[Q&A] SBF CB400 Official Q&A Thread 2009 (PLS ASK YOUR QUESTIONS HERE!)

[slutgarden]

hi bros. when i start my engine early in the morning, it feels like the engine sound feels like choking, having asthma. after awhile, then it sounds alright to me. but whenever i off the engine, then 5 mins later went to start again, the asthma came back. is it normal? please advice. thanks in advance!

 

gotta send ur bike to tune.. mine was like that too, if i were to start a cold start in the morning, need to rev it till 2k rpm for about 20 secs then only idle will be normal..

 

other wise, if never rev, engine will die off, after choking over and over again..

 

its your tuning, or perhaps you need to check your headers, see if it's all hot after maybe 30 secs..

 

could be one of the spark plugs not firing, or could be wet, and it needs time to get 'fired' which might cause your haywire idling or in your case 'choking sensation'..

[tng2377]

When driving the vehicle with the rpm high enough for VTEC operation, the engine control module (ECM) operates the variable valve timing solenoid to open the solenoid and allow oil pressure to be applied to the pistons in the intake rocker arms. This action causes the outer rocker arms to be pinned to the middle rocker arm and now the three rocker arms operate as a unit, using the high-lift camshaft lobe for improved high-end power. When the engine rpm drops below VTEC operation, the VTEC solenoid is not energized and hydraulic oil pressure is turned off. This allows the return spring to return the pistons to their rest position and lets the rocker arms operate independently again. The VTEC transition between low and high rpm is smooth and normally not felt by the driver.

 

The ECM also looks at other inputs for VTEC operation - engine temp, engine oil pressure and vehicle speed (VTEC does not turn on unless the vehicle is moving). A separate oil pressure switch monitors the VTEC system. If a problem occurs, the ECM can turn off VTEC operation and will set a code, turning on the "check engine" light. In some cases, it can also cause a driveability problem.

 

The VTEC oil pressure switch is a normally closed switch. The ECM sends a voltage to the switch and expects the voltage to go through the switch to ground.

 

Maybe ur engine oil pressure or solenoid and wiring connection is no good..that why vteec dont kick in

[Ah Pek]

well not really, because tuning all done, and bike was in tip top condition..

 

went to mech, found out there was leackage ard the engine case area, sealed with new gasket and rubber tubings..

 

still v-tec doesnt kick in, although there is no power loss..

 

opened up the valve, found loads of carbon packed, cleared everything, but still vtec doesnt kick in..

 

now all scratching head, even the mech now trying to trial and error..

 

could be 1) valve worn out

2) vacuum nt really working, air escaping. (but this is just a plausible thing as there is not much power loss.)

 

 

timing and firing all okay, no pop pop or whatever..

 

will update again tomorrow , will be sending bike back to the same shop and see what we can do.

 

You did not mentioned about your oil pressure sensor (its the thing that detect your rpm increase and actuate your the other 8 valves after 6.+ krpm)..have you guys check that. Not sure why the mech did what you mentioned..vaccum, valves? Don't forget before you did what you did, your ride was ok. Since he change the clutch plates etc..check for the sensor cables that runs into the crank case. In the forst place, does he knows where to look for the oil pressure sensor assembly or not?

[Ah Pek]

hi bros. when i start my engine early in the morning, it feels like the engine sound feels like choking, having asthma. after awhile, then it sounds alright to me. but whenever i off the engine, then 5 mins later went to start again, the asthma came back. is it normal? please advice. thanks in advance!

 

Try opening your choke and pull it a few times to start the bike and rev high a few time after warmed up. Likely your butterfly flap is dirty as we hardly use our choke. Carbs tunning normally don't come off tune by itself.

 

If its still a problem..you may want to do an airbox to carbs intake flush cleaning. Let me know.

[loyjwe]

ah pek what does this flushing from airbox to carb does? what help it gives? improve on cold start or?

[sadxjr]

gotta send ur bike to tune.. mine was like that too, if i were to start a cold start in the morning, need to rev it till 2k rpm for about 20 secs then only idle will be normal..

 

other wise, if never rev, engine will die off, after choking over and over again..

 

its your tuning, or perhaps you need to check your headers, see if it's all hot after maybe 30 secs..

 

could be one of the spark plugs not firing, or could be wet, and it needs time to get 'fired' which might cause your haywire idling or in your case 'choking sensation'..

