88 Vmax 1200 "Bobby"

[kwikrider]

Hey guys, I just found the forum and happy to be here. I spent a few minutes looking around and checking out the FAQ and this seems like a great forum. I've been a gearhead most of my life, can't say I'm very good at it, but it's definitely my obsession to take things apart, learn a little about how they work, and hopefully put them back together and go fast quickly!

My current project is an 88 1200 I picked up for nothing. The deal was if I could get it running, the previous owner wanted to ride it one last time, then I could take it from there. Works for me! The only other carb work I've done is the Mikuni 38 (iirc) on my 98 bandit 1200. Boy, was that a walk in the park compared to this.

I have some ideas for body modifications, and would like to have a project to justify buying a welder and practicing fabrication, but for now the goal is to get her running well and hopefully learn something about carb function and repair along the way.

When I got her, she had been sitting for a number of years, apparently outdoors due to the heavy rust on the handlebars and pipes. But, she had been dyno tuned while the owner was stationed on Hawaii, and apparently was a real handful. Needless to say, despite how rough she looked I saw the potential.

After the unloaded her from the trailer, I checked basic fluids and everything looked okay, no major leaks or other red flags. I put some fresh fuel in her and hooked up a jumper pack, and cranked her over. She sounded strong, but obviously didn't start. After a few puffs of ether, she would kick over for a moment and die. Not surprising, but at least I knew she wasn't totally dead. On the to (not) fun part.

After prying (man those things were stuck on!) the carb block out, I got to work disassembling the carbs and cleaning and inspecting all the parts. After many hours in garage with the ultrasonic cleaner and parts diagrams, I had reassembled everything, having to replace only the frozen pilot jets I had to extract and one stuck choke piston (probably should have gotten all 4). With the carbs back on the bike, I was very pleased when she turned over and started on the first attempt after a few cranks, and just purred. After rebuilding the rear master, replacing all the fluids and installing a fresh battery and new tires, she was ready for a test drive! Well, I had hardly made it around the block when I was pulled over for no tags or insurance. To make it worse, I had forgotten to put on my helmet in the excitement. I live in a busy suburb/city and it was just to risky to ride and tune to bike until I could get the owner to update the registration. So, the bike sat for a few more months.

Of course old carbed bikes love to sit for months without being started, and since about a week ago when I decided to push ahead with repairs it's been very difficult to start, and had poor low end response. I work at an auto repair shop, and was able to get the bike there for a better teardown and diagnosis in an unused bay.

The current issue is that the bike wants to die if you goose the throttle. It has almost no response, in fact the rpms tend to drop when I do this. To move from a stop, it has to be revved way up, or it will stall. Looking down into the carbs, I could see the upper left carb looked like it was spraying much more fuel than the rest through the jet needle opening. If I sprayed a bit of carb clean into any of the other carbs, the idle would immediately pick up and the bike would run smoother. Reading around on the site, it looks like a rich condition can cause bogging, so maybe that's a clue, but then why does the bogging go away when I richen the mixture with carb clean? I will update this post with the jet sizes, since they are all oversized.

I took the carbs back apart to make sure I didn't leave something loose or overlook a clogged passage way. I did find I had not cleaned the passages behind the small black vacuum nipples at the bottom of the bowls, so that was an improvement. I also found the main diaphragms did have some cracks that showed leaks with a strong flashlight held behind. On the suggestion of my coworker, I also checked the coasting enrichment diaphragms and found they were badly hardened and very thin/brittle. Before I go further, I'd like to replace these parts to make sure there are no vacuum leaks that could make diagnosing running issues harder. I've been able to find aftermarket versions the main diaphragms on eBay, but not the smaller ones. Am I stuck with genuine ($50-70 a pop) for those?

Thanks for reading, and sorry for being so long winded. I figured I better get the full story of the bike out of the way.

kwik

 

[Fire-medic]

Welcome, if you add your location below your screen name, we know where you are, and someone local to you may be able to offer assistance.

