HELP!! Way to lean!!

greasertrash · Posted: June 3, 2006, 12:50 am Post subject: HELP!! Way to lean!!

Help. I'm having a big problam. My bike is way to lean. I have tried to re-jet it alot Im at a main jet of 200 and a pilot jet of 17.5 The damn thing gets so hot. I think I might have to get new pipes. if you look in the pic's part on the page you can see what kind of pipes I have, it the black cafe racer called MY cafe. I have know idea what the pipes are, they were on it when I bought it. Please help!!

greasertrash · Posted: June 3, 2006, 1:03 am Post subject: Re: HELP!! Way to lean!!

Ok, more info

I have small oil leak out of left jug

head pipes are mac 2-2

some weird univsal tail pipes

carbs 34's

turn's on butterfly's 2

air fuel mix is at about 40

just rebuild carb's

I hate buying other poeple's screw up's

mo650chopper · Posted: June 3, 2006, 8:31 am Post subject: Re: HELP!! Way to lean!!

I'm running the same pipes without a mufflers or baffles with pod filters and they are fine. Other than being hot are you having other signs of a lean mixture? Is it knocking under load? Cutting out at high RPM's? What do your plugs look like?

grizld1 · Posted: June 3, 2006, 9:16 am Post subject: Re: HELP!! Way to lean!!

From the look of it the only engine mod you have is the Mac headers and aftermarket mufflers; it looks like you're running the stock BS34 carbs with stock airbox. I think you or the PO made the mistake of trying to use jetting recommended for the VM34 roundslides in the BS34 CV's. Your pilot jets should be 42.5's; I'm surprised you can even start the thing with 17.5's in it; they're much too small. The 200 mains are way too large; the VM carb bodies are designed to run a much larger main and much smaller NJ; the BS series uses a fatter NJ and a smaller main. Your stock main was 132.5, and with the setup you seem to have (stock air boxes and modified exhaust?) you should be good on the mains somewhere between 140 and 145.

greasertrash · Posted: June 3, 2006, 12:22 pm Post subject: Re: HELP!! Way to lean!!

humm, the plugs are fuzzy white and yes it does cut if im at high rpm's and i try and gun it. Im all so running the air box. but there is no knocking in the engine( thank GOd)

greasertrash · Posted: June 3, 2006, 12:25 pm Post subject: Re: HELP!! Way to lean!!

I had the jets at 135 main and 43 pilot when I got it, but when I started it the pipes turned bright red. haaaaaaaaa

grizld1 · Posted: June 3, 2006, 6:22 pm Post subject: Re: HELP!! Way to lean!!

There is no #43 pilot. Mikuni mains and pilots are sized in increments of 2.5. It may be necessary to go to a #45 pilot jet. Be sure the pilots are the correct series for your bike, which is the BS30/96 type, with the restriction at the barb end of the jet. If the restriction's at the threaded end, you have VM22/210 series jets, which aren't compatible with your carbs. Also, be sure you have 5HX12 needles and Y0 needle jets. Your carb also has a removable air jet in the intake bell. It should be a #135 jet, same small round type as the mains in earlier carbs. If that's not in place it'll turn the mix lean as a winter coyote.

You might use carb cleaner to check for air leaks causing a lean condition. Shoot short bursts;if you hit a leak the idle will change. You might also verify timing with a strobe. On your scoot the stator marks are on a movable plate, and if the PO tampered with it it may have to be reindexed to TDC. Also, what plugs are you using?

Listening for knocking ain't the best way to tell if preignition's occurring. Take a look at your plugs under bright light with the highest-powered magnifying glass you have (a 10X loupe if you have one) and look for aluminum flecks on the insulators.

greasertrash · Posted: June 3, 2006, 8:44 pm Post subject: Re: HELP!! Way to lean!!

thanks for the info, I will give it a try and see what I come up with

greasertrash · Posted: June 4, 2006, 6:58 pm Post subject: Re: HELP!! Way to lean!!

Ok, 145 main makes it way to lean (white flakes on the arm) there is no metal on the white part of the plugs. I put the pilot back to 42.5. The pipes pop and crackle like crazy. I went up to a main jet of 160 and it just gets white fuzzy on the plug arm now, but the pipes still pop and crackle. I forgot to check the air jet in the bell of the carb's I will do the tomorrow. I checked the plugs and there the NGK BP7ES. I checked for air leaks it seemed all good.I just had a small one by the manifold, re-tighted the claps.But it still ran the same. I have to get a timing light and check that next. I’m about to lose all hope. Crap

grizld1 · Posted: June 4, 2006, 8:00 pm Post subject: Re: HELP!! Way to lean!!

Hang with it. These projects can be frustrating, but it'll feel great when you get it straightened out. It's the kind of reward you get from beating your head on a wall--it hurts for a while, but it feels really great when you get to stop. Be sure to check the needles and needle jets--sometimes weird stuff finds its way in. You might want to check float level, too.

And believe me, I feel your pain. I just got my own dose of frustration--degreed my Shell #1 cam, took delivery of it (2 weeks late), looked at the machinist's index marks at the shop where I'd dropped it off, and said "Hey, I think he went the wrong way." "Nah," says the proprietor, "he's a pro; your directions say move the sprocket .037" clockwise measured at the cam boss, that's what he'll have done." Got it home, mounted cam and head cover (without sealant, for the check), verified indexing on the degree wheel, set up the dial indicator, and vwa-la! instead of 4 degrees of retard I got 8. In spite of written directions and explicit reference points, the dude moved the sprocket counterclockwise, just like the scratches told me he had.

