Hi Guys,

I am a new F4i owner and am sure that ppl has find this topic abit boring.

Bike:
01 F4i
mileage : 16000 km
condition very new.

This bike hasnt been running for 5 year. I have changed the fuel pump, FPR, Spark Plugs, oil , and oil filter.

This bike is working, reving up high and riding smoothly.

The only issue is it is idling at 2500 rmp. I tried to adjust the idle screw, i could increase it from 2500 but not going down. Tried adjust start valve. No luck.

When the bike is warmed up, butterflies are close and start valves are all closed.

No lose vacuum tube, and no block vacuum tube.
Used a plastic fishing wire to feed trought the 6 vacuum tube to the cylinder. could see the wire throngt the butterfly hole, so no blockage

NO visual vacuum leak, cos i spray water around all rubber, no change of noise.

I tried to unplug the vacuum tube from FPR, rev increase. ( i think it is normal)

I tried to unplug the vacuum tube from MAP sensor. I could feel the vacuum from the tube, But not reaction from the bike, not rev high or low. ( i think it is abnormal, cause enging would suck more air)
If i connect the vacuum tube back to the MAP sensor and unplug the MAP electrical plug, rpm drop.


There is the question guys, base on the work that i have done.
What is the cause of the high idle? what test should i do?

Is that a broken MAP sensor? or actually vacuum leak some where? or it is TP sensor or IAT sensor?

this problem is doing my head. Please help

 

Being that the bike sat for so long, the idle adjustment screw cable portion may be working, but the portion of the throttle body that closes the butterflies all the way may not be returning to the closed position completely. I've seen this on other models. I'd take some parts cleaner, and shoot it in on where the idle adjustment meets the throttle body and then loosen up the idle adjustment screw again. See if this makes a difference. I'm betting it is just dirty. After that, I'd hit it with PB Blaster or an equivalent. Hope this helps.

And yes, it could be a vacuum line off too. Find the lines off the throttle bodies and trace them according to the service manual to ensure you aren't sucking air.

 

Thanks for your reply

I have visually checked the butterflies area, and used my finger and alcohol to clean the area. it feels smoot. or it is not a good way to check

i have checked the idel adjustment screw. when i turn the screw, i saw the starter valve in the TB moving. so, i assume the adjustmet scress is fine.

 

Hi guys,

Latest update!!

I bought new vacuum tube, a silicone gaskit seal maker and a bottle of carby cleaner from an auto shop.

Today I took it apart! I sprayed the cleaner on the 3 way and 5 way split on the vacuum tube, rpm dropped. I checked the vacuum tube pressure, about 100 mmhg. I changed all vacuum hoses. Vacuum gone up to 125 mmhg. But the service manual said it should be 150-250 mmhg. So somewhere is still leaking

I sprayed in the 4 boots, rpm drops! So boots are leaking. Cos I don't have new boots, I put seal around and test again. Sprayed the cleaner on the boots, rpm drop. So sealant is not working.

My question is, if I buy new boots, are there going be zero leak. If I spray cleaner to the new boots, there should be "absolutely" no rpm change??

Cos the boots in Australia are expensive. Don't want to buy it and still not working.

In fact, this is a 2001 bike, my fd had it sat in garage for 5 year, plus 1-2 year when he actually rode it. So I think they are the boots from 2001. Rubber from more than 10 yr ago. They should not be working, right?

Today after I took it apart and put it back together. Idle is still high and jumping bittern 2500 and 3000

Vacuum leak should make high idle, but what makes it jumps?

Appreciate any discussion!!

 

Which city are you? If in Sydney I could go take a look.

 

Great Kopi,

I am in Sydney, live in leichhardt and work in bankstown. would be great if we can meet up and just have a chat

my email is victor.wong1@yahoo.com.au

 

I'll email you

 

https://cbrforum.com/forum/f4i-main-...e-help-147522/