82 450T Runs great when cold, not when hot. Ideas?

[aardvarkjff]

The bike is an 82 450T with 7,400 miles or so. Bought from seller who let it sit out last winter. Now my Suzuki dealer worked on it and:
Cleaned, adjusted and synched the carbs
New gas
new plugs
compression leakdown test, passed with flying colors
Charging circuit and battery are fine.

When cold, she starts and runs great. It idles at 4k rpm and drops shortly to around 1k or so. But as it warms up, the idle stays around 4k and it take a quick hit from the choke to knock it down. After a few minutes (4-5) of warming up it gets all boggy when the throttle is turned before picking up rpms. left idling it eventually it stalls out. The starter turns fine, but IF it starts, it needs a slight turn of the throttle to do so and it's a very bogged down sound. He said it might be an air leak but not in the top end. Does anyone have any ideas? What might I try to get a better handle on this?

[chuckycheese]

Don't know..

I don't know what the problem is but, from what you said, I'm sure you've spent quite a bit of money with your Suzuki dealer. I would take the bike down there and bug the hell out of them.

Considering your investment in them, I would surely think they would consider it an obligation to help you figure it out. It may very well cost you a few more dollars but my guess is.....they'll figure it out quickly and it won't cost you much. Good luck and please let us know!

[aardvarkjff]

I don't know what the problem is but, from what you said, I'm sure you've spent quite a bit of money with your Suzuki dealer. I would take the bike down there and bug the hell out of them.

Well, not exactly a lot. They are a smal shop with a grat reputation. They have worked on the bike a little at a time and cut me a HUGE break in logging time. When I talk to the mechanic, he gives me the sense of doing it out of nostaglia. His big concern is that for him to start ripping into the engine, now it has the potential to be a money pit. (Who though a mechanic would actually be concerned about MY wallet?).

What I'm hoping to do is see if I can (with the forum's help) is to track down the issue and either fix it myself, or bring it back to him with a better diagnosis. I don't want to wear out my good will with them too early. Great guys at the shop and here too! Thanks.

[nabrams]

Sounds to me like air leaks at the boots that connect the carb to the engine. It could be the o-rings that mate the boot to the engine or the boot itself.
The leak may not be as evident when cold. As the bike warms up, the rubber can become distorted enough to start leaking.
If I were you, I'd also check to see that the boots that connect the carb to the airbox are sealing perfectly as well. It's surprising what a huge affect a small air leak can have on these CV carbs, but true nevertheless.

[Jethro]

Take a plant mist sprayer ($4 at Wally World) and spray all over the carb boots while the engine is hot and running. Any decrease in engine rpms tell you that there is an O2 leak. Beware though, this test is not always conclusive.