RS36 tuning update - Nearly there!

[JimmyR]

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!

[JimmyR]

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.

[rapidray]

Also, go to the 122.5 mains you have & start looking for 125s. Ray.

[JimmyR]

Thanks! I have something else to try now. I'll let you know how I get on.

[JimmyR]

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.

[rapidray]

120s are too SMALL!!! Ray.

[JimmyR]

I think you may be right Ray. I'm getting there though. Today I put the 17.5 pilots back in and for some reason this time the bike seems to like them. Maybe it's because I have the bike synched better? It's probably because I'm getting to know how to do things - maybe! So this afternoon I tried it with the 17.5 pilots, mix screws 1/2 turn out, 120 mains and finally the accel pump off on idle but starting at around 1/4 turn or maybe slightly less. I previously had it out further.

Idle is not quite as smooth as with the 15 pilots but the bike revs better and is less hesitant just off idle. Once I get above 4000rpm the response is fantastic. Idle, although a little up and down (not too bad) is consistent and almost there. It's the bit just off idle between 3-4000rpm where I am still getting pops and hesitation. The accelerator pump helps when I simply turn the throttle but under load is when I get the pops and hesitation.

I'll try the 122.5 mains again tomorrow Ray. I have some 125s on order and they should be here next week. After this afternoon's ride I feel I am closer than ever. Maybe the bigger mains will do the trick. I really do appreciate your help.

[JimmyR]

Today I tried something else - Still with 17.5 pilots and 120 mains (Yes I will be trying the 122.5 this afternoon Ray!) but this time I lowered the needle clip one notch and rode it. At a stand still it was horrible but as I rode it seems to have improved the acceleration just off idle substantially. MUCH smoother.

My mix screws are all about a 1/2 turn out. The idle still seems a bit wandering. It's ok but could be better. I'm thinking about trying some #20 pilot jets. One thing that has become clear to me is that you have to test these things by riding. Just trying it out at a standstill seems to give me misleading results.

[Don-lo]

At the shop where I worked, we built up a KZ for the boss' cousin, and he had RS34s on it. We chased it for quite a while, especially the idle. Those slides would chatter a lot, and I wondered if it was back pressure. I suggested that we degree the cams, and WOW, that took care of everything. It idled like a dream, and pulled smoothly/fiercely to WFO. Checking the cam degree takes some special equipment, but isn't too hard. 106 is a good number to shoot for.

If I remember correctly, that is a fuel screw for idle adjustment. You should be able to set the idle just by playing with the screws; have you taken them out further? I would try taking them 1/2 out further, warm up the bike, put in new (clean) plugs, start the bike and let it idle for 10-15 seconds, then stop and read the plugs. If they still look like new, then you can go out further.

[JimmyR]

Well today I put in some #20 pilot jets and that has helped enormously. The slide chatter is pretty much absent at idle now Don-lo. Idle is near perfect actually. I have left the needle jet clips at second from the top and they seem right there. I am tempted to even go one size bigger in pilots as there is the very occasional reluctance at low revs. It will sometimes complain and pop below 3500 rpm under load. I suspect a 22.5 pilot jet might solve that.

Over the weekend I might try 127.5 mains as I have them. The 122.5 mains seem fine but it will be interesting to see if I can notice the difference. I don't spend a lot of time with the throttle maxed! I am very happy because the bike is running so well. It is nearly flawless and it's a great fun bike to ride. It's sooooo smooth!

With my Harley the mirrors are often - almost always! - blurry through vibration. This bike is so smooth that I can hardly get them to blur.

[JimmyR]

Well I have the 127.5 mains in there now - I guess the top-end is better now but it's hard to tell because I'm going so fast by the time I get there that I have to slow down! At 9000rpm it's just roaring. The bike is running really well. Stoked! I think the 127.5s are better because I can get a big kick in the ass with every gear change if I want.

I have tried putting the jet needle clip on the lowest notch to richen the low throttle area and it's debatable how much better it is now. It just seems to have moved the grumbles I occasionally get at around 2500-3000 rpm to around 3000-3500rpm.

I have a feeling that once I get some 22.5 pilot jets I will be right. It's so good now that I could probably be happy with it but I still want to check out slightly bigger pilots just so that I know. This bike flies!

[JimmyR]

Now I have 22.5 pilots in. I had to move the clips to the second lowest setting because it was bogging down (or so it seemed) with the clips at the lowest notch, as well as some pretty impressive backfires. I tried middle but it carb-farted too much. So the second from bottom notch is best so far but still I am getting carb farts at around 3000-3500rpm under load.

Could I possibly need 25 pilots? I bought some at the same time I got the 22.5s just in case. FWIW I now have 127.5 mains and the mix screws 1 turn out.

So unless anyone here says otherwise, my plan tomorrow is to try the mix screws in a bit - maybe to 1/4. Trying to hear any difference at idle is useless on my bike. I just can't hear any difference. If screwing the mix screws in doesn't do it I will try the 125 pilots. After that I just don't know what to do.

It idles well now, starts off from stopped fine, and screams over 4000rpm. It runs beautifully if I push it. In fact it's fantastic. Everywhere except just over 3000rpm under load.

[Homie]

JR

You sure have gone through a lot of jets searching for the right combination. All those jets are not exactly cheap either if you have to buy a new set everytime you change your combination. You must have a small fortune invested in jets! Who's your source? It seems I'll be needing to make some changes to my combination and I'll be needing some new jets myself. So if you got a good source why don't you share it with me

Thanks!

[JimmyR]

Haha! I'm just glad they don't cost more. I have bought jets from Niche Cycle (off ebay) and from Ian Williams Tuning in Adelaide Australia. Ian is more expensive but he is only one state away from me and his service is excellent - at least for me it is because I can get them overnight.

I have enough now to start a range of Mikuni jewellery.

[JimmyR]

Yay - I think I have have it now! Just came back from an extensive test run. I have a route down to the beach I use which has some fastish bits, some slow bits, some up hill and down hill and it seems to be a good test for the carbs.

So as of today I have 127.5 mains, 25 pilot jets, needle clips are on the middle notch, mix screws are 3/4 turn out. I have completely gotten rid of any carb farts or backfires, from a dead stop it launches like a drag bike and I can pull away in top gear from 40kph with no complaints. Beautifully smooth in my previous problem area around 3000rpm.

I will try screwing the mix screws to 1/2 turn out again because there is a slight surge if I take off from stopped slowly. The engine is very slow then as soon as the throttle opens a bit I think it's the accelerator pump cuts in and causes a slight surge. The only time it is an issue is taking off slowly. So I will tweak that a little but apart from that it is wonderful. It is such a fun bike to ride.