Ok, I admit, it’s been a while. It’s now August 2017, the VFR is showing 74k on the clock, and I finally found the time to get round to checking the valves. I wasn’t overly concerned to be checking 32k after the last. As I have said before, if your engine still pulls like a train, chances are you don’t need to check the valves. But in the interest of good motorcycle husbandry, and being comfortable thrashing the hell out of the VFR’s sonorous V4, and lets be honest, bouncing off the limiter is where every good V4 engine should be, it’s worth checking the valves. If you follow the instructions below, within a full morning, 5 hours or so you should have the job done. You can spend the afternoon balancing the starter valves and lubricating the throttle cables.
So here are the steps (with photos) to checking your valve clearances. Before starting make sure you have the following to hand:
- At least a day of uninterrupted time, ideally a weekend to allow for cock ups, lack of the right tools etc
- A dry space to work
- nitrile rubber gloves — I like the purple ones 😉
- A mini socket set (I highly recommend Proxxon tools)
you’ll need some feeler gauges to check your clearances covering 0.1 -0.4mm in 0.02mm increments usually: 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.38, 0.4
Making sure the engine is cold overnight before starting, take of both side fairings:
Remove the seat, then raise and prop the fuel tank
Remove screws and remove airbox cover and air filter
Unscrew inlet nozzles for throttle butterflies holding down airbox base. Remove airbox base noting where all connectors and hoses connect: There are two PAIR hoses, one at the front and one at the back (see above). The rear cylinder HT coil leads (see above), the grey connector and vacuum hose on the rear right (MAP sensor) one hose for each starter valve (labelled 1,2,3,4 — two on each side of the airbox).
Lift the base slightly and disconnect a white connector (intake air temperature sensor) and two hoses underneath the airbox. Disconnect the connector on the front right of the airbox, this is the variable intake solenoid valve. Disconnect the vacuum hose #12 linking the solenoid to the one way valve, and the hose #10 from the vacuum reservoir mounted on the front of the airbox. Finally remove the pair hose from the front of the airbox. That should be the lot. Remember to plug them all back in when you reinstall. Heres the exploded view form the Honda Service Guide.
Remove bolts from oil cooler and drop it forward. Behind you can see the pair valve and hose which attaches to the airbox and HT leads for each cylinder.
Loosen bottom support brackets and side mounting bolts holding side mounted radiators and drop them down to gain better access to the front cylinder head
Remove pair hose and HT leads. Loosen four boltsholding down cylinder heads and remove
Remove crankshaft inspection cover plate
Using a 17mm socket, rotate the crankshaft clockwise until marks line up as show above for cylinder 1 (rear left hand side when facing forwards). You will feel the compression of the cylinders as you rotate. You want to get each cylinder at Top Dead Centre — you can tell if you have achieved this by looking at the gear driven cams to see where the lines inscribed into them are located. See image below. If the lines are not as shown, rotate the crank another 360 degrees and check again. Measure both inlet and exhaust valves using your feeler gauges. Mark on the sheet. Continue with cylinder 3, then 2 then 4 as detailed below.
- Inlet clearance 0.16mm (+/- 0.03mm) : between 0.13mm and 0.19mm is fine
- Exhaust clearance 0.3 (+/- 0.03mm): between 0.27mm and 0.33mm inclusive is in spec
Gear driven cams aligned for cylinder 1 check
You should be aiming for a firm sliding fit. Some resistance to the gauge but still sliding freely.
If all valves are within spec, you can reassemble, if not you need to take the cams out and measure shims and swap them out for different sized ones. This is a more involved process, but not impossible.
If you have never checked your clearances, I recommend you check them at least once. Allow a week off the road and a weekend plus evenings to do the job. If you need shims speak with your local Honda dealer or get David Silver Spares (UK) or David Silver in the US to sort you out. You could also buy a hot-shims kit from the US via eBay as I did, and never have to worry about getting shims in the future. The VFR uses 7.48mm shims, like the majority of Japanese sportsbikes.
When reassembling, make sure all gaskets are in place and correctly seated including those in the cylinder heads. There is an edge rubber gasket and a gasket for each spark plug (diamond shaped). There are two locating dowels with a rubber o-ring (visible in the photos above) and each of the four cover holding down bolts has a gasket too.
When reassembling it is also worth lubricating the throttle cables, adjusting the idle speed and balancing the starter valves. I will explain how to do this in due course.
If you want a copy of the VFR service manual, drop me a line.
So the VFR’s clock has just ticked over 58k, and the last clearance check was at 42k, that makes 16k miles in my book, so time for anther clearance check on the old V-Four.
I’ll get around to the task soon enough, and when I do, I’ll show you how to check (and adjust if necessary) your valves. VFR is a great bike, but people can be put off by things like valve clearance adjustments. They’re not that hard to do, and with the right tools, a dry space and a bit of patience, you can do it yourself with ease.
First, I want to share with you the excel spreadsheet I developed to perform my valve clearance checks, this makes it easier than doing the calcs by hand, although I would recommend you check and double check the calculations, and don’t rely on the spreadsheet completely. Click on the link below.
Enter your clearances in the boxes, if they are out of spec you will need to take out the cam shafts and measure the shims and type that in the shin box. The spreadsheet will do the maths for you. Essentially if your clearances are too tight you need a smaller shim. If your clearances are too big, you need a bigger shim.
I’ll go into more detail as we go along, but for now, here’s the spreadsheet.
Originally published at www.shiny-side-up.net on January 31, 2016.