Warm Start Issue

[MikeZ06Allen]

Ok folks I have been chasing my tail on this one and quite frankly I am done so I need some assistance from folks alot smarter than me.

 

Last spring I started having issues with my 89 VR backfiring on decel. A new collector from Mark (Mark's Pipes) and an awesome new/used set of stock mufflers from Earl (Skydoc) solved the backfiring on decel. However, in fixing that issue I seemed to have created another problem.

 

Cold start the bike fires right up and after some initial cold engine sputtering and backfiring through the carbs it purrs right along at the set idle speed (1000 rpm on stock tach). However, once warmed up and if let sit more than a minute it is a bear to get restarted. I have done the following:

 

1) Sprayed non-chlorinated cleaner into the top side of the carbs with the diaphragm covers/air cleaner on and off. Focusing on all openings and accessible jets

 

2) Ran 6 to 12 oz Seafoam religiously for over a year

 

3) Drained fuel bowls and checked for gunk suspended in fual (found none)

 

4) Pumped straight Seafoam into carbs while running and let sit two days. Performed this twice as I wanted to make sure I did it right (resultant smoke cloud on restart killed all mosquitos within two miles and fire department has put me on their "watch list" )

 

5) Changed and regapped plugs after each Seafoam treatment

 

6) Cleaned all electrical connections and retightened where necessary

 

7) Battery has been tested numerous times and is pushing more than enough amperage

 

8) Plug wires and diaphragms are less than 2 years old

 

9) TCI and coils are all stock (40,800 miles)

 

At this point I am looking for any other suggestions. I will be attending the SE Texas Maint Weekend so maybe I can get some good pointers there as well. Thanks

[Monty]

Is it dragging, or just spins over alot before starting?

[friesman]

That sounds like the infamous issues with the oem battery cables. Yamaha used a thin gauge of wire on the battery and starter cables and the extra draw that at it takes to start a warm engine fails because the wires can't allow enough current through to the starter. Change those cables to a heavier gauge works wonders on mine.

The other issue is that the oem starter only has 2 brushes and under a hot engine doesntt have enough power, a lot of ppl have changed the starter out. To a 4 brush from 99 or newer venture.

 

Brian

[MikeZ06Allen]

Is it dragging, or just spins over alot before starting?

 

 

Spins over alot and eventually catches and sputters to life. Extremely strong smell of gas each time on warm start. I have not ruled out a flakey TCI but just wanted some feedback before I made that logic leap.

 

No drag but a four brush starter plus heavier gauge battery wires are on the to do list.

[Monty]

Sounds like it's trying to flood, and spark is not hot enough.

 

Here's how I fixed mine....

For some reason, these bikes call for resistor plugs, although the plug wire caps have resistors in them. Since I couldn't find the non-resistor plugs around here, I took the resistor out of the plug caps, and replaced them with copper wire, cut to the same size. After that, it fired up quick every time.

 

There is a thread on it here somewhere.

[Monty]

http://www.venturerider.org/forum/showthread.php?t=41546&highlight=copper

[Venturous Randy]

When the bike is warm, do you give it any throttle when you try to start it? If you do, just hit the start button wothout giving the bike any throttle.

RandyA

[Monty]

Also, if you think it might be flooded, open the throttle all the way up, then start it. This lets in lots of air, easing the starting.

[MasterGuns]

Sounds to me like your problem could be the starter clutch. Did you start using full synthetic after the Marks collector and new pipes were installed? I have had three lst editions in the last 6 years and they have all had over 30000 miles on them. I am a real believer in sythetic oil and shortly after changing to synthetic, the first issue I encountered everytime was the starter clutch wouldn't catch/engage. It would just spin and once in awhile, clutch, grind and make some really interesting sounds. Replaced them with new starter clutches and the problem was solved.

[MikeZ06Allen]

Sounds like it's trying to flood, and spark is not hot enough.

 

Here's how I fixed mine....

For some reason, these bikes call for resistor plugs, although the plug wire caps have resistors in them. Since I couldn't find the non-resistor plugs around here, I took the resistor out of the plug caps, and replaced them with copper wire, cut to the same size. After that, it fired up quick every time.

 

There is a thread on it here somewhere.

 

mmmmm, might give that a try.

