Help Find A Cure for Crazcnuk's bike?

[TopCatGr58]

Hey CrazCnuk,

I used Non resistor caps because it's getting harder to find non-resistor plugs, and the only real purpose of the resistor is for radio frequency interference reduction....I don't use a radio when I ride, but have used an MP3 player, and had NO RF distortion from my setup!
T.C.

[Crazcnuk]

I've ordered a set of Mikes XS coils, wires, and non-resistor caps.

I also ordered a set of needle valves (emulsion tubes?) as mine are slightly out of round and I understand this is an issue with the CV carbs. My BS34 carbs have the 5 step needles that came out in 1980 Canadian model carbs, so I had to get the matching tubes to go with them.

I checked out the coils tht Rasputin sent to me, and they are slightly better than mine, but about the same.

I found an article where they tested the effect of resistance in the wires/plugs, and basically the resistors will not stop spark, but the more you have the weaker the spark is.

However, the spark will be a bit weaker but lasts a little longer.

The main reason for the reisistance, to start with, is to take the high frequency residual off of the signal so that it doesn't interfere with radio equipment.

If you have either resistor wires, caps OR plugs, then you should be fine. I don't know how many of you remember the 'noise' on your TV when the neighbor (or your dad) had the truck idling in the driveway...

here is an interesting article:
http://www.ultralightnews.com/engine...psandplugs.htm

[dbeardslee]

As The Ratchet Turns

Craz - I've been following this thread like my ex used to watch soap operas. Can't wait to see what happens when you put the new coils on. You're gonna need a couple 1/4" spade connectors for the new coils. Have to cut the wires off the old ones and put the female spades on the cut end of the wires to connect to the new coils. I guess you could make up your own wires if you want to keep the old coils intact. A little silicone around the connector where the wire goes in isn't a bad idea either - helps keep the water out. If I had it to do over again, I think I would put 90 degree spade connectors on so they aren't pointing straight forward.

[Rasputin]

Hey Crazcnuk. Glad to hear your back working on your ride. I did not know for sure how good those coils were but hey it was worth a try. I figured any difference may give you some direction to head in. I hope the new ones help with yours. I dynoed mine a few days ago and all I ended up with was 68HP at the rear wheel. It was running way too rich, almost to the point of fouling. I have some new jets coming so we can play around a bit and see what she will make then. After that is worked out, well Hinton aint that far to ride...who knows.

[Crazcnuk]

I've already been playing with my jets. I went from the stock 110's to 115's to 120's.


In a high speed chop test, the 120's looked prefectly clean, but run very rich in the mid range. However, I noticed that my emulsion tubes (needle jets) were a little out of round. I've ordered new ones.

I will have to wait and see what the coils do, then finish with the carbs. The Canadian '80 carbs come with 5 step needles, so I have lots to play with.

[psycoreefer]

just wondering, where did you order new emulsion tubes from?

[egsols]

Originally posted by Crazcnuk

The Canadian '80 carbs come with 5 step needles

They did? I thought you had to use washers to move the needles on the 80/81's? Somebody didn't stick 79 needles and diaphragms in an 80 carb did they? If they did, I'm not sure how that would work as I believe the emulsion tubes are different between 79 and 80.

Also if the 80 tubes were left in and 79 needles used, the wear on each item would be different. Such a situation could definitely cause mileage and performance issues.

[Rasputin]

bump

[Crazcnuk]

The tubes are coming from Mike'sXS.

My carbs have 5 step needles in them, and, if you look on Mikes site, it has 5 step needles with a note saying they were used on XS BS34 carbs in Canada in 1980.

Part #48-0663

Below that is the emulsion tube #48-0662 which says it's a match for the above needles.

The needles seem to be steel and the tubes are brass, which may explain why they wear so easily.

[Crazcnuk]

Ok, I got the new MikesXS coils, and installed them (on the stock mounts with no modification needed)

I bypassed the ballast resistor.

So far the bike starts better when it's cold, still cranky when it's warm. But I have to get back to the carbs.

As I said earlier, I did a chop test with 120's and they looked fine. However 120 seems to be larger than I should need.

I have the new emulsion tubes, so I am going to take the carbs out and put them in.

I am just trying to decide whether I should go gack to the 115s as a starting point.

The 120's made no difference in the top end, but they bike seemed to load up in the mid range (2-4000rpm) and the plugs are black.


any ideas?

[Geezer]

check the pilot jets. There are 2 designs and they look very similar but the newer ones flow 2x or better as much gas for the same number. Look in the end that screws into the carb and if the end is open, then you have the later jet not designed for these carbs.

Geezer

[Crazcnuk]

I haven't touched the pilot jets. They are still the stock 42.5's.

I have 45's on hand, just in case.

Also, tonight, the bike ran a lot better after the sun went down and it got cold.

I take this as another indicator of it running rich.

[Bigleo]

Hi Crazcnuk,
Your bike sounds exactly like mine before I pitched the carbs and went with the Keihin CRS 33mms. I think you are on the right track about the worn emulsion tubes. But it will only partly fix your problem. My theory about the rich running in the mid range, that so many people complain about, is this: The big slide spring gets weak over time. This causes the slide to rise higher than it should, and therefore also pulls the needle out of the emulsion tube more than it should. This causes more gas to be sucked into the venturi. Unfortunately airflow is still being governed by the butterfly opening, which in this case is not open enough. So the bike runs rich until the butterfly is approaching wide open. The only real cure in my opinion would be new springs, but they are not available as far as I know. I guess you could try stretching them, but I doubt it would be possible to get them all evenly tensioned. Maybe Mikes XS will carry them some time?
best of luck
Leo

[Crazcnuk]

Right now, if i twist the throttle wide open in high gear, the bike will stop accelerating at about 7,000rpm.

If I back the throttle off, slowly, there is a point where you can feel when it starts to slow the engine. At that point I can open it up slighlty and it will try and pick up past the 7k.

At that point I can turn the throttle another 5th of a turn, of useless throttle.

I would think it's starving, except that there is no surging, bucking or missing. It just stops pulling.

It did this with 110's (stock), 115's and 120's.

At first it was running so rich that my freinds would not follow me. Setting the floats back to thier stock height fixed that.

When I went from 110's to 115's, nothing changed in how it ran.

When I went from 115's to 120's, it ran the same in the high end, but the bottom bogs more, and the mid range now gets rough if I cruise between 3 and 4k for any length of time. I can shift down and bring the revs over 4k and it will clear itself out.

The only other peculiarity is that my idle screws are only out about 1/4 turn on 1 and 4, and 1/2-3/4 on 2 and 3. This should be a very lean setting, I would think.

Idle now also is too low when cold, and too high when hot. No way to find a happy medium.

Before I started any of this it ran nearly perfectly, but got less than 25mpg. I could race Derwat and his SF, and he would be just slightly quicker.

[Bigleo]

Hi Crazcnuk,
That 7000 rpm situation you describe sure sounds like a weak link in the ignition some where. I would guess ignition wires, or coils, or maybe the ignition timing is not advancing for some reason.
Leo