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1st gear Idling problem and Valve Cover gasket replace

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Kimn2905

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First of all thanks for reading this, I just bought a 86 Vmax, Bike seem start up fine, but when I slightly rev it, bike either turn off or feel like It doesn’t have enough gas, But when I rev it hard, bike seem fine and run fine, it just when it in 1st gear, some time it doesn’t have any power. Do you guys know what cause the problem, and I have oil leaking from the front cylinder, is there any instruction on how to replace the valve cover gasket?
P/s I’m thinking about replace new spark plug I don’t know if it help.
 

MaxMidnight

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I would first check that it is running on all four.

Replacing the plugs won't do any harm; the worst that will happen is that you have spare set of good plugs.
Depending on the age of the bike you may also want to change the caps and leads.
It may also be worthwhile running the bike when it is dark (but NOT i a closed space!) to look for any signs of arcing from the HT system.
Also check coil towers for cracking.
If it is HT related and depending on what you find then installing CoP' may be a viable solution.

It the HT system checks out then you are into the carbs.
Does it idle OK?

Not aware of any specific guides on replacing cam cover seals.
What you need is space to maneuver the lid when re-installing it.
Removing the airbox and carbs will facilitate this.
 

sdt354

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Valve cover gaskets can be daunting. I've tried a few methods. I've tied the gasket to the cover with thin thread, then slipped the thread out before tightening the cover bolts. Using a sticky gasket sealer, to glue the gasket in place always was the best method for me. The half circles, on the sides of each cover, need a little sealer between the gasket and head. Piolet jets plugging are a common issue. Do investigate the shotgun carb cleaning threads here. Even if it isn't related to the current issue, shot-gunning and syncing is something all gen 1 owners need to know about.
 

Kimn2905

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I tested today and everything seem running fine, bike idle ok, I feel like it run a little bit smoother.I will try the pea shooter method tomorrow, If it not get any better I will move on to the shotgun method. My only concern now is the front valve cover leak pretty bad as soon as I rev hard,the leak spot is right behind where the water hose at. btw should I put some Sea foam in the gas tank, because someone told me it should help clean up the carb, and man I don’t really know how to remove those spark plugs, way too deep.
 

MaxMidnight

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If the leak is that bad then before you do anything else you need to sort it if only to stop the mess the oil is making.
Can we assume that you have synchronised the carbs?

Suggest that you look up 'slim fit box spanner' for the plug removal issue.

Using carb cleaner is a good idea.
 

Fire-medic

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First, add below your screen name where you live, someone local to you may be a volunteer to assist in getting things sorted. IT also helps when suggesting parts or service people to you.

Second, downl oad this to your computer for a reference. The factory manual should be read to acquaint yourself with the bike, it sounds as-though you aren't strong in the mechanical skills department. You need to familiarize yourself with the bike before you 'lay-hands' upon it. Note that the front of the manual has updates for different years, additions and modifications of directions for things which changed with different years' models. You should look at your VIN and compare it to the information in the service manual to ensure that you're looking at the info for your year.

I suspect that you have an obstructed pilot jet, there are four of them. One or more of yours, I suspect is blocked, and is not performing low-speed fuel metering according to factory specifications. You can try all the peashooter/shotgun methods you want, but in my experience, disassembly and a thorough cleaning is the way to clear this up.

You should also take a look into your gas tank with a strong lamp. If the tank is 'unlined,' meaning that no one has used an aftermarket fuel tank liner chemical kit to try and stop a rusting tank from shedding rust into the fuel consumed, which is a sure-fire way to have obstructed carburetor jets and gas passages (the rusted-internally gas tank, not necessarily the gas tank liner chemicals, though a poorly-applied tank liner job can also fail to adhere, and will shed-off the tank and clog your carburetors) and poor metering performance), the gas tank interior should appear to be 'shiny-bright' metal. Anything which appears dirty, or which has dull-colored deposits upon the floor/sides of the gas tank, needs to be removed to stop the continual movement of those deposits into your carburetors' small passageways.

Have you changed your gas filter yet? There are many threads on-here about gas filters, you do-not need to buy a OEM Yamaha gas filter for your bike, they are probably three times (or-more) the price of an acceptable substitute from your local auto parts store. I'd recommend one to-you, but not-knowing where you're located, the info may not be of use to you. If you use the search function on here, you can find that info.

Here's a thread that you should read entirely to help you with knowledge about your motorcycle.

Another useful thread, especially for your issues:


A good source for examining parts fiches:

This is also a Yamaha dealer in the USA, for parts.
 

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Kimn2905

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I tried the pea shooter method today, it seem work well, throttle is more response, I will run couple tank with sea foam to get it cleaner. I inspected the tank and it look rusted, kind of rust color inside, I’m not that surprise since bike is 8 years older than me, my Vmax is 86 . I mess with 3 carb screws adjustment a litle bit and yea my carb haven’t been synced since I bought it, I don’t know if the last owner did it, probably not. I don’t have background mechanic, I just use the manual and learn as I go. I’m thinking about buying the carb sync to do it by myself, but yea I’m waiting for the valve cover gasket to come in, that will be the most challenging. I’m from Maryland btw. Do you guys know is throttle cable susposed to be 2 or just 1, because mine only has 1.
 

