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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Stock Carb Rebuild Kits /cgi-bin/YaBB.pl?num=1641171298 Message started by DragBikeMike on 01/02/22 at 16:54:57 |
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Title: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 16:54:57 I thought I would start off the new year with a post that may prove useful. A few weeks back, B-Will did a post on a carburetor problem he was having. The title of his post was “Just Idle Talk”. He eventually figured out that the wrong mixture screw was installed. I was looking for a PWK carburetor kit and I noticed there were a ton of kits for the stock LS650 Mikuni carburetor. I constantly see posts where members are having issues related to bogus carburetor parts. I saw a kit that looked pretty good, and it was only $10.64. I figured why not order one of these cheap kits and see what’s up. I have no plans to rebuild my stock carb, but the kit was so cheap that I thought it would make an interesting project. I will try to point out the important features to be aware of. I ordered the kit from eBay (seller “All_About_Carburetor”). It arrived in my mailbox about seven days later. So far so good. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 16:55:53 The kit came packaged in a nice cardboard box, but there was absolutely no information that could connect the kit to a manufacturer, distributer, or seller. Always a bad sign. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 16:56:36 Even the return address on the mailer provided zero info as to the origin or pedigree of the contents. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 16:57:51 This kit comes with a lot of parts, and zero instructions. If you purchased all these parts from an online Suzuki parts distributer, it would set you back about $203, and then you would have to add shipping charges. Lord knows what a local Suzuki dealer would charge. The Big-Ticket items are the needle valve assembly (OEM $70.45) and the needle jet (OEM $40.45). The OEM bowl gasket alone costs $10.45. Just look at this sack of parts. What a bargain. Only $10.64 for the whole shabang. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 16:59:12 There’s an old saying. If it sounds too good to be true, it must be too good to be true. I view a carburetor “Rebuild Kit” as an item that will restore the mixer to factory specifications. A rebuild kit should have parts that match the design, dimensions, and quality of the original equipment parts. So, now I have this rebuild kit with all brand-new parts, and I also have all the matching OEM parts. Let’s do a comparison and see how the kit stacks up against the genuine parts (design, dimensions, quality). We’ll start with the part that gave B-Will headaches, the idle mixture screw, identified on the illustrated parts breakdown as “piece 41, screw, air, P/N 13269-37400, $10.39”. I started with this part because it’s a dead giveaway that will identify a worthless kit. Look at this jewel, complete with a plastic cover to protect the needle tip. Totally top-notch stuff? |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:00:29 This picture shows the OEM screw compared to the new kit screw. The OEM screw is the shorter item, the one on top. When you look at pictures of a potential rebuild kit, if it has a mixture screw that looks anything like the screw on the bottom, STOP, don’t waste any more time or money. The kit is junk. You want a screw that looks exactly like the screw on top. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:01:13 Not only is the kit screw a lot longer, it also has a different size tapered needle tip, and the straight shank portion where the o-ring normally rides is not straight. So, the needle tip isn’t gonna throttle fuel because its only half the diameter of the OEM needle tip, and the o-ring won’t seal the shaft properly. It’s complete junk, totally no good, unsuitable for this application. Check out this close-up of the needle tips. Good on top, bad on bottom. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:01:59 If you have a carburetor with a mixture screw that looks like this when it’s bottomed out, then you probably have one of these bogus mixture screws. See how it’s almost flush with the carb body, that’s no good. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:02:42 The correct mixture screw looks like this when it’s bottomed out. It’s well down into the carb body. B-Will pointed this out in his prior post. Great observation. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:03:34 Next, let’s look at the jets that come with the kit. The early models came from the factory with a #155 (.061”) main jet and a #47.5 (.019”) pilot jet. Then, in 1995 the jetting was changed to a #145 (.057”) main jet and a #52.5 (.021”) pilot jet. The new main jet and new pilot jet that came in the kit have no markings. You can’t tell what size they are unless you measure them. Oh my! The new pilot jet is only .015”. That’s equivalent to a #37.5 Mikuni pilot jet (at least 4-sizes too small). That’s gonna be tough to dial in. Note that the .015”pin-gage is skewed, the only sloppy workmanship I found on all the parts in the kit. The jet looks just fine at first glance, but inspection indicates it’s not suitable for this application. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:04:52 The main jet is also grossly under size. It is .045”. That’s equivalent to a #115 Mikuni main jet (at least 13-sizes too small). A one-way ticket to melt-down. At least the pin-gage isn’t skewed. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:05:49 The kit comes with another jet that has the correct geometry for pilot air jet number 1 (piece 12 or 46 depending on model year), located in the top of the carburetor. That should be either a #70 (.028”) for the early LS650s, or a #45 (.018”) from 1996 on. The jet provided in the kit was .052” which is equivalent to a Mikuni #132.5. I suspect that would make the afterfire akin to a July 4th celebration. Chop the throttle and KaBooooomerooo! |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:06:44 OK, so none of the new jets are gonna work. We can live with that. Maybe we can use them on a pit bike or a lawnmower. The air jets don’t wear out or get plugged up, so they can usually be reused. The fuel jets are readily available from Sudco or Jets-R-Us, we know the correct sizes, and they are cheap. Forge ahead. Howzabout the needle valve assembly? It’s identified on the illustrated parts breakdown as “piece 19, valve assembly, needle, P/N 13370-24C80, $70.85”. The filter, piece 20 and it’s associated o-ring, piece 21 cost an additional $15. Do the parts provided in the kit meet expectations? The needle & seat assembly looks pretty good. I put the needle into the seat, and it passed the “blow with mouth” test. Should hold fuel. