Starts revved to the moon

[Dougyb]

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Hey guys, new to the forum, seems great

My problem is on a 95 blaster with a vito's 240 kit and a keihin pwk carb.

Couple of weeks ago I noticed the bike would start to rev higher and higher as you sat in neutral after riding.... Well one day I take it for a quick spin, shut it off, and when i start it off, it would run like crap, so I put it away and figured I would try it the next day.

So the next day I start it up, revved super high with choke on but stalled with choke off... took it for a spin and the throttle would stay open after i let it go and then bog down slowly.

I cleaned the carb, checked compression(150) and started it back up, revved to the moon as soon as you start it.

I disconnected BOTH end of the throttle cable, kicked her over, and she purred like a kitten with choke on and off, but I noticed the cable seemed fine and was sliding as it should, so i shot some white lith grease down her and hooked her back up... SAME EXACT THING!!! revved to the moon as soon as you start her.

as you can see the throttle plate is all the way down to the stop... any answers? The cable really did seem to work as intended, could it be anything else?

 

[blasterdemon7]

Major air leak or sticking carb slide.

 

[Dougyb]

The newly edited post shows the pics, the slide is down when started.
As far as an air leak, the bike starts and runs fine when the throttle cables are disconnected, idk if this eliminates the theory of a carb leak or not...?

 

[blasterdemon7]

That slide is sitting open way to much if that is how it's sitting with not touching the throttle.

 

[Dougyb]

thats what i thought but if you look at pic two, there is a stopper plate in the slide groove and it does not let the slide go any lower than that

 

[blasterdemon7]

This is how it should look at closed throttle.

 

[Dougyb]

you are right i just disconnected my throttle linkage again and it was able to go lower, and now its acting like there is an air leak, which is frustrating, but what could be keeping the slide from 1) going down all the way all of a sudden and 2) stay open delayed after releasing the throttle

I will order a leak down tester today

 

[blasterdemon7]

It may be a routing problem with your cable but the first thing I would check is the thumb throttle. Take the cover off and look inside for any problems. If good,check routing of cable to make sure there no thought bends in the cable. The manual should show the correct rout to run the cable.

 

[Larry's Shee]

I was thinking that slide looked high too. If cable route is good might need new cable.

 

[bigwill]

Check you throttle cable adjusters on the top of the carb and on the thumb throttle. Make sure they were not vibrating to the current open position.

 

[Dougyb]

I have only owned the bike for a few months, so im not sure of the correct cable settings(as for how far they are threaded down to their entrance points.. ie. how much thread sticks out in between lock nut and thumb housing/carb housing) but when i took them off the screws were all the way down on both ends... is this what most throttle cables are put in as? The cable was ran as stated in manual, seemed to work fine still, but yet as stated the slide was not going down all the way, which is a new thing thats never happened before on this bike since I've owned it.

 

[blasterdemon7]

Did you check inside the thumb throttle to make sure there wasn't anything loose laying around I there to get in the way of the arm?

 

[blasterdemon7]

I would install the cable on the carb only and check the slide. Take some pliers to the other and of the cable and open / close the carb slid a couple of times to see if it returns fully closed. If it works fine like that, then most likely it's a problem at the thumb throttle itself.

 

[Dougyb]

I had to open the thumb throttle assembly twice and everything is fine in there. I will try the slide idea tomorrow and state what i find

 

[blasterdemon7]

I'll be here to help as much as I can.

 

[Dougyb]

So today after I put a coat of paint on the boat i went to the blaster, and immediately hooked the carb slide and throttle cable back together( I had the the thumb/throttle cable already hooked up from yesterday). I was gonna do your test demon, and just disconnect the thumb/throttle while leaving the carb slide attached, but all of a sudden when i reattached the carb slide to the cable it went down as suppose to. The only guess I have is that maybe Bigwill was right and the adjusters vibrated the cable too tight for the slide to get all the way down. I did readjust the carb adjuster to let in as much cable as possible before i reinstalled...so maybe thats an option for future troubleshooting.

As for a possible air leak, if i start the bike up and the rpms slowly increase up and up with the choke on, or in gear stalls and bogs and has a delayed throttle repsonse... is that a tell tale of an air leak??

If need be I can put a video on here to show exactly what it does. If I do have an air leak I'm lucky to get to it now while compression is still 150

 

[DirtDiggler]

Your Blaster ( as long as the carb is clean and the plug isnt fouled ) should idle with no touching of the throttle to keep it running . A lot of people think a 2 stroke won't idle well , but my Blaster would idle out a tank of gas if i let it . A air leak will manifest itself in several ways . If you stab the idle hard and release it and the revs hang instead of dropping steady , you have a air leak . If the idle steadily creeps up and up ,, you have an air leak , if you start it and it revs to the moon you have an air leak . remember that the carb adjuster at the carb cap can also be a culprit . once adjusted I always wrap it with several turns of electrical tape . Pull your intake manifold and make sure the gaskets are in good shape and use a hi temp RTV copper based silicone adhesive on all mating surfaces , not a gob but just enough to fill any irregularities . check the cylinder nuts that hold it down to the cases , look for any oil streaks or leaks there. check the head bolts and the plug , make sure the plug has its crush gasket , and a little bit of anti-sieze on the plug can't hurt . Beyond that you'd have to investigate the crank seals .