'83 XJ550 rejetting carbs

I have an '83 Yamaha xj550 maxim with pod air cleaners and 4:2 open exhaust (it has the stock collector and I just dropped the mufflers). It has the stock jetting and I've been running like this for years but it was always hard to start in the winter (need starting either). I recently had some sticky floats or sloppy needles (so the bowls were overflowing) so with looking into this I decided to rejet. I read guidelines here indicating I should rejet to 117.5 mains and 37 pilots. Partzilla has similar P/Ns at these sizes for $40 but since this is not stock to my bike I can't be sure these jets will fit right, Actually the guidelines say I should go to an 118.5 main jet but with these p/n's seems it's either a 117.5 or 122.5 so I guess the 117.5 is it.

There is an ebay seller (6sigmajetkit) that offers a kit with main and pilot jets custom for any bike for $80 kit and the kit offers some other stuff (needle shims and a spring and slider mod and a mixture mod but they are not clearly describing any of this stuff)...

I didn't think I would need to shim the needle for this small jet mod (112.5 to 117.5). can anyone provide me part numbers and a source for the jets? How about the needle height shimming? And are there any other recommended mods while I'm in there? I am doing a thorough cleaning but keeping them assembled in the rack. I removed everything except the starter plunger (not sure if I need to remove that to clean the starter circuit and I was worried about the cap getting ripped..) and I also left the air mixture screw?? - The top center screws on the head side I guess for syncing the carbs..

Speaking of syncing and this screw, should I bite the bullet and pull this screw so I can clean that orifice or is that something that never gets clogged so I shouldn't pull it if I don't need to synch the carbs.. I was thinking I would try a bench sync and a sync on the motor if I can get a cheap test set up (not buying a $80 manometer when the bike was running good with the sync set the way they were)....thanks!garyS

 

first read your plugs, then read this
http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html
then look here
http://www.jetsrus.com/

 

Thats awesome polock. The factory pro information puts it in your hands for any carb and bike. But I'm also guessing that there's some xj550 riders on this site that switched to pods and open exhaust and did the rejetting. So anyone out there????

 

I ordered a kit from 6sigma and didn't have any luck with it, they sent me 130 and 135 main jets which caused a very rich mixture on my 650. They also sent me instructions that happen to be exactly what is on the Factory Pro site. With jetting it's going to a lot of fine tuning and finding out what works for your bike specifically. I'm still doing the same myself, on my third set of main jets and 5th set of spark plugs lol. Go to the carb page for XJ4Ever and read through the write ups Len wrote. There's a formula for mods and jetting that'll give you a ball park idea of where to start

 

thanks also colehole. the XJ4ever carb dissection is awesome and made me think about cleaning the emulsion tubes. I pulled them and the tine holes all looked clear but I dropped them in carb soak. and I pulled the starter plungers. they cleaned up nice although one of them had some erosion on the side of the tip. guess I should buy a replacement and maybe the top boots for the starter plungers. The starter plungers have a sealing rubber washer on the end which I'd like to replace but seems the parts list doesn't sell these separately (probably fine as this isn't a fluid seal). All in all though, I was hoping to get some feedback here from someone who rejetted an xj550 like mine. there must be a ton of them, I mean I remember in the 80's everyone modded their jap bikes to use pods (or stacks) and 4:1 open headers. I'm sure it will run fine when I'm done tho - it ran pretty darn good before it stopped running and I am going a tad under the main jet recommendation.