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:07:28 The needle has a soft tip and it’s not screwed up. The little springy pin works smooth, and the spring inside is springy. It looks exactly like the OEM needle. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:08:11 The screen looks good. That part alone costs $9.60 if you get genuine stuff. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:08:52 The seat looks good. The o-ring on the seat looks good. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:09:27 What about the size of the hole? It’s important, has to pass enough fuel. The new seat has a .099” hole. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:10:13 The OEM seat has a .108” hole. It’s only .009” bigger than the new seat. Such a small difference, no big deal, right? Actually, that’s a pretty big deal. The cross section on the new seat is 19.5% less than the cross section on an OEM seat. I suspect the smaller hole will result in a dramatic reduction in fuel delivery. Another one-way ticket to meltdown. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:11:36 OK, I guess we could use the new needle and the new screen with the old seat. The needles have a soft tip, so the seat shouldn’t wear out. Take out the old seat, clean it up, replace the o-ring & screen, reinstall with the new needle. Should work. Let’s look at the needle jet. It’s identified on the illustrated parts breakdown as “piece 11, jet, needle (X-7M), P/N 09494-00861, $40.45”. The needle jet is an important jet. The slide needle and needle jet work together to control your mixture during 99% of your ride. The OEM needle jet is expensive. Let’s hope the new needle jet provided in the kit is up to snuff. Right off the bat you can see a big difference. The new needle jet is brass, the OEM needle jet is stainless steel. Just my opinion, but I think that’s an important distinction. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:13:21 Constant velocity carburetors (the kind with the big diaphragm on top) use a slide assembly that is raised and lowered by air flow through the venturi. Your throttle cable is not connected to the slide. The slide goes up and down based on air flow. Air flows when the intake valves are open; and stops flowing when the intake valves are closed. So, when you are cruising at 3500 rpm, air flow through your carburetor starts and stops 1750 times per minute. That’s about 30 cycles per second. If you have ever looked in the throat of one of these CV carbs while the engine is running, you probably noticed that when you increase the rpm the slide starts bouncing up and down. It’s constantly buzzin. Soft brass needles and needle jets don’t hold up well. I believe that is why the OEM carb uses a stainless-steel needle jet with an anodized aluminum slide needle. They don’t want these critical components wearing out prematurely. It’s an emissions thing, gotta last. So, we have a brass needle jet. It might wear out kinda fast. No biggie, the whole kit is only $10 bucks. Just plan on changing it out a little sooner. How about the dimensions? OEM needle jet orifice is .121”. The new needle jet orifice is .119”. Pretty close. Only a .002” difference. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:14:29 Here we go with them little numbers again. Two thousandths of an inch (.002”) is not a small number in the world of jets, and in particular needle jets. Mikuni needle jets come in increments of about two ten-thousandths of an inch (.0002”). Changing the orifice size (hole) in a needle jet by .002” is essentially like changing 10 sizes. Making the hole .002” smaller is like going ten jet-sizes leaner. It’s like changing from a Q-9 to a Q-0 on a Mikuni VM. How about the emulsion holes? The new brass needle jet has 8 emulsion holes. Each hole is .028”, and they are in the same location as the OEM jet emulsion holes. The emulsion holes on the OEM needle jet are only .026”. Bigger emulsion holes add more air and lean out the mixture. Double whammy. Smaller jet orifice (.119”) combined with larger emulsion holes (.028") equals lean mixture. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:15:55 Let’s look at the slide needle. It’s identified on the illustrated parts breakdown as “piece 10, needle (5C17), P/N 13383-24C40, $14.37”. The OEM needle is anodized aluminum and has a single groove for the locating clip. The new kit needle is brass and has three grooves for the locating clip. The soft brass material is a bummer, but having the additional adjustment afforded by the two extra grooves is nice. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:16:53 An easy way to compare a couple of slide needles is to use a dial caliper. Just see how the needles line up when they are inserted side-by-side between the anvils of the caliper. Close to the tips, the needles are almost the same diameter. Here you see the stock needle (anodized aluminum) next to the new needle that came in the kit (brass). The caliper is set to .100”. The center groove on the brass needle sits slightly lower than the groove on the aluminum needle. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:17:31 With the caliper set to .105”, you see that the new brass needle moves down just a bit more in relation to the the stock needle, indicating it would be a bit richer than the stock needle at about half-throttle. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:18:19 At .110” the brass needle sits even lower in relation to the stock needle, indicating that it would be even richer at about ¼ throttle. