28 replies to this topic

[LD_Framework]

 

 

have used colourtune and then road tesing with success but depends on your start point. if you have chucked loads of things on may not get anywhere near without needle change or modification aswell. Are you just doing a tune up or fitting stage one kit and recommended needle? for idle speed fitting standard airbox and filter shouldn't cause enough restriction to reduce engine idle speed

fitting stage one kit with recommended needle, just want to be sure to use the best options.
what you mean about the idle restriction? the screw is under the box so... need to disassemble every time.

What carb have you got? What air filter?

 

I have the HIFF 44 classic, with the k&N filter (with the original intake box), basically the stage one kit. 

[LD_Framework]

 

 

have used colourtune and then road tesing with success but depends on your start point. if you have chucked loads of things on may not get anywhere near without needle change or modification aswell. Are you just doing a tune up or fitting stage one kit and recommended needle? for idle speed fitting standard airbox and filter shouldn't cause enough restriction to reduce engine idle speed

fitting stage one kit with recommended needle, just want to be sure to use the best options.

what you mean about the idle restriction? the screw is under the box so... need to disassemble every time. 

 

the kit will usually come with free flow air filter and even if this is in the atsndard airbox fitting this after setting up the carb shouldn't drop the idle speed by enough to require removing air filter to adjust again. Just make sure engine is up to normal temp. before adjusting carb. would also suggest holes at front of standard airbox if using that

 

but how can I adjust the idle without a filter mounted? too much air through. 

[Rubbershorts]

 

 

 

have used colourtune and then road tesing with success but depends on your start point. if you have chucked loads of things on may not get anywhere near without needle change or modification aswell. Are you just doing a tune up or fitting stage one kit and recommended needle? for idle speed fitting standard airbox and filter shouldn't cause enough restriction to reduce engine idle speed

fitting stage one kit with recommended needle, just want to be sure to use the best options.

what you mean about the idle restriction? the screw is under the box so... need to disassemble every time. 

 

the kit will usually come with free flow air filter and even if this is in the atsndard airbox fitting this after setting up the carb shouldn't drop the idle speed by enough to require removing air filter to adjust again. Just make sure engine is up to normal temp. before adjusting carb. would also suggest holes at front of standard airbox if using that

 

but how can I adjust the idle without a filter mounted? too much air through. 

 

Take filter off and adjust idle. Put the filter back on and take for a spin. If idle is then too high/too low when you return repeat the exercise in small increments until it's eventually where you want it. It's not massively out with filter off as opposed to filter on. Daz.

Edited by Rubbershorts, 23 December 2024 - 01:56 PM.

[LD_Framework]

 

 

 

 

have used colourtune and then road tesing with success but depends on your start point. if you have chucked loads of things on may not get anywhere near without needle change or modification aswell. Are you just doing a tune up or fitting stage one kit and recommended needle? for idle speed fitting standard airbox and filter shouldn't cause enough restriction to reduce engine idle speed

fitting stage one kit with recommended needle, just want to be sure to use the best options.

what you mean about the idle restriction? the screw is under the box so... need to disassemble every time. 

 

the kit will usually come with free flow air filter and even if this is in the atsndard airbox fitting this after setting up the carb shouldn't drop the idle speed by enough to require removing air filter to adjust again. Just make sure engine is up to normal temp. before adjusting carb. would also suggest holes at front of standard airbox if using that

 

but how can I adjust the idle without a filter mounted? too much air through. 

 

Take filter off and adjust idle. Put the filter back on and take for a spin. If idle is then too high/too low when you return repeat the exercise in small increments until it's eventually where you want it. It's not massively out with filter off as opposed to filter on. Daz.

 

Ok, I tried but without the filter I struggle to keep the engine running, looks like too much air through. I will try again!

