| Author | Message | ||
     Rsm688 |
Well I got my Mikuni HSR 42 installed, and now I have two problems I need to get fixed ASAP as I have a ride planned for tomorrow: 1.) Irregular idle. It seems the idle slightly increases/decreases some when sitting at a light 2.) When letting off the throttle (decel) I am getting a good bit of popping out of the exhaust. No loud banging bad but a lot of popping. If I slowly ease off the throttle it is greatly reduced and almost not present. Im thinking that it is running a little rich. One thing I noticed is that when I installed the choke cable, the plunger did not just drop out of the carb I had to pull it out with some needle nose. It wasnt stuck bad just didnt drop out freely. Also the spring seemed awfully tight as it was bent after putting it and the plunger on the cable before inserting it into the carb. I also noticed when I pull the choke cable, the choke will not stay all the way out. It pops back when I let it go to about 1/3-1/2" out from the bracket. On my CV carb when I pulled the choke cable out all the way it stayed there until I pushed it back in. Thanks, Spencer | ||
| Onahog |
Spencer... Did you use the plunger that was in the carb?..The mikuni one is diff from the CV. You can adjust the tension on the cable to keep it from going back in by turning the knurled nut abit tighter..Dont break it tho!!Popping is usually rick.. That carb came off a stock S2 engine that had S/E ignition | ||
| Cyclonecharlie |
The CV and the Mikuni DO NOT use the same choke cable PLUNGER. They look the same, but they are not. If you used the same cable and plunger from the CV,you need a Mikuni plunger. It sounds like you have an intake leak...do you have the right intake seal for the Mikuni? | ||
| Rsm688 |
Yes I used the plunger and spring that was in the carb Are you talking about the nut at the carb end of the choke cable or the choke knob end? Both of them I tightened down pretty tight by hand. I dont know if I could tighten either of them anymore without risking breaking them Thanks, Spencer | ||
| Cyclonecharlie |
He's talking about the knob end. Just the round knurled part. | ||
| Rsm688 |
Cyclonecharlie- I used the plunger and spring that came with the Mikuni carb. I used the harley choke cable and nut. I though the intake seal was the same for the CV and Mikuni carbs? I just put on a brand new factory intake manifold seal | ||
| Rsm688 |
Ohhhhh okay I got you, like the actual knob itself can be rotated? Not the nut that holds the choke cable to the bracket? | ||
| Onahog |
Yep, thats the one..the round one with the knurled edge...The plunger that was included was the correct one for the mikuni..If you compare them, they are alike but yet different..There was a few jets in the box, maybe try a smaller one.. As said, the engine was stock 1200, S/E ign, supertrapp with 20 discs..it ran good, but appeared rich as well..I never rode the bike, just ran it abit on bike lift. | ||
| Onahog |
Intake seal should be the same as far as I no..Did you adjust mixture screw?..read the manual that came with the carb..It may help you out too.. | ||
| Cyclonecharlie |
Not the knob...the round knurled piece in front of the knob.....google the Mikuni site and they have instructions for the HSR42 and see what they say about the intake seal. Are you using the bracket that holds the carb on the bike? | ||
| Rsm688 |
Mine is a 99 M2 1200, high flow intake, vance and hines SS2R muffler. I believe its the 160 main jet that is in there, I am 375 feet above sea level, about 50* outside. Now would I need to change the main jet, adjust the needle clip, or adjust the air/fuel mixture to lean it out some? The popping seems to happen the worst when coming from 1/2 throttle or more when I let off of it Thanks, Spencer | ||
| Rsm688 |
I am using the bracket to hold the carb to the bike. Did some googling it appears the intake gaskets are the same for the two carbs I figured out what you meant by the round knurled piece in front of the knob I have not tuched the mixture screw, the only thing I did was turned down the idle a little as it was idling pretty high | ||
| Cyclonecharlie |
The Mikuni doesn't have an a/f needle...just an air needle. Which slow jet do you have in it? The bracket I'm talking about bolts to the heads and holds the carb straight. | ||