Sounds like you're on the right track, going through the carbs until they perform properly. The short answer to $$ parts costs is, "if you want it to run properly, get the OEM parts." Not all aftermarket suppliers are 'bad,' but if the bike is going to be something you ride and use, and not a 'flip,' OEM parts are how to proceed.

That said, I do and have-used aftermarket parts. I've used the K&L carburetor parts kits which are available through places like Parts Unlimited.

I have a question: what are the exhaust pipes' markings, i.e., "who made them?" They look like Cobras. The good news about Cobra 4-into-4 full-system exhausts: they look pretty. The bad news about Cobra 4-into-4 full-system exhausts: they cost-you probably 10% of your available RWHP! Yes, that's right, these bikes stock (including the OEM exhaust) make about 110 RWHP, some, a bit more, some, less, but 110 is probably what a VMax shows on a Dynojet dyno, which was actually developed, using a Generation 1 VMax as a benchmark.

Personally, I wouldn't put too-much time into trying to re-do any jetting with those Cobras for your full exhaust system. There are probably hundreds of posts on this forum about the problems with Cobra 4-into-four complete exhausts not-delivering OEM-level power. Research the subject using your 'advanced search' function in the upper-right-hand corner. It's a waste of time and $ to try to 'fix' something which cannot be fixed, Robert Prsig, author of Zen and the Art of Motorcycle Maintenance, called such things gumption traps. They eat-up your time, they destroy your spirit and initiative, and you are left without the results you crave, and need.

My advice in the short term, if indeed those are Cobra exhausts Cobra Slip-On Slash-Cut Mufflers for Yamaha V-Max '85-'07 - WestEndMotorsports.com then just try to get the bike running reliably without spending any $ on dyno testing/tuning, or any other such work. Remember what I said about the Cobra 4-into-4 full exhausts costing you RWHP? Tuning your bike to run at reduced power is counter-intuitive to your bike's original engineering and design parameters: create the best-performing power-cruiser. Finding a OEM exhaust to replace your full Cobra 4-into-4 system is going to do more to do more to restore your engine's power than any $$$ dyno session where you still use your Cobra exhaust, and attempt to tune the bike to-it!

At this point, clean your carbs again, replace deteriorated carb parts like the diaphragms on the slides, or the coasting enrichment rubbers, and the other parts needing it, make-sure that your pilot jets in the jet block are clean, that you can see daylignt through 'em, and that you have no vacuum leaks on your rubber donuts for mounting the carbs, either at the airbox, or to the VBoost manifold, and don't forget the O-rings between the cylinder heads and the intake manifold castings. The traditional way to-check for intake leaks is to use starter fluid spray on the rubber donuts for the carbs to VBoost manifold's connections, and around the intake manifolds to the cylinder heads connections, as-well as the airbox to carburetor rubbers. An air leak is revealed if the rpm's increase as you spray a location.

Did you synchronize the carbs after replacing them? What-about checking and setting the float levels?

 

[02GF74]

A search on eBay for vmax carb should throw up lots of rebuild kits that contain the screws, gaskets, o rings, jets and diaphragms.

From what people have said about the the jets is they're not that great but the remainder should be usable.

Cost £11 but I have seen them for less.
An example.

 

[williamwallace760]

love that carb calibration kit where did you get it

 

[Fire-medic]

I found a Vmax, partially-disassembled, upstate in Florida, listed as an abandoned project. The engine was still together & in the frame, but the frame was without assembled f or r suspension. I've done enough to know what to look-for, and there were many NOS parts, including two Shinkos, new brake pads, new headlamp, etc. He had that set as one of the tools he was going to use to do the work, I was there originally for the bike with title, and when I saw all the other stuff, "I made him an offer which he didn't-refuse."

If you look at Pit Posse, I think they offer something similar. Of course, there are also ebay and Amazon vendors selling something similar. FYI, I have an elderly EMGO bourdon tube gauge analog dial set I bought from JC Whitney, probably 40 years ago, and they work perfectly, still.

