Bike jerks when throttle is fully opened

[skully]

Recently just changed piston and still running in. While doing a hard run-in, my bike sometimes jerk whenever I open the throttle fully. Bike also sometimes jerk when, from full throttle, close to about 70% throttle momentarily, then open 100% full again.

 

Anyone experience this before? Or any pros out there care to explain what's wrong?

 

Thanks.

[Raptor]

What bike you riding?? 2 stroke or 4 stroke? Carburettor or fuel injected??

 

Without more info.. its quite hard to get help.

 

Anyway.. the common cause of throttle lag or bogging as described by you is wrong size of main jet or needle position in a carb engine.

[Demon]

Recently just changed piston and still running in. While doing a hard run-in, my bike sometimes jerk whenever I open the throttle fully. Bike also sometimes jerk when, from full throttle, close to about 70% throttle momentarily, then open 100% full again.

 

Hard running is only safe for new bikes where everything is original from factory.

 

If you have done an overhaul locally, it's is very unlikely everything has been rebuilt to factory specifications so it safer to do a normal run-in. It's more for the safety of the rider rather than the engine

[skully]

Sorry, it's a 4 stroke carb bike. Yea I did overhauled locally to a larger piston..

 

Anyway, thanks for advice.

[Raptor]

Sorry, it's a 4 stroke carb bike. Yea I did overhauled locally to a larger piston..

 

Anyway, thanks for advice.

 

Then that explains it. Bigger piston means more intake.. if you have not rejetted your carb to cater for more air going in..ie with a bigger main jet... you will get a lag in the throttle response.

[spaiduhz]

What bike you riding?? 2 stroke or 4 stroke? Carburettor or fuel injected??

 

Without more info.. its quite hard to get help.

 

Anyway.. the common cause of throttle lag or bogging as described by you is wrong size of main jet or needle position in a carb engine.

 

Jetting! Say, @aRcHeR, lets say i purchased an ivans jet kit over the net, would you be up to install it into my fz1 gen1?

[KeraKing]

i think the bike is too powerful thats why jerk when open full throttle..

does it bring the front wheel in the air too?

 

i suggest trying a smaller rear sprocket.

it will save a bit of fuel too.

[Billemans]

Also look at the spark plug color, this can tell you about the mixture. Guide: http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-analysis