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Really rough and noisy cold start

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rij1

Really rough and noisy cold start

I just got my bike a few days ago and found this problem with it. When the engine is cold the starts and runs like crap and is noisy. It didn't do this the day I purchased it and I don't think it did it the next day. I made a short video of it to show what it sounds like cause its easier then trying to explain it.

http://youtu.be/oWGJfVb-iak

My Bike Information
1982 Honda DOHC CB750F Supersport
4-1 Exhaust with baffle
Stock intake air box
Slow-speed jet #35
Primary main jet #68
Secondary main jet #105
Ventura, California

shinyribs

Re: Really rough and noisy cold start

Administrator

Wow. That does sound rough. Does the sound ever go away when the engine gets fully warm?

I would guess that the carb sync was out if I had to,but I can't swear that's it.

Hopefully a DOHC guru will chime in soon.

Gorgeous bike,by the way!

rij1

Re: Really rough and noisy cold start

Yeah, It goes away about 80-90% after a minute or 2.

My Bike Information
1982 Honda DOHC CB750F Supersport
4-1 Exhaust with baffle
Stock intake air box
Slow-speed jet #35
Primary main jet #68
Secondary main jet #105
Ventura, California

TOOLS1

Re: Really rough and noisy cold start

Administrator

In reply to this post by rij1

Sure sounds like the carbs are out of sync.
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
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seestheday

Re: Really rough and noisy cold start

ya, it sounds like your carbs are out of sync, but since it goes away after it warms up, can you look at your plugs to see if one is fouled/different than the others?

1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

My cb750 video site

rij1

Re: Really rough and noisy cold start

In reply to this post by rij1

I doesn't go away completely.But Yeah, i'm going to have the carb sync'd.

My Bike Information
1982 Honda DOHC CB750F Supersport
4-1 Exhaust with baffle
Stock intake air box
Slow-speed jet #35
Primary main jet #68
Secondary main jet #105
Ventura, California

Johnnylevi

Re: Really rough and noisy cold start

does the noise change if you pull the clutch in?

1981 SS with Kerker 4-1 exhaust and extremely attractive rider.

seestheday

Re: Really rough and noisy cold start

In reply to this post by rij1

rij1 wrote

i'm going to have the carb sync'd.

Much cheaper in the long run to buy the tools and do it yourself. Depending on how much your mechanic charges it might be cheaper the first time you get them sync'd to just do it yourself. It's a pretty easy job.