 

[CaptainKyle]

A search on eBay for vmax carb should throw up lots of rebuild kits that contain the screws, gaskets, o rings, jets and diaphragms.

From what people have said about the the jets is they're not that great but the remainder should be usable.

Cost £11 but I have seen them for less.
An example.
View attachment 75250

From the one's of us that have been around a long time & done 100's of sets of Vmax carbs all I can say is buyer beware with the cheap carb kits.

 

[kwikrider]

Thanks for the responses all. This is the first time I've gotten back to my laptop with some free time to think since I made the post!

Fire: thanks for your thoughtful response. I have read Zen and the Art, that brought back some good memories of clear, well explained philosophies. In fact, on my way to California, I kept my copy in my backpack so that along the way I would have something to fill empty time with. While staying at my cousins, his cat used my bag as a litter box. I think I still have it out in the garage, but the smell will never go away.

I'm not sure about the make of the pipes, just that they are LOUD.

To answer your questions: I have not synchronized the carbs, but did order the tool and it has arrived. I have not set the float levels, and I think that might be a big part of the problem. Maybe I'm not thinking clearly right now, but does that picture show the carb flipped upside down? I thought I had to use a length of clear fuel line to check where the "wet" level was with the bowls filled. Can I set the level dry and forget about it? Is it just a matter of bending the tabs to position them? That sounds much easier.

My couplers seem to still be relatively soft. I'll check the o-rings between the head and intake. We have a smoke tester at work, which makes finding small leaks much easier than spraying carb cleaner.

The small plugs at the bottom of the jet body are pretty dry. They still fit relatively snugly, but I don't think they make a firm seal, especially the smaller ones. I suppose I should replace those too.

My original plan was to make the bike rideable and sell it, but the more time I've spent with it, the more I want to restore it to its glory, if only for a few months before I pass it on. The truth is I may be changing jobs, and if so I wont have a place to keep it and work on it as an ongoing project.

 

[kwikrider]

Alright guys, after much waiting I received the coasting enrichment and needle jet diaphragms and got everything back together. The float levels were way off, so I thought that might be a big part of my issue. The bike ran about the same, which was disappointing. Still sounds weak with the #2 carb sounding the healthiest. All the other cylinders pick up when I spray them with carb clean, on #2 it bogs down. Does that mean its rich, or all the others are lean? It wont rev much over 4k without dying. Oh well.



Anyway, I started with synchronizing the carbs because I never got around to that. I can get them all matched at about 2" hg, which is low. According to my manual it should be a tick over 6. So, started spraying around for leaks and sure enough the idle jumps dramatically when I get between the intake and head, as well as the couplers that run parallel to the ground and connect the front and rear runners. Anybody have a good source for those parts?

 

[Fire-medic]

I order from ronayres.com a Yamaha dealer who has good service for parts. Sean Morley [email protected] also can get you OEM parts, and he's available to answer your pesky questions, a great resource. CaptainKyle [email protected] has I think dealer status with Parts Unlimited/Custom Chrome, and has, like Mr. Morley, lots of used parts.

1988 Yamaha V-MAX 1200 (VMX12U) Carburetor Noncalifornia Model | Ron Ayers

1988 Yamaha V-MAX 1200 (VMX12U) Air Filter | Ron Ayers

Sounds like the thin O-rings for the VBoost to cyl heads are needing replacement, and the VBoost boots, probably from the carbs to the VBoost, and then the VBoost horizontal runner boots too. Might as well check-out thoroughly the airbox to top of carbs boots, too. Fixing all the leaks, your synch values will likely rise.

 

[kwikrider]

Is there any aftermarket support for the couplers?

 

[Fire-medic]

Carbs to VBoost, yes, dunno about the VBoost horizontal donuts. I suggest replacing all 4 of the #7 O-rings for the aluminum manifolds to cyl heads joint, they're cheap.

