Terrible Throttle response

[thlillyr]

I just got a new seca 400. Had a few engine hiccups. Would not rev past 4000 rpms or idle without full choke. Had a mechanic pull the carbs to clean and he tuned it to run very rich. Fixed idle but would not rev past 4000rpms. Throttle response was great at this time. I pulled them myself and found that the main jets were 95 from another brand of carb. Put in the stock 125 mikuni jets. (mikuni carbs) this Fixed rev issue. Revs to 10,000 with strong. Now problem is i have significant hesitation at idle. I mean like 20 seconds significant. I'll be at a light and open the throttle a quarter half or full and it takes a very very long time before it responds it actualy seems to bog down droping revs to about 800 from my idle of 1500. Once my revs are above 3500 rpms my throttle response is very good. However it's a bit surgey while cruising. Meaning it's not a smooth cruise it kind pulls and pushes and at any rpm. Last note is that the more i drive the bike the worse these problems become. I'm guessing that it's running to rich from the mechanics tuning. Any other ideas. If it is just to rich how to I fix that to run leaner? I'm comfortable pulling the crabs.

 

[drewpy]

If you fancy pulling crabs, that's your perogative, I prefer women

shouldn't need to pull the carbs, there is a low rpm mix (pilot) adjuster on top of the carb towards the front, just need to screw it in a revolution and take it from there!

 

[thlillyr]

So weird update. For the last 2 days it's been running like i described. It had sat for a week before i started driving it for the last 2 days. Today for no reason at all it runs perfectly. Don't know why it suddenly changed.

 

[thlillyr]

ok so i lied it's not running great. as the day warms up it runs worse and worse. So looks like its effected by temperature. Why is the air temp affecting my performance so badly?

 

[BuchanZig]

Hey thilillyr, I think Im having this same problem just to a lesser extent. After about a half hour of riding the throttle response is pretty bad and it just gets worse and worse the longer I run it. Did you ever sort this out or figure out what was causing it?

 

[dburrows6735]

Have you guys synced your carbs? Any chance you throttle cable is blown out/ stretched?

 

[drewpy]

I recon there's crud in the carbs and it got sucked up, then settled, then got moved again.

 

[bentwrench]

Main jets weren't stock. How do the pilot jets look? If they were switched too, that would explain no low end...

 

[thlillyr]

Turns out my choke was sticking down by the engine. I greased the slider pole and walay no more boggy bike when it's warmed up. Also My gas milage is back to normal i was getting around 30 mpg but now i get the standard 50 mpg