 

 

When the bike is warm, do you give it any throttle when you try to start it? If you do, just hit the start button wothout giving the bike any throttle.

 

 

Yes I crank te throttle a little otherwise the engine just doesn't seem to want to "catch".

 

 

the first issue I encountered everytime was the starter clutch wouldn't catch/engage. It would just spin and once in awhile, clutch, grind and make some really interesting sounds. Replaced them with new starter clutches and the problem was solved.

 

 

This does not sound like my problem as the motor is actually turning over as I am cranking. I fear, though, if I continue to have the hard start issue then I will need new starter clutches and a new starter.

 

I concur that cranking the throttle wide open does help the starting a little but in my opinion that does not fix the problem as the throttle should not need input on cranking. At least until last spring it did not need throttle to start.

[V7Goose]

I do not know much about the 1st gens, but your problems sound to me like you may still have problems with plugged primary circuits. If this is the case, it starts cold from the added "choke" (enriching circuit), and it idles OK because the butterfly valves have been opened enough to suck gas through the main circuits.

 

Although I won't go into the details here, this theory also supports your afterfire problems and the strong smell of gas when cranking hot. It is also telling that your problems started after a winter sit.

 

Start by checking the vacuum at idle - if it is pulling less than 10", that is a strong indication that the butterflies are too far open for the engine speed (meaning that the adjustment is compensating for insufficient fuel from the pilot circuit).

Goose

Edited March 6, 2012 by V7Goose
correct terminology for CV carbs

[Marcarl]

Another thing you might want to check, is to make sure that when you take off the choke, that the choke plungers actually return to seated position. The choke on these bikes is not a butterfly as one would normally think, but rather an enrichment valve on the outside of each carb that can be easily checked. Sometimes they stick and don't return to fully seated position.

[MikeZ06Allen]

I do not know much about the 1st gens, but your problems sound to me like you may still have problems with plugged primary circuits. If this is the case, it starts cold from the added "choke" (enrichener) circuit, and it idles OK because the slides have been raised enough to suck gas through the main circuits.

 

Although I won't go into the details here, this theory also supports your after fire problems and the strong smell of gas when cranking hot.

 

Start by checking the vacuum at idle - if it is pulling less than 10", that is a strong indication that the slides are too far open for the engine speed (meaning that the adjustment is compensating for insufficient fuel from the pilot circuit).

Goose

 

Goose... I will have someone with more knowledgeable than I and with more tools check the vacuum... I believe you are on the right track, thanks for chiming in.

[MikeZ06Allen]

Is there any way possible to clean the primary circuit without disassembly? I have an air compressor and various common tools just nothing to measure a vacuum.

[V7Goose]

Is there any way possible to clean the primary circuit without disassembly? I have an air compressor and various common tools just nothing to measure a vacuum.

Not really.

 

Note that by "primary circuits", we are typically just talking about the idle jets - those are the smallest holes that tend to clog up before anything else in the circuit. Good liquid fuel additives like Seafoam can do wondrous things, but they have one huge limitation - they cannot clean anything that they do not touch. In the case of jets, they cannot do anything at all for one that is completely closed. This is because the jets do not sit submerged in the fuel, so if the cleaner is not being sucked through them while the engine is running, it cannot even touch the deposits.

 

The only reasonable solution is to pull the carbs and remove the pilot jets to spray carb cleaner through them. And while you are in there, make sure to do the main jets too - they have much bigger holes, but they can clog also. Would be really poor to go to all that work and not make sure BOTH jets are clean.

Goose

[MikeZ06Allen]

Ok I have decided to pull the carbs . I have them disconnected from the motor but the throttle cables are proving to be troublesome at best.

 

I have MBrood's writeup so hopefully that will help. Here goes nothing.

 

http://www.venturerider.org/forum/showthread.php?t=54 (1st Gen Carb Overhaul Writeup)

[MikeZ06Allen]

Ok carbs have been cleaned, dipped and air blasted. All jets cleaned as well. Seems I had a fair amount of almost calcium like deposits. Not sure where they came from unless I got some really bad gas with alot of water in it. Oh well... the good news is everything looked great, no pitting or rust so no trip to the Yama dealer for parts.