 

[kwikrider]

I ended up find a good deal on the carbs to V boost couplers on amazon. The v boost horizontals I made out of a foot of 42mm ID silicon hose that I carefully cut into 18mm sections. The cuts didn't come out perfectly, but they don't leak. I found a similar OD o-ring at work and used those for the manifold/head mating.

I wasted a lot of time trying to figure out why the bike had such poor performance and low vacuum on the lift. It would hardly idle, and would die if I gave it any throttle. I ended up tearing the carbs apart two more times, and found a clogged pilot jet and a float that was disconnected. It still ran crappy. I remembered Fire-medics post about making sure the couplers to airbox were tight, I didn't think it mattered what was happening before the carbs. With everything installed, she started up and immediately ran better, so lesson leaned. Still need to do some tweaking and double check valve adjustment, she's a little hesitant to rev in the lower ranges but seems to clear up above 4-5k. I'd love a really snappy throttle, if it's possible.

She has the slow cranking issue, which made synching the carbs and setting warm idle a chore. Every time she died once hot, I had to wait a few minutes before she would crank quick enough to start. I'll probably put her back on the lift and dig into that next. The idle was tricky to set, she would idle too fast, then too slow, the die, over and over. She's averaging between 4-6 in hg on the carbs and they're all pretty even, so I think that's good enough. Just getting her running well again was huge accomplishment, I was beginning to feel pretty stuck.

kwik

EDIT: I just realized looking at that pic that she's not charging. Maybe that will be resolved once I look into that known wiring issue I was reading on this forum.

 

[Fire-medic]

Look on-here for alternatives to the OEM regulator-rectifier. Also look for the 'crimp-fix,' soldering the brass sleeve on the wires in the harness, which requires some undoing of the wire loom wrapping to expose, probably the biggest change you can make on the bike, for the least amount of $, in terms of making the electrical system better. Checking the stator to regulator plug for signs of a poor connection at the plug is another easy fix. Many eliminate the plug, and solder the wires, the order they're soldered-in doesn't matter.

 

[VMAXXIMUM]

Sean is a great source for a better regulator. Plug and play.

 

[kwikrider]

Thank guys. I don't have much time to work on the bike after hours at work. Used to be able to get in on the weekends but not anymore.

Figured out part of my hesitation/rough running on Friday. When I was pulling off the vac plugs off the manifold to synch the carbs, the bike would die when I pulled 2 and 4, but almost no change when I pulled 1 and 3. Pulled the plugs and #1 still looks brand new, while #3 looks a little darker than 2 and 4. Spark and compression are good. So, carbs need to come back off, but at least I've narrowed it down. I'll start with #1, which is obviously getting no fuel...not sure how's that's even possible.

If the bike is really just running on 2.5 cylinders, I can't wait to see what all 4 feel like!

 

[kwikrider]

Took the carbs back off and double checked float height and that all passages are clear. Really not sure why #1 isn't doing anything, theres no reason it shouldn't be getting fuel. Compression tests showed 180-200 on all except #2 @150, which rose to 210 with some oil in the cylinder.

Looked more closely at the coils and found that on #3 the primary power and ground wires were corroded and frayed at the connection. Desoldered and reconnected those and found that the output looks corroded, similar to what I've seen when there isn't a good connection. I'll probably pick up a few feet of secondary wire and replace all of them. Once that's all done I'll double check spark at #1 and hopefully she'll run well. I'm used to checking automotive spark, which will usually arc and snap bright blue when you pull a wire off the plug near ground. #1 and 3 seemed to have a more yellow, weaker spark than I'm used to seeing, but when I tested 2 and 4 they were about the same. So not sure if there any real issue there.

On a recommendation from my friend who wrenches I took a deeper look in the fuel tank and found some debris. Checked the filter and it's clear. I'll replace it anyway. Since the pickup area is in its own "bowl" I don't think the crust poses an immediate threat, but once I get the bike running I may look into replacing that as well.

