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RS36 tuning update - Nearly there!

  • Thread starter Thread starter JimmyR
  • Start date Start date
J

JimmyR

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Thanks to you guys - esp Rapid Ray - I am getting my engine running better. It's been a while though because firstly I had to wait for new jets, then I had to wait for new shims when I discovered that my valves weren't adjusted as well as they should have been by the "expert" I hired to do them.

So today I finally got the valves sorted and fired the bike up. Even went for a short test ride. Adjusting the valves seems to have really helped - no more backfiring and far fewer pops. And on decel I get a pleasant faint burble rather than pops or bangs. I have installed 12.5 pilot jets (down from the stock 17.5) and 122.5 mains (down from 130 stock) as I have K+N pods but a more stock style exhaust.

Acceleration is ok but a bit hesitant and slightly poppy just off idle. It seems to get better with both speed and with more throttle. I haven't been able to push it much past 60kmh (40mph) yet though.

So my questions to the gurus here - Should I go up on the mains slightly? Or is it an adjustment to the needle valve? And I assume that I should synch the carbs again now that I have adjusted the valves?

Thanks heaps guys - I really feel I have come a long way with your help.
 
Did you clean the carbs properly? Usually you want to increase jet size if going to pods. also will need to sync. them. terrylee
 
They're brand new flat-slide carbs designed to be used with pods and a free-flowing exhaust. My only issue is that my exhaust is more of the older style so not quite as "free-flowing" (or loud!) as drag pipes. So if anything I will be reducing the size of the main jets. Well I have already done that and reduced the pilot jet size and that has helped, but still needs tweaking. Thanks!
 
JimmyR said:
Thanks to you guys - esp Rapid Ray - I am getting my engine running better. It's been a while though because firstly I had to wait for new jets, then I had to wait for new shims when I discovered that my valves weren't adjusted as well as they should have been by the "expert" I hired to do them.

So today I finally got the valves sorted and fired the bike up. Even went for a short test ride. Adjusting the valves seems to have really helped - no more backfiring and far fewer pops. And on decel I get a pleasant faint burble rather than pops or bangs. I have installed 12.5 pilot jets (down from the stock 17.5) and 122.5 mains (down from 130 stock) as I have K+N pods but a more stock style exhaust.

Acceleration is ok but a bit hesitant and slightly poppy just off idle. It seems to get better with both speed and with more throttle. I haven't been able to push it much past 60kmh (40mph) yet though.

So my questions to the gurus here - Should I go up on the mains slightly? Or is it an adjustment to the needle valve? And I assume that I should synch the carbs again now that I have adjusted the valves?

Thanks heaps guys - I really feel I have come a long way with your help.
Click to expand...

What kind of "pops" do you get off idle? If they are back fires, you might be too rich in the pilot circuit or possibly in the needle circuit with the excess fuel popping as you drop down to idle.

When it hesitates at low throttle, is it flat (sound and fury, amounting to nothing) or boggy (like your engine just smoked a pack of Luckys)? Check plugs for sure, but hesitation can be a symptom of rich (boggy) or lean (flat). Where are your fuel and air pilot screws set?
 
Well I have the mixture screws about 2 turns out as this seemed to work best using the highest idle method.I will be rechecking this though. I have 12.5 pilot jets and the bike idles a lot better now than with the stock 17.5s.

Today I will try to analyse the sounds a bit more, but from memory of last night I was getting a LOT less of the hissy, stuttery pops from the carbs than I got before.

BTW, I accidentally left the Pingel fuel tap slightly open last night and this morning fuel had leaked out of the float bowl of the first two carbs onto the starter motor cover. Does this indicate a stuck floatbowl valve?
 
So I just warmed up the bike this morning, and adjusted the pilot screws to get the highest idle. I had put them back to 1 turn out I believe but now they are more like 2 turns out, maybe a little more. On RS36s this means I have made it leaner at idle, right?

So if I turn the idle back down to around 1000rpm it's still a bit rough. I am getting the occasional pop from the carbs - that empty sounding "ffft" that makes the rev pause slightly - and a little crackle from the exhaust if I rev enthusiastically. The main thing is that the idle is a bit up and down. And the engine is a biy uncertain under load. with the bike still it revs very well, but if I'm riding it hesitates a bit, esp in the lower rev range.
 
Hey MrCinders - I'm trying to work out if it sounds boggy or flat. I'm leaning towards boggy, because it's still similar to how it was with the bigger jets even though it's better than before. I don't have any smaller pilot jets than 12.5 and I already have those installed, so I'll have to order some more. But I do have some 117.5 mains so might try those instead of the 122.5s I have in there right now. So I'll try those and see how it goes.

Then I'll see what effect adjusting the needle has.
 
