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how many degrees from RT compression to FT compression?

Old 08-17-2012, 01:48 PM
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how many degrees from RT compression to FT compression?

working on CCT's as i write this. have accessed crank nut and inspection port, have the rear valve cover off and lined up at RT- no pressure on intake or exhaust lobes. all looks great, valves in spec. about to zip tie and pull rear tensioner for modification.

just want to be crystal clear:

how many degrees of rotation on crank from RT to get to correct FT compression stroke?

the manual seems to say 270*... i'd rather not pull the front cover...
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Old 08-17-2012, 01:52 PM
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(12) Now turn the engine over anti-clockwise 450 degrees (one and a quarter turns) until the 'FT' mark lines up with the mark on the alternator cover, you are now ready to remove the front CCT using the same procedure as the rear, without the need to remove the front cam cover.
www.vtr1000.org • View topic - How to remove and refit CCT's on the Firestorm
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Old 08-17-2012, 02:05 PM
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From the manual;

"If the rear timing marks are facing outward(TDC Compression), turn the crankshaft counterclockwise 1-1/4 turn (450 degrees) and align the "FT" mark with the index mark"

"If the timing marks are facing inward, turn the crankshaft counterclockwise 1/4 turn (90 degrees) and align the "FT" mark with the index mark."

not sure where you were looking to see 270.

http://www.superhawk996.net/Honda_VT...ice_Manual.pdf

section 8-21 of the manual
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Old 08-17-2012, 02:05 PM
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beat me to it
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Old 08-17-2012, 02:49 PM
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If memory serves me right, is the manual is going front to rear, though? If that's the case, then from rear to front, 270* would be the proper rotation
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Old 08-17-2012, 04:09 PM
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Originally Posted by 7moore7 View Post
If memory serves me right, is the manual is going front to rear, though? If that's the case, then from rear to front, 270* would be the proper rotation
The manual tells you how to do either front to rear or rear to front.

Yes front to rear is 270* from TDC compression on front cylinder with cam timing marks facing outwards. If the timing marks are facing inwards it's 1 3/4 turns 630* rotation counterclockwise
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Old 08-17-2012, 06:40 PM
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thanks much for all the quick help guys. i'm still just a bit unclear not having worked on one of these before, and from what i scanned quickly in the manual it's 270 front to rear... anyway, here's exactly where it's set:

alternator inspection port at RT, exhaust cam sprocket at R.E dead level with top of case toward rear of bike, intake cam sprocket at R.I level with case toward front of bike, this has to be the "outside position", all pressure off all lobes.

i assume this is Rear TDC compression?

therefore, based on above comments i should go 450* (counterclockwise of course) to hit Front cylinder TDC compression?

will get back on it tomorrow. pulled the rear unit without incident. my plan was to just mod the stock tensioners with a couple 5/16 stainless bolts as some have done, but i don't like the idea of some 4" of unsupported bolt in the gutted housing that will tend to be flexed downward with barely 5/8" of threaded contact... will either weld in a threaded bushing or make some APE style blocks.

Last edited by barncat; 08-17-2012 at 06:44 PM.
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Old 08-17-2012, 06:49 PM
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Originally Posted by barncat View Post
alternator inspection port at RT, exhaust cam sprocket at R.E dead level with top of case toward rear of bike, intake cam sprocket at R.I level with case toward front of bike, this has to be the "outside position", all pressure off all lobes.

i assume this is Rear TDC compression?

therefore, based on above comments i should go 450* (counterclockwise of course) to hit Front cylinder TDC compression?
You got it.
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Old 08-17-2012, 09:54 PM
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My friend did a silly little trick. Once he aligned RT in the window he pulled the SPark Plug slid a long dowl down the hole onto the piston and let it ride to its highest point showing full compression. **** was dead on when he replicated the manual instructions to me (Im still learning).
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Old 08-18-2012, 06:18 AM
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good. and thanks to all. excellent website and kudos to administrator(s).

the stock CCT was in perfect condition, but that flimsy little torsion spring does not inspire a lot of confidence, so back at it today. based on excellent condition and adjustment of rear head i see no need to hassle with front cover...
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Old 08-18-2012, 06:42 AM
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Originally Posted by kardiac996 View Post
My friend did a silly little trick. Once he aligned RT in the window he pulled the SPark Plug slid a long dowl down the hole onto the piston and let it ride to its highest point showing full compression. **** was dead on when he replicated the manual instructions to me (Im still learning).

