Portaz13
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Posts posted by Portaz13
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So pulled the carbs and went through them. Went for a run after a warm up period reved to 12, as the run continued with white a few high rpm /speed runs the revs stated to break down again at 10500 and then under 10000, still pulls bloody hard and I spoke to the dyno guy who is happy to run It to see what's going on. I'm leaning towards spark, I also lowered rev limit to 12500, is it possible spark plugs could cause this as it heats up?
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I've been struggling with carb settings as in long previous thread, I'm thinking I will lower rev limit and go through carbs one more time. Its not really a huge issue as I'm not usually that high up in revs. On occasion it's stalling at idle . Thanks for reply guys I Minda felt 10 is a good place to change anyway well indicated 10 god only knows what it actually is lol
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Was thinking the same, might just put needles back to how it was, mark my throttle position and see if I can get some more clues
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Hi all again,
I've run the old girl (1990 750) for about 500kms now. I've been trying to squeeze a few high rpm runs in and noticed it really doesn't want to rev over an indicated 10500 rpm. Above that it start to sound unclean as in not smooth. I note the Dyna 2000 is set on 14000rpm but it really screaming at 10 and I have too much mechanical sympathy to push it more than that. Assuming the tach is correct is there another setting on my flat slides I should be looking at?
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Looks heaps better than a busa though
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Yep give it some 600 wet and dry then clean and put back together, they will either leak or they won't but looking at pics doesn't look too bad
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Thank you so much guys for all the help. It made the difference for sure. BTW settings were for future reference
Clip 3 on needle
3/4 turn out for mixture screws
Don't have any jet sizing but maybe it may help someone
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Well got it sorted so far, main idle screw was coming loose so fixed that and adjusted pump a bit more and she runs well, went for first decent ride
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6 hours ago, nlovien said:
i'd be checking that when idle the throttle cam is 100% sure closing against the idle stop - not hanging on the cable
also - my previous comment ref: ilde screws was misleading - on these carbs the idle adjustment screws are kinda like a mini throttle - they are not mixture adjustment screws like on some other carbs - they adjust how much of the mixture goes in -- sooo if your say at 3/4 turn adjustment close it down further - say down to 1/4 turn only - ok it will not idle, so now open the throttle cam via the main idle adjustment screw = basically your changing the relationship between idle jet and throttle cam - see if this helps - and try it the other way i.e. more idle adjustment screw / less throttle cam but always ensuring the cam does stop against the - stop
another thing to check - if you've got filters fitted make sure nothing is blocking the idle air jets at the mouth of a carb venturi
edit: just had a play with this - if you find you've got a stumble just as you pick up throttle then you've wound the idle screws in too far - on my AFR gauge it idles nice at almost bang on 14 but if you then open the throttle it goes to 20+ = open the idle screws up
I will pull the tank off again and check the Cam is returning OK, I just can't see why I would need to continually adjust idle. Regardless though definitely making progress
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Thanks for reply, no filters fitted just trumpets. It idles fine now and very minimal hesitation now it simply the main idle screw that needs constant adjusting while riding I haven't touched the pilots since I put carbs back on. They are at 3/4 ish each
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OK so now it idles and runs pretty good, pulls hard just needs a few on road pump adjustments but every time I gave it a bit of throttle when I stopped the idle was high. I adjusted it 5 or 6 times, it came back to 1500 now probs with idle screw. So I'm thinking it it possible that idle screw is moving when I'm on the throttle? I can see how it would even run with probably a total number of 6 turns or so
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They are not round I will take a pic, how do you go about setting on bench with your method?
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These are black, info in could find said 17mm . I left it alone thinking if the float height is a lower number being measured upside down then That would mean more fuel. Am I on right track with that?
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Great thank you, I will have a look again
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Yes all are at 18mm
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Cables are not yet connected however where they were holding throttle shut on either the carbie or the throttle did lower the revs. Can the return spring be adjusted?
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Some progress, pulled carbies off and installed unknown condition mikuni cv carbs, it ran but sounded pretty similar and would need throttle cable adapted some how so I went back to flat slides,. Set mixture screws at 3/4 , adjusted the slides by eye actually and it ran and idled around 1800, still hangs a bit but much better. Tested for air leaks none present. Used manometer to sync and actually it was pretty close and adjusting made it worse. I then noticed one carbie pushing fuel our of overflow so off they came again. Cleaned needles and seat and ran again. Idle was OK not perfect but ok. Haven't hooked up accelerator pump or throttle cables yet. I have a gut feeling I need to flush my tank as filter is showing some crap in it. I'm also wondering if the popping and flames etc could be a plug fowling. Even though they are new they have been through a lot of fuel adjustments. Planning on adjusting pump and cables and getting new fuel and going for a run and see if it cleans up a bit.
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What was the method you used on the bike to get it clean?
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Wow so many great replies, I will take them off and go through it all again, I did kinda think by eye two of the slides had slightly more gap but could be wrong, I left them alone as wasn't sure how to adjust. Valve clearance and compression I'm pretty confident in. Haven't looked for air leaks and maybe I should go that first before I pull them up for again. And yes carbs were synced using a manometer to adjust as best I could, wasn't aware that one was non adjustable. Great tips guys will report back with findings
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They are metal slides and honestly look near new, it won't idle properly and hunts, as in sitting at 1500 then goes to 3000 by itself and hangs there for a bit. Riding I had to open throttle slowly and it built speed pretty quick but was quite raspy sounding which just could be engine. It's a 750 L model apparently the Tuner had not seen cams like it had before and it has head work and 1100 headers, don't know any further specs. If I open throttle quickly it just bogged and woundnt increase rpm.
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What would be the best pilot screw setting to start? From the Dyno it was 2 turns out but previous owner clearly had issues with plugs fowling on the street hence why he sold it. Everything I read points to less than one turn but would love some idea where to start too. Thanks so much for replies guys
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And when you say choke valves seating are you talking about the slides?
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The manual says set it for 1/4 throttle but I did that and it was flat as hell, only thing I didn't dry was adjusting the needle as its on 4th clip, would that make it richer? Manual says set it on 3rd clip but honestly I'm a little confused as to which way is lean and what's rich
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Hi guys, got the old girl running by changing plugs, valve clearance and following mikuni flat slide tuning guide I found on the net. It runs but really won't have stable idle below 2k, it often hunts and hangs around 3 and drops down. It's also very rich and blows the occasional flame. While riding it got better the further I went but still I had to ease throttle to get decent power otherwise it was just flat and popping etc. Read the plugs and they were black. Settings on carbs are as follows, needle on clip 4, mixture screw 1 & 3/4 from stop, all jets Are as per last owners dyno run. I have receipt where shop changed jets 3 times. Float level is 18mm to highest point. The accelerator pump Is now just touching at idle and the stop screw us around 1/4 wound out. When I got a clean run its quite raspy and I haven't ridden an oiler in 20 years and can't really remember how grumpy they were. It supposedly has cams. Head work and 1100 headers as well as the Dyna ignition stuff. Any ideas what to try next?
Scott
Rpm shift point?
in Oil Cooled
Posted
What makes you think that?