 

[Fire-medic]

once I get the bike running I may look into replacing that as well

Plenty of threads on-here about cleaning a gas tank. Use the 'advanced search' function. I've used a pressure washer, but first, be-sure you remove the fuel lever electrical sender! You would leave it off for drainage if you choose to pressure-wash the interior. Once you decide, "I've reached all the crud I can," and decide to use chemicals, then you should use a block-off plate with a schmear of sealant on it, to keep your solvent in. I like the use of vinegar, I use 6%, what's called 'cleaning vinegar,' it's cheap, easy to find, and effective. It comes in higher concentrations, but is much-more expensive. Home Depot has a 30% for about $20/gallon. If you used that, 20% of a gallon of it (a bit-more than two 12 ounce soda cans), mixed with 80% water would give you the same concentration of 6%, but do not leave the fuel level sender in the tank when using vinegar, as it can dissolve the potmetal of-which it's made! When you start with the vinegar, I recommend checking every 6-8 hours. I've done it for a couple of days for badly gunked tanks, once you empty the tank, rinse it thoroughly, dry it immediately and throw some oil into it to coat the surface against flash rust, if you're not gonna fill it with gas. The tank can begin to flash-rust in the amount of time it takes to re-install it!

There are all-sorts of cleaners, like Evaporust, they're all more-expensive.

I've never-tried electrolysis, but if you look on youtube, there are plenty of videos. If you decide to do that, do it someplace outside, because of the byproduct gas of the process, hydrogen (think of the zeppelin Hindenberg). You need an old-school battery charger to make that work, as 'smart chargers' need some voltage to initiate a charge cycle.

If you get the tank clean, you may decide to run it 'as-is.' If you decide to coat it, use a good product, and follow the instructions! CaptainKyle recommends KBS KBS Coatings Cycle Tank Sealer Kit for 5 Gal.Tanks - 52000-S-NM Dirt Bike Motorcycle Goldwing Snowmobile | Dennis Kirk

Gas Tank Sealer - Gas Tank Liner - Diesel Tank Sealer - Fiberglass Tank Sealer (kbs-coatings.com)

Caswell and POR 15 are other gas tank sealants used by members, successfully. Sean Morley has the POR 15 [email protected]

Gas Tank Sealer - Caswell Inc (caswellplating.com)

POR-15 Motorcycle Fuel Tank Repair Kit POR 15 has a lot of other products you may find useful in your projects, I've used the rust treatment, and properly-applied, it works. A list of all POR-15 products

You may find a local radiator shop also coats tanks.

 

[kwikrider]

Thanks for that useful info fire medic. Looks like I'll have plenty of info and resources when it comes time to tackle the tank. Much appreciated.

Today I replaced the fuel filter, all four spark plug wires and re installed the coil I repaired wiring on. While I had the carbs off I triple checked float height, and made sure all the pilot jets were clear. For some reason my jet needles don't sit perfectly centered in the needle jets, but I tried taking them out and all 4 still have the plastic alignment nipple intact, so I don't think I can do anything about that.

She sounded a little different when I started her up, and right away I had a lot of smoke out of #3 exhaust tip and off the #1 header pipe. I was concerned for a minute, but I think its because those cylinders are finally running hot enough to burn up all the fuel and oil that have been collecting while I worked on the bike. Even though the wires and caps all ohmed okay, and I didn't find any issues in the carb, that was a promising sign.

Even puling her out of the shop on choke, she had a little crisper exhaust sound with more bark. I rode her gently around the block again to get hot, then re synched carbs. Took a little longer to get it right this time, but every time I got one cylinder closer, I could feel an improvement in throttle responsiveness, until all four were right around 8" hg at 1000 rpm. Where it would bog before off idle, now it felt much snappier, which was very satisfying.

