Shed Time with Geoff Jones

As mentioned in a previous tome, the R1 has had some issues with valves, namely burning an exhaust valve in cylinder number two. It was corrected by changing the 2001 head for a 1998 unit that happened to be sitting on a spare motor that has become added clutter in the shed, handy though in this instance.

I had time over Easter to repair the 2001 unit and try to work out why the valve failed. Prior to the holiday break, parts from the US and a valve tool from Frankston arrived so I was able to remove the failed valve and explore the reasons for the failure. On fitting the replacement valve and bolting on the exhaust camshaft with the original 1.65mm shim, I soon found the fault - no valve clearance.

Out with the valve and swap it for the existing one in the same cylinder to find the same clearance issue. So it was not a different length replacement valve but a fault with the valve seat moving into the head. After modifying two tap holders to suit the different space available around the inlet and exhaust valves I proceeded to lap in the 20 valves on Good Friday, a sort of religious event. Each valve was rotated with the tap tool using coarse, then fine grinding paste. On completion of lapping in each valve I replaced the seal, spring keeper and collets using the very effective tool and did a solvent leak test on each combustion chamber, regrinding till I was happy with the leak down, or lack of it, in each case.

Grinding completed, I replaced the cams and checked the clearances. All OK except the failure location. A 1mm shim, down from 1.65mm corrected the clearance; I replaced the head on the 1998 motor, but not bolting it on, ready for further use if required.

One way to while away a day …

There are many differences in the oiling system of the two heads. They both have hollow cams but the 2001 unit has welsh plugs in each end of both cams and different drillings in the cam bearings which use oil under pressure to do the lubrication. The 1998 unit relies more on splash feed and wells at each valve to keep oil where it is needed. The 1998 unit produces more valve noise on start up than the later unit but starting has improved and the bike is running OK now that all cylinders are at approximately the same combustion pressure.

So, the reason the valve failed is clear. But why that particular valve lost its clearance remains a riddle to mull over. It could have been the lean jetting experiments, I guess.

I know that Yamaha have improved the oil system. My problem now is to resist changing the heads over.

On another Shed Time note, I have received and assembled a tyre changing unit that seemed to be too cheap at $119 delivered. It is made in China. It seems to cover all aspects of changing a tyre, a bead breaker included. I have not used it in anger yet as there is still some tread depth left on the existing Pilot Road 2. Two used tyres purchased on eBay have arrived, a Road 2 and a Pilot Road.

Last time I attempted a tyre change using just levers I destroyed a rear rim. More care this time. The worst case scenario is that the unit adds to the shed clutter.

As her article in April's magazine suggests, Cindy needs to replace her VTR which met its end on my recent Meredith ride with some painful effects on Cindy.

On Saturday 1^st May, Cindy arrives at Melton station. Val and I meet the train and, after dropping Val off at the local pokie palace, Cindy and I proceed to inspect a GSXR750 K3 that is on the market at an amount that suits Cindy and the seller. No registration and a flat battery. A jump start has the bike running and a check of the voltage across the battery confirms the charging system as AOK. Vernier caliper on the discs and a check of other functions confirms the healthy state of the bike. Cindy leaves a deposit and is back on two wheels when she feels up to it. The bike feels a bit tall for Cindy but suspension mods should enable a less tiptoe stance when stopped.

Sort of a Shed Time activity I think.

Geoff Jones