 

Now I have to figure out how to get all these linkages back together, and reverse the throttle cable removal process.... this thing better run like....well let's start with running.

[Rosie1965]

Seems I had a fair amount of almost calcium like deposits. Not sure where they came from unless I got some really bad gas with alot of water in it.

I have seen this from ethanol blended fuel in some carburetors I worked with back in the 90's. I always tell people with carbs that the ethanol is ok unless it's going to sit for any extended period of time.

[Venturous Randy]

It is probably not the easiest way, but I take the handle grip apart and connect the carbs up and then put the hand throttle back together.

I was also a SSgt in the USAF. Got out in 73.

RandyA

[MikeZ06Allen]

It is probably not the easiest way, but I take the handle grip apart and connect the carbs up and then put the hand throttle back together.

I was also a SSgt in the USAF. Got out in 73.

RandyA

 

 

I ended up taking the left fairing off because I could not get enough slack with it in the way. Probably the long way to get the rack out but it was my first time.

 

Yeah I spent almost ten years as a career Airman until a liver disease put an end to that dream. Had a line number for Tech at the time but medical board ruled me disabled so I got out and now work as a Contractor for the DoD and other Federal Agencies.

 

In 1973 I was 5 not saying anything...just saying .

[MikeZ06Allen]

I have seen this from ethanol blended fuel in some carburetors I worked with back in the 90's. I always tell people with carbs that the ethanol is ok unless it's going to sit for any extended period of time.

 

Makes sense as this bike sat unused for a several extended periods. I got the bike a year and a half ago and it only had 26k original miles and the lion share of those miles was when the PO rode it back from California to Maryland.

[Venturous Randy]

I ended up taking the left fairing off because I could not get enough slack with it in the way. Probably the long way to get the rack out but it was my first time.

 

Yeah I spent almost ten years as a career Airman until a liver disease put an end to that dream. Had a line number for Tech at the time but medical board ruled me disabled so I got out and now work as a Contractor for the DoD and other Federal Agencies.

 

In 1973 I was 5 not saying anything...just saying .

 

I can't complain. I made Staff in three years and was in NC except being in Ubon Thailand for about six months on a TDY out of Seymour Johnson AFB. Yeah, that was a long time ago and we had F-4E Phantoms.

RandyA

[MikeZ06Allen]

Yeah, that was a long time ago and we had F-4E Phantoms.

RandyA

 

 

Still do, well at least ten years ago; although mostly used as drones now but a few are still in service.

[MikeZ06Allen]

Well carbs have been throughly cleaned and are back on the bike. However the warm start issue still persists . Although I believe a carb sync will help the issue and possibly find a dealership with an EGA to set the idle air mixture.

 

To that end does anyone know of any reputable shops near San Antonio that can work on these bikes?

 

Definately acquired a new appreciation of the work involved with removing and servicing the carbs on these machines. Can't say I will ever do it again though

[MikeZ06Allen]

Ok took the bike for a spin today (wonderful weather) and found that I was getting serious afterfire on accel and decel.

 

I was also getting an occassional backfire through the carbs. One was so bad it unseated the carbs from there boots. Got the bike home and shut it down and noticed I was getting a steady drip of gas out of the side of the carbs. Yanked the airbox and found fuel in the tops of the carbs and more flowing in even with the key off. I then determined my problem seemed to be an overpressure on the gas tank. HMMMMM

 

Back last spring, Skydoc and I removed the charcoal canister in order to eliminate potential vacuum leaks. With my understanding of the gas vapor purge circuit being very limited I thought I hooked everything back up correctly; apparently not.

 

Once I disconnected the purge solenoid and tank vent the gas stopped pouring into the carbs and bike cranks much better with this stuff disconnected. I will plumb the recirc lines into a filter to eliminate dusting the engine but for the most part the gas tank is now venting to atmosphere and the purge circuit has been eliminated.

 

Sorry for the long post but I wanted others to learn from my goof up and say sometimes it is just better to leave well enough alone.

 

Update:

 

Warm start issue has been solved. Bike is back to starting without throttle input; now I need carb tune and I will be back in business. Thanks to all for the inputs and guidance; most if not all comments were incorporated in fixing the issue.

Edited March 12, 2012 by MikeZ06Allen
Update