Snatchy throttle

[user 11561]

Link : http://www.miniriders.com.au/minimotards/28727-snatchy-throttle.html

Gents, hope you can help!

On both my bikes I have a snatchy throttle responce from fully closed and rolling the throttle open.
One bike has org been setup by my mech and as i remember it didnt do it just after he had is but not sure and the other is brand new and have only been tunes by ear and god advice!

Bike one: 155Z with V2 head with matching high comp piston and Mikuni VM26 (org - not aftermarket)
Bike two: Stock RevMX, unitfilter fitted


What can i do to over come this?
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[sean01]

what do you mean by snatchy throttle

and post both engines jetting mate

 

[user 11561]

what do you mean by snatchy throttle

and post both engines jetting mate

When i go from 0 throttle and start, slowly, too roll on the throttle it kickes in fast - a bit like releasing the clutch!

Bike one: have to look what jets i have
Bike two: K#40 pilot jet, Needle clip on the second groove from the TOP, and a K#102 main jet. I've played around with the air-screw so not to sure where that is!

 

[dafunk]

mine was bad at the mintard night .
i couldnt get on the gas without getting slides
when we ran reverse direction it got even worse !
dean was also having the same symptoms
better have a look before friday
i feel mines too rich

 

[sean01]

sounds like its running lean down low.. k102 should be on the money for the mainjet
and id be susing out the mixture setting as this is determined from the pilot...
best is @ around 1.5 turns, if it runs better at more than 2-2.5 turns than a smaller pilot is needed if it runs better fully closed then a larger pilot is needed.
any glowing exhausts?

just remember too guys, its getting really cold at night now and also pretty cool during the day so jetting can be thrown out easy

 

[dafunk]

no glowing exhaust
mine would surge at full lean with a just opened throttle
and at one point would open throttle and nothing would happen for a second then pow and slide wobble wobble
tried mine mixture screw closed and it was worse [too rich]
3 turns open not much better if any
worse as it got colder [too lean]
does temp affect your londin?

 

[sean01]

hmm, what octane fuel are you using?
and has either of you checked your valve clearances lately(just to rule that out)

no glowing exhaust
mine would surge at full lean with a just opened throttle
and at one point would open throttle and nothing would happen for a second then pow and slide wobble wobble
tried mine mixture screw closed and it was worse [too rich]
3 turns open not much better if any
worse as it got colder [too lean]
does temp affect your londin?

can you post what engine your running and carb type and jets

 

[09crf_149]

says it in the first post

 

[dafunk]

yx 187cc taki head and piston, fmf ex
oko carb jets cant remember full rich on the needle clip
using premium pump gas
i havent cleaned the carb for a while will look tomoro
but strange we had the same snatchy feeling???

 

[sean01]

yeah it is strange...
and yeah let us know jet sizes and any thing else you find.
give the carb a good blow out

 

[dafunk]

i wonder if nocrfhere had any tuning drama?
there proberly un related problems ?
thanks to londin for sharing his snatchy feeling!

 

[sean01]

is it the same during daytime temps?

lean carb will make it really really crisp and responsive which is probly what your feeling

 

[thump*140]

i'm thinking the pilot is a bit lean... cold night, would have made the engine feel very crisp, with heaps of response, as sean said... same reason Drag racers love night racing..... cold air makes more power, and better throttle response... cold nights, probably better running the 45 pilot on the TTR, not so sure with the other one...

 

[dafunk]

after inspecting carb and plug
it looks lean
thanks guys

 

[no_crf50_here]

i wonder if nocrfhere had any tuning drama?!

Pete's bike is never well enough tuned

 

[dafunk]

flat slide looks great
did you have any drama at the last minitard night?

 

[user 11561]

I also found that I had popping after full noise in 4th gear - it got less the colder it got! So i adjusted the mix screw and that helped! Will have to try some different jet on Fri/Sat.
Funk maybe we should just harden up and go sideways out of the corners....oO(or highside!)

Bike 1 didn't feel like it have the problem when it was warmer...so a bigger jet would help? Have i understood it correct?

 

[sean01]

i think plug chops in the problem rev range will be your only way..

also make sure your exhaust is sealing good.. and incase you havent yet, check yr valve clearances..

popping on deceleration after full noise can be a lean pop or exhaust leak, sucking in cold air..

 

[dafunk]

im going with the bigger pilot jet 45
i didnt plug chop ,but it looks lean
i think it would help yours londin
do the checks sean recommended too

 

[dafunk]

i rekon the drift car crew would like to see some top gear highsides!!!