high reving issue

[Guest]

hey all so im running into a bit of an issue. when i get to a stop light or any stop really, i drop down into first (sometimes second gear) and then the bike starts to rev up really high (rpms), i can manipulate it by releasing the clutch a bit and the reving will drop. but it concerns me at just how high and loud the rpms get. i tried lowering the idle but if i go any lower it seems to stall at stops instead. what should i check out to maybe fix this issue??

 

[Guest]

You have a lean condition, check for air leaks on carb boots to motor, and air box. When were the carbs last cleaned?

 

[Rob S.]

You have a...air leak...

That's what it sounds like.

 

[Guest]

just cleaned the carbs i would say last month. all the gaskets for the bowls and such were intact and seemed fine tho a replacement kit is on my wish list. ill check the boots for good seals. thanks guys

 

[geol]

If the enrichener plunger pads are shot, they won't seal and the engine will rev. If you jiggle the choke a bit, see if it comes down. If it doesn't the plunger pads need to be renewed or the plungers replaced. The rubber just gets hard on older bikes.

 

[tom203]

just cleaned the carbs i would say last month. all the gaskets for the bowls and such were intact and seemed fine tho a replacement kit is on my wish list. ill check the boots for good seals. thanks guys

Just replace all the carb o-rings : the boots will fool you especially their o-ring at head interface part #27 in attached fiche.
Go to www.cycleorings.com and take a look

http://www.alpha-sports.com/spst/1981 GS450T/15.htm?q=suzuki-parts

 

[bobgroger]

If the enrichener plunger pads are shot, they won't seal and the engine will rev. If you jiggle the choke a bit, see if it comes down. If it doesn't the plunger pads need to be renewed or the plungers replaced. The rubber just gets hard on older bikes.

DO you mean the caps, the o-ring, or the rubber part under the needle? I am fighting this as well...

 

[Guest]

When the bike is shut off and restarted warm, how does it idle before you touch the throttle? If it idles fine before you touch the throttle then try......
When the bike is idling high cycle the kill switch repatedly, don't let the bike stall. Does the engine return to "normal" idle?
if the answer to these questions is yes, you probably have plugged or very restricted idle circuits.
If the answer is no, vacuum leak or enrichment circuit.

...or I could be full of it

 

[geol]

DO you mean the caps, the o-ring, or the rubber part under the needle? I am fighting this as well...

The caps on the enrichener tubes make no difference. The small orings under the pilot mixture needles make la little difference but the pads on the enrichener plugners can't be hard or deteriorated as the bike's revs will shoot up as described by the OP. The pilot circuit being dirty will also do it (I know he said he cleaned carbs but folks don't know how to check the pilot circuit a lot of the time) and the throttle cable too tight will also cause high idle issues but not like you are having... plunger pads will.

 

[Tiny]

What are plunger pads and where are they?

 

[Steve]

A mis-adjusted enrichener ("choke") cable will also keep the plungers from seating properly.

The "plunger pads" are the little o-rings on the far end of the barrel that is thought of as the "choke". It goes sideways across the top of the outlet of the carb on the BS series carbs (CV-type) and is vertical, on the right side of the VM carbs. The linkage will pull on the plunger to open the enrichment circuits for fuel and air. The fuel comes up past the smaller, almost pointy tip at the end of the plunger. Where that tip meets the plunger is an o-ring that seals the fuel passage when closed. If there is not enough clearance on the "choke" cable, those plungers can be held out slightly.

Now, back to the OP, my guess is that you need to change the o-rings on the intake boots. Your symptoms are a classic example of running lean, bad o-rings are a likely culprit.

.