How many turns are the pilot air and pilot fuel screws? You should be able to dial those in before changing pilot jets again. If you only have a single pilot screw, then I guess pilot sizes are the answer.
 
If I understand u right......you adjusted thee valves but haven't synced yet.......do that ......you may be chasing ur tail....
 
Yeah I was wondering about that. I have synched the carbs but that was before I sorted the valves.

And Mr Cinders - I seem to have only one adjustable pilot screw per carb. What it does I have no real idea!

Thanks guys - something for me to do tomorrow.
 
So now I have adjusted the valves to spec, synched the carbies (not easy with RS36s!), changed the mains from 122.5 to 117.5 and still have 12.5 pilot jets. Adjusted as best I can via highest idle and the mixture screws are around 2 turns out. It's getting closer all the time. Today I was able to take it around the local neighbourhood and it was fun, but still not quite there yet.

I seem to get a popping from the carbs at low revs, particularly #2. I noticed it was #2 carb when I was doing the synching. The popping is a kind of "FFFt"and the power goes down. It seems really good at the middle rev range but is quite hesitant at idle and low revs. Would this indicate that the mains might be about right but the pilots need altering? I also noticed that the popping got worse on the way home after having ridden a little. Could the synch screw have come loose on one of the carbs? That would be annoying.
 
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Woohoo! It's getting better all the time, and today I had a great ride. I thought I should go back a step as I had kinda skipped a size in mains and pilot jets. So on a whim I put in 120 mains (up from 117.5) and 15 pilot jets (up from 12.5) I tried setting the mix screws via the highest idle method but they seemed to make no differences, so I left them at 1/2 turn out. You would think that would indicate that the pilot jets are too big but it idles better than ever.

I managed to get the carbs synched really well this time. They are very close.

It revs very strongly from about 1/4 to WFO and is a complete blast at higher revs. It's a lot of fun. The only glitch is just off idle to about a 1/4. Idle is more consistent than it has been and there are no pops until I move the throttle. Then it hesitates and does the occassional pop. Acceleration is strong but a little patchy in the lower rev range. I don't know if this is because of a too rich mix or a too lean.

So my plan is to try raising the jet needles a notch to richen it slightly and see what that does. Mind you, it looks like it will be tricky to do that.

Any suggestions?
 
You now have the mixture screws in the neighborhood of where they should be. You will need to be up around 125 on the main when you get to that point. I have never had to go smaller than a 15 pilot in RSs so I don't know what's up there, Have you backed the accellerator pump off all the way yet? If not, do that & see if the issue right off idle goes away. Ray.
 
I am going to leave the number selection to the guys who know about this stuff, my only suggestion is that when you are doing stuff like this, just change one thing at a time. Yeah, it's going to take more time (maybe) and the carbs might be in and out a few more times (maybe), but by changing just ONE thing, you will know whether it helped or not. You changed both the main and the pilot, so you don't really know which one of them helped. Maybe one of them is masking a bigger problem on the other.

.
 
Just so you know Steve, the mains & pilots don't affect each other on RSs. Good advice though about doing one thing at a time. Ray.
 
I was hoping you would show up, Ray. I am pretty happy with how it idles now. It's the just above idle bit which is the only issue. I'll try the raised jet needle and see what that does. I thought that a bigger main jet shouldn't affect it just above idle? I am happy to try a bigger main jet if you think it will help! I have some 122.5 mains but no 125. I'll also adjust the accelerator pump if the jet needle thing has no effect - that should be simple enough.

Thanks guys - I can't do this without your help!
 
Ok so I tried the needle clips a notch lower and it didn't like it. Tried a notch higher than middle and it liked it even less. So I guess I'll put the clips back to the middle and try something else. Ray, you reckon back off on the accelerator pump? I'll try that tomorrow.
 
Thanks! I have something else to try now. I'll let you know how I get on.
 
No test ride yet, but I went back to the middle notch on the needle - that seems better. I can get a decent idle and the just off-idle is better than a notch either side. Switched to 122.5 mains and backed off the accelerator pump so that it doesn't come on until more like 1/2 way. So now just off idle seems a lot better but higher revs are nasty. The engine sounds very harsh at 5-6000rpm and shakes a lot - not very pleasant.

So this afternoon when I have work out of the way I will take a test ride and maybe switch back to 120 mains just to see if that smooths out the higher revs. It's one thing to rev it at stop and another to ride it. I think the accelerator pump thing might have helped. Very simple to adjust - I wish it was all like that!

Don't forget I don't have a wide open exhaust. It's not exactly whisper quiet (!) but it's no drag racing unit either.

The other worry is that when starting the bike with choke I am noticing white smoke in the exhaust - definitely smells like burning oil. I think I may be well on the way to needing new rings.
 
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