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| Carb synching my H2 with 34mm Mikunis. http://www.kawi2strokes.com/forum/viewtopic.php?f=14&t=4708 |
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| Author: | ZERO [ Mon Oct 22, 2012 4:12 am ] |
| Post subject: | Carb synching my H2 with 34mm Mikunis. |
Iv'e recently rebuilt an H2 and am currently getting ready for the "dry" season. I have 34mm Mikunis with powerjets installed. In the past, Ive stuck a finger into two different carb inlets and touched the throttle to make sure that the carbs are all opening exactly together. (To adjust the slides) There is still an issue with the running and with the engine not wanting to decelerate cleanly. It revs up fine but takes a moment to go back to idle and the engine sounds uneven while it does so. I know that my air screw adjustments are still out, etc. Also if I rev the engine in neutral and hold it, say at 3000 R.P.Ms, the engine jumps all around like the three cylinders are not happy with each other...It made checking the timing hard at best .I've attempted to remedy this by fiddling with the air screws. Right now they're at one turn out, and it is rideable, but has some jerky "run on" when I shift. I've found no air leaks. I have uni pod filters and the same jetting as when the bike was running great before I took them apart and mismatched the slides and the air screws! Any tips? Have I forgotten something? |
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| Author: | Zambia [ Mon Oct 22, 2012 7:30 am ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
You might need a bigger pilot. What size do you have it there? I'm sure you have been through this..but it might be worth another look (from resource page): 4- Adjust air screws (one carb at a time) for highest idle RPM with a warm engine. It will require that idle screw is turned to increase RPM for the cylinder to be adjusted. Air screw adjustment should be made at >2000 rpm. Adjustment should be made in slow, small increments. If air screw is out more than 1 3/4 turns for highest RPM, a smaller pilot jet should be fitted. If air screw is out less than 1 1/4 turns, a larger pilot jet should be fitted. Return idle to normal and repeat for next cylinder. Idle RPM should be 1250-1400 RPM. The airscrew is a fine-tuning adjustment designed to allow the carburetor to be slightly adjusted for variances in atmospheric conditions. The air screw works with the pilot jet, mainly affecting the engines initial starting, idling and initial power delivery. Proper adjustment of the airscrew can offer direct feed back on pilot jet sizing. When adjusting the air screw, tightening the screw is richer and loosening it is leaner. If you get no RPM fluctuation when adjusting the air screw there is a good chance that there is something clogging the pilot system or the wrong size pilot jet is installed. In most cases, the pilot jet should be the same as original stock, ref: http://kawtriple.com/mraxl/carbspec.html Clean the system thoroughly with carb cleaner and blow out with compressed air. A lean setting will cause your engine to surge at very low RPM’s, bog or cut-out when the throttle is opened quickly and have trouble idling down. A rich pilot setting will result in hard starting, plug fouling at low RPM’s, sputtering as the throttle is cracked opened. - Note: Kaw specs for air screw setting is just a starting point. Adjustment is required for best performance. Each carb must be ADJUSTED for optimum idle. That is done via AIR SCREW adjustment.... seeking the point where idle rpm for that cyl is highest. That is the point where the fuel/air mixture is optimum at idle rpm. Starting from scratch, unless you're extremely lucky, there is no "balance" between cyls or carbs.... one cyl will be pulling the other two. When this condition exists ONLY the carb on the pulling cyl will respond to adjustment. Setting the idle stop to insure that the "pulling" cyl carb is in control of idle rpm will then allow adjustment of that carb to be seen in rpm changes. An alternative is to pull the plugs of the cyls not being adjusted so it would be apparent which cyl is "pulling". If, using this method, an air screw has no effect on idle speed, something is wrong. On a new stock bike setting air screws X number of turns is "close". Changes in altitude, humidity, pipes, or filters and all bets are off. |
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| Author: | Looney Cylinders [ Mon Oct 22, 2012 10:22 am ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
ZERO wrote: bike was running great before I took them apart and mismatched the slides and the air screws! Any tips? Have I forgotten something? Be sure all the slides have the same cutaway angle as marked on the bottom of the slides. Also check the clip positions on the needles are all three in the same groove. Ensure the cables all have some slack at the adjusters and the cable runs free (often things will partially jam up if the 4 way junction was opened) If all the above checks out try lifting the needle (lower the clip) 1 position on all three needles.. J |
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| Author: | Jim [ Mon Oct 22, 2012 10:54 am ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
Mraxl's carb tuning manual is a valuable resource: http://www.3cyl.com/mraxl/manuals/carbtune/carbtune.htm |
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| Author: | ZERO [ Mon Oct 22, 2012 4:50 pm ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
The jets are #30 and it runs best at 3/4 of a turn from closed. (air screws) I've got the needle clips on the 3rd groove, two notches further down than previously. I was able to pretty satisfactorily synch the carbs and it runs much better. Now the main symptom is: it has a buzz at low speed and only runs well when it's on the throttle a bit. It's not happy just putting around, but I also haven't gone too fast yet because of my new crank and pistons, etc. How could it be lean? (If in fact, that is the verdict) |
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| Author: | RODH2 [ Mon Oct 22, 2012 5:52 pm ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
ZERO wrote: and only runs well when it's on the throttle a bit. It's not happy just putting around, Ummm... That would be a characteristic of every triple I have ever ridden!? |
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| Author: | Ja-Moo [ Mon Oct 22, 2012 6:00 pm ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
RODH2 wrote: ZERO wrote: and only runs well when it's on the throttle a bit. It's not happy just putting around, Ummm... That would be a characteristic of every triple I have ever ridden!? Have you ridden one with reeds Rod? |
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| Author: | RODH2 [ Mon Oct 22, 2012 6:14 pm ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
I haven't, John, and I'm sure that is a great mod, just maybe not for me! I just spent a couple of hours on a '76 Suzuki waterbottle on the weekend, and the "surge" was something fierce! Did not like a trailing throttle! I am sure a H2 with VM34's will still have more bottom end than my ZX10 - maybe not so much up top! 
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| Author: | Zambia [ Mon Oct 22, 2012 9:40 pm ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
Zero, I think the buzz you're feeling is four-stroking. This is symptomatic of too big a pilot or not enough air through the air jet. I am still looking for a happy medium with my H2. If I open the air screw the four-stroking goes away and throttle response is awesome, but I can't control the idle. |
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| Author: | Looney Cylinders [ Tue Oct 23, 2012 1:05 am ] |
| Post subject: | Re: Carb synching my H2 with 34mm Mikunis. |
Zambia wrote: If I open the air screw the four-stroking goes away and throttle response is awesome, but I can't control the idle. My H1 did this sort of thing when I ran the 28s. It may have had air leaks then but adjusting the needle 1 clip groove richer brought the uncontrollable high idle back to normal...Might be worth a try...  J |
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