start up takes a long time 78 gs 750

[MoMakkawi]

I cleaned and rebuilt the carbs and put them back on, before i did that the bike would start without having to pull the choke up and warmed up rather quickly, now the bike only starts with the choke up and takes forever before im able to let it down so the bike wont die.. any hints to what may be the problem would be great more so i pulled the front rim and tire off but the rod wont come out so it is stuck on the rim with the disc brake still their i cant seem to get the rod out

[Nessism]

Where are the fuel and air screws set? Did you replace the intake boot pipe O-rings? Replace all the O-rings inside the carbs?

[btbarb]

Pilot fuel screws

I cleaned and rebuilt the carbs and put them back on, before i did that the bike would start without having to pull the choke up and warmed up rather quickly, now the bike only starts with the choke up and takes forever before im able to let it down so the bike wont die.. any hints to what may be the problem would be great more so i pulled the front rim and tire off but the rod wont come out so it is stuck on the rim with the disc brake still their i cant seem to get the rod out

Are your pilot fuel screws and your air screws the same number of turns out now as they were then?

I think the normal setting for the fuel screw is about 1 turn out from lightly seated and the air screw 1.5 or so. If it takes longer to warm up than you'd like, you can try turning your fuel screw out a quarter or half turn.

[Big T]

How many steps of the Top 10 Newbie mistakes did you skip ?

[tkent02]

How many steps of the Top 10 Newbie mistakes did you skip ?

Ding Ding Ding!!!

[MoMakkawi]

i replaced all o rings including the intake boots .. i pulled and cleaned the carbs twice... and set the air and fuel screws to what they were before since i had it written down from the first time following the guide on this forum. And to newbie mistakes i have probably done many but this is my first motorcycle so give me break...

[Nessism]

So where are the screws set? Did you check to make sure the fuel screw tips were not broken off in the carb bodies?

[BassCliff]

Hi,

Have you adjusted the float heights and performed a bench sync before you put the carbs back on the bike? Has anything changed with the air intake system? New air filter? No air filter? Pods? Airbox?

For reference, this is the proper carb cleaning procedure:

Mikuni BS(CV) Carburetor Rebuild Tutorial
(Mr. Nessism)

However, this is the guide for your particular model of carbs:

VM Carburetor Rebuild Guide
(Courtesy of GSR and Paul Musser)

As was mentioned, this is the "stuck pilot screw" scenario:

Remove Stuck Pilot Screws
(by Mr. Hoomgar)


It sounds like the axle is stuck in the wheel. You'll have to keep soaking it with your favorite penetration solution, like PB Blaster or Liquid Wrench, and it that doesn't work try a little heat and some impact persuasion. Don't hit the axle directly with a hammer. Put a piece of wood or something in between. Keep us informed.


Thank you for your indulgence,

BassCliff

[BassCliff]

Hi,

...And to newbie mistakes i have probably done many but this is my first motorcycle so give me break...

We've all made mistakes. We've tried to document them so that others can be saved the same grief that we've been through. CLICK HERE to read the information usually referred to as "The Top 10 Newbie Mistakes". Hopefully it will help.

Thank you for your indulgence,

BassCliff

[7981GS]

Valves adjusted or stuck open? I.E.: No/low compression.

Eric

[Big T]

i replaced all o rings including the intake boots .. i pulled and cleaned the carbs twice... and set the air and fuel screws to what they were before since i had it written down from the first time following the guide on this forum. And to newbie mistakes i have probably done many but this is my first motorcycle so give me break...

MoMakkawi,

We'll gladly give you all the info you need, and more. But, check out your Megawelcome completely and report back. Plus, we like pictures, because they're worth a 1,000 words

Hard starting issues for VM carbs are typically:

1. Tight valves
2. Low compression (see #1)
3. Dirty carbs

Since you say it started well before, I'm guessing you got something misadjusted in the carbs. Float height is critical. Fuel screws should be about 7/8 turn, air screws about 1 1/2. You didn't break off the fuel screw tips? Read the VM guide above and see what you did or didn't do

[MoMakkawi]

thanks for all your help, ill try to post some pics of what ive been doing tmmrow since ill also be putting the brakes together again and my new rear tire on however I did set the float heights and do a bench sync before putting them back in the jet screws all have new o rings on them and all seemed in rather good condition , however the other week i was checking the valve clearances and i had 4 valves that were exactly .03mm the others seemed ok around .05 and a few of them had blemish marks. could that be the issue causing it, the PO said he had never one a shim clearance job on it and the bike has 11,000 , i for sure thought the clearances would be out of spec but the manual say .03 is in spec am i wrong?

[chuck hahn]

.05 is optimal but at ,03 you know that none of the shims are holding any valves skight,y open and thats a good thing. So as suggested, the next step down stream is a compession check. As for that front tire..Take the calipers off the forks and let them dangle there. Loosen the big nut on the end of the axle. Then loosen the 4 nuts on the bottom of the fork caps.take barass hammer or similar and give the big axle nut a few medium taps and the axle should just slide out. You can put a phillips thru the hole on the other side and pull and twist it out. Clean the crud off it and regrease it upon reinstallation.

[7981GS]

Clean the crud off it and regrease it upon reinstallation.

I just take a wire wheel to the entire bolt, threads and the nut.
As Chuck said, grease the shaft lightly as well as the threads.
I use synthetic grease on the shaft and anti-seize on the threads but grease is fine for the threads also.
They always seem to be coated with rust and pitting. The grease will help keep it from rusting/pitting again.

Eric

[MoMakkawi]

ill try to get that damn rod out tomorrow with some of the ideas you guys have suggested. ive tried whacking it with a hammer to see if that would free it out but no cigar maybe tomorrow will be different, so is having a little blemish on the cam lobes ok then if their is still space?