Sheep Posted March 29, 2017 Share Posted March 29, 2017 (edited) I will try to keep this short,as I have already written a longer version but pressed the wrong key and lost it all....arse. I have fuelling issues I believe with my RS36's.Runs well from 1/4 throttle up....still running it in so cannot WOT. I have had it bored to 1230,MTC forged pistons along with reworked head and lots of associated new stuff that goes with it. Thought I had an issue with oil burning due to blue smoke on start up although that has decreased significantly..(oil hanging in bore hatch or popped stem seal had been discussed)but I did everything very carefully when rebuilding. Anyway,when its hot and when in neutral I rev the motor,it emits grey smoke,pops a red flame or two on over-run and idle is crap..always has been,even after a bench synch and I cannot get all four gauges to match when using those....maybe three,not four. Tonight I took a video for a mate showing the little oil smoke but it was hardly there,some water vapour perhaps..good..but it was still rich.I have all the correct jets in according to the book,new last year too,mixture screws out 1/2 turn...but I tried an experiment...I turned the screws out 3 turns on two carbs...engine got slightly lumpier and it started to emit a blue flame at idle...(I didn't rev the motor)..ok..so its definitely getting richer...I then turned the screws on all four in till they stopped...the idle smoothed out,and the flaming stopped and it gave of almost no smoke/fumes when revved..now we are getting somewhere it seems...before you ask they are new 17.5' idle jets,as recommended by Mikuni.I replaced them when I found 120's in there last year.... My question is (there is always a question lol) can I go down a size to 15 idle jets??...I know its physically possibly to fit them but should I.Logic tells me yes if it sorts my idle/low fuelling out and it will give me more scope for adjustment on the screw but I would have thought an engine with increased cc would demand more,not less!!...am I wrong??Maybe these have been the issue all along. Oh and do the mixture screw affect the whole fuel range or just the idle circuit.? Any advice appreciated...I need it running well for Donny Edited March 29, 2017 by Sheep Quote Link to comment
canamant Posted March 29, 2017 Share Posted March 29, 2017 a bigger engine will give a harder "suck" on a given jet so will sort of compensate by providing more fuel for the increased air flow. You could well go for the smaller pilot jet especially while running in. Cregnybaa has some good experience of getting RS36 and 38s running on big engines. Quote Link to comment
nlovien Posted March 30, 2017 Share Posted March 30, 2017 check where you have the pumper starting - if it starts as soon as throttle touched - try backing it off ( sounds like you might be pumping fuel in - avoid excessive throttle tweaking ) - also you could try a larger pilot air jet as an alternative to a smaller fuel jet - its the AFR your trying to get right , the idle screw on these is a "volume" adjuster versus an AFR adjuster Quote Link to comment
Solcambs Posted March 30, 2017 Share Posted March 30, 2017 I'm with nlovien. If the jets are those recommended .. they shouldn't be causing a seriously rich issue - which is what it sound like .I'd be tempted to first check the air jets. They may be some blockage in one or more of them that is causing the richness at 0-1/4 throttle on the idle circuit.. Likewise you could take the pumper out of the equation by adjusting it for further up the throttle opening. Quote Link to comment
Sheep Posted March 30, 2017 Author Share Posted March 30, 2017 I have backed the pumper right off after advice from Grumpy so it didn't mess with the running in period. As for the air jets (0.8's) that's quite a good idea.It also saves taking the carbs off the granite-like rubbers lol.... Oh and just to mention,these carbs have always had Ramair individual foam filters with rubber 'collars' fitted and I have noticed that they have a 4mm step inside them which actually obscures the air jets,it doesn't block them off i think but it can't be very good for them receiving free flowing air surely?? Quote Link to comment
Reelinfeele Posted March 30, 2017 Share Posted March 30, 2017 I'm having almost the same issue. 1170 motor, fresh. I tried the 15 pilots, it leaned it out alright, but I had 3 turns out on the screws. Ran very shit ty below 1/4 throttle. 127.5 mains needle in center. I put the 17.5 pilots back in, about 1 turn out. Synched the carbs Damn near perfect. Still runs very rough 1/4 throttle. Motor has about 1000 miles on it now. The oil burnout has subsided for me. No head work, just all new valves and cleaned up. I get a slight pinging at load on low throttle. Very slight. I may take some timing out of it. I would be interested to what you come up with. I am at sea level approximately 70' F. Good luck. Quote Link to comment
Sheep Posted March 31, 2017 Author Share Posted March 31, 2017 I read on a Mikuni site that if you have to go more than 3 turns either way to get the fuelling you desire means you need to go up/down a size on the jet...its a shame they do not make a 16 size jet to get a happy medium.... I have been looking for some air jets but no luck yet this side of the Atlantic lol... Quote Link to comment
gshub Posted March 31, 2017 Share Posted March 31, 2017 I got my Air Jets from Grumpy 1260 and now it goes like a bat outer of hell... Quote Link to comment
Sheep Posted March 31, 2017 Author Share Posted March 31, 2017 Fuck my old boots..Really???...He is only 10 mins down the road from me.I will give him a bell. 1 Quote Link to comment
Reinhoud Posted April 15, 2017 Share Posted April 15, 2017 I only read half of it, measure your A/F!! That's the only way to determine what you have to change and about how much. Be aware, too rich or too small can have similar symptoms. Measure and take the guess work out. 1 Quote Link to comment
Sheep Posted April 15, 2017 Author Share Posted April 15, 2017 Its running a lot better now after putting 0.9 air jets in.....Idle is still not that of a 2017 Gsxr but then again the slides do have some flutter.Pulling away is much cleaner now,plugs look good but I have yet to do a plug chop on WOT as I am still running it in....nearly there.. 1 Quote Link to comment
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