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:19:08 And by .115”, the brass needle is runnin away from the stock aluminum needle. This indicates that the new kit needle would be a lot richer at very small throttle openings. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:20:12 The new kit needle is right at .0990” at the tip, same as the stock needle. At the shank (top), the new kit needle is .1170” while the stock needle is .1180”. That might seem like a good thing. Hey, the new needle is richer, right? But the orifice that it goes in is .002” smaller than stock, so the end result will be leaner everywhere. I might be able to find some use for this new brass needle, but it’s a total crap shoot. Who knows, it might even work OK with the screwy needle jet provided in the kit, but I suspect it would be a struggle. Let’s face it, none of these parts would qualify as a component that meets or exceeds factory specifications. This is certainly not “rebuild” quality. Last thing to look at is the gasket. This is how the plant-fiber gasket came out of the package. I’m not putting that in a fuel system. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:21:29 A new carburetor (13200-24C42) costs $573.54. If you substituted genuine Suzuki parts for the items provided in this kit, it would set you back about $203 and you still would have the same old TEV and slide assembly. The only kit I could find on-line that looked like it might have a good chance of working was the Parts Unlimited kit (1003-1386) offered by Dennis Kirk (currently out of stock). This is a picture of the parts in that kit. The material list states that the main jet is a #145 and the pilot jet is a #52.5 (always a good sign when the sizes comply with specs). Note that the mixture screw looks correct, and the slide needle is anodized aluminum, and the gasket looks like actual composite gasket material (not plant fiber). This kit will set you back about $40 to $50 bucks. Five times more expensive than the All About Carbs kit, but ya get what ya pay for. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:22:20 The Parts Unlimited 1003-1386 kit is available from several vendors on eBay. I was able to find it without too much effort, but ya gotta be careful. For instance, an outfit called “lytleracinggroup” offers the Parts Unlimited kit for $47.94, but they want $100 bucks for “economy shipping”. I’d hate to see what they want for expedited shipping. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:23:02 One potential source looks like “powersportusa”. They offer the Parts Unlimited Carburetor Repair Kit 1003-1386 for $41.95. Economy shipping is $3.95. Not bad. If you ordered the same parts from the OEM, it would set you back about $140. Question is, how good are these kits? The picture indicates the parts are correct, but the proof is in the pudding. |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:23:51 I went to the Parts Unlimited website and tried to find the kit. Searching using the motorcycle make, year & model gave zero results. They list no parts at all for a Suzuki LS650. However, if you search using their part number 1003-1386 the kit pops onto the screen. Unfortunately, it is out of stock. That’s a bad sign. No listings at all for make & model, and the part number shows out of stock. Slim pickins for the stock carburetor. Have any of you tried one of these Parts Unlimited kits? If yes, how did it work? Where did you get it? |
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Title: Re: Stock Carb Rebuild Kits Post by DragBikeMike on 01/02/22 at 17:25:28 I haven’t tried installing the All About Carbs kit. It seems fruitless. My engine is highly modified. I have almost no confidence that it will even run with that kit installed in the stock carb. I doubt that a bone-stock LS650 will run correctly with this kit. The only parts in the kit that look useable are the float needle, the filter/screen for the needle seat, the o-ring for the needle seat, and the clip for the slide needle. The shame here is the manufacturer of this kit has the skill and equipment to make the parts. The machine work is good. If they made the parts to the correct dimensions the kit would be OK. I think the key to this issue is to look carefully at the picture of any kit you are considering. If you see the bogus mixture screw, then I wouldn’t buy the kit because you know up front that at least one of the parts in the kit isn’t gonna work. If you have a bike like B-Will, that runs lousy, and you see the mixture screw way out of whack, it’s a good indication that someone put one of these joke kits into the carb. I can just imagine how difficult it would be to troubleshoot. Every circuit in the carb (idle, mid-range, high-speed) would be completely out-of-whack. What a nightmare. It’s cruel. I generally recommend OEM parts when it comes to the stock carburetor. However, the stock stuff is getting prohibitively expensive and scarce. Maybe one of the Parts Unlimited 1003-1386 kits will do the job. The trick is to find one. If any of you have used one of these kits it would be nice to hear about your experience. I hope some of you find this post useful. Best regards, Mike |
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Title: Re: Stock Carb Rebuild Kits Post by TheSneeze on 01/02/22 at 18:18:53 Mike, I had tears coming from my eyes on that write up! The "blow with mouth" test... ;D ;D ;D Coming from a quality control career in metal fabrication, I like how you operate! Maybe someday we can have a cold one. Maybe. 8-) |
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Title: Re: Stock Carb Rebuild Kits Post by ohiomoto on 01/02/22 at 19:04:57 Another great post DBM. Only genuine Mikuni or Keihin parts for me. I believe most people that come on here asking about rebuilding their carbs are about to do more harm than good. There really isn't much to "wear out" in these things other than the coating on the slides and the float needle. If it's "dirty" tossing a fresh main and pilot might be in order, but most other parts (the ones NOT sitting in fuel in the bowl) are usually salvageable. |
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Title: Re: Stock Carb Rebuild Kits Post by Edub on 01/11/22 at 19:21:00 Excellent write up, DBM! |
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