Mark Haycock and you with two pages of tips.
Q: Hi Mark, been interesting to read your stuff about oil filters. I have a very tidy Yamaha XS500 myself, a 1980 model and it has the spin-on conversion oil-filter. When I got it, it had a Hiflo HF303 in place and to change the filter you had to take the side of the bike off to get to it, but if you use a Hiflo HF204, this basically is the same filter but about one inch shorter. This means you can change the filter without having to strip half the bike! Dave Cutler A: That is interesting, because I see from the application list for the HF204 one of the many bikes it will fit is the Honda CB900F2. In other words it has the same dimensions as the Honda filter I used and thus could replace it. Great minds think alike! One thing I should point out is that this filter has an M20 rather than M22 thread, so it will not act as a direct replacement for the original Yamaha filter.
1988 Honda BROS 400
Q: Hello from Dublin! I recently purchased a 1988 Honda Bros 400. The bike is a nice example and has survived fairly well. I’m looking to do a tidy-up on her to make a good usable motorbike. Firstly the paint: there is a rust patch around where the seat meets the tank and it has spread under the paint in places. I’ve been advised to strip and repaint the whole tank for best results but she made it this far it seems a shame to get rid of the original paint job. Would it be possible to touch up the area affected? I’ve been advised against this but would like an opinion. The colour seems to be a metallic black; is it still available? These bikes have an issue with the drive-gear stripping the splines off the shaft: mine hasn’t, but I’m wondering as to the cause so as it can be avoided in the future. Some forums suggest an incorrect chain tension. Last question, the switchgear has been badly bleached from the sun; are these generic part or specific to the Bros? Bernard Mccann A: Is your paint black with blue metallic particles? If so the colour is called Granite Blue. You can confirm this as somewhere under the seat you should see a label with the paint code PB184MU on it. I think you would be highly unlikely to get a touch-up spray or a brush-on tin but if you quote the Honda paint code you might be lucky. Otherwise it will need a respray but someone who knows what they are doing will make it look not just as good as, but better than new. Or you could take the opportunity to change the colour to whatever you want. There does appear to be an issue with the splines on the gearbox output (counter) shaft which drive the sprocket. I have seen pictures of splines nearly worn out and find this very curious, as it seems to be a problem which affects some bikes and not others. One cause might be that some shafts were incorrectly, and hence insufficiently, hardened but the common theme among owners is that the chain is often run too tight. This is no doubt because the design of the rear suspension is such that the chain tension varies widely depending on rear wheel position. The recommendation then is to set the tension to be rather more slack than you would normally expect. The common Honda sprocket mounting arrangement using a plate and two M6 bolts allows, by design, the sprocket to move slightly on the splines in use (this is to allow for slight misalignment or sprocket deformation) and so the shaft needs to be well lubricated. The area by the sprocket is bound to be well lubricated if adequate chain lubrication is carried out. I think the handlebar switches were unique to the NT400/600 and they do not seem to be commonly found, so you might be best advised to stick with what you have.
Q: A two-stroke timing query. Back in the early 70s when I was an apprentice bus mechanic, I got to be a whizz, with my trusty DTI, at timing up my mates’ points-equipped two-strokes (the improvement of 250 Kawasaki triples with three sets of points was astounding). The DTI made sure the piston was in precisely the correct position and a test lamp across the points made sure each set were opening at exactly the right time (though the improvement only lasted about a week). On modern electronic ignitions although the DTI bit is still the same, the electrical bit seems to consist of lining up a couple of marks by eye. Given the precise nature of electronics, this method of setting the electrical side seems a little hit and miss, especially on anything highly-tuned. I mean, how do you know the marks are where they should be? Or what if the engine has been modified? Still, seeing as none other than Sir Stan of Stephens does it this way, it must indeed be accurate enough to do the job. John Randall A: I think your conclusion is correct. Although it may be that the specification is, say, 2.6mm as on the S1, what does that mean? Simply that in Kawasaki’s tests when the engine was being developed 2.6mm turned out to be the best compromise between a number of different factors. The engines produced at the factory were not identical clones and there must be a range of dimensions and weights that will affect the way the engine runs, to a small extent. It could well be that on a particular engine 2.5mm would work a bit better but it is just easier to set it to 2.6mm as that is a recognised compromise. And as you say, with points ignition it does not take very long for the setting to change. So lining up the marks is perfectly adequate for normal engines. For a tuned engine, the experimental process must begin again unless of course rules of thumb are applied.
Q: I’ve bought a tank for a Honda CB500 K on ebay: it’s in excellent condition, really solid but inside the tank is rusty. It’s not flaky rust just powdery. Can you recommend a process for cleaning inside, or is there someone who you can recommend? I’m having it resprayed at some point so a company who can do both at the same time would be even better. Alan Evans A: I think you are wise in getting a professional to do the spraying as you cannot expect to do that at home using modern durable paints which do need specialist equipment to apply them. Lining the tank is a DIY job though, and I shall be looking at that in a separate article soon. Or, check our back issues for tank expertise from our own Steve Cooper in February 2014 and he told us how to remove a tank liner in August 2017.