 

Here they are:

HCP12013 Aftermarket Mikuni starter plunger valve seat DUST CAP, rubber seat cinches to the screw-in brass plunger seats and provides a dust- and air-tight seal that the plunger valves slides through. Most originals are hardened and inflexible due to heat saturation and no longer provide a good (or any!) sealing at all. Fits all XJ550, 1984-85 FJ600, XJ650 Turbo, and XJ700-X, XJ750-X carbs. NOTE: some later-issue factory replacement (parts counter) choke plungers for the XJ550 carbs had a THINNER shaft than the original plunger valves.....the originals were 4.80mm O.D., while the "later" over-the-counter replacements were only about 4.50mm O.D. These replacement rubber caps are designed to fit the original (and our repro) 4.80mm plunger valves; on the skinnier valves, it will allow a vacuum leak leak to occur. We do not have the correct vac caps for the thinner 4.50mm O.D. plunger valves. Each:[/b]

 

thanks chacal. I wish I knew you sold parts here... but I already ordered one starter plunger (duh, I needed a part and just googled a part number and found it on partzilla.). looking at my starter plungers I saw one had a groove on the tip (I can't imagine how the brass could erode away on one tip like that). so I hope that plunger comes in with the same stem od. and then as for my plunger dust caps, at $21 to replace the four caps, I'm going to take a chance hoping if it aint broke then don't fix it.. the caps didn't look cracked or dry rotted and my bike ran well except for sometimes sticking at a high idle (it eventually/usually would return to normal and sometimes a throttle blip would help it) and it never started in the cold without either.. it has stock jets with pods and an open exhaust so I'm hoping the bigger pilot jet (going to 37 from a 35) will help that. Also, I sprayed out the starter plunger circuit and that might help (but having trouble confirming I have clear passages - I'm looking around on this site again for instructions on cleaning that circuit..

but again, I took the carbs off because the float bowl pin(s) were leaking and overflowing the carbs. the rubber tips on those pins looked good but I'm thinking maybe I should buy new pins to make sure they shut off good. do you sell those pins or rubber tips?

 

Do a COMPLETE and THOROUGH carb rack rebuild first. THEN. You won't end up putting it on, off, on, off, etc..... Like you're finding out-----

 

Thanks hog but I haven t been finding that out at all. I bought the bike for $500 and rode the shit out of it summer and winter doing only what was necessary.the floats used to stick and I would hit the carbs with s brick to unstuck them until I took them apart. Carbs with pods come off in 5 minutes. And the bike ran pretty good so I don't see the sense in complete rebuild.

 

Well, not according to the above posts.... But that's ok--- suit yourself. I have no further suggestions or help to add to this thread then.

Carry on.

 

Why rebuild when carrying a brick with you works . . . . .

You are fooling yourself if you think a 33 year old bike shouldn't have carbs (brakes & lines and cables) FULLY rebuilt.

 

haha, I actually carried a big rock in my tank bag one season a few years ago. this last time tho, the carb was leaking and a wrench cured it but I went for a ride and then after it sat a couple hrs it wouldn't start. I thought ignition but it has spark and there was a lot of fuel in the boots when I pulled the carbs. ?? 33 year old bike? my Honda is a 1978 and Harley is a '76. some people spend a lot of time "rebuilding" everything and others ride. I used to get 4-5 years out of a battery because I rode so much in the winter. guess what, when you ride regularly, you don't get that green snot and varnish in your carbs. The carbs worked fine except for the float pins sticking, and they were crazy clean inside (I cleaned a million gunky carbs in a small engine shop so I do know how bad they can get.). this is a daily rider, I changed a throttle cable this year and a clutch cable a few years ago (needs lube now), and I flushed the brakes when I bought it about 6 years ago (brakes work great!). I figure there's always a chance to screw something up when working on it so if it aint broke...

 

so any of you carb experts know where to get the float needles?

 

you can find all the parts you need here...

http://www.xjbikes.com/forums/index.php?forums/xj4ever-supporting-vendor.23/

just so you know, it isn't a matter of the carbs being clean, it's more a matter of the 30+ year old rubber parts that have hardened and become useless. most importantly the throttle shaft seals, fuel tube O-rings, pilot screw O-rings and the enrichment plunger rubbers. you can have spotless carbs, but if the aforementioned rubber parts aren't up to snuff, you got nothing.

CN

 

thanks, noob.

