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Hard to start and runs awfull. Need help

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MrBassMan

Hard to start and runs awfull. Need help

Hi all,

I'm new here so this is my first post. I love the CB750F I bought a year ago, but it's starting to become a headache to me... I just can't figure out what the problem is.

Here's the situation. Last week I pulled the bike out of my garage to get it out of hibernation and make the firdt little ride of the year. I drained the carbs, put new fuel in the gas tank and after a few tries it fired up nicely. It had some difficulties to run idle, but after the engine warmed up, no problem anymore and a smooth ride it was.

This week i decided to change the oil and filter, and yesterday i wanted to go for another ride. But the engine refused to start. I had to try at least 20 times to start it and nothing happened. Even with start pilot it was another 5 or 6 tries before it finally started. But it ran so bad! The engine would not rev up and when i decided to make a short test run, it just was not acting like last week.

Could it be that the oil change caused this? I used the correct oil and filter, but it might be that there is too much oil in the bike. The problem is that i dont have the original stick to measure the level of oil. I added 3,5 liter of oil as described in the manual. The old oil that came out of the engine was only about 1,5liter

Any tips or tricks to get it back to run like last week?

birdmannn101

Re: Hard to start and runs awfull. Need help

Check spark, wet plug and compression.

66 S90
64 C102
65 C100
65 CT200 Trail 90
74 CB350Four
73 CB750K3
76 CB750A
03 VTX1300S
Bicycle with HF engine

TOOLS1

Re: Hard to start and runs awfull. Need help

Administrator

In reply to this post by MrBassMan

You would need to fill the engine up to the point of oil coming out the top to cause a problem like this. What you have is bad gas, dirty petcock, or dirty carb. The first thing I would do is run some Seafoam in the gas. It is amazing how it will clean a fuel system. If that does not do it, you will need to clean the carbs.
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

shinyribs

Re: Hard to start and runs awfull. Need help

Administrator

TOOLS1 wrote

You would need to fill the engine up to the point of oil coming out the top to cause a problem like this. What you have is bad gas, dirty petcock, or dirty carb. The first thing I would do is run some Seafoam in the gas. It is amazing how it will clean a fuel system. If that does not do it, you will need to clean the carbs.
TOOLS

What he said ^^^

Also, what year bike do you have?

If it's a SOHC ( 75-78) then you need to drain the oil tank to remove all of the oil in the system before refilling.

MrBassMan

Re: Hard to start and runs awfull. Need help

I'll check the fuel system

The bike is from 1981