Throttle Revving to 4k Revs!

[AlexClarke]

Hi I previously owned a zxr 400 L8 model about 3 years ago and sold after an accident and bought a zx636r. I wanted to get myself a project bike for the winter so bought myself a H1 model needs alot of cosmetic work. However I took it out the other day and when stopping at junctions it will sometime rev down to 4k revs then stay there for a while then return to 1.5k revs at idle even when the throttle is completely shut. This also happens by slightly turning the throttle, the revs shoot up to 4-5k then after a little while calm down. Above this level i can rev the bike normally then comes down to 4k revs. This does not occur all the time probably every 2 in 3 times.

When starting the bike up from cold runs fine and idles well at about 1.5k revs. Only when touching the throttle will it shoot up to 4k revs.

Could this be down to the throttle cable?

[noodleface]

air leak around the carb rubbers, or a too-rich pilot system.

when its cold do you need choke to start the bike, if the answer is no you are probably rich on the pilot system, this excess of fuel as the bike gets hot causes the revs to rise as the bike gets hot.

if its not an air leak try turning your pilot air jets 1/4 turn counterclockwise and see if that makes any difference to how it fires up in the cold, or how the revs hang when coming to idle.

-nf

[AlexClarke]

Hi no afraid not. I do need to hold the choke on to start the bike up. If i don't the bike will idle very low then cut out. This revs up to about 6/7k when on. Unfortunately the revs build up to 4k when the bike is cold and also warm just from a slight turn of the throttle.

[KwakKwak]

Could this be down to the throttle cable?

Throttle cables, deccelerate on mine was set up badly, it basically didn't, worth a try.

[AlexClarke]

Ok well im gonna be checking out the carbs aswell as the throttle cables tomorrow. Should be something simple.

[KwakKwak]

and bought a zx636r.

Discuss

2013???
Please tell me it's crap Contrary to every opinion I've checked thus far.

[cargo]

Should be something simple.

Clearly you've not searched the forum............................


Probably one of the most discussed and argued topics ever seen on ZXR world.................perhaps second only to de-restricting.

[AlexClarke]

and bought a zx636r.

Discuss

2013???
Please tell me it's crap Contrary to every opinion I've checked thus far.

No no no 2004 636 lol. dont think i could deal with a 2013. ive heard they are crap

[ross46]

did you sort this out? had similar problems a few times when not putting stuff back together properly when i first got the bike. as has been said before, check the throttle cables are lubed, the return cable is adjusted right, that the mixture is set up properly, symptoms sound like a lean mixture to me as the revs hanging is a classic symptom of that. and check for air leaks, i also had a problem with a set of carbs i rebuilt that the idle was too high even with the idle adjuster removed turns out that the carbs had been balance by an idiot and where held open by the balancing screws rather than the idle adjuster, also i had to replace the vacuum hoses where you attach the guages as their was a leak. why do they have these hoses in the first place? on other bikes they have just had screws put in with copper washers to seal?

[KwakKwak]

turns out that the carbs had been balance by an idiot

This fooker seems to get about, according to this forum the giraffe is everywhere

I reckon you've solved Cargo's most discussed subject ever here, tenner says he's hiding in that zoo, or some dodgy figure offering a derestricting service. Be on the lookout, a shady looking long necked man with two humps who knows ZXRs well, be warned, after all these years we're onto you.
He'd obviously rejetted my carbs on your side of the water, idiot wouldn't dare come over here though, his nemesis lies in wait.

[ross46]

i was fucking confused when i started the bike and it revved to 8000rpm!, backed the idle adjuster off... same thing. i took them back off as i had just put new seals in and thought i must have done something wrong! then when checking i noticed the butterflys werent open evenly, so checked my other set... all butterflies closed without idle adjuster in, so closed them all up with the screws, put them back on and wahey! sorted, felt very proud of myself if only electrics were as easy...

[AlexClarke]

I hope he aint been messing with this one aswell then Didnt get a chance to look at it last night so looks like a weekend job to strip. Ill keep my eyes open for any split pipes and also strip the carbs down to check these are okay. Cheers for the info.

[ross46]

My money is on lean mixture personally, take a note of how many turns the mixture screws are out

[AlexClarke]

Hi Guys

Finally got round to taking it apart. First of all took the tank off to find that the fuel was still coming out when off. See images below for as there was a nice chunk missing between the reserve and the outlet port so petrol was always coming out of the tank when in the off position.




After replacing the seals in the tap and refitting it I then took off the air filter box off to gain access to the carbs. As soon as I took the bolts out of the carbs and removed the main part of the airbox I could instantly see something wrong with the airbox but I am unsure what affect this would have on the running of bike.


Looks as tho the rubber joint that goes into the carbs have been melted!!

Any ideas Guys? I will be stripped the carbs down shortly to see what everything has been set up to and how everything looks.

[AlexClarke]

Awaiting for admin to approve the images then I can upload the larger versions.