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Fire-medic

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Uh oh, sounds like another "better be taking a close-look at that motorcycle, from one end to the other!" case of prior owner neglect/butchery.

A stock VMax has two throttle cables! It's a "push/pull" system. I suppose if someone really-wanted to make it operate with one throttle cable, it could be done.

Your bike actually looks pretty-good, from that one pic. Give us a bunch of pics. Instead of standing next to it, squat-down so your camera is about at the height of the saddle top. Take side pics, both sides, then front/rear, again, position yourself low. For the handlebars and faux gas tank gauges, "stand-back and stand by" oops, sorry! stand-tall and show us the details. That should allow us to see what you've got.

I suspect your sidestand is the only stand on the bike, no centerstand? Is there a thick hose attached to the top of your oil filler cap, on the right-rear of the engine?

The front wheel looks like it's been replaced with a new-style wheel; same for the rear wheel (replaced w/the newer style). I have an '86 which has the same pair of wheels as the '85, which I believe to be correct fitment. Other than the Kerker, the bike appears stock. If you have the oil breather ass'y. chances-are that it's got a Stage 7 Dynojet system. Show us a good pic of the carbs to the cyl heads, so we can see if the VBoost butterflies have been replaced with the simple tubes of the Dynojet Stage 7 kit.
 
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MaxMidnight

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I concur with Mr Medic's suggestion of acquiring a manual, either the Service manual, Haynes or Clymer.

As suggested previously sort the cam cover gasket out first.

The next thing to do would be to give the bile a full service which among other things will synchronise the carbs.
Have a look here for a check sheet.

Armed with your manual also drain the fuel from the float chambers into a glass vessel. See what comes out and if it is contaminated with rusty bits then you will need to address that or else you will continually have issues with the carbs.

The throttle has two cables so there should be four in total (two from the twist grip [6 & 7] to the splitter [10 t0 14] and two from the splitter the carb linkage [68 & 69]),


Handlebars and cables.jpg
Carburettor.jpg
 

Kimn2905

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that messed up, I only have one cable, I don’t know if that make the bike weak, my Dad he used to have a 07 Vmax back when I’m in Vietnam, it fast as hell, explain why I fall in love with this bike. I’m pretty sure the last owner abuse and ride the hell out of it, I can tell by the way he test ride it for me. It just for 2500$ bike and a Vmax leather jacket I just couldn’t resist I’m at work now, I will go home and check the cable again tonight to see if it missing anything, I will take a lot of pictures tomorrow morning, I really want to do an oil change, but I probably will wait until the gasket problem sort out. What oil do you guys recommend? I’m thinking about doing Castrol 10w-30. I also heard for the type of old bike you cannot run synthetic oil on it . Thanks for you guys reply so far.
 

Fire-medic

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You need to read the thread for new VMax owners, before doing any wrenching, oil changes, or anything else. Work from a point of knowledge and correct information, guess and things could get expensive. Yes you can use synthetic oil, if it's for motorcycles. Many guys use Shell Rotella, which is for diesels, it's cheaper than synthetic motorcycle oil. Read the thread!

Remove the faux air box cover, and if the decal inside, (on the underside of the cover) with the bike specs is still there, it contains a lot of user-friendly info that you will always have close at-hand. If it's not-there, you can order another from Yamaha, they're cheap.

One thing you should check soon, is the air pressure in the front forks. They probably need air. You only add a small-amount of air! Using a gas station air chuck to try and fill-it, and you can blow-out your fork seals! The Progressive Suspension front fork springs allow you to not need to use air pressure. The only way you're gonna know if you have PS fork springs is to remove the fork caps, and to remove the springs to examine 'em. You better-have the front end of the bike in the air when you remove the fork caps, because otherwise the weight of the bike will collapse the front suspension. Sean Morley one2dmax@aol.com has a video on youtube that you can use to service your front forks, you can use the search function on the forum to see it.
 
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Kimn2905

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yes sir, I will make sure to read everything before I did anything, talk about front forks, yes front forks feel a little stiff for me, I try to sit on it and push it down hard but it only go down a tiny bit, well I will keep it update, I will upload pictures of closer look of the bike tomorrow morning.
 

Tom Determan

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I did a quick scan of this entire post and maybe I missed the mileage somewhere, but if the valve covers are coming off for gaskets isn't this a good time to check / adjust the valve lash ? Maybe that was mentioned. Is the odo sitting at 22K ? (Noobe here too)
 

Kimn2905

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just an Update, I replace 4 sparks plug and it run like new again, old sparks plug look rusted and black, the idling and lose power is resolve, now just the valve cover gasket and crab syncing. This is fun, I own couple bike before but this is my first time actually care for the bike and fix it. Thanks for you guys help so far.
 

MaxMidnight

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When you sort the cam cover gaskets you only need a few dabs of silicon to keep the gasket in place and a smear around the half moons as belt and braces.

The PO must have had plenty of the orange sealer they wanted to get rid of and IMO had used far too much.

Helpful hint: Black sealer is sooo much cooler. :p
 

Fire-medic

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Yeah, I could see from an engine close-up, you don't have the engine breather and the line into the gearbox through the oil filler cap. So, no Dynojet Stage 7, likely.
 

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