Erratic Idle...GS450TX

[yakobo5]

Just finished putting together a 82 450tx and for the life of me, I can't get the idle to settle...Idles great when I first start it up with the choke and once it warms up, it purrs at 1200rpms. Its after it gets hot that it jumps up to 4-5k and lopes sometimes...I've been running the mixture screw 2.5 out as it had been 'tampered' with...is this the right setting? Everything else is stock except for a new Mac Exhaust. I took apart the carbs and replaced all orings and the gaskets/diaphrams look great. The Carb boots also look good with no visible cracks etc. I did purchase new boots/orings just in case but wanted to see if anyone had this issue before I tore it apart again. I did the wd40 thing on the carb/intake boots and it didn't change the idle either...not sure what to do next...bike has 12K miles.

[BigD_83]

Someone with a 450 can be more specific, but you are describing a classic hanging idle, where an air leak is causing the engine to run lean (and very, very hot). There are a number of threads here that can be found using the search feature. Try "hanging idle" in Titles Only

#27 on this parts diagram is your likely culprit

http://www.boulevardsuzuki.com/fiche_section_detail.asp?section=92550&category=Motorcycles&make=SUZUKI&year=1982&fveh=2100

Good luck with the diagnosis and fix

[yakobo5]

Thanks for the response! I'll certainly check out your stickies..

[yakobo5]

Btw, here's a pic of my bike...love it...rode a M50 for 4 years and then downgraded to this as I didn't ride as much as I'd like (had a new kid on the way). The 450 is definitely a fun, light bike...and CHEAP...did the paint myself with rattle cans too.

[pete]

Hi and welcome, and yeah the 450's are definitely great little bikes! I love my E.

You definitely have the hanging idle going by your description.

I found with my carb boots that even though I could get the carbs to seat, they had shrunk, meaning the outside diameter was too small for the clamps to clamp and seal properly and getting the carbs inside required a light application of rubber grease. The flat and brittle O rings didn't help either.

I had the hanging idle with those and I replaced both boots and O rings and now no issues whatsoever.

[yakobo5]

I will replace both boot and oring this weekend. On that note, does the intake boots on a 450 require the use of a gasket? I got two fiber gaskets with my kit but didn't see that part in some of the diagrams I googled. Thx

[yakobo5]

Ok...so I replaced both intake boots and orings with all new parts...bike ran 200% better and idles decent...only prob is that the idle changes from time to time when it warms up...I set it at 1200rpms but sometimes it lingers in the 800 range up to 1500rmps...is this normal? I've also come to the conclusion that these bikes are cold blooded and take a long time to warmup.

[Nessism]

Ok...so I replaced both intake boots and orings with all new parts...bike ran 200% better and idles decent...only prob is that the idle changes from time to time when it warms up...I set it at 1200rpms but sometimes it lingers in the 800 range up to 1500rmps...is this normal? I've also come to the conclusion that these bikes are cold blooded and take a long time to warmup.

Did you vacuum sync the carbs?

[BigD_83]

Ok...so I replaced both intake boots and orings with all new parts...bike ran 200% better and idles decent...only prob is that the idle changes from time to time when it warms up...I set it at 1200rpms but sometimes it lingers in the 800 range up to 1500rmps...is this normal? I've also come to the conclusion that these bikes are cold blooded and take a long time to warmup.

My 650 experience tells me otherwise. I can be riding without choke in 30 seconds, and I'm not running rich.

I haven't looked at your other posts, but did you get a chance to do a full cleaning of the carburetors before putting it all back together?

Does the idle drop below 1200 when you give it a little gas sitting at a light, and then slowly rise back up? 2.5 turns out may be causing it to run a little rich now that you've got the intakes sealed up properly.

[yakobo5]

Have not yet vaccuum synced the carbs as I don't have the means but will look into buying a sync meter soon. As far as cleaning the carbs, everything was soaked and all orings were replaced when i first acquired teh bike. The choke seems suspect too as the bike idles poorly with it on hot or cold.

[pete]

Unless I'm blind I also can't see above if you've checked your valve clearances yet...

Sync'ing definitely made a different to my carbs though and as for warming up, I run it on choke while putting my helmet and gloves on and then off choke and on the way.

However, to get it fully warmed enough to reliably set the idle screw requires probably another 5 to 15 minutes depending on the air temperature...

Normally when leaving work after the bike sitting idle all day I don't need the choke, but now in the middle of winter I've had to use it a few times on the colder days, again just while putting helmet and gloves on...