Only problem with that method is if you're not sure which RT you are starting from you could turn the motor to TDC on the exhaust stroke and not know it. Loosen the CCT and you will hear the cam spin as it jumps teeth.

I.E. if barncat has his rear head at TDC compression, and uses your dowel method, he will turn the crank 90* and find the dowel sticking up like TDC, but it will be on the wrong stroke and make more problems.
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Old 08-18-2012, 09:33 AM
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Originally Posted by 98VTRrider View Post
Only problem with that method is if you're not sure which RT you are starting from you could turn the motor to TDC on the exhaust stroke and not know it. Loosen the CCT and you will hear the cam spin as it jumps teeth.

I.E. if barncat has his rear head at TDC compression, and uses your dowel method, he will turn the crank 90* and find the dowel sticking up like TDC, but it will be on the wrong stroke and make more problems.
He was utilizing the lobe positions as well for check and balance against which stroke he was on. All I know is the RI RE marks are flush with the head and the RT mark was dead on in the window. I'm pretty sure there are a few methods of resolving the same madness. Was simply mentioning another check and balance. So of course you would have to know where you were at in the strokes to use this method properly.

Last edited by kardiac996; 08-18-2012 at 06:08 PM.
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Old 08-18-2012, 11:36 AM
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Originally Posted by kardiac996 View Post
He was utilizing the lobe positions as well for check and balance against which stroke he was on. All I know is the RI RE marks are flush with the head and the RT mark was dead on in the window. I'm pretty sure there are a few methods of resolving the same madness. Was simply mentioning another check and balance. So of course you would have to know where you were at in the storkes to use this method properly.
The OP was trying to set his front cyl without removing the front valve cover, so he couldn't view the front cam lobes or timing gear marks.

He was going off the rear cyl, and needed which rotation from rear TDC compression to get to front TDC compression without removing the front valve cover

The dowel works good for getting exact TDC, but you need a way to verify which stroke by cam lobe position or timing marks.
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Old 08-18-2012, 05:44 PM
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Originally Posted by 98VTRrider View Post
The OP was trying to set his front cyl without removing the front valve cover, so he couldn't view the front cam lobes or timing gear marks.

He was going off the rear cyl, and needed which rotation from rear TDC compression to get to front TDC compression without removing the front valve cover

The dowel works good for getting exact TDC, but you need a way to verify which stroke by cam lobe position or timing marks.
I strayed off topic for sure but figured it was worth mentioning since I have seen many recent TDC questions and CCT failures. My bad on the accidental hyjack fellas
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Old 08-18-2012, 06:04 PM
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The easiest way to tell is to remove the spark pug and screw in a compression test lead... as you turn the engine you will feel it pushing air through the lead on the compression stroke then line the mark up fot tdc...
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Old 08-19-2012, 06:14 PM
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i successfully completed the mod. glad for the heads up on this issue on the site.

it's been documented before, but this is pretty straightforward if you:

1) remove the easy access rear valve cover and verify that you're at RT compression (see above) all pressure off 4 lobes

2) zip tie your cam chain to sprockets just to be safe

3) uninstall stock CCT then install and ADJUST a manual CCT and cut off zip ties

4) rotate the crank CCW exactly 450* to FT at inspection port

5) uninstall stock CCT then install and ADJUST a manual CCT for front cylinder

as mentioned above, i didn't like the gutted housing mod so i built a couple units out of 3/4" thick aluminum stock with stainless 5/16" carriage bolts cut to 4 1/2" long with nut tack welded to exposed end. used teflon tape on bolt where it mates with mounting block to prevent oil seepage.

also took out all PAIR plumbing and made a couple block off plates while in there.
Attached Thumbnails how many degrees from RT compression to FT compression?-im003733.jpg  

Last edited by barncat; 08-19-2012 at 06:25 PM.
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Old 08-20-2012, 07:20 AM
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Good work
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Old 08-20-2012, 07:46 AM
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98VTR and Wicky- thanks again for help on this.

as with any bike that's new-to-you, it takes a little getting up to speed on the layout. there are plenty of opportunities to drop screws into very bad places. anyone doing this mod should proceed methodically-- with caution.
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