| Onahog |
Mix screw will lean out abit..mostly idle to 1/2 throttle..If popping on decel under load, means rich as its clearing out unneed fuel by popping..Id try mix screw first, then plug checks etc..ya may need to downize jets.. | ||
| Cyclonecharlie |
Does the slide snap shut(do you hear a clunk) when you release the throttle? Is there slack in the throttle cable? Just stuff to check. | ||
| Rsm688 |
Yes I am using the bracket that bolts the carb to the heads. I do have a little problem with my throttle and idle-return cables being off (got some new ones coming). It does snap shut when I release the throttle, I checked that before putting the filter back on. On the mixture screw, which was leans it and which way richens it. I am looking at the Mikuni tuning manual and it doesnt say specifically only to turn it in til idle gets irregular then turn it out til idle gets irregular and put it in between those two | ||
| Cyclonecharlie |
It's just air...turn in,less air means rich..out means lean. If it takes too many turns out, you need a smaller SJ, too many in , you need a larger SJ | ||
| Rsm688 |
Update, played with the idle mixture screw and couldnt tell much of a difference. The bike does not want to start cold at all, it has been sitting for 3 hours and would only start with choke fully engaged, i backed off on the choke and it died. Choked it again and slowly eased off of it while giving it a little gas and once it had warmed up a little bit the bike would idle but it was a very low idle and seemed like it was on the verge of dying. Maybe I was wrong and the bike is too lean? | ||
| Cyclonecharlie |
What slow jet is in the carb.....I run a 165/20...needle in the middle. Im at sea level | ||
| Rsm688 |
I believe its 160/20, havent checked the pilot jet or needle but I am assuming its the factory. | ||
| Cyclonecharlie |
I wouldn't assume | ||
| Cyclonecharlie |
Are you running VOES and your vac. line is connected good? | ||
| Rsm688 |
I've got some more jets on the way, when they get here I'm gonna pull them and see whats in there and re jet if need be. And yes running VOES and everything is hooked up. Bike ran great with cv40, only thing I changed was the carb and replaced some bad exhaust gaskets Put a new fuel line from the tank to carb as well, high quality fuel injection line for use with ethanol as the original one was cracking | ||
| Cyclonecharlie |
If you have an air leak at the exhaust your gonna get some popping.... Did you run your new hose a new route? | ||
| Firemanjim |
Too lean slow jet, with Mik set up properly you almost do not need to use the enrichner. Did you check your intake seals at the head? And the idle mixture screw should make big changes in bikes running at idle or something is wrong. | ||
| Rsm688 |
I replaced all the intake seals and manifold seals two weeks ago, exhaust gaskets replaced two dad ago. I had a ticking where I had an exhaust leak before I put the new seals in that is gone now so I'm pretty sure no leaks there, sealed the header and muffler junction up good as well. I'm gonna try a 25 slow jet tomorrow when it gets here and see what that does Mixture screw made little difference in the idle as it barely idled no matter where it was at, when the screw got farther out it stalled and backfired out of the carb so I'm hoping richer slow jet will help. I'm thinking maybe the popping when letting off the throttle at higher Rpms is because when the main jet cuts out and it goes to slow jet only it's too lean. I believe I rEad that somewhere in one of the Mikuni tuning guides as well Hopefully the slow jet will get my idlin taken care of and then I can tune from there to take care of the rest. It Definately seems lean at idle as it takes a lot of choke to get it going Thanks, Spencer | ||
| Rsm688 |
165 main, 25 pilot, idle mixture screw 1.5 turns out and she runs like a champ. Fires up cold first start with no choke, no popping out of the exhaust. All I can say about the Mikuni is WOW. It made a huge difference over the old CV carb. I would definately reccommend the swap to anyone who wants greatly improved throttle response and better performance. Im loving it. Thanks again for all the help guys, Spencer | ||
| Firemanjim |
Told ya---  |
