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Author Topic: rd350 right side misfire  (Read 789 times)

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Offline Giddie

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Re: rd350 right side misfire
« Reply #30 on: November 14, 2017, 01:09:02 AM »
ok so this arfternoon i didnt get much time so didnt get round to trying all the suggestions. however i pulled the baffels out to see if that might be an issue. went for a strap and bloody hell wheel off the ground in first and than a proper power band through all the gears down the street!! the thing rips!! waited at a set of lights for about 30 sec and then the dream was short lived... right side flooded... went back home swapped another new set of plugs. kicked the hell out of it without the plugs and fuel off. put the baffels back in but switched sides and no change... back to square 1 again missing on right cylinder than flooding...

see what tomorrow brings. it was good to feel a bit of power from it though. will try swaping the carbs first i suppose

Offline teazer

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Re: rd350 right side misfire
« Reply #31 on: November 14, 2017, 08:22:25 AM »
Are the jets and needles new and have you flow tested them?

When you say it's flooding, that could be ignition breaking down on that side or too rich. Did you swap coils yet?

Offline Giddie

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Re: rd350 right side misfire
« Reply #32 on: November 14, 2017, 08:52:07 AM »
Jets and needles are unknown age. They are all genuine and the right size though. Swapped coils was one of the first things i did. Along with swapping pretty much everything else.

After all that i bought a dyna s and some hv coils from economy which unfortunately didnt fix it.

Offline teazer

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Re: rd350 right side misfire
« Reply #33 on: November 14, 2017, 09:18:21 AM »
Old jets are always a crap shoot. I always replace the brass unless I know its history and with a problem like yours I would "flow test" them just to be sure both sides are more or less the same. And I'd check needles for wear and needle jets. 

Back on the electrics for a moment.  Changing coils and fitting a DYna was a good start.  I assume the plug caps are new to go with the new coils. Old ones deteriorate over time.

What's the chances that you have a poor connection in the ignition system?  You could set up a new set of wires from battery to a small switch to coils and dyna and see how that runs. If it fixes the problem, you know what to replace and if not, borrow a different set of carbs and see if that fixes things.

I don't remember what the compression was on each side - are they the same? I had a couple of sets of RD carbs in Melbourne, but I bought them back to the US with me last time I was down there.
« Last Edit: November 14, 2017, 09:19:58 AM by teazer »

Offline Cosmic

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Re: rd350 right side misfire
« Reply #34 on: November 14, 2017, 09:49:33 AM »
Old jets are always a crap shoot. I always replace the brass unless I know its history and with a problem like yours I would "flow test" them just to be sure both sides are more or less the same. And I'd check needles for wear and needle jets. 

Back on the electrics for a moment.  Changing coils and fitting a DYna was a good start.  I assume the plug caps are new to go with the new coils. Old ones deteriorate over time.

What's the chances that you have a poor connection in the ignition system? You could set up a new set of wires from battery to a small switch to coils and dyna and see how that runs. If it fixes the problem, you know what to replace and if not, borrow a different set of carbs and see if that fixes things.

I don't remember what the compression was on each side - are they the same? I had a couple of sets of RD carbs in Melbourne, but I bought them back to the US with me last time I was down there.

I think the above point on poor connection might be very valid. This could be it.

Offline whyzee79

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Re: rd350 right side misfire
« Reply #35 on: November 14, 2017, 10:15:15 AM »
After it starts,runs perfect, floods and dies, immediately pull the plug and ground a new, dry plug and see if you even have ignition.  If there is no spark, you are barking up the wrong tree with the carb. 

Offline Giddie

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Re: rd350 right side misfire
« Reply #36 on: November 14, 2017, 10:21:39 AM »
Ok will sus the jets aswell. Might even be worth buying some new carbs. Sussed some float valve seats and just them alone were 30 bucks a pop.

New plug caps and wire aswell. I dont know much about electrics. What would make a good switch or is there a factory part i can buy??

120psi on both pots.

Melbourne seems like a hot spot for rd's!! Out of the 3 currently for sale in australia 2 of them are in victoria/ melbourne

Offline Giddie

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Re: rd350 right side misfire
« Reply #37 on: November 14, 2017, 11:14:15 AM »
Will give the plug grounding a go thank you.

Offline jrotten99

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Re: rd350 right side misfire
« Reply #38 on: November 14, 2017, 12:46:49 PM »
I have 2 dyna ignitions. Both of them after installation cooked a coil or two. I kept replacing until one was strong enough. No clue if itís the dyna or the aftermarket coils but PITA either way.

Offline enginear

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Re: rd350 right side misfire
« Reply #39 on: November 14, 2017, 09:04:24 PM »
The spark plug test mentioned above can be misleading.  Of course, if you don't see ANY spark, you have found the problem.  But I had a coil go weak after a few minutes of operation and it produced an anemic orange spark across the gap of a new test plug.  The spark has to be a strong blue spark.

Another place to look is oil contaminated points.  As the oil on the surface of the point heats up (with use) it becomes an insulator.
The layer of oil can be hard to see.  Make sure the points are clean and oil free.  A quick cleaning with a point file and degrease with alcohol will fix this.
Lubricate the point felt wick sparingly to avoid splattering the point with oil.

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Offline Giddie

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Re: rd350 right side misfire
« Reply #40 on: November 15, 2017, 01:04:59 AM »
again not much time this arvo to try all the things mentioned.
tried pulling plug after hot and flooded. put lead with new dry plug and earthed it out, spark is nice bright blue.

tried swapping the carbs over... that was dead end... slides dont go all the way down and bike wouldnt start at all. i imagine due to the slides being stuck at half throttle minimum.

got i suppose another weeks wait until jets can get here. see how that goes...

Offline mkane63t

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Re: rd350 right side misfire
« Reply #41 on: November 15, 2017, 05:51:42 AM »
  Got to move the slides with the carbs. Suppose you figured that out for yourself.
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Offline teazer

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Re: rd350 right side misfire
« Reply #42 on: November 15, 2017, 09:56:39 AM »
If there's a nice blue spark, immediately after if wet its pants, that suggests it's back in the carbs.  Not definitive, but likely.

Rather than swapping both carbs around, maybe try swapping the float needle and seats first to see if that makes a difference. While the carbs are off to do that , pull the main jets and pilot jets and spray WD40 or carb cleaner through them to see if they are similar. And pull (Push) the needle jets out.  Remove one needle and slip it into one of the needle jets and then repeat in the other. What you are looking for is the amount of slop/clearance between the jet and needle.  Use the fat end of the needle for that and check to see what numbers/letters are on both.

While you have one needle out, see how it is marked and visually compare it to the other one - side by side.  An easy check for needles is to hold them together and put a caliper on them. digital or old school doesn't matter.  If one is smaller diameter than the other it will slide down further. If that doesn't make any sense, I'll take a picture for you to make the process clearer.


Offline rickdecollo

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Re: rd350 right side misfire
« Reply #43 on: November 16, 2017, 03:55:30 PM »
I had the same problem with my 73 rd. Turned out to be bad coils from
HVC

Offline dfphoto

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Re: rd350 right side misfire
« Reply #44 on: November 16, 2017, 05:11:38 PM »
Hi I had a problem where I had flooding on my RD250, actually twice. A. the had the floats in either I flipped them or had the right and left reversed. B. I had the slides in backwards!!! I'm pretty stupid...