[Rubbershorts]

 

 

 

 

 

have used colourtune and then road tesing with success but depends on your start point. if you have chucked loads of things on may not get anywhere near without needle change or modification aswell. Are you just doing a tune up or fitting stage one kit and recommended needle? for idle speed fitting standard airbox and filter shouldn't cause enough restriction to reduce engine idle speed

fitting stage one kit with recommended needle, just want to be sure to use the best options.

what you mean about the idle restriction? the screw is under the box so... need to disassemble every time. 

 

the kit will usually come with free flow air filter and even if this is in the atsndard airbox fitting this after setting up the carb shouldn't drop the idle speed by enough to require removing air filter to adjust again. Just make sure engine is up to normal temp. before adjusting carb. would also suggest holes at front of standard airbox if using that

 

but how can I adjust the idle without a filter mounted? too much air through. 

 

Take filter off and adjust idle. Put the filter back on and take for a spin. If idle is then too high/too low when you return repeat the exercise in small increments until it's eventually where you want it. It's not massively out with filter off as opposed to filter on. Daz.

 

Ok, I tried but without the filter I struggle to keep the engine running, looks like too much air through. I will try again!

 

In that case there is another problem. When fitting my stage 1, I accidently left the needle proud of it's seat which starved the engine of fuel. It ticked over okay with the filter on, but struggled when I took the filter off. This was rectified once the needle was correctly seated in the piston. If you still have your jet wound right open, as much as in the original post picture,  you may need to check the needle is pushed right home first. Then start again with the carb by going back to the original recommended amount of turns. I don't think I would be winding that idle screw all the way in to counter act something else that is wrong.

[ACDodd]

Ahem, you can’t tune without using a method to measure your fueling.

Ac

Edited by ACDodd, 23 December 2024 - 06:32 PM.

[Rubbershorts]

Absolutely true mister Dodd👍

The above is an answer to the idle screw adjustment query only😉

[Ethel]

Back in the old days, when wet moss was considered instrumentation, you set up yer SU by lifting the piston, with the lifting pin (if provided) or tip of a screwdriver if not. The revs should climb a tad, then recover, if the mixture was right. If it stalled it was lean & if it revved it was rich.

 

It's more art than science, but it's still useful to get you out of a jam, or to get it running well enough to use something more sophisticated.

 

https://youtu.be/4nvGLgO6pj0?t=328

[68+86auto]

If your air filter is changing your idle much, you've got something wrong.

[timmy850]

Back in the old days, when wet moss was considered instrumentation you set up yer SU by lifting the piston, with the lifting pin (if provided) or tip of a screwdriver if not. The revs should climb a tad, then recover, if the mixture was right. If it stalled it was lean & if it revved it was rich.

It's more art than science, but it's still useful to get you out of a jam, or to get it running well enough to use something more sophisticated.

https://youtu.be/4nvGLgO6pj0?t=328

This was the factory suggestion, but only on the assumption you already had the right needle for your particular engine spec

These days with different parts and fuels you really need to check, measure and adjust accordingly

It’s also interesting to compare the “lift pin” method with an air fuel ratio gauge

[Ethel]

Yes, a stopped clock-twice a day situation.

 

Still useful to know though. As hinted at by a lot of comments, if it doesn't work it  can help diagnose something else: like a leaky throttle spindle if it runs rich after being set up to idle properly.

[LD_Framework]

Ahem, you can’t tune without using a method to measure your fueling.

Ac

what method do you suggest for this?

[timmy850]

You need an O2 sensor in the exhaust pipe joined to an air fuel ratio (AFR) gauge. It’ll tell you the ratio of air to fuel and if the engine is running rich, lean, or in the ideal zone

I use an innovate mtxl plus, but there are also other good options

https://www.innovate...KDhCmRmrPT2tFeQ

I’d suggest watching a few of AC Dodds videos. A good starting point is the 4 part series from CMC Riviera Run from about a year ago

https://youtube.com/...8cTwvBqXfZqPnfC

[LD_Framework]

thanks guys!