Last week I picked up a fairly ancient Honda VFR750 that was about three inches thick with dust and detritus. It was cheap and I have to confess for having a bit of a soft spot for them so it was loaded on the van and transported back to Powell Towers for some special attention. Those of you that know me now will know I always like to run bikes up so I know what is good and what is not and so I can make a sensible decision as to whether to break or do up for sale.
This one was already half in bits as the last owner had bought it as a project which he had never got round to. Lots of bits were fitted loosely but it was together enough to try a start.
The golden rule with these things is to never just rush in and press the start button – you can do a hell of a lot of damage if a bore is full of oil or water – you never know and it does happen
So I did my usual trick of whipping out the plugs and turning by hand before spinning on the starter with the plugs still out. All was good so a compression test was run on all 4 – absolute figures are not important but it is important that all read about the same – mine did. My gauge always reads low – it showed about 75 PSI which is a paltry 5 to 1 compression ratio but I know that equates to a real world 160 psi which is right where it should be. The pots were all within a gnat’s cock of each other. By the way – it’s important to run a compression test with all plugs out and the throttle wide open or carbs removed – otherwise you get incorrect readings.
So with all that done I put some fuel in and watched it all come back out again. Bugger. It was really hard to see where the fuel was leaking from with the carbs on the bike so they had to come off. Being a V4 engine the carbs are an absolute sod to remove but with a bit of judicious wiggling, levering, swearing, sweating and general mistreatment, they came off and got taken to the bench.
I expected the leaks to be either over filling bowls or the pipes that take petrol between the carbs but it soon became apparent that it was the float bowl gaskets that were not doing a very good job of sealing. As I had to take them apart I cleaned them all anyway.
What I did next is not good practice really but as I don’t have any gaskets and am most unlikely to find any I applied a bead of RTV sealant before carefully reassembling them. I will leave it overnight to cure and will give the fixing screws an extra ¼ turn in the morning to make sure they seal correctly. If all is good they will get put back on the bike. If you are going to do this job yourself you will need a really thin walled 10mm socket to remove the needle valve seats with – the pillars that support the float pivot are very close to the valve body and only the thinnest of sockets will do the job.
One thing that upset me is that somebody has been ham fisted in the past and has broken a piece of aluminium casting where a bolt goes to hold the carbs together – without that it’s likely the joiner pipes would leak. It was quite an easy fix with some JB Weld and a washer. I glued the broken piece back on, reinforced around it and then stuck on a washer to make a good solid job of it. As it’s Epoxy resin it will be left a good 18 hours or so before any strain is put on it. I may even build up around it a bit more to make really sure of it.
The rest of the bike is full of minor issues – the brake calipers need rebuilding – the ignition switch doesn’t work properly, the paintwork isn’t brilliant and it’s custom so would be really hard to fix. It’s missing a mirror, it needs a full service and it’s borderline as to whether it’s worth doing. However, these bikes are becoming more and more desirable now and it’s only done 40 thousand miles, which is nothing for one of these – I have seen them with 150k on them and they are still as fresh as a daisy.
As a footnote, while I was test running it I noticed a pool of oil forming on the floor – some ham fisted git has snapped off one of the bolts that hols the engine cover on and oil is leaking through the hole – oh great another job to do – drill, retap and fit a new bolt. Ho hum.
Article provided by David Powell of Boston Bike Bits.
