Back here after a year in which I [very slowly] totally overhauled my 1994 400 2 stroke.

It is back in service as of yesterday and all is well except is has a "miss" on acceleration that was not there before. I rung my local mechanic and said it is just like when watching Super Bikes etc and traction control cuts in [or in fact cuts OUT the spark] and he asked if my bike has reverse override and I said yes and he said well it sounds like your bike thinks it is in reverse.

so first I simply tried pushing override button but that had no effect.

to explain, the main item was a new cylinder, rebore etc, and I cleaned every contact on the ignition system at the time but that was a year ago and in tropics on beach everything grows fungus over wet season.

so I am looking for suggestions of most likely cause of the splutter and should mention that I did a lot of patching of exhaust system and it could be leaking a bit at several points [which also seems to cause power drop on 2 strokes]

 

if the overide was kicing in, it would not come out of it and would be kicking in right of idle pretty much. yes an exhaust leak would loose power some, but not a great deal. imo

 

Thanks stendori,

In fact I spent the day yesterday working on both issues and will be testing it again today once I put it back together.

However there WAS a good deal of rust/corrosion on most terminals etc of the ign system [and this time I will use stainless steel bolts etc as I have done on all other parts of bike] so I should have a way better spark hopefully.

Also the "beer can" style fix I did where tail pipe joins engine had come partially adrift and I have hopefully corrected that as well.

Will report on the outcome but I have my fingers crossed that it will be OK now

 

OK, all is well - the problem appears to have been the exhaust leak at end of U Bend, to which I have now "applied a better beer can". The splutter has gone.

The time spent on the ign side was however well spent as corrosion was very bad and now it starts instantaneously every time.

Time to go fishing again up the beach, but now with the whole underframe replaced with timber, so no more rust.

Thanks again for help.

 

glad you got it straighten out.

 

One more question.

The throttle on my bike is simply depress the thumb and a cable mechanically lifts a piston in carbie, but it says on top of throttle it is an electronic throttle [for your safety] and sure enough there are "electrics" going into the housing with the thumb lever.

So what is the function of the electrical side of the throttle control?

 

ETC is there for a safety .........If the Quad was started and you had no way of knowing if the cable is hung up.........This will prevent wide open condition and keep you ride from taking off on you. also will detect a broken cable and will loose tension at the switch..........Hope that helps...Caper.......

 

If your ATV ever starts staling at idle the ETC throttle adjuster is the first thing to look at.

 

thanks for that and now things make sense.

when I put in new piston etc and first started engine it was revving very high at idle and I found that the piston in carbie was being held above the level of the idle adjust screw [I am assuming a previous owner did an adjustment because the old engine was so poor it needed more than the idle screw could give].

So I fiddled with the adjustment at both ends of the cable till I at least got the piston to sit on the base, then propped it up with a slight turn of idle adjust screw.

I am thinking now I might need to check this out again from what you say. Can you please explain how it actually works, eg does it feed back to ign system and do similar to the rev control for reverse

EDIT - OK I have looked at it again and can see it is a micro switch [which I assume simply acts as a cutout on engine] and without a stuck cable can only give problems at idle. In fact my adjustment did not give full pressure on the micro switch so that would explain why it cut out at idle once. I have readjusted and will take it for a run later.

 

If there is throttle cable tension lose,a switch in the throttle housing closes. This grounds The CDI and disables the ignition system. Here's a video about it.http://www.ehow.com/video_4468404_po...intenance.html


Has no bearing on idle speed, the idle screw does that.#26 The last owner may of fooled with the top adjusters that control the #7 slide and #5 needle height like you said. Here's how you clean those carbs.http://www.ripperd.com/ftp/admins/carb_rebuild/