 

Try opening your choke and pull it a few times to start the bike and rev high a few time after warmed up. Likely your butterfly flap is dirty as we hardly use our choke. Carbs tunning normally don't come off tune by itself.

 

If its still a problem..you may want to do an airbox to carbs intake flush cleaning. Let me know.

 

slutgarden, i dont have to rev then it sounds normal. after parking one night at mscp, like what i said, it always seems like having asthma when i start. but after awhile its okay. my engine also never die off. now lets say i travel from hougang to changi then i off engine, then 5 mins later i start again. i believe my engine has already warmed up. why does it feels like asthma again? would it be any other problems? thanks for your point bro.

 

ah pek, thanks for your info. i will try it out. anyway, what is the use of airbox to carbs intake flush cleaning? care to elaborate more?

[Ah Pek]

ah pek what does this flushing from airbox to carb does? what help it gives? improve on cold start or?

 

Its a process where you spray in circular action a solvent specifically formulated to quickly and easily remove gums, sludge, varnish and dirt build up in the carbs caused by carburetor deposit.

 

You have to have a 'tool' to insert into the 4 carbs thru its inlet via the airbox. I have done it only to non vtec..not sure about vtec bikes air box intake system but should be able to.

 

Save you a $70 job for carbs washing for only $10. Does just a good job without having to dismantle the carbs and unscrewing all the components afterall when you start and blow..all 'shits' will be exhausted out. You want you can call it "Carbs Servicing"..

 

This is usually done because the flaps are not fully open as we hardly use the choke..and there are bound to be clogs of gums, sludge, varnish and dirt build up in the links and area around it.

[Ah Pek]

ah pek, thanks for your info. i will try it out. anyway, what is the use of airbox to carbs intake flush cleaning? care to elaborate more?

 

At least yours started but some ppl are unfortunate. There is someone here from this forum got such problem and ended up not starting at all along Bedok North in the early hours just past mid nite sometime back. I did what I said earlier and all was well.

 

 

 

>>airbox to carbs intake flush cleaning? care to elaborate more?

 

Its a process where you spray in circular action a solvent specifically formulated to quickly and easily remove gums, sludge, varnish and dirt build up in the carbs caused by carburetor deposit.

 

You have to have a 'special tool' to insert into the 4 carbs thru its inlet via the airbox. I have done it only to non vtec..not sure about vtec bikes air box intake system but should be able to.

 

Save you a $70 job for carbs washing for only $10. Does just a good job without having to dismantle the carbs and unscrewing all the components afterall when you start and blow..all 'shits' will be exhausted out. You want you can call it "Carbs Servicing"..

 

This is usually done because the flaps are not fully open as we hardly use the choke..and there are bound to be clogs of gums, sludge, varnish and dirt build up in the links and area around it.

[ElfTech]

Help...someone pull out my fuel tank tube connected to the carb...i can't put the small tube in...pls advise

[Ah Pek]

Help...someone pull out my fuel tank tube connected to the carb...i can't put the small tube in...pls advise

 

If its the smaller tube..its the vaccum. Don't fred..your bike can't idle iszit? Ok..if its out from the tank reservoir..there is only one small nozzle..just plug it back. If its dangling from the tank, means it came out from below.

 

Look behind the back of the engine block (left side)..there is a metal type nozzle sticking out..just plug it back in. Its preety small but can see.

 

Sometime, this tube does comes off at high rev especially if the tube is harden and flare at the lips opening and there is no locking clips.

 

Good luck.

[dragonforce]

hi

 

i am facing a minor problem here, i want to take out my crashbar so that i can sand it and spray a new colour as the paint have already dropped. but the right side crashbar cannot be taken out cos its blocked by the engine casing as circled.

http://i46.photobucket.com/albums/f128/inflames85/crashbarscrew.jpg

how do i remove this screw and nut?

thanks..

[slutgarden]

In the forst place, does he knows where to look for the oil pressure sensor assembly or not?

 

that question troubles me though, because vtec can be quite complicated and im not sure whether or not my mech knows much, because the shop only does mostly 2b bikes and i do not see much 2a bikes (well perhaps gsxr400,and the 2 strokers old timers)..

 

i guess i've sent it to the wrong shop in this case..

