incradeble lag time in trottle response

[ducatigirl100]

Hi 

I puzzled whit a problem and I cant' find the source of it 

When I twist the throttle very hard ( when I don't' use my brain and just want floor it !  )

it's like I twist the throttle to give gas but the bike doesn't move ( well not as fast it sould)  there's a considerable time betwen when I twist the throttle and the time the bike react ( 3sec. at lest )

1995 m900

possible sources of problem ?

1) clutch plate completely burn and worn off
2) I've bleeded the clutch but after 10k the liquid was already all black
3) some crap entered the carburetor ?
4) throttle cable on the brink of total failure ? ( that the one that worries me the most 

[battlecry]

Not sure if your M900 has a tachometer, I think the early Monsters only had a speedo and lights.  If it has a tach and a speedo, go out and floor it again, watching to see if the RPMs increase immediately in the tach and the speed lags.  That may indicate a clutch slip issue.

If it is not a clutch slip issue, could you be in too high a gear? Floor it again in a lower gear and see if it responds better.

I'm not familiar with the carbs on the M900.  I know on some carburetors without accelerator pumps opening the throttle suddenly leads to a bog, a flatspot in power delivery, because the extra opening on the throttle reduces the available vacuum the carb can use to evaporate the gas.  Somebody with more experience on these carbs, and there are many on this board, will probably chime in soon.

Good luck!

PS - The clutch fluid turns black no matter what you do.

[Slide Panda]

If the clutch was slipping, the engine would spin up, increase in RPMs but the bike would not got faster - at least not as expected. So if the engine RPM is still matched to the speed - don't worry about the clutch.

Throttle cable is not likely the cause either. But it's not hard to check it's condition. You can see the end attached to the carbs, and access the other end at the twist. If you disconnect the cable from the throttle tube and carb cam it should move in the jacket with little resistance. If it's binding, it probably just needs lubrication. Cable lube can be purchased at most bike shops. It'd be shocked to hear the cable was wearing out. Unless it's been bent or abused there's really no strain on that cable.

It's probably a carb issue - exactly what... now that's the question. I'd start by running a couple tanks through with a cleaning agent like Sea Foam or Techron through to see if that leads to improvement.

But it's quite possible that the carbs need a thorough service. They are 18 years old after all - do you know if they have ever been serviced?

[ducatigirl100]

The carb dosent' seam to have been services ...it surely dosent look like it ....

also I change the place of the crakcase filter (pod) now it's direcly on the crankase whit no hose this could be it ?

[Slide Panda]

#1 having 18 year old carbs unserviced carbs is the most likely the cause. You probably need to have them fully serviced - replace soft parts and jets

#2 moving the breather would not cause throttle lag

[ducatigirl100]

update

while I was bleeding the clutch ( just in case)  the bolt whit the valve (bleed valve) on the slave cylinder  stayed in my hand        

where can I get one? or does somebody as one one laying around  ?  

[bond0087]

I'm not quite sure what you mean about the bolt on the slave cylinder staying in your hand, so I don't have any advice on that problem, but back to your original problem, it sounds to me like torn vacuum diaphragm(s) in the carbs. That's a guess, though, but it's a guess that isn't too hard to check. You can access the vacuum diaphragms by taking the top of the carbs off, and then you can hold them up to the light and check if you see any light coming through.  If so, you can get replacements from a Suzuki dealer for about $20-$30/ea (see cheap alternatives thread).

[Ddan]

update

while I was bleeding the clutch ( just in case)  the bolt whit the valve (bleed valve) on the slave cylinder  stayed in my hand        

where can I get one? or does somebody as one one laying around  ?  

The bolt won't just go back in?  Can you take a pic?

+1 on the carb diaphragms

[ducatigirl100]

here's the bleeder . I've called the dealer and they told me that they don't sold it separately so I would have to get another clutch slave cylinder....but my uncle (he's a mechanic) says mechanic have usually this part in a miscellaneous box somewere I'll check the nearest auto part store I just have to find a bolt whit the same tread ...

I thoroughly check both diaphragm from the carburetor and they hare sparkling clean and not damage... I've tried the bike after and the lag is still there.

the liquid of the clutch that black out only after 10k is a sign that there someting wrong whit the clutch

andthe throttle cable is check to and it's fine

[koko64]

Hey 100
The dealer should sell the bolt and bleeder nipple/screw as a unit. They are seperate from the slave cylinder. Not too expensive.

Have a look at your spark plugs to see what they say. They may tell us what your carbs are doing. With the throttle lag, is it rough, lumpy, coughing or slow and smooth?

[ducatigirl100]

Hey 100
The dealer should sell the bolt and bleeder nipple/screw as a unit. They are seperate from the slave cylinder. Not too expensive.

Have a look at your spark plugs to see what they say. They may tell us what your carbs are doing. With the throttle lag, is it rough, lumpy, coughing or slow and smooth?

When I called the dealer they say they don't sold it separately from the slave but I'm pretty sure that a load of crap!   it's the "blonde girl syndrome" probably 


and the lag is really slow and smooth.... it's like the gear just doesn't go in ( but the gear is definitely in !)  that'swhy I'm looking more outward the clutch

[battlecry]

Your father is right.  We call them "banjo bolts with bleeder screws".  They should be around $15 US.  Make sure the thread and length match.  Get some washers also.  You can mail order them if they are hard to find locally.  A mechanic can probably extract the broken part with an "easy off extractor" and then you only need the screw.

The black fluid is not an issue on the clutch slave.  It might be on the brakes.  On the clutch the fluid turns black rather quickly and does not seem to impact operation.

I'm curious.  If instead of suddenly opening the throttle fully, you turn it quickly, does the bike still seem sluggish?

[ducatigirl100]

I'm curious.  If instead of suddenly opening the throttle fully, you turn it quickly, does the bike still seem sluggish?

when I turn it quickly is does it ... it's only when I take my time that    the throttle response seams to be ok ... I noticed it because it was a really "sudden "symptom that appeared 2 weeks ago

I cheeked the spark plugs and there are all black out whit carbon ( to rich ) and there some oil deposit on the tread... I changed them but I will have to look into that ..suddenly the "carburetor" theory look more plausible

[Howie]

Possible needle jet time on your carbs.  They wear oval over time and cause the bike to run rich on part load.  Only a guess, but a magnifying glass will tell you. 

I think this is your screw
http://www.yoyodyneti.com/ProductInfo.aspx?productid=LVF125/1S
and your washers
http://www.yoyodyneti.com/ProductInfo.aspx?productid=LVF125/1S
if you can't find them locally.

Call Fred to make sure the part is correct
973 386 0040
Fax: 973 386 0042

[ducpainter]

Kinked vent hoses can cause a lag too.

Plugs usually foul, or are at least very sooty.