Frustrated with idle

[Pissed off Veteran]

I have a 1988 Vmax. The first start of the day I usually put choke about half way and she fires right up. When the gauge shows temperature at the first black line on the temp gauge which is plenty warm. The choke is completely off, the bike can not maintain idle and stalls, I know the bike should idle. I have to turn the idle screw about 1 -2 turns in to idle about 1000-1100, Now as the bike heats up more and more I have to turn idle screw down and down to maintain 1000-1100 idle. The next day the process starts all over. Carbs were ultrasonic cleaned then blown out with air compressor and then cleaned again with berryman. I have a new fuel tank, new hoses, new fuel filter, new air filter and all new rubber joints. all the carbs O-rings and gaskets are K&L kits. I wonder if I should have replaced at least the idle jet?

 

[Fire-medic]

I hate to say it, but I suspect that your equipment is out of synchronization. You replaced a lot of pieces which are known to give trouble on an older bike with many miles. Of course, all the Gen. 1's are 'old' as the newest is 2007. Do you have a synchronization set of gauges? The bourdon tube gauges are perfectly adequate to synchronize the carburetors. The bike will idle better, it will hold a steady idle and the throttle response will be better.

This is a typical set.
https://www.amazon.com/Alltooetools...le+synchronization+gauges,aps,128&sr=8-4&th=1

There are cheaper ones but this one has more adapters than the less-expensive (by $18) ones. This one is $55.

 

[Pissed off Veteran]

Did it 4 times over past week and as a matter of fact I did it yesterday, all good. Bike has 14900 miles

 

[Fire-medic]

Yeah, there's something fundamentally-wrong with what you're doing, either as an error of omission or not diagnosing it properly.

Be advised I am not a pro mechanic. I am merely a hobbyist. I have friends who are motorcycle mechanics, machinists, and racers. I learn from them.

The pilot jets are probably the smallest passages in the carburetors. If you can see through them, they should be OK.



Using a stainless steel single strand to poke through any sediment plugging a pilot jet.

 

[Pissed off Veteran]

Yeah, think I'm going to pull them carbs and go thru them again. I was a certified Pennsylvania inspection tech and emissions inspector. Most cars are fuel injected so it's been a long time since I worked on carbs.

 

[Fire-medic]

Yes, I think that's a good choice. I know my friend who builds 6 second drag bikes, when he has issues with something, he 'goes back to the beginning,' and does it all-over again.

I was at his shop and here he is, working on a GSXR1000 dragster, with a 1-1/2" billet oil pan and a modification to an oil routing tube in the crankcase to increase oil pressure. The oil pickup swings back and forth to allow constant oil flow, and to prevent oil starvation.

Pictures will be added when the internet catches-up with my typewriting.

Fitting the GSXR1000 1-1/2" aluminum billet oil pan.



Adding an .040" deeper oil passage tube to increase oil pressure in a GSXR1000



The swinging oil pick-up in a GSXR1000 to allow constant oil feed during acceleration as oil moves backwards in the oil pan. This is a drag build.

 

[Pissed off Veteran]

I used the search function trying to find out anything on my predicament but all I found was posts with opposite, there bikes would heat up and idle drop. I was thinking maybe my problem was a cracked hose and when it heated up and softened the crack would close but it has all new hoses. Has to be carbs.

 

[Fire-medic]

Assuming that your bike isn't having other issues, using the synchronization and air bleed screw adjustment to attain the highest rpm has been what has worked for me.

 

[Pissed off Veteran]

I will try it. I think I posted on here last year about my buddy riding my triumph trident 660 and he blew right past me, anyway raced him yesterday again, I just watched his headlight fade away, but anyway the bike has come along way from the clunker I bought last year.

 

[Fire-medic]

Back in '74, my neighbor had a Triumph Trident 750 triple. There was a famous factory Trident 750 triple, "Slippery Sam," named because of a tendency of the racer to expel oil from the crankcase. It won multiple races over the early 1970's, and including the Isle of Man and the French endurance race, the Bol d'Or.

No way could a stock VMax lose to a stock 660cc Triumph triple. Yours must have been running on 3 cylinders or something.

 

[Pissed off Veteran]

It was, diaphragm in cylinder 3 carb was not seated correctly. Spark plugs looked original. The bike as a whole was in poor condition.

 

[Fire-medic]

OK, good news that you persevered to find that.

I think there's a lot of satisfaction in getting a bike running, and taking care of issues, to get it safely operational and running well.

 

[putin]

I have a 1988 Vmax. The first start of the day I usually put choke about half way and she fires right up. When the gauge shows temperature at the first black line on the temp gauge which is plenty warm. The choke is completely off, the bike can not maintain idle and stalls, I know the bike should idle. I have to turn the idle screw about 1 -2 turns in to idle about 1000-1100, Now as the bike heats up more and more I have to turn idle screw down and down to maintain 1000-1100 idle. The next day the process starts all over. Carbs were ultrasonic cleaned then blown out with air compressor and then cleaned again with berryman. I have a new fuel tank, new hoses, new fuel filter, new air filter and all new rubber joints. all the carbs O-rings and gaskets are K&L kits. I wonder if I should have replaced at least the idle jet?

So the bike idles good when hot? I start riding with choke closing litle by little as engine warming up. Dont close it just by marks in the temp gauge.

 

[Pissed off Veteran]

Yes sir Idles good when hot, well I discovered the rubber joints between carbs and intake manifold the bottom clamps I didn't tighten. I still pulled the carbs debating whether or not to replace pilot/idle jets.

 

[Pissed off Veteran]

Quick update. I put carbs back on, tightened all clamps and the bike runs and idles perfectly.

 

[Zeus36]

Was going to post a modified Shotgun method, but you got it fixed!

 

[Zeus36]

Quick update. I put carbs back on, tightened all clamps and the bike runs and idles perfectly.

Thanks for the update!

 

[Dorney]

That sounds like the problem when it's cold it's sucking air when it's hot things are expanding & sealing up.

 

[Pissed off Veteran]

Yes sir that was the problem, actually Fire-Medic stated about going back thru and checking everything, I did and found my problem. 4 loose clamps. I was racking my brain out. JEEZ.

 

[Fire-medic]

Yes sir that was the problem, actually Fire-Medic stated about going back thru and checking everything, I did and found my problem. 4 loose clamps. I was racking my brain out. JEEZ.

Well, you found it, and it didn't cost anything to fix. Perseverance.

Using starting fluid on the rubber donuts for the airbox/carbs and the carbs/VBoost will reveal loose or otherwise leaking boots. Don't forget the tiny thin O-rings between the cyl head and the VBoost aluminum manifold. If one's leaking, replace all four. You have to remove the VBoost manifold from the cyl heads, and that alone may be enough to tear or compromise the structural integrity of the rubber O-rings.

Some people who are very brave use propane. They hook a hose to the tank, and they let it flow around the suspected areas of leakage, the places I previously named. Do this outside! I wouldn't use propane in the first place. Nor would I use natural gas. Too-much of a risk of a potential ignition. Leaking propane or natural gas can go 30 ft until it finds a source of ignition, such as a gas-fired water heater.

I recall one fire call we had, where the natural gas service to a single family residence was ruptured, below-grade. Once the house fire was extinguished we found that the gas was coming through the soil, and igniting a short distance above the ground! When it reached the proper flammable range, it ignited. The gas company had to search for the branch line from the street to the house to shut that off, as we had already shut-off the gas valve at the meter into the house.

I hope everyone has a couple of 10 pound ABC extinguishers wherever they work on their bikes.