 

i'm really in need of desperate help, anyone knows which reliable shop that knows about the v-tec system and is able to rectify the problem ?.

and also , would the shop be able to 'rent' me their bike say if i have to leave it there?. own transportation is a must for me, and public is a no no, i know some shop practice that, well renting the the bike to their customer who needs to leave their own bike at their shop for repair..

 

well any reliable good shop to recommend?.

 

well ahpek, i guess so maybe its the oil pressure or the oil pressure sensor nt working..

well i did mentioned about that when i went to shop, he says that is not likely so, but did not give me a reason as to why did he nt check.. sigh...

 

but really power no loss, i guess it brings it down to the oil pressure thingy..

 

thanks a million for narrowing it down ahpek.. great help..

[Ah Pek]

that question troubles me though, because vtec can be quite complicated and im not sure whether or not my mech knows much, because the shop only does mostly 2b bikes and i do not see much 2a bikes (well perhaps gsxr400,and the 2 strokers old timers)..

 

i guess i've sent it to the wrong shop in this case..

 

i'm really in need of desperate help, anyone knows which reliable shop that knows about the v-tec system and is able to rectify the problem ?.

and also , would the shop be able to 'rent' me their bike say if i have to leave it there?. own transportation is a must for me, and public is a no no, i know some shop practice that, well renting the the bike to their customer who needs to leave their own bike at their shop for repair..

 

well any reliable good shop to recommend?.

 

well ahpek, i guess so maybe its the oil pressure or the oil pressure sensor nt working..

well i did mentioned about that when i went to shop, he says that is not likely so, but did not give me a reason as to why did he nt check.. sigh...

 

but really power no loss, i guess it brings it down to the oil pressure thingy..

 

thanks a million for narrowing it down ahpek.. great help..

 

 

Always welcome. Should thank tng2377 (just a few post back) too for the description of how Vtec in S4 works and his conclusion as to what may be faulty in his last sentence..which is generally the same as what I suspect. I believe it was somewhat accidentally meddled or mishandle during the clutch change.

 

I don't think it would be a overnite job but may be a few hours. Have to let the shop know and see what they say before over handling the bike. I'll check see around my area here and see if anyone can do it.

[Ah Pek]

hi

 

i am facing a minor problem here, i want to take out my crashbar so that i can sand it and spray a new colour as the paint have already dropped. but the right side crashbar cannot be taken out cos its blocked by the engine casing as circled.

http://i46.photobucket.com/albums/f128/inflames85/crashbarscrew.jpg

how do i remove this screw and nut?

thanks..

 

Looks like its a bolt and the head is under the other side. You would need to piece of the similar tools..looks like size 10 or 12 to me. First have to get to the bolt head from the under side..a 180 degree shivel type box wrench should do the job and for the top (as shown in the pic), you need a "ring" spanner (preferred) or a "C" spanner to hold it in place while you turn the other side...or either way. Spray some WD40 or anything similar before doing so as that area are always expose to water and grits etc..and tend to be very tightly 'jammed'.

[9073]

hi all,i'm new here and needed some advise from all the experience pple out there with REVO...

 

Recently i have this problem...

 

1) when changing gear,pull out the clutch,the engine stop & when let go the clutch,engine will restart.

 

2) when i start the bike the rpm stands @ below 1 and now fuel consumption is high...

 

3) black smoke seems to come out & strong petrol smell.

 

4) now i can't restart as per normal,i have to push start.

 

this is a new bike which i have not made any changes yet....

anyone can plse assist urgently ....

 

Rgds

9073.

[sadxjr]

At least yours started but some ppl are unfortunate. There is someone here from this forum got such problem and ended up not starting at all along Bedok North in the early hours just past mid nite sometime back. I did what I said earlier and all was well.

 

 

 

>>airbox to carbs intake flush cleaning? care to elaborate more?

 

Its a process where you spray in circular action a solvent specifically formulated to quickly and easily remove gums, sludge, varnish and dirt build up in the carbs caused by carburetor deposit.

 

You have to have a 'special tool' to insert into the 4 carbs thru its inlet via the airbox. I have done it only to non vtec..not sure about vtec bikes air box intake system but should be able to.

 

Save you a $70 job for carbs washing for only $10. Does just a good job without having to dismantle the carbs and unscrewing all the components afterall when you start and blow..all 'shits' will be exhausted out. You want you can call it "Carbs Servicing"..

 

This is usually done because the flaps are not fully open as we hardly use the choke..and there are bound to be clogs of gums, sludge, varnish and dirt build up in the links and area around it.