Took her out onto the main road, and ho-lee shit. I can't believe I thought I was running on full power before, this is not even close to the same bike. When the vboost opens, the whole bike squats back and the acceleration is immense. I definitely need to look into upgrading the suspension. It was honestly scary to ride as it is now, I had a hard time keeping it on WOT because it felt so unstable. I owned a gsxr thousand for a year, and that bike was probably faster on paper, but the rush of torque and the sound from this bike is impressive and exhilarating. I took it to my friends shop down the block, and him and his buddy agreed this bike was way faster than they expected. Last time I brought it around, I got some laughs because of the general condition of the bike and its age, but now they both want one for a project

I still have to diagnose that charging issue, which may help the ignition keep up. It still seems weaker on 1 and 3, when I pull the vacuum caps off there's less of an idle change than 2 and 4, but it's better than before. Once I deal with charging, I think I'll look into upgrading the suspension so it's a little more stable at speed. I love this bike! All the hard work is paying off.

 

[kwikrider]

View attachment IMG_4065 (2).mov

 

[Fire-medic]

Another True-Believer convert!

These bikes are a guilty pleasure, they aren't for everybody. Fortunately, they're reasonably-priced on the market, usually, replacement parts are still available, used if-not new, and the knowledge is out-there on how to address shortcomings, and how-to better things.

Now you can imagine how the world changed upon its release. A tough-looking bike which made no-excuses, made its own path, and drove all the challengers out of the market. And, it lasted 22 years as essentially the same bike! That's unheard-of in a market where the new sportbike retires the 'old' sportbike in less-than the duration of a Presidential term.

You want to gain security in the operation of the bike, I suggest switching to radial tires is in my experience the #1 best change you can make. You need to replace the rear wheel at a minimum, to either a 17" (better acceleration as it's not as-tall as-stock, so it's effectively like gearing it lower/higher numerically) or 18" (not as-much of a 'gearing change,' as it's taller overall, and you still maintain your top speed, but how-often do you go 150 mph?) . You can add a radial front tire to the OEM wheel, but it's at-least an inch too-narrow for the radial tire to take the proper 'squat' on the rim, where its wider profile maximizes handling. If you do choose to just add a front radial tire to the OEM rim, do-not oversize it larger than stock width! Doing that further compromises the spread in width of the radial tire on the OEM rim, you don't want that.

Front end changes in springs and a cartridge emulator pair, or RICOR's (both remove the damping rods' function to wave-washer stacks, not expensive, they're tuneable, and once dialed-in, you will be very-happy with the results) with the radial tires, and you'll have done the best changes to handling you can make on some sort of a budget, where you aren't spending the cost of the bike you just bought, to make it handle better, like fitting an USD front fork can do.

Rear shocks are another area where improvements can be had, shorter people often go for something shorter than the 13" OEM shocks, but a good pair of shocks is several hundred dollars, and great shocks are half a grand, or double (Ohlins, Penske). If you choose shorter, the maximum to lose is 1-1/2". I prefer the OEM length to maintain lean-angle and ground clearance.

Front fork braces, solid motor mount spindles, frame braces, and braced swingarms all have their champions. The latter is probably the most-expensive of these mods, and usually the swingarm is modded to allow a wider wheel/tire combo also. Some after strip performance enhancements go with longer swingarms too, but bring a wallet well-stuffed.

I suggest that you make good use of the 'advanced search' function, as these topics and parts have probably thousands of posts collectively, and you can learn a lot by reading them. I suggest that for now, concentrate upon getting the bike to operate with no-known issues, and then decide upon a plan working towards your goals for the bike. Used parts can help you modifying the bike on a budget, and there are members on here who 'break' bikes regularly (U.K. term for parting-out bikes) so you can pay-attention and find bargains.

Since you've tasted the possibilities of a properly-operating stock bike, you can have confidence in knowing that there is much-joy in being the owner/operator of a bike which can surprise many current bikes in terms of acceleration, and with a prudent application of known modifications and enhancements, the handling can become much-more reassuring. At triple digit speeds, rolling on radials gives you a much-more stable feeling than bias-ply tires, especially in turns.