More carb questions ('83 750E)

[QuaiChangKane]

Alright guys - I'm miffed.


She's been progressively becoming more cold-blooded, and high RPM power is lacking.

I synched the carbs with no real improvement. I checked the valves - all were within spec. I took the carbs off expecting gunk, but they were clean as a whistle. The ONLY problem I found was that the o-rings on the fuel rails were cracked, and I've replaced all of them.

She's running rich (hence the cold-blooded problem), so the cracked o-rings wouldn't have caused that. All carb boots and boot o-rings are in good shape and sealing well. She'll fire right up at half choke, and will run fine at moderate RPMs once warm. At higher speeds in higher gears, there just isn't any real power there. And she takes FOREVER to warm up. Once warm, she cools down quickly and I have to warm her with the choke again - AND IT'S THE MIDDLE OF SUMMER IN CALIFORNIA!!!

I just put the carbs back in and am trying to get the air mixture screws sorted. Here's the skinny:


'83 750 E - stock airbox and filter.

Supertrapp 4-1 (header's a bit beat up underneath).

Jets

Mains - 122.5 (OEMs are 117.5)
Pilot - 37.5 (OEM)
Main Air Jet - 155 (manual claims OEM is 1.7???)

Of course, I didn't write down the number from the needle jets. And another thing - what the hell is meant by raising the needle jet or needle jet clip by a position???? Correct me if I'm wrong, but there are no needle jet positions on my carbs - there is an indexing pin which aligns the needle jet, then a washer and the main jet screws into the needle. Once you snug up the main jet, the needle jet is pulled all the way to the top of the passage - no adjustability....


Help? Please? The mains are as I found them - I did not rejet them, so I don't have the OEM jets - and (of course) my manual doesn't list the adjustment for the idle air screw, so I hope someone can help me there, too!!!!


I'm about to go back out and clean the plugs, then run and read them....

Thanks in advance,

-Q!

 

[maddoctor]

I Don't Want To Be...

I Don't Want To Be...

the bearer of bad news, Grasshopper, but I must.

It sounds like your carbs are gradually being clogged by varnish from evaporating gasoline. The jets may be clear, but the passages in the carb bodies are not.

Best bet is to remove the rack of carbs from the bike and take the entire rack to your local Suzuki dealer. Have the carbs cleaned out, and rebuilt, if necessary. This may cost you a few bucks, but it'll be worth it in the long run.

Mad Doctor

 

[lhanscom]

Just clean them yourself, check out the carb cleaning series in the garage.

Here's another thought though. Check the voltage at the coils, if you're having low voltage it will cause a cold spark, and a 'rich' looking condition.

 

[Anonymous]

ABSOLUTLY,

Do the carbs yourself, too many horror stories from the dealers,
You want it done right , YOU do it, Its actually simple...

get the series with great pic. here.. on the home page I think..
Stimpy,

 

[QuaiChangKane]

I did clean the carbs - one by one, peice by peice (kinda had to take them apart to get the numbers off of the jets, y'know? :wink: ).


But they were nearly perfect inside. I did get my idle mixture sorted yesterday - 4-1/2 turns out on the air screws. She'll fire up and idle without choke after warmed to just under 160. Smooth like butter....

But I'm still running a bit rich - revving over 6 grand produces a nice puff of the black stuff. She pulls strong, but I couldn't test her out much yesterday due to a slipping clutch - new plates are in now, so I'll take her on the freeway this evening.

I'm thinking that the cracked o-rings on the fuel rails were definitely the culprit - that's why I had to run with the choke on for so long until she warmed up enough to run on the lean mixture since the carbs were sucking air through the o-rings.

Or not....

I'm going to clean the plugs again and run her around the block a few times without the air filter - if this leans out my mixture enough, I'll go with pods.


-Q!

 

[oldschoolGS]

GSXR CV flatslides will cure your problem. Stock Carbs off the air/oil cooled models will bolt right up, 34's work real nice, mine are off the 86GSXR1100 and can be had for about $150. Good Luck, Ed.
1983GS750ED