Vince that's great news. Funny about that jetting though. With bigger bore, gas velocity rises compared to the "before" state and that should draw in more fuel. So it's surprising that he is up to such large jets. Ask him to take the main jets out and try it without mains. It should fall flat on its face as the throttle picks up.
If not, there's a restriction in the fuel supply. Could be the petcock or the float needle and seat that are restricting flow.
Amal jets are flow rated and not a mm size, so 220 is similar to a 135 large round or Keihin style main jet IIRC
If that's not the issue, have him back off the timing slightly and see if that helps to drop the plug tip temperatures.
I'd recommend spending time on a dyno with sniffer (exhaust gas analyzer) to see what the mixture is actually doing.
Japan Meets Britain
Teazer, thanks for the info and encouragement. I forwarded your suggestions to John, so we'll see how things progress.
One of the problems (at least in this neck of the woods) is finding a) someone with a dyno and b) someone who knows what they're doing. I'll do a bit of research and ask around to see who might be a good fit with this bike -- of the places that I've seen in the Baltimore region that have dynos, they're all Harley-type places, so I don't know if I'd feel confident in them going through my bike (though maybe it's just paranoia on my part!). I do agree, however, that a dyno/sniffer would provide definite answers to what is going on, so I'll do a bit of digging.
Just spoke with John a little while ago, and he checked all the things that Teazer suggested (he had already been considering them to prior to my having forwarded that post to him). Everything checks out fine (he also removed the main jets and it did run crappy), so we're back to the main jet size. Interestingly, the header pipes haven't changed colour at all, but I don't know how long something like that would take if the jetting was off.
John has 220 jets, and he's also going to get 210's and 230's just in case. I'm going to do more road testing on Friday, so hopefully will have it nailed pretty close this time around. I'm going to hold off on the dyno testing for now and see what John comes up with (seeing that he knows the bike better than anyone!).
More updates -- additional road testing will happen tomorrow (Friday). Two of the three springs in the starter motor clutch thingy (behind the rotor) were compressed, so he replaced them with gun springs, of all things(!), and it's now fine. Turns out the float in the right carb had a pinhole in it and was full of fuel, so that has been replaced with a good used one. John has additional jets now, so hopefully some combination or other will finally work and we can hit 130mph at full throttle. The engine side cover has been welded, and that will be going to the powder coater next week.
Think that's about it for now!
More road testing this morning....
I did three more hot runs, and we tried 220's, 230's and 250's. Plug colour is looking really good now (with the 250 mains), and I hit 105mph @ 8300rpm. John's going to get 260's, 270's and 300's and we're going to do one more set of runs. As well, we might change the rear sprocket from the current 29 tooth to 30 tooth. We're really close!  On a totally unrelated note, I understand that Graham/NOVA transmissions has only built 5 of these transmissions. If so, then it is a rare jewel indeed! Vince,
You are on the home stretch now. BTW, the tip of the plug doesn't tell much about the mixture even with a good plug chop. The mixture rings is down inside the plug. If those are stock D8's I'd expect them to be more or less white at the tops and then I'd be looking at the electrodes for signs of distress and for color. The real measure is top speed under identical conditions. If that keeps going up, you are headed in the right direction. When you peak, do a plug chop with those plugs at WOT and drop in a pair of D10s and repeat or D7s and see the difference in plug readings with the same jets. With race gas, we use D10 or even D12 (I'm down to my last set) and with street unleaded gas, we run D8s to burn them nice and clean at the tips. Different fuels color the plugs differently, so try not to refill the tank with different gas in the middle of those tests.
We're probably going to do more tests this week, and I'll see if I can get the other types of plugs (yes, those are standard D8's, BTW). As well, the conditions are the same, I'm doing the run on the same stretch of road every time, and I am using the same gas every time. So all that's consistent -- heck, I'm even wearing the same clothes every time!
Do you think that going one tooth up in the rear sprocket will affect its ability to reach a higher top speed? Or will that simply raise the rpms? My thought is because it's only reaching 8300rpm at WOT, it's not being allowed to 'wind itself out' because the rear sprocket is too small. I even have a 32 tooth sprocket, but that might be getting too big. I feel a lot better with the direction the bike is taking now, and I'm sure we'll nail it down this week. On another note, the right side engine cover was welded, but it ended up with a bunch of pinholes -- apparently, as the welder was working on it, all this oil would be leeching out from the cover itself, and he had a bit of a time with it. The powder coater told me that the powder coating will not fill in those pinholes, so the welder is going to see what he can do to fix it. It does look really good though without those two big holes and that grease fitting! Lee's finished painting the black on the tank, and hopefully he should clear coat it this weekend. We're going to let it sit for a week or so after he's done before putting any gas in it.
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