ANDY'S CAM CHAIN TENSIONER MODIFICATION.DOC AUGUST 15, 2011

Z:\Data Files\Motorcycle\Honda Magna (1985) VF750C\Cam Chain Tensioners\Andy's Cam Chain Tensioner Modification.doc Page 1 of 6

Cam Chain Tensioner Modification

After 27 years under tension the cam tensioners were no longer strong enough to stop the cam chain from slapping and creating loud ticking noises as it rotated at idle. It stands to reason that the action was even worse at higher revs but this could not be heard at riding speed because of the wind noise and riding position. Before you plunge into this, poorly adjusted/synched or dirty carbs can result in unequal firing of the cylinders resulting in uneven action of the cam chains causing the chain to go slack-tight-slack- tight and slap against the chain guide making a sound like loose valves. Replacement tensioners are not available from Honda – nor were springs. Additionally, they were not available from aftermarket sources. Salvaged tensioners could be found but there was no way to determine if they were in better condition – i.e. stronger. The picture shows the extent of the disassembly required by the three projects:

• dual gas tank reconditioning,

• carburettor rebuilding,

• Cam chain tensioner modification. Most of the rear end disassembly was required to be able to remove the auxiliary gas tank which can only be removed through the space covered by the inner rear fender. During reassembly, all the gas lines will be replaced with new ones and the single gas filter will be augmented by a second one to increase the protection for the carburetors and the fuel pump. I DO NOT want to be repeating this!!!

1985 VF750C-E Honda Magna

FEEL FREE TO USE THIS TO YOUR OWN BENEFIT – BUT IT REMAINS MY PROPERTY. AUGUST 15, 2011

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Cylinder Bank 1-3

Top cylinder bank (1-3) after the cover, sub cover, cam chain cover, and oil crossover tubes have been removed. Note the plastic tie on the rear cam sprocket. This is used to ensure that the cam chain does not slip over a tooth which would affect the valve timing. There is no tie on the front cam sprocket because the cam must be removed to allow the tensioner to be removed. Torque on all head bolts had to be backed off and then just snugged up to avoid warping the head since the centre bolts were

removed. The top of the cam chain tensioner can be seen below the cam chain between the two sprockets. Note the paint marks on each cam sprocket and chain links. These are used to ensure that the front cam goes back in exactly the same orientation. Timing mark locations were also noted before any disassembly.

Main Wiring Harness

Clutch Hydraulic Line

Zip tie to maintain timing

Zip tie in place

FEEL FREE TO USE THIS TO YOUR OWN BENEFIT – BUT IT REMAINS MY PROPERTY. AUGUST 15, 2011

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Cylinder Bank 2-4

This shot shows the front cylinder bank after the cover has been remover and has the cam cover, and oil crossover tubes in place. This bank of cylinders does not have a sub-cover. Ignore the yellow extension chord.

This shot shows the cylinder bank after the cam cover, oil cross-over tubes and front cam caps have been removed. Note the paint marks on front and back cam sprockets and chain links. The plastic tie on the rear cam sprocket is barely visible right at the top of the picture. There is no tie on the front cam sprocket because the cam must be removed to allow the tensioner to be removed.

Fan hanging on bungee – later

removed.

FEEL FREE TO USE THIS TO YOUR OWN BENEFIT – BUT IT REMAINS MY PROPERTY. AUGUST 15, 2011

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This shot shows the top cylinder bank after the front cam and the tensioner tower has been removed. The cam chain is pulled up and tension is maintained on the bottom end using a bungee cord. Note the yawning chasm just begging to have oily stray nuts and washers dropped into it like stones down a well.

These are the parts removed in order to remove the tensioner tower (outside the tray) which has been partly disassembled by removing the chain slipper (laying on top of the other parts) to allow it to come off the cam chain. The wire sticking out of the tensioner tower is bent into an “L” shape and used to lock the arm into place against the tension of the spring. To avoid ANY possibility of mixing parts that shouldn’t be mixed, I didn’t take the banks apart at the same time.

Cam Chain Guide

Front Cam and Sprocket

Cam Tensioner Tower

Cam Slipper

Oil Crossover Tubes

FEEL FREE TO USE THIS TO YOUR OWN BENEFIT – BUT IT REMAINS MY PROPERTY. AUGUST 15, 2011

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Cam Chain Tensioner Tower as removed from the bike

Disassembled Cam Chain Tensioner Tower with marks to show the relocation of the spring anchor.

Tensioner Spring Tube

Tensioner Locking Tab

FEEL FREE TO USE THIS TO YOUR OWN BENEFIT – BUT IT REMAINS MY PROPERTY. AUGUST 15, 2011

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The rolled over end of the Factory pin was ground back to the hole diameter to allow the pin to be punched out and reused. UPDATE: the experience of someone that did a similar mod but put the pin at “A” has convinced me that the location I used might be a bit marginal and “B” would be safer. His cam chain hit the end of the spring and pin – chewing through them

Modified and reassembled tensioner tower ready to be reinstalled. The original pin was reused in the new location and welded to the tensioner arm. The weld was ground down to the original thickness of the rolled over pin end. Yes, I know the weld looks crappy – that welder had a jerky wire-advance system. That’s my excuse and I’m sticking to it! Re-installation is a fairly predictable reversal of the removal EXCEPT for the torquing of the different sized bolts. Look up the torques and: 1. torque ALL bolts to the torque for

the smallest diameter then move up a size, and

2. torque ALL the size and larger bolts to that torque.

3. repeat until all sizes have been torqued.

This process minimizes any chance of warping the heads. Happy in Hondaland, MagnAndy Brampton, Ontario, Canada

Factory Spring Anchor Pin

Action Line of Tensioner

Spring

New Pin Location

New Action Line of Spring

“A”

“B”