I was looking through chacal's parts but it's a slow (but interesting) read. yes of course on bad old rubber in carbs can't be joyous. but again, Mine was running fine except for the cold start issue (and the idle moving around which probably could be fixed with a complete carb rebuild (but ahem, I don't need to do that this winter especially while I'm working on another bike which will get most of my attention and riding time come spring)). STILL LOOKING FOR THOSE float needles, and then how do I order from chacal?

 

Hey Gary, just send us an e-mail or use the "start a conversation" feature on this website and we'll take it from there!

 

well leaking throttle shaft seals, pilot screw seals and the cold start plunger seals will cause the problems you describe, so there you go. and len has the float valves you need too. have you checked the valve clearances lately? they get tight as they wear, and will cause hard cold starting also. they must also be in spec before you do any carb tuning, or you will just be chasing your tail.

CN

 

I decided not to break the rack apart so I'm not looking at throttle shaft seals. I guess I could buy the cold start plunger seals (enrichment plunger rubbers?, is this the dust cap that seals to the shaft or the flat rubber washer that is on the bottom of the plunger?).. My cold start plunger caps look ok and I thought that was more of a dust seal. I'm waiting for my new plunger to come in to see the shaft diameter so I figure no sense in ordering the dust caps yet anyway. Pilot screw seals, I don't see any seals on the pilot jet? and then the float valves you speak of I guess you mean needle valves. I'm getting them and going through chacal's part's last night I found the O-rings that go on the needle valve seats so yes getting them too.

 

Delamination of rear brake pads shouldn't be taken lightly . . . You won't know it's broke until it is too late (unless you take a look). Even if it isn't broke an aged set of shoes should not be trusted.
http://xjbikes.com/forums/index.php...r-brake-bike-owners-please-take-a-look.15874/

 

not being able to accelerate; is an inconvenience. not being able to stop; is a problem. and having the brakes lock up unexpectedly; a huge problem!

CN

 

This is my rear brake that I just replaced. Delaminated just like they said

 

I changed my rear last summer and saw my rear brake was pretty low but I slapped it back together. It's adjusted way down now. Ain't no big thing. it isn't original, I'm pretty sure I did backs and fronts when I got it.

 

I'm "pretty sure" I put a parachute on - see you guys on the ground . . . Geronimo!

 

I've been riding street and dirt a for 43 years and haven't had a brake shoe delam. I've done all my motorcycle brake jobs. Hell I've been driving that long and doing all my brake jobs on a lot of cars/trucks too without seeing a delam there either. But way long time ago, I think the friction material was put on with rivets. I googled brake shoe delam this morning and see it happens on other kinds of bikes too (and probably cars too). Makes sense that this isn't a Yamaha thing as all the brakes are made by a handful of manufacturers. NTL, a few of the guys talked about getting old bikes and running them after storage and attributed the failures to moisture induced corrosion upsetting the adhesive bond. Like I said, I put a lot of miles on these brakes (I think all the miles) but they are low and will get done when it warms up. Geronimo.

 

quick follow up as the bike is running pretty good now (cept for a petcock/fuel issue). The jets at 117.5 and 37 work great without any main needle shimming. I screwed around with idle mixture and ended up at 2 & 3/4 turns out. I did a bench sync using a strobe light and just eyeballing for light down the carb throats. going to check carb sync when I assemble a manometer. I was fooled thinking my original problem was just carbs because I had spark on #1 and had fuel leaking from carbs (needle stuck) but with carbs rebuilt (partial rebuild) I found #2 & 3 were not firing (this is what took the bike down), isolated to the bottom pick up coil. Oh then my starter died and needed rebuild and the neutral sending wire broke where it feeds through the case. And somewhere in there my ignition switch which has been intermittent for a year finally died and replaced that with new aftermarket. Runs like a champ now but last time out I had to switch the petcock to prime.. (tested the line and the petcock and both OK but this spring I did install an inline fuel filter.)/

 

and the back brakes are low.