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I made an RD400 wheel fit some years ago: http://www.xs650.com/threads/lets-see-the-xss.170/page-160#post-355798 Custom spacers, new bearings, stock rear disk with custom offset spacers to align the brake caliper bracket and the rubber sprocket bolt thingys replaced with aluminum bushings.

My guess is that the magnets set the dwell angle of the coil. The position of the pickups set the timing between cylinders. I would also guess that the magnets are opposite polarity and so one magnet can only turn the coil on and the other off. I do not know the hall-sensor type but I guess it's...

No port/vent blocking is happening. I made sure of that. Straight through tube same diameter as the carb mouth. Foam filter and about 15cm empty space behind the filter. However the tube end is not tapered out like with velocity stacks and that does cause turbulence and restricts flow. And...

Interesting discovery about intake runner length: I have had issues with the engine hesitating ot "losing pull" or "falling on its face" or generally feeling that someone is cutting the throttle while riding at around 4000rpm in 5th gear. I have also complained about this earlier in this...

Hi Howard, I actually started programming the Arduino board to test my concept but ran out of interest after buying a new bike. Also, my great idea of a firmware needed two 16bit timers to be easy to implement and the AVR on the Arduino board only had one 16bit and one 8 bit timer. I used the...

Don't know about jet sizes but to me it sounds like it is starving for fuel. Does the petcock flow enough? A friend had a Sportster with similar issue. It died after WOT acceleration but run just fine when riding "easy". Turned out that the tuned engine wanted more fuel than the small...

I think it was the same pitch as the original studs on the rubber bushings. Don't remember the exact number. The new bushings sit on a lip/shoulder in the bottom of the holes. However one bushing ended up being a bit lower than the others so it might be a good idea to bolt on a sprocket to hold...

Glad you like it! I removed the rubbers with excessive force, bad language, hammer and chisel. I guess you should be able to pull them out but mine just ripped off the inner part and the outer sleeve was stuck in the hole. Be careful while hammering. I almost ruined the shoulder on the bottom of...

Something I learned today: The plastic needle holder is indexed! I had this strange stumble / hesitation when cruising at part throttle around 3000 - 3500 RPM. Eventually I removed the slides and noticed that one of the five "legs" of the needle holder was blocking the slide hole. Then I...

I used bigger bearings and had custom spacers made. RD has a smaller axle than the XS.

I had an adapter for a year but the rubber bushing things on the hub did not like the added offset. I removed the rubbers and a friend turned and tapped solid aluminum cylinders that are "glued" in place with 638 Loctite. I have been running them for 10000km with no issues. A pic can be found...

Ok. Simple enough... :wtf: I think I'll stick to measuring vacuum. :) Turns out that actual MAP sensors are cheaper than HD VOES switches. Just need to do some experimentation with the intake vacuum vs. MAP output signal.

Yeah. Higher compression. Less advance needed and so on. Ambient temp would be an easy variable to add. I wonder how Harley did the VOES? Does it account for the temp or elevation changes? According to the internet the car people are doing this by the ear. Like: "If it pings under load you...

I've been running 4-pin HEI for three seasons now. No problems with it but the advance mechanism is wearing out and WOT timing is all over the place. The reason why I really asked about the vacuum advance was that after couple of years of thinking about it I ordered a 8-pin HEI module and an...

Pretty much the same as I've been thinking. After reading stuff online... I found your thread by accident. Good info on the combustion chambers. EDIT: The hand adjustable timing should not be too "dangerous". I mean, that's how it was done back in the day. A friend of mine still rides a...

Because I do not want to. Any comments on ignition timing?

I bet it is the Airtech. http://www.airtech-streamlining.com/yamaz/XS6501970-79.htm

Maybe I should have said MAP sensor instead of vacuum advance. Not talking about rotating the distributor... Why not use an off-the-shelf ignition? Because I can build my own. :doh:

Ok. Lets imagine that there is a programmable ignition that has the option to use vacuum advance to control ignition based on engine load. Vacuum advance should increase mileage when "just cruising". Maybe not much but some anyway. How would you use the engine load signal to change the...

I have been running a 4-pin HEI module with Toyota reluctor and Camaro coil for couple of years now. Works great. Thanks to MrRiggs for the reserch! Also built a system to a friends sidecar MX bike with a Mopar reluctor. Works fine but the reluctor is a bit too big to fit the points the housing...