At least I know my calculations were right; .037" the wrong way was exactly another 4 degrees of retard. This time I'm gonna scribe the buzzard myself like I should have done to start with.

greasertrash · Posted: June 5, 2006, 8:23 pm Post subject: Re: HELP!! Way to lean!!

I found it!! I think? Hummmm, Well my timing is WAY off. I looked in my little book and I have no clue what it is ignition coil, TCI, pickup coils, I really have know experance in this kind of things,Help Im all most there!!!

grizld1 · Posted: June 5, 2006, 9:59 pm Post subject: Re: HELP!! Way to lean!!

The ignition coil is the item bolted to your frame under the tank that powers your spark plug wires. The pickup coils are in a little ovoid housing on your stator cover. Both Haynes and Clymer manuals provide pictures and procedures. The TCI box is a black rectangular plastic box; most wiring diagrams identify it as "ignitor unit." If in doubt you can identify it by the wire colors given in your manual.

Before you conclude that your timing's off, find top dead center and check the position of your timing plate.

greasertrash · Posted: June 6, 2006, 10:19 pm Post subject: Re: HELP!! Way to lean!!

Ok, Im back. your right it was not the timing. I checked the top dead center and it was on. So I went back and check it with the engine at 1200 rpm and it's right on. So went back to the carb's. I put in a 150 main jet and a 45 pilot, and bammm. RICH, yay, but only rich on one side (the right side) The left was a like lean but not to bad. The rich side runs really cool and the left side run HOT, even the air coming out of the pipes are hot and cool. So I looked at my float levels, with the tube test and there both right on. Then I looked at the butter fly screw and hook up a air senser to it and the right( rich side) is in the 25's and the left side is in the 40's. And now it runs like real s***. So do I take my carb's of and look for blockage in the left side? HUmm any hint's? IM GETTING SO CLOSE I CAN TASTE IT!!!

grizld1 · Posted: June 7, 2006, 7:38 am Post subject: Re: HELP!! Way to lean!!

I have two suggestions. First off, your bike looks like a modified Heritage Special. Those had a single vacuum petcock drawing vacuum from the left carb boot. Check the barb and vac. line for air leaks. Also, you don't mention attempting to adjust the fuel screws. They're recessed in vertical tubular castings on the forward ends of your carbs which may still be covered with metal plugs which have to be drilled and pulled. Check the turns on the right cylinder, then see where the left side's set.

greasertrash · Posted: June 13, 2006, 7:17 pm Post subject: Re: HELP!! Way to lean!!

Ok, I said the hell with those pipes and got the comando ones fro Mike's. THEY WORK GREAT. It runs way better then the other ones. I balanced the carb's but the mix is still to high (35.), but there both the same now. Left side is at 4.5 turns out and right 2.5. Im at a 157.5 main jet now runs still a little hot, after riding for a few miles it seems to rev-up at stop lights. So I went up to 162.5. I will have to see how it runs now. The plug's are just a little white on the tips and the bottom ring is a dark color. So I think im getting close. But if im not im going to have to get some 170's jet's I don't have any of those. Im also starting to think some one screwed with the butter fly values on my carbs. 4.5 to 2.5 seems like a big jump tp me.

grizld1 · Posted: June 13, 2006, 8:33 pm Post subject: Re: HELP!! Way to lean!!

It is a big jump--definitely a problem. There could be a problem with float level or pilot circuit obstruction on the lean carb (even experienced wrenches sometimes have to go through these units twice to get 'em right). You might also try this: set fuel screws one at a time while you run on one cylinder--use a wire between plug terminal and cap and ground it to cut one cylinder out at a time (your TCI may get unhappy if you just yank a cap). When that's done, set the synch. You may be compensating for an out-of-synch problem with the fuel screws.

greasertrash · Posted: June 18, 2006, 11:26 pm Post subject: Re: HELP!! Way to lean!!

Ok, I went throw the carb's again and my floats were of. They were at 2. mm the book I have said put them at 2.5mm, is that right? I found some info that said 2.7. So I put the jets back at stock and I got all my power back, I forgot to tell you It would lug at 4 to 5000 rpm, sorry. The plugs are still lean and it's running very hot around 350 on the right side and 400 on the left. Do think I should start playing with the air jets on the back of the carb's there at 135 now? Im going to give it one more try then think think im going to take it to a shop. I would really like to ride this summer. Thanks for all your help!

grizld1 · Posted: June 19, 2006, 9:00 am Post subject: Re: HELP!! Way to lean!!

You have the late BS34's. Yamaha lists 22 mm. as float height for '82 and '83. The lower the float height, the higher the fuel level (float height's checked with carb bodies inverted, so lower's higher when ya turn 'em right-side-up). Sounds like the PO had the same issues and did some foolin' around with the setting at 20 mm. Don't set the floats higher than spec. You may find you have an air leak problem; unstable idle is a major symptom of that. If there's no air leak, optimize idle with the fuel screws one side at a time and synch. the carbs. Don't fool with the air jets. You know that your left cylinder is running leaner than the right, in spite of the richer fuel screw setting. That ought to tell you something. Check the vacuum line.

After 3 turns out, Mikuni fuel screws don't meter efficiently anyway. The left side fuel screw may be turned out so far it's passing air. Check both fuel screws to be sure the O-rings are intact, and make sure the rubber plugs over the pilot jets are in place and intact.

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