TOPIC:

i recently changed my gearing, i went from a 15/39 to a 15/33, my bike was running lean prior to the sproket change so i had to run it with the choke partially on, tonight i drilled my jets out with a 5/64, up from a 1/16 bit.

befor the changes, without the choke on it looked somewhat grey and brown, now with the gear/jet changed its very grey and after about 15-20min of riding it runs like shit, it misfires/hesitates under aceleration, and has a very very light poping noise under decelleration.

its running an open 4:1 header, could the gear change cause the engine to be under too much of a load and cause it to overheat.

i run it between 2.5k and 4.3k usually hovering at 3k

edit: i didnt know what forum to post this in becase it contains engine/gearing/carb.

Post edited by: themachine, at: 2007/07/29 01:28

To answer your question about gearing affecting the temp of the engine, I doubt it.


"befor the changes, without the choke on it looked somewhat grey and brown, now with the gear/jet changed its very grey and after about 15-20min of riding it runs like shit, it misfires/hesitates under aceleration, and has a very very light poping noise under decelleration."
All this sounds like too lean a mixture.

Popping under deceleration sounds like a leaking exhaust gasket.


"after about 15-20min of riding it runs like shit, it misfires/hesitates under aceleration"

Are you sure that the vent in the gas cap is open? Is it possible that after fifteen or twenty minutes of riding your fuel can't drain because of a vacuum in the tank?

Just a bunch of guesses.

kzcsi

hurm, i'll have to check the vent out.

Just start riding when the performance falls off open the tank and keep riding. If the vent's plugged you'll know right away.

kzcsi

Standard jobber drills do a pretty crappy job
of making a hole.Unless you want to spend the
money on some real small reamers,I suggest buying
larger jets.I have known several people that have
had bad luck drilling jets.Let me know your engine,
cam,carb specs and I might be able to suggest jets
that will get you close.

1982 csr1000 m2 J-motor
bored to 1170cc wisco 10.25:1
ported/polished head with ape street/race valvesprings
stock csr cams
stock ignition, coil mod soon,
mukini 34mm's
pods
vance and hines 4:1 header with just a turndown off the header
gearing 15/33
avon venom rear tire 130/90/16

i plan on getting the full dyna ignition package this winter along with the ape turbo/juice cams and possibly the juice kit.

You drilled the jets? bad idea, the jets are not the same size now and the flow has been messed with, you might as well buy some new jets in the size you need then start checking for other problems.
The motor dosent know what gear it has