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Discussion Starter #1
I have an 83 Yamaha 650 SECA. The bike appears to be running great - not a whole lot of noise aside from some tapping (im guessing this is normal noise on a DOHC motor.. Though I will be checking the clearances when i get the specs / a manual).

My problem is with cold starting. The area I live in gets pretty cold overnight (even in my heated garage). And I have to wind the bike over for quite a while before it starts (30 seconds or so sometimes), with the choke all the way. The bike starts fine if it's in the sun for a while or if it's still warm.

I have checked to see that the choke lever is actually connected to anything - it is. And I have installed new spark plugs.

I had an 82 seca before this one that never had any trouble starting (half twist on the throttle and it started right up).

Anyone have any advice on how to troubleshoot / fix this problem?

[Preferrably not "turn up th heat in your garage."]

-Ease
 

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the problem is that it is just the nature of the beast. That vintage Yamaha is very lean on the pilot jets and fuel screw settings in order to meet emmission standards. The cure is to remove the carbs, remove the fuel screw plugs from the underside of the carb bodies(right in front of the float bowl) and turn the screw out some. Try 1/2 a turn to start with. The plugs are blank aluminum and need to have a small hole (1/8")drilled in them and a sheet metal screw started and pull out with pliers. Pilot jets can be drilled out or replaced with the next size up if you can get them. Of course since you are going to be messing with the cabs anyway, at this point I would pull the airbox and replace it with pods and throw away that stock exhaust and replace it with a 4-1.

Good luck,
Ken

AHRMA 412
Vintage racing - old guys on old bikes
 

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Discussion Starter #3
Well I guess I'll hold off for a while on it and hope I don't burn up my starting motor in the meantime (no kick on my bike <img src=icon_smile_dissapprove.gif border=0 align=middle>).
I was planning on getting a 4-pod setup and jetting the carbs when I get the cash for a k&n system (any cheaper / better kits?).
Allready have a 4-into-1.

Thanks,
Ease
 

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Ease,
If you already have a pipe on it without rejetting, You have made the lean mixture problem worse than stock. How do your plugs look? They should at least have some slight color to them. One trick you can try, especially if your in private so nobody can see you looking silly is this: You can temporarily raise the level of the fuel in your floatboals to dump a little raw fuel in the intake. You can do this by turning the fuel petcock to Prime and then laying the bike over to the left and then the right. The farther the better (try not to drop it). Or you can shake the bike back and forth hard and bounce it on the suspension. These techniques allow some more fuel to get past the float valve as the floats bounce around. Like I say, It looks silly but does work until you can re-jet.

Ken

AHRMA 412
Vintage racing - old guys on old bikes
 

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Discussion Starter #5
I had some major starting problems again, so I took out the plugs and checked them... They were sooted up a good bit and 3 of them were soaked with gas.

The dry one concerned me so i switched it to another cylinder and the bike started up fine, but ran a bit off (OK, alot off).

After 1 - 2 minutes of running the bike I got an inclination to touch the header pipes to see if they were all hot... the one with the crappy plug was still cold (So I immediately turned the bike off and replaced all 4 plugs with new ones).

The bike ran fine for the rest of the day - but when i stopped it for a while and it got pretty cold the bike had a hard time starting - and ran rough once it did.

I havent taken the new plugs out yet, But if I were a bettin man I'd say the same plug (#2) is probably fouled again.

I guess my question(s) is(are), is my bike running lean or rich?
As stated before, there is a 4-into-1 exhaust on it (that was there when I got the bike) BUT I'm not sure if the carbs have been done, and I have no real way of finding out.
Might a 4-Pod air cleaner solve this problem (without re-jetting)? I'm trying to avoid having to tear the bike down...

- Ease
 

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4 pod air filters will just add another ingredient to your bikes problems.

You need to disassemble and clean all the jets and orafices of each carb. Do one at a time so you don't misplace parts.

You also need to make sure you air screw is turned out the same amount for each carb. And then balance the carbs using a carb balancer tool (mercury level).

Most old bikes run very well after the above...
 
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