 

alright. thanks ah pek for your help/info! i will see if the problems get better first.

[ah_xian]

as u say its a new bike, send it back to agent [boon siew, if agent bike] PI then back to the shop where u bought your bike if still under warranty.

[dragonforce]

Looks like its a bolt and the head is under the other side. You would need to piece of the similar tools..looks like size 10 or 12 to me. First have to get to the bolt head from the under side..a 180 degree shivel type box wrench should do the job and for the top (as shown in the pic), you need a "ring" spanner (preferred) or a "C" spanner to hold it in place while you turn the other side...or either way. Spray some WD40 or anything similar before doing so as that area are always expose to water and grits etc..and tend to be very tightly 'jammed'.

thanks ah pek.. problem solved already, it was easier than i thought.. its actually it U shaped metal holding both the bolts, loosen both then can push the U metal down and unscrew the nut..

[slutgarden]

Always welcome. Should thank tng2377 (just a few post back) too for the description of how Vtec in S4 works and his conclusion as to what may be faulty in his last sentence..which is generally the same as what I suspect. I believe it was somewhat accidentally meddled or mishandle during the clutch change.

 

I don't think it would be a overnite job but may be a few hours. Have to let the shop know and see what they say before over handling the bike. I'll check see around my area here and see if anyone can do it.

 

oh yes, credits to tng2377, i did not do so, because i did not knw how to multi quote.

[Eray]

hi all,i'm new here and needed some advise from all the experience pple out there with REVO...

 

Recently i have this problem...

 

1) when changing gear,pull out the clutch,the engine stop & when let go the clutch,engine will restart.

 

2) when i start the bike the rpm stands @ below 1 and now fuel consumption is high...

 

3) black smoke seems to come out & strong petrol smell.

 

4) now i can't restart as per normal,i have to push start.

 

this is a new bike which i have not made any changes yet....

anyone can plse assist urgently ....

 

Rgds

9073.

 

this is a trottle senor problem.. i had this problem during Jan.. bring to boon siew n ask them to fix it..

[loyjwe]

just now went returning home, was turning into TPE exit to sengkang and going upslope, den car infront stopped so need slow down. i clutched in to let it roll upslope, den suddenly realise the low oil pressure light is on and rpm is 0!! lucky there was no car behind mi i quickly crank again and luckily can start, so moved on(i already step down to 1st gear). was think if any1 got any clue wats the reason for this? coz i find if this happens it can be very dangerous. any1 thanks

[Ah Pek]

just now went returning home, was turning into TPE exit to sengkang and going upslope, den car infront stopped so need slow down. i clutched in to let it roll upslope, den suddenly realise the low oil pressure light is on and rpm is 0!! lucky there was no car behind mi i quickly crank again and luckily can start, so moved on(i already step down to 1st gear). was think if any1 got any clue wats the reason for this? coz i find if this happens it can be very dangerous. any1 thanks

 

Even if you didn't crank to start..letting off the clutch would give a kick start too. How often does this happened or is it just this once? Likely wiring problem or clutch switch glitches...ever kena oso but problem go away by itself.

[loyjwe]

really ar i didnt know if let go lutch also can but im on 1st gear so clutch is in.

yesterday happened 1st time but scare will happen again. will monitor this

hope it go away by itself.

 

thanks pek

[Ah Pek]

really ar i didnt know if let go lutch also can but im on 1st gear so clutch is in.

yesterday happened 1st time but scare will happen again. will monitor this

hope it go away by itself.

 

thanks pek

 

No..do it on second gear, 1st gear is to hush. If down slope, 3rd gear. If this method does not work, its definitely your wiring problem like the "kill switch" wire.

[bryan_LaZY]

just now went returning home, was turning into TPE exit to sengkang and going upslope, den car infront stopped so need slow down. i clutched in to let it roll upslope, den suddenly realise the low oil pressure light is on and rpm is 0!! lucky there was no car behind mi i quickly crank again and luckily can start, so moved on(i already step down to 1st gear). was think if any1 got any clue wats the reason for this? coz i find if this happens it can be very dangerous. any1 thanks

 

Seems like ur bike idle til die off... just let it roll in gear 2, shld be able to push start.

 

happen to me b4, early morning when gg to work. Cos late liao, so no time to warm up.... happen only when my bike didnt warm up enough.