tried ETL CCT's? (camchaintensioners.co.uk)They appear to be a well engineered product. The adjustment shaft is designed and machined to seal via double O-rings in the housing rather than a compressed O-ring under the lock nut. That negates the need for sealant on the threaded portion like many. I've had them around for some time and with this "social distance" going on, I'm donating my APE's to a friends SH and finally installing them on mine.
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SuperSport
Joined: Jul 2018
Posts: 565
I have not tried them though they do like nice. If it matters to anyone I am currently working on a secret project that involves an auto tensioner that will not fail....it will be cheaper, easier, self adjusting and of better construction than pretty much anything available. It even has a little of that new fangled design engineering behind it.
AV
AV
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